H Class JK-Ui Book.. CojpglitN CQHRIGHT DEPOSIT. THE A^O AMERICAN TEXT-BOOK OF OPERATIVE DENTISTRY IN CONTRIBUTIONS BY EMINENT AUTHORITIES. EDITED BY EDWARD C. KIRK, D.D.S., Professor of Clinical Dentistry in the University of Pennsylvania, Philadelphia; Editor of "The Dental Cosmos;" Officier de l'Academie de France. THIRD EDITION, REVISED AND ENLARGED. ILLUSTRATED WITH 875 ENGRAVINGS. LEA BROTHERS & CO., PHILADELPHIA AND NEW YORK. 1905 CLof THE LIBRARY OF i OONORESS. Two OcDHes ttertelved ' OCT. 18 i905 ; / 3L90 &' OOP Entered according to Act of Congress in the year 1905, by LEA BROTHERS & CO., in the Office of the Librarian of Congress, at Washington. All rights reserved. WESTCOTT & THOMSON, EUECTROTYPERS, PHILAOA. WITH THE CONSENT OF THE CONTRIBUTORS THIS BOOK IS DEDICATED TO JAMES TRUMAN, D.D.S., THE CHARACTERISTIC OF WHOSE LONG PROFESSIONAL CAREER HAS BEEN THE INCULCATION OF THE PRINCIPLES UPON WHICH THE WORK IS BASED. PREFACE TO THE THIRD EDITION. The early exhaustion of the second edition of this work has afforded opportunity for its complete revision, the results of which are now pre- sented in a third edition. The excellent chapter on Dental Embryology, by Dr. R. R. Andrews, has been omitted because the growth of that subject and, indeed, of all that pertains to dental anatomy and histology has compelled the retention in this work of only those special anatomical features which are directly applicable to the elucidation of dental oper- ative procedures. The number of excellent treatises now exclusively devoted to dental embryology and histology makes it no longer neces- sary to include the general treatment of these topics in a work strictly devoted to Operative Dentistry. As new matter, there has been added to this edition a chapter upon the Use of the Matrix in Filling Operations, by Dr. Crenshaw, which, it is confidently expected, will prove to be an addition valuable and helpful to teachers as well as to students. The section on Orthodontia has been treated anew, from the stand- point of occlusion as the scientific basis from which this important departure should be studied. With the cordial consent of the late Dr. Clark L. Goddard, the treatment of the subject of orthodontia was committed to Dr. E. H. Angle, the chief exponent of the modern trend of thought upon ortho- dontia as a problem of occlusion. The text of each chapter has been carefully revised by its author, with the exception of those originally written by the late Dr. H. H. Burchard, whose work has been revised by the Editor. It is due to each of the contributors to state that the Editor is respon- sible for the terminology used throughout the work. In assuming this responsibility the terms upon which divergence of opinion was found to be greatest were " canine " and "cuspid," "bicuspid" and "premolar," " maxilla " and " upper," or " superior, jaw," " mandible " and " lower," or " inferior, jaw," " approximal " and " proximal." In each instance the 8 PREFACE TO THE THIRD EDITION. term which seemed to be most in harmony with the trend of good scien- tific usage was adopted, regardless of the preferences of individual writers, in order to avoid confusion and to secure that harmony of treat- ment so necessary in a text-book for the use of undergraduate students. The Editor records his sense of deep personal loss in the death of Dr. Clark L. Goddard, whose rare attainments, both as a man and as a dental teacher, could ill be spared from the ranks of contributors to the literature of dentistry. The thanks of the Editor are heartily accorded to his associate, Dr. Julio Endelman, for his painstaking work in the preparation of the new and copious index for this edition ; to many colleagues for helpful suggestions ; to the contributors for their cordial co-operation in the revision of the work, and especially to the large body of dental teachers, whose practical use of the work in the instruction of their classes is the most satisfactory commendation of its usefulness as a text-book. The present edition is issued in the confident hope that the work will, in even greater degree, merit the approval which has been so gen- erously accorded to its predecessors. E. C. K. Philadelphia, 1905. LIST OF CONTRIBUTORS. EDWARD H. ANGLE, M. D., D. D. S., President of the Angle School of Orthodontia, St. Louis, Mo. HENRY H. BURCHARD, M. D., D. D. S., Late Special Lecturer on Dental Pathology and Therapeutics, Philadelphia Dental College, Philadelphia. CALVIN S. CASE, M. D., D. D. S., Professor of Orthodontia, Chicago College of Dental Surgery, Chicago, 111. DWIGHT M. CLAPP, D. M. D., Clinical Lecturer on Operative Dentistry, Dental Department, Harvard University, Boston, Mass. WILLIAM CRENSHAW, D. D. S., Dean and Professor of Operative Dentistry and Dental Pathology, Atlanta Dental College, Atlanta. M. H. CRYER, M. D, D. D. S., Assistant Professor of Oral Surgery in the University of Pennsylvania, Philadelphia. EDWIN T. DARBY, M. D., D. D. S., Professor of Operative Dentistry and Dental Histology in the University of Penn- sylvania, Philadelphia. C. L. GODDARD, D. D. S., Professor of Orthodontia, L'niversity of California, College of Dentistry, San Francisco, Cal. S. H. GUILFORD, A. M., D. D. S., Ph.D., Professor of Operative and Prosthetic Dentistry and Dean of the Philadelphia Dental College, Philadelphia. JOSEPH B. HEAD, D. D. S., M. D., Philadelphia. 10 LIST OF CONTRIBUTORS. LOUIS JACK, D.D.S., Philadelphia. EDWARD C. KIKK, D. D. S., Sc. D., Professor of Clinical Dentistry and Dean of the Department of Dentistry in the University of Pennsylvania, Philadelphia; Officier de l'Academie de France. FREDERICK B. NOYES, B. A., D. D. S., Professor of Dental Histology in the Northwestern University Dental School, Chicago, 111. LOUIS OTTOFY, D. D. S., Professor of Clinical Therapeutics, Chicago College of Dental Surgery, Chicago ; Attending Dental Surgeon St. Luke's Hospital, Manila, P. I. C. N. PEIRCE, D. D. S., ' Professor of Dental Physiology, Dental Pathology, and Operative Dentistry, and Dean of the Pennsylvania College of Dental Surgery, Philadelphia. Lecturer on Nitrous Oxid, Department of Dentistry, University of Pennsylvania, Philadelphia. ALTON HOWARD THOMPSON, D. D. S., Professor of Dental Anatomy, Kansas City Dental College, Kansas City, Mo. JAMES TRUMAN, D. D. S., Professor of Dental Pathology, Therapeutics, and Materia Medica in the Uni versity of Pennsylvania, Philadelphia. CONTENTS. CHAPTER I. PAGE MACKOSCOPIC ANATOMY OF HUMAN TEETH 17 By Alton Howard Thompson, D. D. S. CHAPTER II. DENTAL HISTOLOGY WITH REFERENCE TO OPERATIVE DENTISTRY 53 By Fredrick B. No yes, B. A., D. D. S. CHAPTER III. ANTISEPSIS IN DENTISTRY 117 By James Truman, D. D. S. CHAPTER IV. THE EXAMINATION OF TEETH PRELIMINARY TO OPERATION- METHODS, INSTRUMENTS, APPLIANCES— RECORDING RESULTS, ETC 133 By Louis Jack, D. D. S. CHAPTER V. PRELIMINARY PREPARATION OF THE TEETH— REMOVAL OF DE- POSITS AND CLEANING OF THE TEETH— WEDGING— OTHER METHODS OF SECURING SEPARATION— EXPOSURE OF CERA'I- CAL MARGINS BY SLOW PRESSURE, ETC 141 By Louis Jack, D. D. S. CHAPTER VI. PRELIMINARY PREPARATION OF CAVITIES— TREATMENT OF HY- PERSENSITIVE DENTINE BY SEDATIVES, OBTUNDENTS, LOCAL AND GENERAL ANESTHETICS— STERILIZATION, WITH A BRIEF CONSIDERATION OF THE PHYSIOLOGICAL AND THERAPEUTICAL ACTION OF THE MEDICAMENTS USED 149 By Louis Jack, D. D. S. 11 12 CONTENTS. CHAPTER VII. PAGE PREPARATION OF CAVITIES— OPENING THE CAVITY— REMOVING THE DECAY — SHAPING THE CAVITY - CLASSIFICATION OF CAVITIES 175 By S. H. Guilford, A. M., D. D. S., Ph. D. CHAPTER VIII. EXCLUSION OF MOISTURE— EJECTION OF THE SALIVA— APPLICA- TION OF THE DAM IN SIMPLE CASES, AND IN SPECIAL CASES PRESENTING DIFFICULT COMPLICATIONS— NAPKINS AND OTHER METHODS FOR SECURING DRYNESS 199 By Louis Jack, D. D. S. CHAPTER IX. THE SELECTION OF FILLING MATERIALS WITH REFERENCE TO CHARACTER OF TOOTH-STRUCTURE, VARIOUS ORAL CONDI- TIONS AND LOCATIONS, DEPTH OF CAVITY, AND PROXIMITY OF THE PULP— CAVITY LINING WITH ITS PURPOSES 209 By Louis Jack, D. D. S. CHAPTER X. TREATMENT OF FILLINGS WITH RESPECT TO CONTOUR, AND THE RELATION OF CONTOUR TO PRESERVATION OF THE INTEG- RITY OF APPROXIMAL SURFACES 221 By S. H. Guilford, D. D. S ,, Ph. D. CHAPTER XL THE OPERATION OF FILLING CAVITIES WITH METALLIC FOILS AND THEIR SEVERAL MODIFICATIONS 227 By Edwin T. Darby, D. D. S., M. D. CHAPTER XII. USE OF THE MATRIX IN FILLING OPERATIONS 261 By William Crenshaw, D. D. S. CHAPTER XIII. PLASTIC FILLING MATERIALS-THEIR PROPERTIES, USES, AND MANIPULATION 289 By Henry H. Burchard, M. D., D. D. S. CONTENTS. 13 CHAPTER XIV. PAGF COMBINATION FILLINGS 329 By Dwight M. Clapp, D. M. D. CHAPTER XV. RESTOKATION OF TEETH BY CEMENTED INLAYS 353 By Joseph Head, D. D. S. M. CHAPTER XVI. THE CONSERVATIVE TREATMENT OF THE DENTAL PULP— DEVI- TALIZATION AND EXTIRPATION OF THE PULP 385 By Louis Jack, D. D. S. CHAPTER XVII. THE TREATMENT AND FILLING OF ROOT CANALS 413 By Henry H. Burchakd, M. D., D. 1). 8. CHAPTER XVIII. DENTO-ALVEOLAR ABSCESS 467 By Henry H. Burchard, M. D., D. D. 8. CHAPTER XIX. PYORRHEA ALVEOLARIS 493 By C. H. Peirce, D. D. S. CHAPTER XX. DISCOLORED TEETH AND THEIR TREATMENT 523 By Edward C. Kirk, D. D. S. CHAPTER XXI. EXTRACTION OF TEETH 549 By M. H. Cryer, M. D., D. D. S. CHAPTER XXI {Continued). EXTRACTION OF TEETH UNDER NITROUS OXIDE ANESTHESIA . . 621 By J. D. Thomas, D. D. S. 14 <<> STENTS. CHAPTER XXI {Concluded). PAGE LOCAL ANESTHETICS AND TOOTH EXTRACTION 631 By Henry H. Burchard, M. D., D. 1). S. CHAPTER XXII. PLANTATION OF TEETH 639 By Louis Ottofy, D. 1). S. CHAPTER XXIII. MANAGEMENT OF DECIDUOUS TEETH 657 By Clark Goddard, A. M., D. D. S. CHAPTER XXIV. ORTHODONTIA 677 By Edward H. Angle, M. L>., D. D. S. CHAPTER XXV. THE DEVELOPMENT OF ESTHETIC FACIAL CONTOURS 849 By Calvin S. Case, D. D. S., M. D. INTRODUCTORY. A study of the advances which have of recent years taken place in the field of Operative Dentistry will reveal, besides the important addi- tions to our knowledge in the shape of novel methods and improved technique, a vastly more important advance manifested in a better and more general understanding of scientific principles, and the application of dental science to dental art, resulting in a more rational practice. Especially is this true in regard to the etiology of dental and oral pathological conditions, and the rationale of the modes of treatment indicated for the morbid states constantly confronting the dental practitioner. The modifications in surgical methods and the greatly improved results which are the outgrowth of modern scientific studies in bacterial pathology, while they have made a considerable impress upon dental operative methods, have not, however, received that universal practical acceptance among dental operators which their immense importance demands. There is no field of special surgery in which the import- ance of exact knowledge with respect to aseptic and antiseptic treat- ment is more marked than in the practice of dentistry. The dental operator is continually confronted with septic conditions, so that pre- cise knowledge of their origin, causes, phenomena, and treatment are essentials to the legitimate practice of the profession. The performance of any operation, and especially those which are classified as capital, with unclean hands or infected instruments would in the present stage of surgical art be regarded as criminal malpractice. It should be so considered in dentistry. The loss of a patient's life as the result of surgical septic infection is no longer permissible. Lack of antiseptic precautions in certain dental operations may directly lead to and as a matter of fact has been the cause of fatal results. It has been shown conclusively ! that a large variety of pathogenic micro- organisms are almost constant inhabitants of the oral cavity. In addi- tion to the numerous forms which bring about an acid reaction, there are many specific organisms which produce in inoculated animals pyemia and septicemia in their several clinical classes. But while the dental practitioner is not often called upon to face the issues of life 1 W. D. Miller, Dental Cosmos, November, 1891. 15 1 6 INTROD UCTOR Y. and death in the course of his work, his responsibilities as related to the issues with which he does deal demand of him the same care and thoroughness in order to attain the character of result which the pos- sibilities of modern dentistry require of him. In the following pages the importance of asepsis and antisepsis in dental operations is con- stantly impressed upon the mind of the student. By the term asepsis is specifically meant the condition under which are excluded those influences or causes which induce infection by patho- genic micro-organisms ; when a tissue or surface has been rendered germ-free it is said to be in an aseptic condition. By antisepsis is meant the means by which the septic state is combated or the aseptic state is attained. Under the aseptic condition repair of tissues takes place normally without interference, wounds and injuries heal with a minimum of dis- turbance, and the inflammatory concomitant is of the simple traumatic type, Avithout suppuration or tendency to diffusion. The aseptic state, in many operations in the mouth, is not readily attainable and cannot be maintained for any length of time ; but in all operations which involve the pulp and pulp chamber, as well as the periapical region through the pulp canals of teeth, strict aseptic con- ditions, as regards external infection, are perfectly attainable through exclusion of the oral secretions by means of rubber dam, the use of suitable disinfectants, and sterilized instruments. It is the class of operations here alluded to which are most prolific of disturbance from infective inflammations caused by ignorant or careless manipulation. The time is at hand, if indeed it has not already arrived, when puru- lent inflammations following dental treatment will be regarded with the same condemnation by the dentist as by the general surgeon. The operative section of this work is written in full recognition of the prin- ciples here indicated. OPERATIVE DENTISTRY. CHAPTER I. MACROSCOPIC ANATOMY OF THE HUMAN TEETH. By Alton Howard Thompson, D. D. S. 1. Definition. — The teeth are properly defined as hard, calcareous bodies situated in that portion of the alimentary canal near the ante- rior or oral extremity. In man they are confined to the oral cavity and are supported by the maxillary bones only. In the lower verte- brates they may be scattered over all of the bones and cartilages sur- rounding the mouth. 2. Function. — The main function of the teeth is the mechanical sub- division of substances used for food, preparatory to their digestion ; these organs therefore belong to the alimentary system. The elements of their function are prehension, incising, crushing, mastication, and insali- vation. For the performance of these various offices, different forms of teeth are found in the denture of man. In lower animals food-habit induces the evolution of many various and extreme forms of the teeth. The secondary offices of the teeth in man are as adjuncts in vocal- ization and articulate speech ; they also bear an esthetic relation to the mouth and face. Fig. 1. The formatiou of single teeth from the single cone and its repetition in complex teeth. 3. Mechanical Design. — All tooth forms are evolved by modification from a simple cone, which is the primitive, typal form. The teeth of fishes and reptiles are but simple cones, and those of higher mammals are modifications of the single cone or combinations of two or more cones 2 17 18 MACROSCOPIC ANATOMY OF THE HUMAN TEETH. fused together. Thus in man the incisors are formed of a single cone, the base of which is compressed to form the wide cutting edge (Fig. 1, a). The canine or cuspid is a single cone, the base of which is com- pressed into a trihedral point, or pointed pyramid (b). The bicuspids are composed of two cones fused together, the forms of the cones being quite distinct the entire length of the tooth, as in the upper bicuspids (c). The typal upper molar is formed by the addition of the third cone to the bicuspid form, as plainly noticed in the three roots and the primitive three cusps (d). The usual quadricuspid form is made by the addition of a cingule. The lower molar consists of four cones, which may be plainly distinguished by an analysis of its elements (e). Each cone in the structure of a tooth is surmounted by a cusp or tubercle. Extra cusps above the number of primary cones are but cingules or undeveloped cusps. In the genesis of tooth forms, therefore, the complex teeth, as the bicuspids and molars, are formed by the repetition and addition of cones and their accompanying cusps, both laterally and longitudinally of the jaw. 4. The Dental Arch. — The teeth of man are arranged around the margins of the upper and lower jaws in close contact, and have no Fig. 2. Square. Rounded Square. Bounded. The main types of the dental arch. Rounded V. interspaces between them. The basal arch is a graceful parabolic curve, with some variations which lead from the round arch to the incomplete parallelogram or even to a well-defined V shape. These variations may be classified as follows : First : The square arch (Fig. 2, a). This is found usually in persons of strong osseous organization, of Scotch or Irish descent — i. e. of Gaelic extraction — and is probably derived in the first instance from a dolichocephalic people. The squareness is more or less dependent upon the prominence of the large canines, which stand out very markedly at the angles of the square. The incisors present a flat front and project slightly, with little or no curve of the incisive line. The bicuspids and molars fall backward from the canines with no per- ceptible curve. The two sides are quite parallel, but sometimes there may be a slight divergence toward the cheek at the rear. This is the low form of arch which appears in the apes and some low races. THE OCCLUSION OF THE TEETH. 19 Second : The rounded square (Fig. 2, b). This is the medium arch and is the form usually met with in ordinary, well-developed ro- bust Americans. The canines seem to be only so prominent as to give character to the arch without a resemblance to the arches of the lower animals. The incisors are vertical and the line curves slightly from one canine to the other. The bicuspid-and-molar line curves slightly outward from the canine and converges at the rear. Third : The rounded arch (Fig. 2, c). This is the circular or "horse-shoe" arch. It is nearly semicircular, the ends curving in- ward at the rear, the outlines of the arch tracing a decided horse-shoe shape. The canines are reduced to the level of the arch, so that there is no prominence of these teeth. The bicuspids and molars follow the line of the curve. This arch is quite characteristic in some races, as the brachycephalic South Germans. Fourth : The rounded V (Fig. 2, d). In this form the round arch is constricted in front or narrowed so that the incisors mark a small curve whose apex is the centre. It is the arch of beauty and is that most admired in women of the Latin races. These are but the basal forms of the dental arch. Ordinarily, mod- ifications of these types occur in all degrees ; it is the variations, the composites, which are most met w T ith in dental practice. 5. The Occlusion of the Teeth. — The upper teeth describe the seg- ment of a circle larger than that of the lower teeth ; so that the edges of the anterior teeth above close over those below, and the buccal cusps of the grinding teeth above close outside of the buccal cusps of the lower teeth (Fig. 3). By this arrangement the buccal cusps of the lower grinders are received into the de- pressions or sulci between the buccal and lingual rows of the cusps and tubercles of the upper molars and bicuspids, and the lingual cusps of the upper grinders are received into the sulci of the lower grinders. By this arrangement the whole of the morsal surfaces of these teeth are brought into contact in the several move- ments of mastication, thereby rendering the performance of this function more effective. Then, again, the upper incisors usually close over the lower for one-third of their length. This allows of the shearing action by which the incisive func- tion is performed as the edges of these teeth are drawn past each other. The line of the horizon of occlusion (Fig. 4, A-B) presents a decided Incisor Fig. 3. Bicmpids. Molars. The relative position of the upper and lower teeth in occlusion. 20 MACROSCOPIC ANATOMY OF THE HUMAN TEETH. curve from front to rear, of greater or less degree in different forms of the arch. Tims it is high at the incisors, curving downward at the bicus- pids, reaching its lowest point at the first molar ; it curves upward rap- idly at the second molar, and is highest, again, at the third. In the rounded arch the plane is more flattened, and it exhibits the extreme Fig. 4. The horizon of the line of occlusion and plane of occlusion. downward curve in the square arch. Between these extremes there is of course every variety of modification. The form of the plane of occlusion is shown in Fig. 4, C. Fig. 5. The apposition of the upper and lower teeth. The tendency of the bolus of food is toward the lowest part of the curve at the region of the lower first molar, so that the extraction of this tooth always affects the performance of mastication. In the apposition of the teeth of the opposite jaws the mechanical THE OCCLUSION OF THE TEETH 21 arrangement is such that the dynamics of mastication is subserved and the greatest effectiveness secured (Fig. 5). Thus the morsal sur- face of the upper central incisor is opposed to all of that of the cen- tral incisor below and to the mesial half of the lateral ; the upper lat- eral opposes the distal half of the lateral below and the mesial face of the canine ; the upper canine, the distal half of the face of the lower canine and the mesial half of the first bicuspid ; the upper first bicuspid opposes the distal half of the lower first bicuspid and the mesial half of the second ; the upper second bicuspid opposes the distal half of the lower second bicuspid and part of the lower first molar : the upper first molar opposes the distal part of the lower first molar and the me- sial half of the second ; the upper second molar opposes the distal half of the lower second and part of the third ; and the upper third covers the remainder of the lower third molar. By this method of apposition the teeth are so arranged that two teeth receive the impact of half of two of the opposite jaw, thus distributing the force of occlusion and ensuring the safety and strength of the teeth. This " break-joint " arrangement permits each tooth to bear two opposing ones, and also helps to preserve the alignment. Fig. 6. Incisors. Canines or Premolars or cuspids. Bicuspids. Molars. The classes of the teeth, comprising the left half of a full denture. Then again, if one tooth be lost, the opposing teeth still rest against two teeth, one at each side of the space. The normal condition of the articulation is rarely preserved, however, as mutilation usually dis- turbs it ; the teeth move on account of the force of occlusion, and effec- tive mastication is more or less destroyed. 22 MACROSCOPIC ANATOMY OF THE HUMAN TEETH 6. Number and Classes of the Teeth. — Man has thirty-two teeth, divided into four classes, viz. — (1st) incisors, (2d) canines or cuspids, (3d) premolars or bicuspids, and (4th) molars (Fig. 6). This is expressed by the dental formula as follows : . 2—2 1—1 ,. 2 — 2 3 — 3 00 i. , c. , ox. -, m. == 32. 2-2' 1 — 1' 2—2' 3 — 3 (1) The incisors are eight in number, four above and four below, — two on each side of the median line. The two next to the median line are called the central incisors, the ones next to them distally, the lat- eral incisws. (2) The canines are four in number, two above and two below, — one on each side immediately approximating the lateral incisor on the distal side. (3) The bicuspids are eight in number, four above and four below, — two on each side approximating the canines on the distal side. The first of these next the canine is called the first bicuspid, the one next to it on the distal side the second bicuspid. The same designa- tion applies to both upper and lower bicuspids. (4) The molars are twelve in number, three on each side of each jaw, approximating the second bicuspid on the distal side. The molar next to the second bicuspid, both above and below, is called the first molar ; the next one distally is called the second molar ; the next one distally, and the last tooth in the jaw, is called the third molar or " wisdom tooth " {dens sapiential). Functionally, the incisors are formed for cutting, as their name im- plies ; the canines for prehension and tearing (for which purpose this tooth in lower animal forms is often excessively developed). It also serves in guiding the bite. The bicuspids are the crushing teeth, and the molars are formed for grinding, triturating and insalivating the food. The Incisors. 7. The Upper Central Incisor. — This is the first tooth in the den- tal series in man. It is situated in the front of the mouth, next to the centre of the arch, which is the mesial border of the intermaxillary bone. In adult man these bones fuse with the anterior borders of the right and left superior maxillary bones. Their junction with each other marks the centre of the dental arch. The general form is that of a truncated cone with its base ^flattened out to form the cutting edge. Its function is to cut or incise food, hence its name from the Lat. incisus, " to cut into." THE INCISORS. 23 The mechanical structure of the crown is a matter. of importance. It will be observed that it consists of several elements : first, a broad cut- ting blade (Fig. 7, a) supported by two strong lateral columns (6) on each side, and that these columns are upheld by two strong marginal The mechanical design of the crown of the upper central incisor : a, the blade ; b, the two columns supporting the blade ; c, the marginal ridges acting as guys, brac- ing the columns ; d, the basal ridge as the base of attachment for the guys. d f Diagram of the labial face of the upper central incisor. ridges (c) leading up from the lower ridge (d). These ridges are but- tresses, which guy and uphold the columns which contain and carry the blade. Hence, when these ridges are destroyed by caries or in operating, the support of the column is lost and the blade readily breaks away. The form of the crown is spade-like, or a compressed-wedge shape, the edge being quite thin and the thickness increasing rapidly to the base. It is slightly bent toward the lingual side, or much curled over in some cases. The labial face is imperfectly square or oblong, the cervical margin being rounded (Fig. 8, a). It is convex from side to side, but only slightly so from cervix to edge. Two shallow depressions or furrows extend the length of the face perpendicularly (b) dividing it into thirds, called lobes, — the mesial, (c), median (d) and distal lobes (e). These furrows and lobes are quite conspicuous when the tooth is erupted, but are abraded by age and the wear of use and denti- frices, until the face becomes smooth. The mesial margin is a little longer than the distal so that the cutting edge slopes upward toward the distal side (/). The lingual face is smaller than the labial, being on the inner and smaller curve of the crown, and is narrower from side to side (Fig. 9). It is triangular in outline, being wide at the edge and narrow and rounded at the base or cervix. The marginal ridges (a) are high and conspicuous, and extend from the basal ridge to the edge on the Diagram of the lingual face of the upper central in- cisor. 24 MACROSCOPIC ANATOMY OF THE HUMAN TEETH mesial and distal margins of this surface. The basal ridge (6) is a strong elevation continuous with the marginal ridges at the base of the crown. It is sometimes developed into a raised cusp, the ridge at the base of which forms a cingulum. A ridge or lobe (c) extends from the basal ridge to the centre of the edge, uniting with the median lobe from the labial face to form the median tubercle. A depression or fossa (d) is found on each side of the median lobe between it and the marginal ridges, or, when the lobe is low or entirely absent, these fossae may be continuous. A fault or fissure at its junction with the basal ridge forms the seat of caries in teeth of low structure. The mesial face (Fig. 10) is a rather long triangle in shape, with a concaved base at the cervix of the tooth (a), and a long point toward the edge. It is nearly straight in a longitudinal direction, but rounded and convex transversely. It is longer than the distal face, the edge descend- ing in that direction. The enamel line dips downward into this face, and there is a de- Mesiai. Distal. 9 pression above it (b) which sometimes extends The mesial and distal faces and upward on the root. The point of contact edge of the upper central in- . . . cisor. with the opposing tooth is near the cutting edge. The distal face is also triangular in outline (Fig. 10) but it is more curved in the longitudinal axis, so that this surface is convex in all directions. It is most curved in the transverse direction. The enamel dips downward into the surface (df), as in the mesial, but there is not so much of a depression above this line. The point of contact is one-third of the distance from the angle (e). The edge, or morsal margin, of the crown is formed by the com- pression of the top of the truncated primitive cone. It is quite wide and square except at the distal corner, which is rounded. The angle with the mesial face is acute (Fig. 10, /). When the tooth is first erupted, the edge has three prominent tubercles (g), which correspond to the ridges on the labial and lingual faces. These are soon worn off with use, so that the edge usually looks straight. The pitch of the edge is toward the median line. The neck of the central incisor is a rounded pear-shape in outline, the labial half being wider (Fig. 11, a) than the lingual. There is not much constriction of the tooth at the neck. The enamel edge curves upward on the root on the labial and lingual sides, and dips down- ward on the mesial and distal faces. It terminates abruptly on all sides, especially on the lingual, where a considerable ridge is some- times raised (Fig. 10, c). THE INCISORS. 25 Fig. 11. The root of the upper cen- tral incisor. The root is cone-shaped and tapering (Fig. 11, b). The rounded pear-shaped section continues almost to the end. The pulp chamber is spacious and open, and of the general form of the tooth (a and c). The radi- cal portion of the canal gives free access, but the flattened coronal portion is difficult to cleanse. In young teeth the cornua or horns of the pulp may project far toward the angles (c). 8. The Lateral Incisor. — This tooth approxi- mates the central incisor on its distal side, and is also implanted in the intermaxillary bone. It is of similar spade-like form and of the same architectural design as the central, modified by the distal half being more rounded in every direc- tion. As the crown is narrower than the central, the destruction of the marginal ridges on the lingual face weakens the edge still more, so that it breaks off more easily. The crown is narrower in the mesio- distal diameter than the central, but, still almost as wide labio-lingually, the relative difference of thickness in the two directions is more ap- parent. The tooth has the appearance of being compressed mesio- distally. The thickness increases rapidly from the edge to the neck (Fig. 12, b). Fig. 12. B C D The upper lateral incisor. The labial face (Fig. 12, C) is more rounded than that of the cen- tral. It is half incisor and half canine (a), the mesial half toward the central incisor resembling that tooth (6), and the distal half toward the canine resembling it (c). The mesial angle* of the edge is quite acute, while the distal angle is rounded and obtuse. The three lobes may be well developed, similar to those on the central incisor, but are usually indistinct, although the central ridge is prominent. The lingual face (Fig. 12, D) is much depressed, but less concave than that of the central incisor. The marginal (d) and basal ridges (e) are quite prominent. The basal ridge is often raised into a prominent cingule or talon, an exaggerated example of which is shown in Fig. 13, which is a revival of the basal talon found in the lower quadrumana, — and the insectivora. This cingule occurs more frequently on the lateral 26 MACROSCOPIC ANATOMY OF THE HUM AS TEETH. incisor than on any other of the anterior teeth. The depression above it is often the location of a fault, a fissure or pit, which be- comes the seat of caries. The basal ridge is sometimes cut by a fissure which leads down quite upon the neck of the tooth (Fig. 12,/). Sometimes the entire surface is full and rounded without any concavity whatever. The mesial face (g) is of triangular form similar « to that of the central incisor. It is rounded toward the edge labio-lingually, but flattened at the neck, with a depression at the enamel line which leads Showing unusual develop- . ment of the cinguie or upward upon the root. Ihe labial angle is sorne- hasai talon on an incisor. timeg the geat of a depression (h), which gives the (From case reported hy Dr. r \ /> o w. h. Mitchell, Dental Cos- angle a hook shape. The depression varies in mo,,vol.xxxiv.p.l036.) ^^ and depth &nd may becQme the geat Q f caries. The point of contact with the central incisor is at the junction of the lower with the middle third of the length of the face. The distal face is more convex in all directions and resembles the canine in form, being in harmony with the general form of the distal half of that tooth. From cervix to edge it is rounded and the contact eminence in the middle third is very full (i). From this point it rounds off rapidly to the edge. The upper third is depressed rapidly toward the cervix, with a considerable depression at the enamel line leading off to the distal groove on the root. The edge is divided into two portions by the prominent tubercle (j) in the middle which terminates the prominent central ridge of the labial face. The mesial half is straight, like that of the central. When worn, these features disappear and the edge becomes almost straight. The pitch of the edge, like that of the central, is toward the median line. The neck is much flattened mesio-distally, and is of a compressed pear shape, or flattened oval on section. The enamel margin pursues the same course as on the central incisor, rounding upward toward the root on the labial and lingual sides and dipping downward on the distal and mesial. It does not terminate so abruptly as that of the central incisor, and presents less of a ridge at the gingival margin. The root is commonly longer than that of the central incisor, is narrower, flattened mesio-distally (Fig. 12, A, B). It tapers gradually, not rapidly like the root of the central incisor. It is a flattened oval on section (e). Sometimes there is a hook at the end, curved distally. Grooves sometimes occur on the mesial and distal sides. The pulp canal is flattened in conformity to the shape of the root, but is readily entered if the root be straight. THE INCISORS. 27 The lateral incisor is very irregular as to form, presenting various degrees of deformity or abnormality, and may sometimes be reduced to a mere peg. It is also erratic as to eruption, being sometimes sup- pressed, not appearing for several generations of a family. It follows the third molar in the frequency of its irregularities both as to form and frequency of non-eruption. The third incisor of the primitive typal mammal sometimes reap- pears in man, and is known as a supernumerary. It rarely assumes the proper incisor form and position in the arch, but usually erupts within the arch and is a mere pointed-peg-shaped tooth. 9. The Lower Incisors. — These are most conveniently described as a group, as they are very similar in form, having but slight variations between the central and lateral incisors to be noted. They are located in the anterior portion of the lower jaw, upon each side of the median line, opposite the incisors above. Their function is the same as that of the upper incisors, the cutting of food, which they per- form by opposing the upper. The lower central opposes only the cen- tral above ; the lateral, both the upper central and lateral incisors. The lower central incisor is the smallest tooth in the dental series. It is of spade-like form (Fig. 14), the crown being a double wedge shape (a, b). The first wedge (a) is observed on viewing the crown from the front, the widest portion being at the morsal edge and the point at the cervix. The second wedge is observed from the side (b), the widest part being at the neck and the point at the morsal edge of the crown. The edge is thin, but the labio-lingual diameter increases rapidly to the cervix, which is the . , . . The lower incisor. widest part. I he crown is widest mesio-distally at the edge, but diminishes to the neck, which is scarcely more than half the width of the edge. The tooth cone is therefore compressed in one direction at the edge, and in another at the cervix. The mechanical elements are the same as those of the upper central, but with the parts less strongly marked. The labial face is a long wedge shape («), the widest part at the edge and narrowing to the cervix. It is usually straight, or nearly so, longitudinally, and straight across the edge, but round and con- vex at the neck and the cervical half. Sometimes vertical ridges are found on these teeth when they are first erupted, but these soon wear off. The lingual face is depressed and concave from edge to cervix (c), but less so from side to side. The marginal ridges are often well 28 MACROSCOPIC ANATOMY OF THE HUMAN TEETH. marked. In the lateral incisor the fossa is often more marked and the marginal ridges more distinct. The mesial and distal sides are of wedge-like form, straight from edge to cervix and widening in the same direction. A depression runs across the neck just above the enamel line. The neck is much compressed disto-mesially, and the root partakes of this flattening through its entire length. The section presents a compressed oval (e). The enamel line dips downward on the labial and lingual sides, and curves upward on the mesial and distal, in a manner characteristic of the incisors. The edge is perfectly straight from side to side, after the three tuber- cles, found when first erupted, are worn off. The root is flattened like the neck, and frequently a groove runs the entire length on the mesial and distal sides. Occasionally complete bifurcation results, which recalls the form of this tooth found in lower animals. The pulp canal (e) is of similar form to the root, and is flattened and thin, so that it is often difficult to effect an entrance to it with instruments. The lateral is similar in form to the central incisor, but is wider at the edge and the distal corner of the edge is slightly rounded (d). In all other features it resembles the central incisor. The Canines or Cuspids. 10. The Upper Canine. — This is the third tooth from the median line and approximates the lateral incisor on its distal side. It is the first tooth posterior to the intermaxillary suture and is imbedded in the maxilla proper. It is commonly said to form the spring of the arch, and conveys the impression of great strength, as is indicated by its strong implantation. It is more strongly implanted, and by a longer and larger root, than any of the other teeth. Zoologically it is the largest tooth in the dental series, but in man is much reduced from its prototype, the larger carnassial canine of lower animals, especially the carnivora. It is the principal prehensile tooth, and is therefore first in order of function in the dental series. The canine in man preserves the typal form, for its mechanical structure is still that of a single cone, brought to a point (Fig. 15, a). This is the earliest form of teeth found in the lower verte- brates, the fishes and reptiles, which present only simple conical teeth in all parts of the jaw. It has an older history than any other tooth, and still bears the marks of the many changes through which it has passed in the course of its evolution. THE CANINES OR CUSPIDS. 29 The crown has a spear-head shape (6), hence the name, cuspid, by which this tooth is frequently designated, from the Lat. cuspis, " point, pointed end." It is constructed essentially for piercing and tearing. The central cusp or point is braced in all directions.; the edges leading up to it both mesially and distal ly (which serve for cutting as well), the Fig. 15. The upper canine. strong labial ridge coming downward from the cervix (c) to the median ridge leading up on the lingual surface (d), all support it in the office of prehension and the laceration of flesh. The labial face (b) presents the outlines of the spear shape, more or less rounded in different cases. Starting from the well-defined cusp just in front of the central axis of the tooth, it widens sharply for about one-third of its length, whence it narrows gradually to the gum line, which is fully rounded. In some cases the mesial and distal angles are rounded and the outlines are more of a leaf shape (e). The surface is slightly rounded mesio-distally, so that the sides slope roundly or flatly away from the central ridge. This ridge descends from the middle of the cervical margin, curving slightly forward and then backward to the point of the cusp (c). This curve recalls the curving shape of this tooth in the Felidse. It is usually a sharp, prominent ridge, but may be reduced and rounded so as to be scarcely perceptible. The three lobes of the surface are imperfectly marked, — the central ridge dominating and dwarfing the lateral ones. The lateral furrows on each side of the central ridge separating it from the lateral lobes are more or less marked, especially toward the edge. Wear reduces in time the prom- inence of the lobes and ridges and obliterates the furrows. The Ungual face is of similar spear shape (d), but is more flat. It is rarely concave. The thickness of the crown increases gradually to the lateral prominences, which gives a blade-like edge, then rapidly to the shoulder at the base. A strong vertical ridge extends from the cusp to the basal ridge (d), with a slight concave depression on each side. The basal ridge is well marked and sometimes develops into a cingule, more or less marked. The marginal ridges lead up on each 30 MACROSCOPIC ANATOMY OF THE HUMAN TEETH. side only so far as the lateral protuberances. They are not strongly marked as a rule. The fossae on each side of the vertical median ridge, between it and the marginal ridges, may be quite deep but are usually shallow and ill defined. The mesial face in outline is not unlike the central incisor, but its contour is very different, for it is more or less rounded in all direc- tions, and the lateral eminence in the lesser third makes this part espe- cially full (i). From this point the surface is depressed roundly to the enamel line at the neck, where a depression of greater or less depth is found. It is somewhat flattened at the cervix. The point of contact is at the eminence, which touches the lateral incisor. The distal face is of similar form to the mesial, except that it is more full and the eminence more pronounced, which gives the increased width of the crown on that side. The surface descends rapidly toward the neck and is rounded labio-lingually. The point of contact with the first bi- cuspid is on the lateral protuberance. The morsal edge presents a prominent cusp which is almost central to the long axis of the tooth. The side facets slope away, but still retain their cutting edge (b). The distal side of the edge is longer than the mesial, by reason of the increased size of the distal protuberant angle. The sharp point is soon worn off to a rounded cusp, and, as wear increases with age, it may be reduced to a straight surface between the mesial and distal protuberances (g). The neck is a flattened oval on section, or the lateral direction of the labial portion may be greater than that of the lingual (A). The enamel line preserves the same curves as on the incisors, i. e. rounding upward on the labial and lingual surfaces and dipping downward on the mesial and distal. The enamel terminates gradually with but a slight ridge, unless it should be on the lingual side. A depression occurs on both mesial and distal sides above the curve, which may lead up as a groove on the root, The root is longer than that of any other tooth, and it is at least one-third larger than that of the central incisor. It is of a rounded trihedral form, or irregularly conical. It is usually straight, and tapers to a slender point, which may be curved or very crooked. In well- arranged dentures, where it has erupted naturally, it is usually straight. The root canal is large and open, of the same form as the tooth, and easily entered. It is regularly formed except in those cases where the root is curved, and even in these it can be filled if not too crooked, as it is so open and accessible. 11. The Lower Canine. — This is similar to the upper in form and outline, except that it is somewhat smaller, more slender, and more rounded in form (Fig. 16, a). It differs also in being more compressed THE CANINES OR CUSPIDS. 31 mesio-distally and in being flattened in the neck and root. The crown "leans backward on the root so that the mesial face is almost straight the entire length of root and crown. It forms the spring of the lower arch, and is strongly built to oppose the strong upper canine in the act of prehension and tearing. It opposes the mesial surface of the canine above and the distal surface of the upper lateral incisor. a be The lower canine. The labial face is a long oval (a), the cusp being blunt and the neck rounded while the mesial side (c) is flattened. The lobes are indistinct and the central ridge rounded from side to side. The entire face is in- clined inward to accommodate the occlusion. The crown in many cases presents the appearance of being blunt toward the distal side. The lingual face (6) is flat, sometimes cup-shaped, and the marginal ridges are not prominent. The central ridge sometimes stands out strongly. The basal ridge is weak and is rarely developed into a cingule. The crown increases gradually in thickness from the point to the neck. The morsal surface presents a mere rounded eminence ; the cusp may be sharp in childhood, but usually it is soon reduced by wear. Some- times it remains sharp and prominent. The lateral edges are not devel- oped, but are mere ridges leading down to the lateral faces, which are not prominent, except the distal (d), which is often full. The mesial face is quite flat, and straight with that face of the root. The eminence is not marked. It is rounded only at the eminence, but flattened at the cervical third (c). The distal face has the most prominent eminence (d), the crown being bent in that direction. The cervical third of this face is flat. It descends rapidly from the eminence. The neck is usually oval (/) or, when compressed, spindle-shaped upon section (g), being depressed on the mesial and distal sides at the origin of the grooves running up on the root. The enamel line is not so variable as on the incisor, but more nearly on a level on all four aspects. 32 MACROSCOPIC ANATOMY OF THE HUMAN TEETH. The root is long, flattened, and tapering (a, 6, c). It is shorter than that of the upper canine. It is grooved on the mesial and distal sides, — so much so as to tend toward bifurcation. This, indeed, sometimes hap- pens in man, thereby recalling the form usual to the primates and some other lower animals. The root canal is of the same general form as the root, often pre- senting the spindle shape on section. It is somewhat difficult to enter on account of its flattened shape and narrowed channel. The Bicuspids. 12. The Upper Bicuspids. — The upper bicuspid is formed by duplica- tion of the primitive cone and cusp in a transverse direction (Fig. 17, a). Viewed from the standpoint of com- J " '* ~ parative dental anatomy, the external I \ I \ (^mk/ b 1 \ cone * s ^ e can ^ ne cone — an d to this is / \ ' l ^Pf | I f% added the internal or bicuspid cone, the V \ b \^^ ( i/d ^M tooth being a double canine. The bi- I ) /lpp% ( s\ cuspids are the first of the complex vV "piijlf /^jr \ teeth. The internal cusp is formed a be foy fo e ra i s i n or f the inner primitive The upper bicuspids. J #» i • i -i i cusp of the canine and the develop- ment of a root to support it. The distinctive feature of the architec- ture, therefore, is its formation from two cones, and this makes it a weak tooth as regards its mechanical structure and resistance to mas- tication, for the binding of the bases of the cones and cusps depends upon the connecting power of the two marginal ridges (6, b), and when these are destroyed the cones readily part and split off. The bicuspids in man are homologous with the premolars of the quadrumana and other lower mammals. They succeed and displace the molars or grinders of the deciduous set. They are placed next after the canines in both jaws, and midway between the cutting and grinding teeth. Their function is the crushing of food preparatory to mastication. The upper first bicuspid approximates the canine on the distal side. The buccal face (c) is of spear-head shape, similar to that of the canine. This is more apparent in some lower mammals than in man, in whom it is much reduced and rounded, so as to give usually the appear- ance of a long, rounded oval. The buccal cusp (c) rises sharply and prominently from the lower centre of the face, from which a strong ridge (d) leads up to the cervical border. The mesial and distal lobes (e, e) are rarely conspicuous, and the furrows between them and the central ridge lead but half way up the crown. The lobes sometimes have prominent points at the morsal margins which in lower mammals become pro- THE BICUSPIDS. 33 nounced cingules. The buccal marginal ridges descend from the points of the cusp to the points of the lateral lobes. The distal ridge is usually longer than the mesial. The cervical border is rounded and oval from side to side. The lingual face (/) is full and rounded, more or less straight perpen- dicularly and rounded mesio-distally. It is convex in both directions. The lingual cusp rises over it full, but is blunt and round ; the mar- ginal ridges are rounded, not angular, and curve sharply round to meet the mesial and distal marginal ridges. The mesial face (Fig. 18, g) is wide and flat transversely, full at the morsal surface at the marginal ridge, which is prominent, and de- scending flat to the cervix, where a depression (h) occurs which ex- FlG - 18, tends well up the face. The distal face is of similar form, but is rather more convex and the portion at the marginal ridge more prominent. The de- pression from the root does not extend so far up on the face. The morsal surface shows an abrupt change from that of the canine next to it, as it presents two distinct cusps or points instead of one. One cusp is on the buccal margin (j) of the crown, and one on the lingual (&), and they are named the buccal and lingual cusps. The buccal cusp is sharp and prominent, and is not unlike the single canine cusp. The lingual cusp is broader and more rounded — indeed it is preferable to term it a tubercle. The outline of the morsal surface is imperfectly quadrate and is bor- dered by well-marked marginal ridges, named as follows : The mesial marginal ridge (7), bordering the mesial face of the crown ; the distal marginal ridge on the distal side (m), the buccal marginal ridges (n) descending from the point of the buccal cusp to meet the buc- cal terminations of the distal and mesial marginal ridges at the angle formed by the junction with the buccal lateral lobes (o), and the lingual marginal ridges (_p), descending from the lingual tubercle to meet the lingual termination of the mesial and distal marginal ridges. The triangular ridges descend from the cusps toward the centre of the tooth and unite at the central groove. In defective teeth they do not fuse, leaving a fault or fissure which becomes the seat of caries. This groove or sulcus extends from one lateral marginal ridge to the other mesio-distally (r) and widens into the mesial and distal sulci at each end. The triangular grooves (s) run from the mesial and distal sulci toward the mesial and distal angles, dividing the marginal ridges 34 MACROSCOPIC ANATOMY OF THE HUMAN TEETH. from the triangular. They also become the seat of caries in imperfectly formed teeth. The neck of the first bicuspid is compressed or spindle-shaped (t) 9 the enamel line rising on the buccal and lingual sides and dipping down on the mesial and distal. The enamel margin tapers off gradually on to the root. A wide, deep depression usually occurs (u) on the mesial side of the neck, leading to the groove on the root. On the distal face this is not so well marked. . The root is much flattened mesio-distally, with a decided groove ex- tending up both sides. This grooving tends to cause bifurcation of the root, which actually occurs in one-third of the cases, especially in persons of strong build. This bifurcation is a persistent relic of lower forms of the premolars, as in the apes. The root canal is flat at the neck, and nearly always bifurcated, even when the root is not separated. This is readily seen by holding a bicus- pid having one root, up to the light, when the central portion will be ob- served to be translucent. The usual bifurcation necessitates the search for both canals in every case in treating this tooth. The upper second bicuspid (w) approximates the first on the distal side, and is similar to it in every way, except that it is usually smaller and more rounded in all directions. The sharp features, conspicuous ridges, etc. are not so strongly marked. The cusps are reduced, the ridges more rounded, and the morsal face more flattened, and it is often wrinkled. The triangular ridges are more likely to be united, thus making the crown stronger. The crown is thinner mesio-distally. The neck is more rounded or oval. A most conspicuous difference is in the root, which is narrower labio- lingually, is more rounded, and is rarely bifurcated. It is sometimes cylindrical or cubical in form. It is disposed to be turned, and is often crooked. The root canal is single and readily entered. 13. The Lower Bicuspids. — These are placed next after the lower canines on the distal side. In form they are not truly bicuspid, for the first is unicuspid and the second is tricuspid in the pure typal forms ; but they are arbitrarily termed bicuspids on account of their position as compared with the upper bicuspids, which are typically bicuspid. The architectural form of these teeth is that of the single cone, the crown being augmented in various directions by the addition of cin- gules to the primitive cusp. The lower first bicuspid is a well-formed transitional tooth, for it grades from canine to bicuspid and is typically composite. It more closely resembles a canine than a bicuspid in its usual form, because the inner cusp is almost suppressed and is rarely as large as the outer one (Fig. 19, a). In fact, it looks like a canine with a cingule raised THE BICUSPIDS. 35 upon its inner face. This cusp is really a cingule, for it is rarely raised to the full height of a cusp. It varies much in size from a mere point on the basal ridge (6) on through various degrees of development, up to a full cusp as large as the buccal cusp, when the tooth becomes a true bicuspid. The tooth is therefore essentially a primitive unicuspid premolar, of the form of this tooth in some of the lower primates. The buccal face (c) is caniniform, or a long oval in outline with the cusp rising as an abrupt point above it. The angle of the junc- tion of the marginal ridges may stand out prominently. The face The lower first bicuspid. curves markedly toward the lingual side, so that the buccal cusp becomes central to the long axis of the tooth (a). The cervical border is rounded at its margin and convex from side to side. The lobes are not marked. The lingual face (d) is convex from side to side and straight vertically, but is not perpendicular, as it is directed toward the lingual side. Its height depends upon the height of the lingual cingule, which varies from a mere buccal ridge through various degrees up to the full-sized cusp. The mesial and distal surfaces are of similar form, convex from side to side (a, 6) slightly flattened at the cervical border and flaring out to meet the full marginal ridges, which are round and prominent. The prominence of these ridges and the inward inclination of the lingual face gives the crown a decided bell shape, tapering to the neck (d). The morsal surface (e) is peculiar and differs from every other tooth in its great variability and the extremes which it may present, from being a full bicuspid to a mere canine. This face is nearly circular in outline, the widening of the lateral surfaces by the spreading of the marginal ridges (/, /) adding to the width. The buccal cusp (g) is large and prominent, and is also drawn toward the centre of the tooth to accommodate the occlusion. Sometimes it is high and sharp when the lingual cusp is reduced, and is low and blunt when the latter is en- larged, — appearing to have an inverse ratio in size to the inner cusp. The lingual tubercle or cingule varies much in size, from a mere point on the basal ridge, above the cervical border, to a pronounced cingule, a larger cingule, a small cusp, then a full cusp, the basal ridge (h) 36 MACROSCOPIC ANATOMY OF THE HUMAN TEETH being raised with it. The ridges are the mesial and distal marginal ridges (i, l), which are bowed out round and full and are always pro- nounced ; the buccal marginal ridges (/, /), leading down from the buc- cal cusp to form an angle with the mesial and distal marginal ridges ; the basal ridge, when the lingual cingule is lowered (6) ; and the tri- angular ridge of the buccal cusp, which is always large and when the inner tubercle is reduced leads down as a high central eminence. The lingual cingule, as a rule, possesses no triangular ridge. The central groove usually crosses the central ridge (k), but not always, being often bowed around its lower termination. Sometimes the ridge is crossed by a sulcus. The groove terminates in a sulcus at each end, with slight triangular grooves branching up on the buccal cusp. The neck is usually oval on section, being much constricted, the crown flaring upward from the cervical portion, giving the crown the well- known bell shape. The enamel line dips but slightly, being usually level on all four sides. The buccal border sometimes presents a prom- inent ridge. The root is single, long, tapering and may be nearly round, but is usually flattened mesio-distally. It is sometimes thick the greater part of its length, and terminates in an abrupt, round, blunt apex (c, d). It is very liable to be crooked. It is rarely bifurcated and does not pre- sent grooves on its lateral faces. The pulp canal is constricted and flattened at the neck, and the back- ward inclination of the teeth makes it difficult to enter. The possibility of the root being crooked and the peculiarity of its anatomical rela- tionships x also increase the uncertainty of treatment, which makes the root canals of the lower bicuspids difficult to deal with. The lower second bicuspid approximates the first on its distal side. It resembles the first as regards the general form of Fig. 20. ^he crown, its tapering bell shape, the constriction of the neck, and the shape of the root. In all these features there is little difference between these teeth, and the description of the first will apply also to the second bicuspid. The morsal surface (Fig. 20), however, differs very materially from that of the first. This is circular in The morsal surface of outline like the first, and the buccal cusp is full and the lower second bi- , .. , N , , , , • t • i i 1 cuspid . rounded (a), but the inner cusp is divided by a groove (b) running over it, into two parts, so that it is really divided into two tubercles. This makes the lower second bicuspid in its typal form a tricuspid tooth ; so that it differs from the lower first, which has but one cusp, and from the others, which have but two cusps. The 1 See page 606, Chapter XXI., on Extraction of Teeth. THE MOLARS. 37 lingual tubercles vary much in size, so that one may be suppressed and the tooth seem bicuspid. The mesial lingual tubercle (c) may be of large size and be developed at the expense of the distal (d) ; this may be a mere cingule on the distal marginal ridge and appear on the distal side, but it is always present. The morsal groove (e) is triangular in design, passing between each of the three tubercles. A well-marked triangular ridge descends from each of the cusps. The tricuspid form of the morsal surface of this tooth is, of course, a reproduction of the trituberculate premolars of the lower primates, and of still lower mammals, although the triangular form of the crown is lost in man. The Molaes. 14. The Tuberculate Teeth. — Molar teeth appear early in the scale of vertebrate life ; mere crushing teeth are found in fishes, and slightly tuberculate teeth in the reptiles. The grinders are of simple form in the lowest mammals. The Bruta have simple, flat-crowned molars, which are undifferentiated and used merely for crushing. Tuberculate molars appeared early in the placental mammalia, the trituberculate molars being found in numerous fossil species, which are the typal form and forerunners of the tuberculate molars in the higher mammalia. The simple-crowned tooth with a single tubercle (haplodont, Cope), becomes duplicated and doubled, with a crown supporting several tubercles (bunodont). The transition from simple to complex teeth is accomplished by the repeti- tion of the type in different directions and the addition of cusps and roots both laterally and longitudinally of the jaw. The upper molar is formed by the addition of the third cusp to the bicuspid type and has three roots, which support three or four tubercles. Lower molars con- sist of four cones which support four or five tubercles. The lower mo- lar is therefore the more complex tooth. The bicuspid is more complex than the canine, the upper molar than the bicuspid, the lower than the upper molar. The molar teeth of man are bunodont in form, i. e. they have simple rounded tubercles on the grinding face. They are of simple and primi- tive type, and indeed are most like the molars of the bears and other omnivorous animals. They are not highly specialized like those of the carnivora on the one hand with high sharp blades for cutting flesh, nor like those of the herbivora on the other, which are extended laterally for grinding tough vegetable fibre. They are of low organization as regards their functional development. The molars in man are twelve in number, three on each side of each jaw, and are placed at the rear of the arch, opposite the strong triturat- 38 MACROSCOPIC ANATOMY OF THE HUMAN TEETH. ing muscles, for the purpose of crushing and masticating food. They are important factors in alimentation and contribute to the function of digestion by preparing food for the stomach. Their loss impairs this function seriously and leads to derangement of the stomach by over-tax- ing it with imperfectly masticated food-substances. 15. The Upper Molar. — The typical upper molar is formed by the fusion of three cones, as is plainly observed in the three roots and the three tubercles (Fig. 21, A). The tricuspid molar, therefore, is a primi- tive form, and is occasionally seen in man, the normal form being quadri- tuberculate. The fourth additional cusp, the disto-lingual (6), is merely a supplemental cusp added to the crown. An upper molar is, there- fore, composed of three tubercles, and a cingule which has not yet developed a root to support it. The trituberculate molar is the primitive form of this tooth, the quadrituberculate appearing later, and is found in only a few living forms, as some of the lemurs and the insectivorous and carnivorous mammalia. In man there is sometimes a reversion of the upper molar to the trituberculate form, which is a marked degeneracy in the form of this tooth. In an analysis of this tooth, therefore, the mesio-buccal tubercle (c) is the canine cusp ; the mesio-lingual, the bicus- pid cusp (d) ; the disto-buccal, the molar cusp (e), and the disto-lingual is but a supplemental cusp, — it is not a true cusp, as it has no root to support it. The architecture of the upper molar presents some interesting features. We observe that the crown is in a general way a geometrical form, a cube (/), when perfect and symmetrical. It is suggestive of symmetry, but when taken with the root form is not quite perfect, for it is sup- ported on three roots instead of four to correspond with the four tuber- cles at the four corners. So it lacks the " harmony of adequate sup- port," which is a cardinal principle in architecture. But the crown separately is a symmetrical form, a cube, although the angles are rounded off and the corners and points are toned down and not acute. We no- tice that there are four strong columns, one at each of the four corners (g). They are connected on the four sides by the marginal ridges acting as strong connecting arches (A). These arches are related to the col- umns of the crown, and both are impressively proportioned. The cusps may be likened to the capitals of the columns, and the descending mar- ginal and triangular ridges to the cornice, gathered together to form the capitals. The triangular ridges may be considered girders (i), bind- ing the four together and also bracing the square obliquely. Or, the four triangular ridges running to the centre may be regarded as half- ardies or buttresses, supporting the roof vault, — the grinding face. Other elements could be marked out in an architectural study of the crown of this tooth, showing its beautiful design and symmetry. THE MOLARS. 39 The upper first molar approximates the second bicuspid on its distal side. There is a marked and abrupt change in form, as the molar has double the number of cusps of the bicuspid,— being formed like two bicuspids fused together. The four tubercles mean an extension of sur- face and a further adaptation to functional requirements. The crown is large and cubical in form, and more or less rounded. Fig. 21. d t g h i Architectural diagram. 1 s q The upper molar. The buccal face (K) is wide and rounded. It is twice the width of the bicuspids. It is broadest at the morsal margin, narrowing upward to the cervix, where it is widely rounded or arched. A vertical depression, the buccal groove (I), extends from the cervical border to the morsal margin, dividing the face into two oblong rounded eminences, the mesial and distal buccal lobes (m m). The lingual face (N) is more rounded than the buccal, the cervical por- tion being the most convex (o), the mesial and distal sides being depressed toward the single lingual root. The morsal half is divided by the lingual groove (q), which descends over the lingual marginal ridge be- tween two lobes, the mesial (r) and distal (_p), which are usually much rounded. The morsal half of the face curves toward the grinding sur- face. The mesial lobe sometimes presents the lingual cingule (s), a sort of fifth tubercle of greater or less size. A groove branches from the lingual groove and extends over, between the cingule and crown. The mesial face (T) is flat longitudinally, descending from the marginal ridge to the cervix in a nearly straight line. Bucco-lingually it is 40 MACROSCOPIC ANATOMY OF THE HUMAN TEETH. convex, nearly flat at the marginal i^dge, and rounded at the cervix, being depressed toward the lingual root. Sometimes a depression from the bifurcation of the mesio-buccal and lingual roots extends part way up on the face (u). The distal face is similar to the mesial except that it dips more toward the cervix, and is, perhaps, more rounded toward the lingual root. The morsal surface (Fig. 22) is the most important part of this tooth, and shows features that make it interesting and unique. The abrupt Fig. 22. :i f .i d h j c The morsal surface of the upper first molar. change from the bicuspid form is notable, for there are presented four cusps, a doubling of the number ; the outline of this face presents a square form with tubercles at each corner, the mesio-buccal (a), the disto-buccal (6), the mesio-lingual (c), and the disto-lingual (d) ; the lat- ter is erratic and may be either pronounced or quite reduced in size. There are four marginal ridges — the mesial (e), buccal (/), distal (g) lingual (h), the oblique (f), and the four triangular ridges (j). The oblique ridge connects the mesio-lingual with the disto-buccal tubercle and is really the remnant of the marginal ridge of the tricuspid molar ; the fourth cusp, the disto-lingual, being raised up on the disto-lingual side. The four triangular ridges descend from the four tubercles toward the centre of the tooth, the oblique ridge being formed by the fusion of the triangular ridges of the mesio-lingual and disto-buccal cusps. There are two fossae (k), one mesial and the other distal to the oblique ridge. Sometimes the latter is cut by a groove or sulcus (I) which extends from the mesial to the distal fossa. Sometimes by the reduction of the disto-lingual lobe and cusp, the mesial fossa is extended and becomes central to the crown. A groove extends from the mesial fossa over the buccal marginal ridge (m) quite on to the buccal face, dividing the mesial from the distal buccal lobes. A groove also extends over the lingual marginal ridge (n) down upon the lingual face, dividing the lingual lobes. When this groove becomes a fissure, caries ensues and the disto-lingual cingule readily breaks away, this cingule being a weak feature in the mechanical design of this tooth ; cutting the distal mar- ginal ridge also weakens this cusp. The triangular grooves branch from THE MOLARS. 41 the two fossae on to the cusps, dividing the triangular from the marginal ridges. The neck of this tooth is of rounded rhomboid form on section (o), widest at the buccal side. The enamel is almost level on all four sides, dipping downward slightly on the mesial and distal. A depression occurs at the bifurcation of the buccal roots, and an inward inclination on the mesial and distal sides. The roots are three in number (Fig. 21), two on the buccal side, which are small and flat or round, and one on the lingual side, which is large and rounded. The roots are usually separated, but may be found united, by a septum of cementum, in various directions. The mesio- buccal root is the larger of the two buccal roots, and forms a second turning-point or spring of the arch All the roots are slightly bent and may be very crooked. The pulp chamber branches into three canals, one in each root. The lingual canal is large and open and is readily entered. The canals of the two buccal roots are small and fine, and, with the possibility of crooked- ness in the roots, present the most difficult problems as to treating and filling found in the whole denture. The upper second molar is similar to the first in some respects but very different in others. It is rather smaller, is not usually full and square, but disposed to become rhomboid in form (Fig. 23, a, b), by disto-mesial compression. The buccal face is similar to that of the first molar, and the same description will apply to it. If any difference is found it is that the face is strongly com- pressed from front to back, and the disto- lingual cusp is more reduced as a con- stant feature. The lingual face (c) is different from % he ^ second molar. that of the first molar in that by the sup- pression of the disto-lingual tubercle (d) and the distal lobe, the mesio- lingual lobe is enlarged so that it occupies the entire face, which is full, rounded, and convex (e). It is rarely divided into two lobes as in the first molar, owing to the enlargement of the mesial lobe and the pushing backward of the oblique ridge, which throws the lingual groove on to the disto-lingual angle (d) ; or the groove may be absent altogether. The mesial and distal faces are similar in form to those of the first molar, being perhaps more flattened. The morsalface is similar to that of the first molar, except that the tubercles are less pronounced and the distal ones are reduced in height to accommodate the upward curve of the line of occlusion at this 42 MACROSCOPIC ANATOMY OF THE HUMAN TEETH. point. The disto-lingual cingule is smaller than that upon the first molar, and is often barely marked. This throws the oblique ridge more to the distal side and enlarges the mesial fossa. The various grooves are the same as on the first molar, except that one, the lingual, may be lost. The neck is less regular in outline than that of the first molar, as the crown varies so much in shape. It is more flattened mesio-distally and depressed toward the roots. The roots are the same in number and general form as in the first molar, but spread less and are more irregular in form. They may con- verge or be crooked, or may be fused together. This makes the pulp canals more difficult to treat. Sometimes the three roots are completely fused, as in the third molar, and the canals may coalesce ; or the canals of the two buccal roots may run into one. The irregularity and uncer- tainty of the form of the roots make this tooth difficult to deal with in treating its root canals. 16. The Lower Molars. — The lower first molar approximates the lower second bicuspid on its distal side. It is the first of the true grind- ers of the lower jaw and the largest tooth in the dental series. Unlike the upper molars the transverse diameter is less than the mesio-distal. The greater width is found across the base of the disto-buccal tubercle. The crown is square or trapezoidal in form, depending on the size of the fifth tubercle. Being quinquituberculate, the crown is broadened by the multicuspid grinding face. The buccal face is inclined toward the centre of the tooth, for its morsal half, to accommodate the occluding teeth. Architecturally, the tooth is formed of four cones (Fig. 24, J), and Architectural diagram. 9 f The lower first molar. may be roughly divided into four quarters. There are four primitive cones with their tubercles and one cingule in the structure. THE MOLARS. 43 The raorsal surface (2?) is trapezoidal in outline, the buccal line being the longest. The buccal angles are acute, while the lingual are rounded and obtuse. There are five tubercles, two on the lingual margin and three on the buccal. They are named the mesio-buccal (c), median buccal (d), disto- buccal (e) f disto-lingual (/), and mesio-lingual (g). These tubercles are less obtuse and more rounded than those of the other grinding teeth, the mesio-buccal usually being the largest, the others are not so prominent, rarely raised and sharp. The ridges are: the marginal ridges — buccal, distal, lingual, and mesial — and the five triangular ridges descending from the five tuber- cles toward the centre of the tooth. The grooves and sulci upon the morsal surface are very irregular. A deep sulcus traverses the face from the mesial to the distal marginal ridge. A groove runs off toward the lingual side, dividing the lingual cusps (i), sometimes cutting the lingual marginal ridge, but rarely reaching over on the lingual face. A groove runs toward the buccal side, dividing the mesio-buccal from the median tubercle (j), cutting the marginal ridge and extending over quite on to the buccal face. This groove often becomes the seat of caries owing to the enamel structure being faulty. Another groove extends toward the disto-buccal angle (k), dividing the median from the disto-buccal tubercle, and rarely extends over on to the buccal face. A groove may extend distally cutting the distal marginal ridge (I), and one mesially cutting the mesial marginal ridge (m), but these are not usually marked. The triangular groove run- ning up on each side of the triangular ridges (n) divides these from the marginal ridges. Supplemental grooves may divide the triangular ridges again. The pits at either end of the sulcus may become the seat of caries through faulty formation. The buccal face (C) is an irregular trapezoid in form, the morsal margin being longest ; the mesial and distal sides converge toward the cervical border, which is rounded. The morsal margin is broken by the three tubercles rising upon it. The buccal face is convex in all directions, that from the morsal to the cervical borders being the most marked owing to the morsal half converging toward the centre of the tooth. The buccal groove (o) leading over from the morsal face, divides the face into two lobes which are full and rounded. Sometimes the disto- buccal groove cuts off another lobe, thus making three lobes on the buccal face. These grooves sometimes lead to the cervical border, but usually terminate in the middle of the face in a pit, which may become the seat of caries through faulty formation of the enamel. The lingual face (D) is wide, rounded, smooth and convex, rather straight perpendicularly, leaning in the lingual direction. It forms a 44 MACROSCOPIC ANATOMY OF THE HUMAN TEETH sharp angle with the morsal surface, which is surmounted with two tubercles. Sometimes, but rarely, the lingual groove passes over on to this face. The mesial and distal faces (s) are wide and flattened transversely, but convex vertically. They are trapezoidal in outline, the morsal border being longer. The cervical border is more convex, and dips toward the neck of the tooth. The neck (t) is very regular in outline and contour. It is approxi- mately square with all four sides depressed in the centres. The mesial and distal are depressed at the origins of the grooves leading down upon the roots ; the lingual and buccal are depressed at the bifurca- tion of the roots, the depression, which is wide and deep, extending up on to the neck, especially upon the buccal side. The enamel line is quite irregular, dipping down on the lingual and buccal, and leading well up on the mesial and distal sides. The roots are two in number, placed with their longer diameter trans- versely to the jaw. They are wide bucco-lingually, and flat and narrow disto-mesially, being situated distally and mesially to the crown. The posterior is formed of the two posterior cones, and the anterior of the two anterior cones (A). This is plainly shown in the formation of the roots, which are grooved both distally and mesially, and in the tendency to bifurcation, which sometimes actually occurs. They divide close to the crown, so that the grooves of bifurcation extend well up on the neck. The distal root is thicker and more rounded than the mesial, the latter being more flattened, with the grooves deeper, and it is more often bifurcated. Both are deflected from the median line. The root canal is shaped like the roots, with two main branches. The distal branch is the larger, being round and open, as the root is more rounded. The mesial branch is flat and spindle-shaped, being difficult to enter, and usually having two sub-branches following the buccal and lingual divisions of the root. These sub-branches are small and hair- like and troublesome to enter. The lower second molar (Fig. 25) differs from the first in many respects. It is of the same general form, but is more quadrangular, as it has but four tubercles. It is more rounded and symmetrical than the first, the four cones and four primitive tubercles being well marked. The absence of the fifth tubercle leads to most of the differences between the second and the first molar. The morsal face (c) has but four tubercles, one at each corner of the face, differing from that of the first molar, which has five. The fifth tubercle rarely appears in the higher races of mankind, but is some- times found in the low and savage races, and occurs regularly in the apes. It is not uncommon in the negro, but is absent as a rule in THE MOLARS. 45 the European races. The tubercles are symmetrical, rounded and obtuse, the lingual being, however, sharper than the buccal. The sulci describe a cruciform shape, separating the four tubercles symmetrically from each other. The buccal groove sometimes continues on to the buccal face, rarely to the lingual. The triangular grooves run up on the morsal triangular ridges. The marginal ridges are well marked, the mesial and distal being often divided by grooves. The triangular ridges are usually well marked, leading to the centre of the tooth. They are full and strong. The buccal face (d) is convex and of more regular form than that of the first molar. It is divided into two lobes (e, e) by the buccal Fig. 25. h h The lower second molar. groove (d), which is rarely deep. A pit is often found in the centre of the face, which may become the seat of caries. The face is curved toward the centre of the tooth, as in the first molar. The lingual face is similar to that of the first molar, but may be more rounded toward the morsal border. It is symmetrically convex in both directions. The mesial and distal faces (/) are similar to those of the first molar except that, the crown being smaller, they may be more perpendicular, but are well rounded. The neck (g) is more regularly formed than that of the first molar, the margin of the enamel line being quite as irregular. It may be more constricted. The roots (h, h) are similar to those of the first molar, but are more rounded in shape, are usually crooked, and on that account difficult to treat. The root canals are similar to those of the first molar, but the tend- ency to crookedness renders treatment quite difficult. The direction of irregularity of form is so uncertain that no rule can be applied to it. 17. The* Third Molars. — The upper and lower third molars can best be described together, on account of their similar eccentricities. They are very irregular as to the time and to the frequency of their appearance in civilized man. About one-half of the individuals of European races 46 MACROSCOPIC ANATOMY OF THE HUMAN TEETH. erupt them at the normal period, i. e. seventeen to twenty-one years of age. In one-fourth they erupt at irregular intervals to the thirtieth year, and in the remainder they may appear later, or the first, seeond, third, or all of them, may be absent altogether. In one series of forty •adult skulls observed, twelve had one or more absent. The absence and other erratic peculiarities of these teeth sometimes seem to be hereditary and can be traced in families through several generations. This tooth is often reduced in size and may be a mere peg (Fig. 26, a). It is of very irregular form in civilized races, but is as large and as well formed as the other molars in most races low in the ethnological scale. The contraction of the jaws through disuse has much to do with the mal- development of this tooth, and it is often so cramped for room as to pro- duce distressing irritation which ne- The upper third molar. . . cessitates its removal. Impaction and malposition of the third molars render them difficult of extraction and are the fruitful source of many serious lesions. (See the chapter on Extraction of Teeth.) The upper third molar is more or less similar to the other upper molars when perfect and well developed, but it is very erratic as to form and structure. This tooth, when well formed, is of trituberculate form (b), the disto-lingual cingule being suppressed. This cingule diminishes grad- ually from the first molar, in which it is well formed, to the second, where it is reduced, then to the third, where it is almost or entirely absent. The oblique ridge thus becomes the posterior marginal ridge (c), as in the typical trituberculate molar. The three tubercles are reduced and rounded. The sulci usually degenerate into fissures, as the formation of this tooth is notoriously faulty. The enlarged mesial fissures thus become the seat of extensive caries. The buccal face resembles that of the first and second molars, but is more rounded. The lingual face (d) is full and rounded, with but a single lobe, owing to the reduction or absence of the disto-lingual tubercle. The mesial face (e) is similar to that of the second molar, but reduced, and the distal face is round and short, as no tooth succeeds it in the rear. The neck is constricted and tapers toward the conate roots. It is of a rather rounded triangular shape. The three roots of the upper molars are, in the third, usually more blunt, conate, short in form, and may curve backward. In lower races and sometimes in individuals having strong osseous organizations, the THE MOLARS. 47 The lower third molar. typical three molar roots are found. Sometimes there are multiple roots, which are likely to be curved in various directions and may have decided hooks. In the large conate root, the root canals usually coalesce, but in cases in which the root is divided there will also be division of the pulp chamber. The lower third molar is similar to the other lower molars in general form (Fig. 27, a), but is probably not so erratic and not subject to such extreme variations. The crown is quadrangular in section, the angles rounded. On the morsal face (6), there are four principal tubercles as in the second molar, but this may be supplemented by the ex- tension of the disto-marginal ridge into a cingule or heel (c). This heel is rather erratic ; it may be large or small, thus modifying the size of the morsal sur- face. Sometimes the face is wrinkled and, like this tooth in the orang utan, the sulci exhibit the cruciform shape similar to that of the second molar. The many grooves leading away from the main sulcus may be imperfect and become the seat of caries. The buccal groove running from the morsal on to the buccal face (a) is very subject to imperfection. The four lateral faces are similar to those of the second molar, except that the distal is more convex and full, and often very prominent if the fifth cingule is well developed. The neck is of similar shape to that of the second molar. The roots are similar to those of the other lower molars, but generally smaller as compared with the crown (d). They are usually divided like the others, but the two may be fused together, or be closely opposed. In either case they are usually projected distally more or less, leading backward into and under the ramus, thereby rendering extraction of this tooth difficult and dangerous, especially where the mandible is of Fig. 28. The fourth molar. dense structure or where there is impaction. The roots are usually more rounded, especially the distal one, than those of the other molars. The pulp canals are generally divided, whether the root is or not, 48 MACROSCOPIC ANATOMY OF THE HUMAN TEETH. As the roots are usually crooked, the difficulty of entering them is increased, as the canals follow the form of the roots. Fourth molars sometimes appear as supernumerary teeth, and are either fused to the upper third molar in a variety of uncouth forms (Fig. 28, a) or erupt separately as mere peg-shaped teeth between the buccal faces of the second and third molars (6) or at the distal aspect of the latter tooth. The fourth molar rarely appears as a full molar, except in some of the large-toothed races, as negroes, Australians, etc., and then usually in the lower jaw. Among the negroes in Africa the fourth molar is sometimes found in full form as a typical molar. Fig. 29. Negro jaw with fourth molar. The Deciduous Teeth. 18. The deciduous teeth are those which appear in infancy and serve the purpose of dental organs during the first years of the develop- ment of the individual, until the jaws and their environment are ready for the larger, permanent teeth to come into place. They bear a direct relationship to the conditions of the digestive apparatus and the food required at that early stage. The food of infancy being simple and requiring little mastication, the deciduous set are small and insufficient for the reduction of more resisting substances. As these foods come to form part of the dietary, the larger teeth of the permanent set appear, and perform the duties of higher functional activity. The crowns of the deciduous teeth resemble, in a general way, those of the permanent teeth which succeed them, except the deciduous molars (Fig. 30, a, d), which are very different from the bicuspids of the permanent set which displace them. The incisors of both jaws precede the analogous teeth of the same series of the permanent set. They are similar in form, but reduced (6), and do not have the main features so characteristically marked. They are infantile in form and function. The roots of these teeth are THE DECIDUOUS TEETH. 49 resorbed at from the fifth to the ninth year, when the permanent incisors come into place, beginning with the lower centrals. The canines (c) of both jaws are still more reduced from the strong, Fig. 30. The deciduous teeth. full form of their permanent successors, and are but little more specialized than the incisors. They are of the same general form as the permanent canines, but much less developed. But in the deciduous molars are found some important features which mark distinctive differences. They are of true molar form as compared with the permanent molars, but they occupy the place of the bicuspids. There are no bicuspids in the deciduous set, the molars being of full molar pattern (a, d). The deciduous molars of both jaws are of irregular, quadrangular form on the morsal surface, diverging rapidly outward to the neck, which presents a large buccal ridge standing out at the margin of the enamel, and is rounded off suddenly to the neck, which is much con- tracted. This thick ridge is characteristic of the deciduous molars and is absent in those of the permanent denture. It is somewhat more prominent and bulging on the buccal than on the other faces. In adjusting ferrule crowns to these teeth, the gold need not be carried beyond this ridge but burnished over it slightly. The morsal surface (e) of the upper deciduous grinders presents the characteristic pattern of the upper molars, four tubercles, oblique ridges, etc., but reduced and contracted. A distinctive feature is that the marginal ridges and angles are more acute and sharp than in the per- manent molars. Sometimes the two lingual cusps are reduced to one and the lingual border is rounded and crescentic. The second molar is larger than the first and the morsal surface is wider. 4 50 MACROSCOPIC ANATOMY OF THE HUMAN TEETH. The transverse diameter of the crowns of the upper molars is the longest. The lower molars (d) are similar to the permanent molars in pat- tern, but are more irregular as to the contour of the morsal surface (/). The tubercles may be higher than in the upper molars, and the tri- angular ridges more marked. The central fossa may be large and wide, or divided by the triangular ridges. The second molar is five-lobed, unlike the second permanent molar, which has but four cusps. The morsal face is decidedly trapezoidal in outline, the mesio-distal diameter being greater than the transverse. The roots of the deciduous molars are similar to those of the other molars, except that they are very divergent to accommodate the crown of the advancing bicuspids. They are thin and long, and difficult to enter and fill. The pulp chamber is large and open in the crown ; as a consequence of this caries soon reaches the pulp. Treatment and filling of the canals is difficult and uncertain. The Variations of Tooth Forms. 19. The teeth may vary quite extensively from the typal forms which have been described, and these variations may be due to a number of causes. Through all degrees of variation, however, the type is still pre- served, unless the tooth form is quite destroyed by pathological causes. The general causes of variation may be enumerated as follows : (1) Incompleteness of development. (2) Reversion to primitive types. (3) Temperamental impress. (4) Pathological lesions. (1) Under incompleteness of development may be grouped all those varieties of stunted growth which are the effect of disuse and the consequent effort of Nature to reduce and suppress the teeth as useless parts. The third molar teeth suffer most from these suppressive attempts of Nature in the effort toward economy of growth ; next to these teeth, the upper lateral incisors are most frequently affected by reduction of size, stunted growth and suppression. Other teeth are rarely affected, or but very slightly, by this influence, except in rare cases. (2) Under the second head, reversion to primitive types, we have a variety of interesting phenomena in the form of parts of the human teeth which seem to be a zoological legacy. These consist of conspic- uous features which reappear and seem to recall forms of the teeth observed in some of the lower animal orders, especially the quadrumana and insectivora. Among these features may be mentioned the curved upper central THE VARIATIONS OF TOOTH FORMS. 51 incisor with the prominent cingule on the lingual -buccal ridge, making a notch which recalls the incisors of the moles ; the prominent cingule on the lingual face of the lateral incisor, which is not uncommon and recalls the form found in the insectivora and some of the quadrumana ; the extra-long, curved canine, with extra-large median ridges, which recalls the large forms of this tooth in the baboons and in the car- nivora ; the double root sometimes found in this tooth is also a re- version to the insectivorous type ; the three-rooted bicuspid is a quad- rumanous reversion ; the upper tricuspid molar is a primitive typal form, leading back to the lemurs and beyond them to the early typal mammals found in fossil formations ; the notched and grooved incisor recalls the divided incisor of the Galeopithecus ; the double-rooted lower incisors and canines recall insectivorous forms ; the unicuspid lower first bicuspid is an insectivorous type and is often quite marked in man ; the fifth cusp on the lower second molar is a quadrumanous rever- sion ; the wrinkled surface of the lower third molar is like that of the orang. There are other features that might be named illustrating the work- ings of the law of atavism, by which parts once lost in evolution may reappear and be reproduced. (3) Under the third head, temperamental impress, may be noticed those differences of form and structure which have relation to the domi- nant temperament in the constitution of the individual. Great differ- ences exist between the teeth of different persons, and' these are mainly dictated by temperament. The teeth of the primary basal temperaments present the following physical peculiarities, which are characteristic of the particular tempera- ment : The bilious temperament presents teeth that are of a strong yellow ; large, long, and angular, often with transverse lines of forma- tion, without brilliancy, transparency, and of but slight translueency ; firm and close set and well locked in articulation. The sanguine temperament has teeth that are symmetrical and well proportioned, with curved or rounded outlines, and round cusps ; cream color, inclined to yellow, rather brilliant and translucent ; well set, and occlusion firm. The nervous temperament has teeth which are rather long, the cutting edges and cusps long and fine ; color pearl-blue or grav, very transparent at the apex ; the occlusion very penetrating. The lymphatic temperament presents teeth that are pallid or opaque, dull or muddy in coloring ; large, broad, ill-shaped, cusps low and rounded ; the occlusion lose and flat. Of the binary combinations: 52 MACROSCOPIC ANATOMY OF THE HUMAN TEETH. The sanguineo-bilious has teeth which are large, with strong edges and large cusps ; color dark yellow, and quality good. The nervo-bilious has teeth that are long and narrow, with long cusps ; color yellowish or bluish or both combined ; the enamel strong, the dentin soft. The lympho-bilious has teeth that are large, with thick edges and short thick cusps ; yellowish in color ; enamel of good structure and polish, and dentin fair. The bilio-sanguineous has teeth of average size, round arch, well- developed cusps and edges ; rich dark -cream color ; excellent in quality. The nervo-sanguineous has teeth of average size, good shape, round arch, good edges and cusps ; rich cream color ; enamel and dentin of excellent structure. The lympho-sanguineous has teeth of more than average size, shapely edges and cusps, rounded arch ; color grayish cream ; enamel and dentin fairly good. The BiLio-NERVOUS has teeth variable in size and form, sometimes broad, again very long with more pointed and long cusps ; the color generally bluish ; enamel fairly good, dentin soft and sensitive. The SANGUINEO-NERVOTJS has teeth of average size, good shape, round arch ; color grayish blue ; soft and frail. The bilio-lymphatic has teeth usually large, with thick edges, short thick cusps, and flat arch ; color yellowish ; quality good. The SANGTTiNEO-LYMPHATic has teeth of more than the average size, broad round arch ; color gray ; enamel and dentin poor. The nervo-lymphatic has teeth of average size, good shape, aver- age length, rather round arch ; color bluish gray ; soft and poor. Combinations of the binary temperaments are of the most common occurrence in individuals, but there is usually one basal temperament that preponderates over the others and gives its characteristic to the teeth as a predominating influence. (4) Under the fourth head, pathological lesions, are to be included all those disturbances of nutrition which eventuate in faulty formation of the teeth, whether due to specific hereditary diseases, mere malnutri- tion, idiosyncrasies, predispositions, defective functional life, etc. But this leads beyond the province of this chapter into the field of special pathology. CHAPTER IT. DENTAL HISTOLOGY WITH REFERENCE TO OPERATIVE DENTISTRY. 1 By Frederick B. Noyes, B. A., D. I). S. The development of our knowledge of the cell has had a most pro- found effect upon the entire practice of medicine ; in fact, the progress of modern medicine dates from the studies of cell biology, the germ theory of disease being only one of the phases of this development. In terms of the cell theory the functions of the body are but the manifest expression of the activities of thousands or millions of more or less independent but correlated centres of activity : if these centres or cells perform their functions correctly, the functions of the body are normal ; but if they fail to perform their office, or work abnormally, the functions of the body are perverted. In the last analysis, then, all physiology is cell physiology ; all pathology cell pathology. To modern medicine his- tology, or the cell structure of the organs and tissues of the body, together with cell physiology, is the rational foundation of all practice. This is as true for the dentist as for the physician so far as regards all of the soft tissues of the mouth and teeth that he is called upon to treat and handle. AYith caries of the teeth, the disease which most demands the attention of the dentist, the case is somewhat different. Caries of the teeth is an active destruction, by outside agencies, of formed materials which are the result of cell activity (the tissues them- selves being passive). The cellular activities of organs and tissues of the body may have an influence, but this is only in producing those conditions of environment which render the activities of the destructive agents efficient in their action upon tooth tissues. Though the enamel and dentin are passive, we can understand the phenomena of caries only as we understand the structure of the tissues ; and not only must the treatment of caries be based upon a knowledge of the structure of the tissues, but the mechanical execution of the treatment is facilitated by that knowledge. In the preparation of cavities the arrangement of the enamel wall is determined by our knowledge of the direction of enamel prisms in that locality, and to a certain extent 1 In the preparation of this material I am indebted to Dr. G. V. Black for the use of his large and valuable collection of microscopic slides, and for much advice and many suggestions. 53 54 DENTAL HISTOLOGY AND OPERATIVE DENTISTRY. the position of the cavity margins must be governed by our knowledge of the structure of the enamel. In the execution of the work a minute knowledge of the direction of enamel rods becomes the most important element in rapidity and success of operation. From the standpoint of comparative anatomy, the teeth are found to be not a part of the osseous system, but appendages of the skin, and are to be compared with such structures in the body as the nails and the hair. The teeth are a part of the exo-skeleton, and their rela- tion to the bones of the endo-skeleton is entirely secondary, for the pur- pose of strength, the bone growing up around the tooth to support it. If we examine the skin of such an animal as the shark, we find the entire surface covered with small calcified bodies which are reallv Fm 31. Shark's skull {Lamna eomubica), showing succession of teeth. small simple cone-shaped teeth. The mouth cavity is to be regarded, when viewed in the light of its development, as a part of the outside surface of the body which has been inclosed by the development of the neighboring parts, and the dermal scales or rudimentary teeth which were found in the skin covering the arches which form the jaws have undergone special development for the purposes of seizing and masti- cating the food. In the simplest forms there is only a development in size and shape of these scales, and they are supported only by the connective tissue which underlies the skin. These teeth are easily torn off in the attempt to hold a resisting prey, and, as in the shark, they are constantly being replaced by new ones (Fig. 31). In the more highly de- veloped forms there is a growth of the bone of the arch forming the jaw DENTAL TISSUES. 55 upward around the bases of these scale-like teeth, to support them more firmly and render them more useful. If we compare the structure of the hair with that of the tooth, we find in the case of the hair a horny structure formed by epithelial cells resting upon a papilla of connective tissue ; in the case of the tooth, a calcified structure formed by epithelial cells resting upon a papilla of connective tissue which is also partially calcified. The relation of the bones of the jaws to the teeth is entirely a secondary and transient one. The bone grows up around the roots of the teeth to Fig. 32. *; ^JS? ' "%*, Changes in the mandible with age ; buccal and lingual view. support them, and is destroyed and removed with the loss of the teeth or the cessation of their function. In this way the development of the alveolar process takes place around the temporary teeth ; all of this bone surrounding their roots is absorbed and removed with the loss of the temporary dentition, and a new alveolar process grows up around the roots of the permanent teeth as they are formed. This development of bone around the roots of the teeth leads to the changes in the shape of the body of the lower jaw, increasing the thickness above the mental foramen and the inferior dental canal. When the teeth are finally lost this bone is again removed and the body of the jaw is reduced in thick- ness from above downward (Fig. 32). These phenomena are of im- portance in their bearing upon the causes and treatment of diseased con- 56 DENTAL HISTOLOGY AND OPERATIVE DENTISTRY. ditions of the teeth, particularly those which involve the supporting tissues. Dental Tissues. — The human teeth are made up of four tissues (Fig. 33): 1. The enamel covers the exposed portion of the tooth, or crown, and gives the detail of crown form. Its function is to protect the tooth against the wear of friction. 2. The dentin forms the mass of the tooth and determines its class form, the number of cusps and the number of roots being indicated by the dentin form. 3. Cementum covers the dentin beyond the border of the enamel, overlapping it slightly at the gingival line and forming the surface of the root. Its function is to furnish the attachment of the fibers of the peridental membrane, which fastens the tooth to the bone. 4. The pulp or soft tissue filling the central cavity in the dentin is the remains of the formative organ which has given rise to the dentin. Its functions are the formation of dentin and a sensory function. In describing the structure of the teeth and the arrangement of the structural elements of the tissues directions are described with reference to three planes : The mesio-disto-axial plane, a plane passing through the centre of the crown from mesial to distal and parallel with the long axis of the tooth. The bucco-linguo-axial plane, a plane passing through the centre of the crown from buccal to lingual and parallel with the long axis of the tooth. The horizontal plane, at right angles to the axial planes. The Supporting" Tissues. — The human teeth are supported on the maxillary bones, their alveolar processes growing up around the roots of the teeth, so that the roots fit into the holes in the bone. The calcified structures of the tooth and the bone are not, however, united, but the roots are surrounded by a fibrous membrane, the peridental membrane, or pericementum, which fastens the tooth to the bone. Enamel. The enamel differs from all other calcified tissues in the nature of the structural elements of which this tissue is made up, in the degree of calcification, and in origin, being the only calcified tissue derived from the epiblast. The enamel is formed from an epithelial organ derived from the epithelium of the mouth cavity and indirectly from the epiblastic germ layer, while all other calcified tissues are products of the mesoblast. In the case of bone and dentin the formative tissue is persistent. It 57 Ed, Ground section of a canine : E, enamel ; Cm, cementum ; D, dentin ; Pc, pulp chamber ; Be, dento- enamel junction ; Ed, enamel defect ; G, junction of enamel and cementum at the gingival line ; Gt, granular layer of Tomes. (Reduced from photomicrograph made in three sections.) 58 DENTAL HISTOLOGY AND OPERATIVE DENTISTRY. is possible in the bone at least, therefore, to have degenerative and re- generative changes, or the removal of part of the calcium salts and their replacement through the agency of the formative tissue ; while in the enamel no such regenerative change is possible, as the formative tissue disappeared when the tissue was completed and before the eruption of the tooth. The enamel is the hardest of human tissues. Chemically it is com- posed of the phosphates and carbonates of calcium and magnesium and a very small amount of the fluorids, water, also a very small amount of organic matter if any. 1 The enamel in the natural condition, bathed in the fluids of the mouth, contains a considerable amount of water. If dried at a little above the boiling-point of water, it gives up part of it and shrinks considerably, so as to crack in fine checks. If heated almost to redness, it suddenly gives off from 3 to 5 per cent, (of the dry weight) of water with almost explosive violence. These facts were demonstrated some years ago by Charles Tomes, 2 and account for most of what was formerly recorded as organic matter in old analyses. If we observe under the microscope the action of acids upon thin sections of enamel, when the inorganic salts are entirely removed, the structure of the tissue vanishes, there being no trace of organic matrix left as in the case of bone or dentin. In the growth of bone and dentin the formative tissue produces first an organic matrix in the form of the tissue, and into this the inorganic salts are deposited, combining with the organic substances of the matrix. This union is compara- tively weak, however, for by the action of acids the combination is broken up and the inorganic salts are dissolved; or by heat the organic matter is removed, and in either case the form of the tissue will be maintained. In the case of the enamel, the formative organ produces organic substances containing inorganic salts, and the substances are arranged in the form of the tissue after the manner of a matrix ; but finally under the action of the formative organ all of the organic matter is removed and substituted by inorganic salts, whatever organic matter is 1 Von Bibra gives the following analysis of enamel : Calcium phosphate and fluorid 89.82 Calcium carbonate 4.37 Magnesium phosphate 1.34 Other salts 88 Cartilage 3.39 Fat 20 Total organic 3.59 " inorganic • . 96.41 2 Journal of Physiology, 1896. EN A MEL. 59 found in the fully formed tissue being the result of imperfect execution of the plan. The enamel is composed of two structural elements, the enamel rods, or prisms, sometimes called enamel fibers, and the interprismatic or cementing substance, both of which are calcified. It is to the arrange- ment of these structural elements that the characteristics of the tissue with which we are most concerned in operative procedures are due. While both the prisms and interprismatic substance of the enamel are calcified, or, better, composed of inorganic salts, the two substances — that is, the substance of the rods and the substance between the rods — show markedly different properties both chemical and physical. If treated with acid, the interprismatic substance is acted upon more rapidly than the rods, so that the latter become more conspicuous. By this means sections of the enamel may be etched to render it easier to study the direction and arrangement of the rods. If the action of the acid is carried far enough, the rods will fall apart before they are them- Fig. 34. Enamel rods isolated by caries. (About 465 X.) selves entirely dissolved. Fig. 34 is from the debris in a carious cavity, and shows rods isolated by the action of the acids of caries. The interprismatic substance is not as strong as the rods, so that in splitting or breaking the enamel the tissue separates on the lines of the cementing substance, occasionally breaking across a few rods but fol- lowing their general direction, the lines running between rods, not at their centres. In cleaving the enamel the chisel does not enter the tissue sepa- rating rod from rod, but the edge engages with the surface, and the 60 DENTAL HISTOLOGY AND OPERATIVE DENTISTRY. force applied at an acute angle with the direction of the rods fractures the tissue in the lines of least resistance. If the edge be keenly sharp, it will enter the tissue slightly, and then the bevel acts as a wedge in addition to the force applied to the shaft of the instrument ; but if the edge be dull, it will rest across the ends of many rods, will not engage with the surface, and the force applied will break and crumble the tissue but will not cleave it. The enamel rods, or prisms, are long, slender prismatic rods or fibers, five- or six-sided, pointed at both ends and alternately expanded and constricted throughout their length. They are from 3.4 to 4.5 microns 1 in diameter, some of them apparently reaching the entire distance from the surface of the dentin to the surface of the enamel ; but as the diameter of the rods is the same at their outer and inner ends, and as the crown surface is much greater than the surface of den- tin covered by enamel, there are many rods which do not extend through the entire thickness. These short rods end in tapering points between the converging rods which extend the entire distance. To express this in terms of development : as the formation of enamel begins at the surface of the dentin, the increasing area of crown sur- face requires more ameloblasts, and as new ameloblasts take their place in the layer the formation of new enamel rods begins between the rods which were previously forming. These short rods are most numerous over the marginal ridges and at the points of the cusps, and will be considered more fully in connection with those positions. In ground sections cut at right angles to the direction of the rods 2 the tissue has the appearance of a mosaic floor, the outline of the rods being more distinct if they have been marked out by treating the section slightly with acid (Fig. 35). In longitudinal sections (Fig. 36) the sides of the rods are not smooth and even like the sides of a lead pencil, but are alternately expanded and constricted. They are well illustrated by taking balls of soft clay and sticking them together one above another to form a rod, then putting a number of rods together so that by mutual pressure they take hexagonal forms. This illustrates also the manner of growth of the tissue in formation. The expansions and constrictions can be seen in rods that have been scraped from a cleaved surface of enamel, but better by isolating rods by the slight action of dilute acid (Fig. 37). In the construction of the tissue the rods are so arranged that the ex- 1 A micron is the unit of microscopic measurement, and is equal to one one-thousandth of a millimeter. 2 In describing the direction of enamel rods they are always considered as extending from the dentin to the surface, and the angle is formed at the surface of the dentin with the locating plane, either horizontal or axial. ENAMEL. 61 pansions of one rod come opposite to the expansions in the adjoining rods, and do not interlock with their constrictions. This arrangement Fig. 35. Transverse section of enamel rods. (About 8' leaves alternately a greater and a less amount of cementing substance between them. Fig. 36. Enamel rods in thin etched section. (About When observed under the microscope, the enamel rods show a char- acteristic appearance of light and dark lines running across them. These markings are similar to the striations of voluntary muscle fibers, 62 DENTAL HISTOLOGY AND OPERATIVE DENTISTRY. and are described as the striation of the enamel. It is seen not only in isolated rods (Fig. 34), but also in sections ground in their direction (Fig. Fig. 37. Enamel rods isolated by scraping. (About 800 X.) 38). This appearance of striation in the enamel is caused by the alter- nate expansions and constrictions of the rods refracting the light like a Fig. 38. Enamel showing striation. (About 1000 X.) lens. In sections the expansions in adjoining rods are opposite to each other, the difference in the refracting power of the prismatic and inter- prismatic substances producing the same effect. ENAMEL. 63 The appearance of striation is the record in the fully formed tissue of the manner of growth, each dark stripe, or expansion, in a rod representing a globule of partially calcified material. The ameloblasts build up the rods by the addition of globule after globule, surrounding them with a cementing substance and completing the calcification of both. In this sense the striation of the enamel may be said to record the growth of the individual rods. While the enamel is a very hard substance when its structure is complete and perfect, its most striking physical characteristic is a ten- dency to split or crack in the direction of its structural elements when a break has been made in the tissue. While it is difficult to cut across the rods or make an opening on a perfect surface, if a break has been Fig. 39. Enamel showing direction of cleavage. (About 70 X.) established it is comparatively easy to split oif the tissue from the sides of the opening when the rods lie parallel with each other. Fig. 39 shows a field of enamel illustrating the way in which the tissue splits or cleaves in the direction of the rods. Upon the axial surfaces the enamel rods are usually straight and parallel with each other, except where there has been some flaw or disturbance in development ; but upon the occlusal surface, although sometimes straight, they are very often much twisted and wound round each other, especially at their inner ends. This difference in the arrangement of the rods causes the greatest difference in the feeling of the tissue under cutting instruments. Such a specimen of enamel as shown in Fig. 40 can be cut away easily, the tissue breaking through to the dentin and splitting off in chunks ; while a specimen like Figs. 41 and 42 will not cleave if supported upon sound dentin. If the outer 64 DENTAL HISTOLOGY AND OPERATIVE DENTISTRY. Fig. 40. Straight enamel rods. (About 80 X.) Fig. 41. Gnarled enamel. ( About 80 x.) ENAMEL. 65 ends of the rods are straight, they will split part way to the dentin (Fig. 42) ; but where they begin to twist round each other they will break across the rods. If the dentin is removed from under such enamel, it will break in an irregular way through the gnarled portion. From a study of the arrangement of the enamel rods in the forma- tion of the crown it is apparent that the plan is such as to give the Fig. 42. Gnarled enamel. (About 50 X.) greatest strength to the perfect structure, and may be likened to an arch. At the gingival border the rods are short and are inclined apically 6 to 10 centigrades 1 (20° to 35°) from the horizontal plane. These short rods 1 In the Centigrade division the circle is divided into one hundred parts, each called a centigrade. One centigrade is equal to 3.6 degrees of the astronomical circle, 25 centigrades to 90 degrees, 12£ centigrades to 45 degrees. The cut gives a comparison of the two systems of meas- uring angles. 270 180 Centigrade division. 66 DENTAL HISTOLOGY AND OPERATIVE DENTISTRY. are overlapped for a short distance by the cementum. This inclination grows less and less, and at some place in the gingival half of the middle third of the surface they are in the horizontal plane. At this point they are also usually perpendicular to the surface of the dentin. Passing from this point they become inclined more and more occlusally from the horizontal plane, at the junction of the occlusal and middle thirds about 8 to 12 centigrades (28° to 40°) in bicuspids and molars, and 8 to 18 centigrades (28° to 65°) in incisors and canines. In the occlusal third the inclination increases rapidly, and often the outer ends of the rods Fig. 43. / Diagram of enamel rod directions, from a photograph of a hucco-lingual section of an npper bicuspid. are inclined more than the inner ends. Over the point of the cusps and the crest of the marginal ridges the rods reach the axial plane, though they are often very much twisted about each other in the inner half of their length. This position does not always correspond with the highest point of the cusp, but is inclined slightly axially from that posi- tion, and corresponds with the highest point of the dentin cusp. Passing down the central slope of the cusp, or ridge, the rods become again inclined away from the axial plane toward the groove, or pit, leaning toward each other where the two plates meet. The degree of inclination of the rods on the central slope of the cusps depends upon the ENAMEL. 67 height of the cusps ; the higher the cusp the greater the inclination from the axial plane. Fig. 43, a diagram from a photograph of a bucco- lingual section of an upper bicuspid, shows the plan of arrangement and illustrates the arch principle in the construction. Fig. 44. Stratification of enamel ; the cusp of a bicuspid : De, dento-enamel junction ; Ed, enamel defect showing in the heavy stratification band ; Ig, interglobular spaces in the dentin. (About 40X.) In the study of longitudinal sections of the teeth, one of the most conspicuous structural features is the stratification bands, or brown bands of Retzius. These bands are not parallel with either the outer surface of the enamel or the dento-enamel junction. They begin at the tip of the dentin cusps and sweep around in larger and larger zones. These stratification bands are better seen in comparatively thick sec- tions, and are caused by the varying amount of pigment deposited with 68 DENTAL HISTOLOGY AND OPERATIVE DENTISTRY. the calcium salts in the development of the tissue. They record the growth of enamel of the crown as a whole, as each line was at one time the surface of the enamel cap. These stratifications, or, better, incre- mental lines, are shown in Figs. 44-46. At the time the rod at A (Fig. 45) was completely formed the rod at B was just beginning to form at its dentinal end. From this it would Fig. 45. Incisor tip showing stratification or incremental lines. "Rods at A were fully formed at the time the rods at B were beginning to form. (About 50 X.) seem that any structural defect due to imperfect development would not follow the direction of the enamel rods from the surface to the dentin, but would follow the stratification lines ; and if these structural defects influenced the penetration of caries, we should expect to have the direc- tion of penetration modified. Fig. 44 shows a structural defect in the enamel over a cusp following the stratification band, and it will be noticed also that there is a structural defect in the dentin at a corre- sponding position. HISTOLOGICAL REQUIREMENTS IN ENAMEL WALLS. 69 HISTOLOGICAL REQUIREMENTS FOR STRENGTH IN ENAMEL WALLS. 1. The enamel must be supported upon sound dentin. 2. The rods which form the cavo-surface angle must run uninter- ruptedly to the dentin and be supported by short rods, with their inner ends resting on the dentin and their outer ends abutting upon the cavity wall, where they will be covered in by the filling material. 3. That the cavo-surface angle be cut in such a Avay as not to expose the ends of the rods to fracture in condensing the filling material against them. The first step, then, in the preparation of an enamel wall is to deter- mine the direction of the enamel rods by cleavage with a chisel or hatchet. Fig. 46. Enamel showing both striation and stratification. (About 80 X In Figs. 47 and 48, No. 1 shows an enamel Avail after cleaving the enamel with a hatchet. It will be noticed that the split has not followed the direction of the rods exactly, but has broken across them, slivering the rods as wood slivers in splitting. This would cause in the cut surface a whitish, opaque appearance. The plane of the enamel Avail should be extended so as to form a small angle with the plane of the dentin Avail, by shaving the surface with a very sharp hand instrument. No. 2 shoAvs the same Avail after it has been extended somewhat ; but it will be seen that it has not been extended enough, for the rods forming the sur- face at A do not reach the dentin, but run out at B on the cavity "rail, and that piece would chip out in packing against it or if force came upon the surface afterward. The angle should be extended so as to produce 70 DENTAL HISTOLOGY AND OPERATIVE DENTISTRY. a 5 & $ c s g o S-g Sd £ Jt HISTOLOGICAL REQUIREMENTS IN ENAMEL WALLS. 71 Preparation of enamel wall in gnarled enamel: 1. Enamel wall as cleaved, showing breaking across rods and slivering at a. 2. Wall as smoothed but not extended to remove short rods whose inner ends are cut off at b. 8. Wall extended and trimmed to a position of strength. D, dentin; De, dento-enamel junction ; c, cavo-surface angle: b, point where inner ends of rods are cut off; a, slivering of the tissue. (About SO x.) 72 DENTAL HISTOLOGY AND OPERATIVE DENTISTRY. the plane shown in No. 3 ; then the cavo-surface angle may or may not be bevelled as the position demands. In some positions, as on the axial surfaces, it is not possible to ex- tend the plane of the entire enamel wall as described ; all that can be done is to shave the cut surface, leaving the wall in the direction of the enamel rods, and then the margin is strengthened by bevelling the cavo- Fig. 49. Occlusal fissure in an upper bicuspid, showing direction of rods. (About 80 X.) surface angle, so that the rods forming the margin are supported by at least a few rods which are covered by filling material. In cutting out the fissures on the occlusal surfaces of molars and bicuspids, the rods are inclined centrally from the axial plane, as seen in Fig. 49. In opening a fissure the lines of cleavage will not be in the axial plane, but sloping inward toward the body of the cusp, in the HISTOLOGICAL REQUIREMENTS IN ENAMEL WALLS. 73 direction indicated by the direction of the cracks in Fig. 49. The outer ends of the enamel rods must be shaved away, to bring the plane of the enamel wall parallel with the dentin Avail or into the axial plane. When this has been done a strong margin has been formed, for the Fig 50. Preparation of enamel walls in occlusal fissure cavities (the same as Fig, 49). rods which form the point of the cavo-surface angle are supported by the piece A, B, C (Fig. 50), made up of rods resting upon sound dentin and covered by the filling material. Often the angle will be too sharp, however, and the cavo-surface angle should usually be bevelled to pro- tect the margin from accident. This illustration may be taken as typ- ical of occlusal cavities. 74 DENTAL HISTOLOGY AND OPERATIVE DENTISTRY. Fig. 51. Preparation of enamel walls in a buccal cavity in a molar: G, gingival wall; 0, occlusal wall (About 70 X.) HISTOLOGICAL REQUIREMENTS IN ENAMEL WALLS. 75 Fig. 51 shows a cavity prepared in the buccal surface of an upper molar. The occlusal margin is placed in the occlusal half of the middle third, and the gingival margin in the gingival half of the gingival third Fig. 52. 2. Wall as trimmed. Preparation of occlusal wall of Fig. 51. (About 70 X.) of the surface. In the occlusal wall the rods are inclined occlusally about 8 centigrades (28°) from the horizontal plane. After cleaving, the broken and slivered rods should be shaved away, but the angle can- 76 DENTAL HISTOLOGY AND OPERATIVE DENTISTRY. not be increased without making the margin of filling material too thin ; the rods forming the margin should therefore be protected by bevel- ling the cavo-surface angle. At the gingival wall the rods are inclined apically from the horizontal plane about 6 centigrades (20°). The wall should be shaved in that plane, increasing the angle a little, and the cavo-surface angle should be bevelled. Fig. 52 shows the occlusal enamel wall alone, after cleaving and trimming into form. Such enamel walls may be taken as typical of axial surface cavities, the Fig. 53. Structure of enamel about a fissure : B, buccal side ; L, lingual side. (About 70 X. angle of the enamel with the dentin wall being determined by the direction of the enamel rods in the position where the margin is laid. Grooves, fissures, and pits are always positions of weakness, and when a cavity approaches a groove or pit a good margin, histologically, cannot be prepared without cutting beyond it. Fig. 53 shows an occlusal fissure in a bicuspid, which illustrates the conditions of struct- ure characteristic of these positions. The rods are inclined toward the fissure, and between the bottom of the fissure and the dentin are very irregular. If a cavity wall were made to approach this fissure from the lingual side, so as to come to the dotted line, the wall would have to be inclined 6 to 8 centigrades (20° to 28°) from the axial plane toward HISTOLOGICAL REQUIREMENTS IN ENAMEL WALLS. 77 the fissure, and then the cavo-surface angle bevelled, when the condi- tions would be similar to those in the wall of an axial surface cavity, and not as strong as the location requires. Not only is this true, but it also leaves a vulnerable point next to the margin of the filling — a point of liability. Cutting just beyond the fissure, the wall may be left in the axial plane and have an ideally strong margin, and the point of liability is removed. To state the conditions in general ^■HHHk Fig. 54. ! H|. i ■ ■ • wk .- I 1 1 B A Bucco-lingual section of upper bicuspid. Enamel is broken from grinding . A to B, area of weak- ness for enamel margins. (About 20 X.) terms, a strong margin is more easily obtained where enamel rods are inclined toward the cavity than where they are inclined away from the cavity. The points of cusps and the crests of marginal ridges are positions of strength in the perfect tissue ; but when a cavity margin approaches them they become points of weakness, because it is impossible to sup- port properly the rods which form the margin. Over the marginal 78 DENTAL HISTOLOGY AND OPERATIVE DENTISTRY. ridges are many short rods which do not reach the dentin, and these are usually very much twisted about each other, so as to form the strongest possible keystone in the perfect structure. In preparing a Fig. 55. Enamel over tip of dentin cusp : D, dentin cusp. (About 80 X.) margin in such a position it is impossible to have the rods which form the margin reach the dentin with their inner ends, and these short rods are sure either to break in completing the operation or to HISTOLOGICAL REQUIREMENTS IN ENAMEL WALLS. 79 break out later. The arrangement of enamel rods in such positions is to be borne in mind, especially when extending approximal cavities in incisors toward the lingual side and in large pit cavities in incisors. A similar condition is found over the points of the cusps. Fig. 54 shows a bucco-lingual section of an upper bicuspid. It will be noticed that the rods forming the point of the cusp are not in the axial plane, and Fig. 56. n incisor. (About 50 X.) do not reach the tip of the dentin cusp, but reach the dentin a little way down on the outer slope. The enamel covering the tip of the dentin contains many short rods, and they are very much twisted about each other, so that the area from A and B to the point of the cusp is an area of weakness for the cavity margins. If the margin reaches this area, the cusp must be cut away and the enamel wall carried out in the horizontal plane. Fig. 55 shows this area more highly magnified ? and 80 DENTAL HISTOLOGY AND OPERATIVE DENTISTRY. illustrates the structure. It will be noticed that, in grinding, some of the short twisted rods have broken out of the section. Fig. 56 shows the tip of an incisor in labio-lingual section, and is of interest in relation to the formation of margins in step cavities in in- cisors. The tip of this tooth has been worn off in use. The illustration shows that the great inclination of the rods toward the axial plane in the occlusal third of the incisors is such as to bring the wear almost at right angles to the direction of the rods. Dentin. The structure of dentin is of comparatively little interest in the present consideration, as its histological forms do not directly influence Fig. 57. Dentin at dento-enamel junction, showing tubules cut longitudinally : Dt, dentinal tubules ; D, dentin matrix. (About 760 X .) the cutting of the tissue in the excavation of cavities. Its histological forms have, however, much to do with the penetration of caries and with other considerations which are of importance to the intelligent practice of operative dentistry. DENTIN. 81 Dentin belongs to the connective-tissue group, and is made up of a solid organic matrix impregnated with about 72 per cent, of inorganic salts 1 and pierced by minute canals or tubules, which radiate from a central cavity which contains the remains of the formative organ, or pulp. The minute canals, or dentinal tubules, are occupied in life by protoplasmic processes from the odontoblastic cells which form the outer layer of the pulp. Dentin contains two kinds of organic matter, the contents of the tubules and the organic basis of the matrix. The dentin matrix, after the removal of the calcium salts by acids, yields gelatin on boiling and resembles the matrix of bone, reacting in a similar, though not identical, way with staining agents. The portion of the matrix immediately surrounding the tubules shows different chemical Fig. 58. c * Dentin showing tubules in cross-section: ^.dentinal tubules: A dentin matrix; S, shadow of sheaths of Neumann. (About 1150 x.) characteristics from the rest of the matrix, resembling elastin, and re- sisting the action of strong acids and alkalies after the rest of the tissue has been destroyed. This portion of the matrix surrounding the tubules and lying next to the fibrils is known as the sheaths of Neumann. The dentinal tubules are from 1.1 to 2.5 microns in diameter, and are separated from each other by a thickness of about 10 microns of 1 Von Bibra gives the following analysis of dentin : Organic matter 27.61 Fat 40 Calcium phosphate and fluorid 66.72 Calcium carbonate 3.36 Magnesium phosphate 1.08 Other salts 83 82 DENTAL HISTOLOGY AND OPERATIVE DENTISTRY. dentin matrix. This is fairly uniform throughout the dentin. The character of the tubules is different in the crown and root portions. In the crown the tubules branch but little through most of their course ; but in the outer part, close to the enamel, they branch and anastomose with each other quite freely. Fig. 57 shows a field of dentin just beneath the enamel, as seen with a high power, and shows the diameter of the tubules, their branching, and the amount of matrix between one tubule and the next. The relation of one tubule to each other is shown also in sections cut at right angles to their direction (Fig. 58). In the crown portion the tubules pass from the pulp chamber Fig. 59. Crown of a molar, mesio-distal section, showing penetration of caries : A, caries penetrating den- tin ; B, line of abrasion ; P, pulp chamber. (About 20 X.) to the dento-enamel junction in sweeping curves, so as to enter the pulp chamber at right angles to the surface, and end next to the enamel at right angles to that surface. This produces S- or F-shaped \ or /) curves, which are known as the primary curves of the tubules. Through- out their course the tubules are not straight, but show a great many wavy curves, known as the secondary curves. These appear as waves when seen in longitudinal sections, but are really the effect of an open spiral direction, as is seen by changing the focus of the microscope in studying sections cut at right angles to the direction of the tubules. DENTIN. Fig. 60. 83 Dentin from the root, showing tubules cut longitudinally. (About 700 X.) Fig. 61. Dento-enamel junction. (About 70 X-) 84 DENTAL HISTOLOGY AND OPERATIVE DENTISTRY The branches throughout their length are few and small, and are given off at an acute angle to the direction of the tubule ; but just before the enamel is reached the tubules fork and branch, producing an appearance similar to the delta of a river. These branches are given off from the tubules for some little distance back from the enamel, and they anasto- mose with other tubules very freely. The branching of the tubules in their outer portion causes the spreading of caries just beneath the enamel, the micro-organisms growing through the branches from tube Fig. 62. Interglobular spaces in dentin: Ig, first line of interglobular spaces; Ig', second line of inter- globular spaces. (About 30 X.) to tube, and so spreading sideways beneath the enamel plates, and then penetrating the dentin in the direction of the tubules. Fig. 59 shows the penetration of caries in the dentin. It will be noticed that in decay starting at the contact point there has been more spreading under the enamel than in that starting at the gingival line, but in both positions the penetration has followed the direction of the tubules. In the root portion the tubules pass out from the pulp canals at right angles to the long axis of the tooth and pass directly out to the cemen- tum, showing only the secondary curves. Throughout their course they DENTIN. 85 give off a great many fine branches passing through the matrix in all directions from tubule to tubule. These branches are so numerous that in sections which have been mounted in such a way as to leave air in them, or if the tubules have been filled with coloring-matter, they give the impression of looking through a hazel bush ; or they may be likened to the fine rootlets of a plant. These fine branches are shown in Fig. 60, and the character of the dentin in the root portion is to be compared with that in the crown portion as shown in Fig. 57. The Fig. 63. Granular layer of Tomes : L, lacunae of cementum ; Gt, granular layer of Tomes ; /#, interglobular spaces. (About 200 X.) outermost layer of the dentin next to the cementum contains many small irregular spaces, which connect with the dentinal tubules and give to the tissue when seen with low powers a granular appearance. This layer was first described by John Tomes as the granular layer, and has since been usually called the granular layer of Tomes. The spaces of the granular layer are probably filled by the enlarged ends of the den- tinal fibrils. The same appearance is sometimes seen beneath the enamel, but is never as well marked as next to the cementum. The dentin at the dento-enamel junction seldom presents a smooth surface, but the inner surface of the enamel plate shows rounded pro- 86 DENTAL HISTOLOGY AND OPERATIVE DENTISTRY. jections, between which the dentin extends. In sections this gives to the dento-enamel junction a scalloped appearance, as shown in Fig. 61 ; and often the deceptive appearance of the dentinal tubules penetrating for a short distance between the enamel rods. In many specimens made by grinding dried teeth large irregular spaces are very conspicuous in the dentin. They usually occur in lines or zones at about uniform depth from the surface. These have been called the interglobular spaces. They are really not spaces at all, but are areas of imperfect development in which the dentin matrix has not Fig. 64. P — ■ .■ ' ■ —A Secondary dentin : A, margin of primary dentin, showing a few of the tubules continuing into the secondary dentin ; P, pulp chamber. (About 80 X.) been calcined. The dentinal tubules pass through them without inter- ruption. Tn a dried specimen the organic matrix shrinks, and the resulting space becomes filled with the debris of grinding, so as to give the appearance of black spaces. Fig. 62 shows two quite distinct layers of interglobular spaces, the second much more marked than the first ; and in the enamel at a position corresponding to the first is seen an im- perfection of structure marked by the very dark stratification band. This is shown best in the region of the cusp (Fig. 44) from the same section. Interglobular spaces in the root portion of the dentin are shown in Fig. 63, close to the granular layer of Tomes. PULP. 87 The formation of dentin is not complete at the time of eruption of the tooth, but continues for an indefinite period, thickening the layer of dentin at the expense of the pulp. When the typical amount of den- tin has been formed the growth ceases, and does not begin again unless excited by some irritation to the pulp or the pulp of some other tooth of the same side, which leads to the formation of secondary dentin. Secondary dentin is never as perfect in structure as primary dentin ; the tubules are smaller, fewer, and much more irregular. Often in ground sections several periods of formation can be determined by dif- ferences of structure, each deposit becoming successively more and more imperfect in structure. This is shown in Fig. 64. Pulp. The dental pulp is the soft tissue occupying the central cavity of the dentin. It is made up of embryonal connective tissue and contains a large number of bloodvessels and nerves. Like all connective tissues, the intercellular substance is large in amount and the cells are widely scattered in this soft, jelly-like tissue, which contains but few fibers. We recognize four kinds of cells in the pulp : the odontoblasts, form- ing the outer surface of the pulp next to the dentin ; and round, spindle- shaped, and stellate connective-tissue cells. ARRANGEMENT OF CELLS. The odontoblasts are tall columnar cells, sometimes club-shaped, and in older tissues, which have ceased to be functional, sometimes becoming almost spherical. They form a continuous layer over the entire surface of the pulp, being everywhere in contact with the dentin. The layer has been called the membrana eboris, or the " membrane of the ivory." The nuclei of the odontoblasts are large and oval, containing a large amount of chromatin, and are very different from the nuclei of ordinary connective-tissue cells. Three kinds of processes have been described in connection with the odontoblasts : 1. The dentinal fibril processes, or fibers of Tomes. These are long, slender protoplasmic processes projecting from the dentin end of the cell into a dentinal tubule, and running through the tubule to the outer surface of the dentin. Usually there is but one fibril extending from each odontoblast, but sometimes two can be seen, extending into two tubules. These fibrils can be demonstrated in decalcified sections or by removing the pulp from a recently extracted tooth by cracking the tooth and carefully lifting the pulp out of the pulp chamber, and then either teasing or sectioning. Fig. 65 shows the fibrils projecting from 88 DENTAL HISTOLOGY AND OPERATIVE DENTISTRY. the surface; but in this section the cut was not in the direction of the long axis of the odontoblasts, but obliquely through them. Fig. 66 (from a photograph by Rose) shows the form of the odontoblasts in a Fig. 65. Odontoblasts. The section cuts obliquely through the odontoblasts : F, fibrils ; N, nuclei of odontoblasts; N', nuclei of connective-tissue cells; W, layer of Weil, not well shown. (About 80 X.) young tooth in which formation of dentin is actively progressing, with the fibrils in the dentinal tubules. 2. Lateral processes projecting from the sides of the cells and unit- ing one with another in the formation of the layer. 3. Pulpal processes, projecting from the pulpal ends of the odonto- blasts into the layer of Weil. The odontoblasts, as the name indicates, are the dentin-forming cells. They superintend the formation and calcification of the dentin matrix, the fibril being left behind surrounded by the formed tissue. Whether the fibrils have any share in the formation and calcification of the dentin matrix has been a matter of controversy. The relation of the fibrils to the transmission of sensation is also a matter of dispute ; but at present the weight of evidence is that they in some way transmit impressions to the sensory nerves of the pulp. Just beneath the layer of odontoblasts is a zone which contains very few connective-tissue cells. In thin sections, especially in the body of the pulp, this appears as a clear layer about half as thick as the layer of odontoblasts. It is known as the layer of Weil. Just beneath the PULP. 89 layer of Weil the connective-tissue cells are especially numerous and form a more or less distinct layer of closely placed cells. In the rest of the body of the pulp the cells are about uniformly distributed through- out the intercellular substance. These connective-tissue cells are of the characteristic forms, rather small, containing a small but deep-staining nucleus, the protoplasm stretching out into slender projections in two directions to form the spindle cells, or in more than two directions to form the stellate cells. The stellate forms are more common in the body of the pulp, the spindle form in the canal portions. The round Fig. 66. Odontoblasts and forming dentin: E, forming enamel; Z», forming dentin; 0, odontoblasts; Dp, body of dental papilla. (From photomicrograph by Rose.) cells are comparatively few in number, and are probably young cells which have not yet acquired the adult form. BLOODVESSELS OF THE PULP. The blood-supply of the pulp is extremely rich, several arterial ves- sels entering in the region of the apex of the root, often through several foramina. These large vessels extend occlusally through the central portion of the tissue, giving off many branches which break up into a very close and fine capillary plexus (Fig. 67). From the capillaries the blood is collected into the veins, which pass apically through the central portion of the tissue. A very striking peculiarity of the bloodvessels of the pulp is the thinness of their walls. Even the large arteries show scarcely any 90 DENTAL HISTOLOGY AND OPERATIVE DENTISTRY. Fig. 67. Diagram of the bloodvessels of the pulp. (Stowell.) condensation of fibrous tissue around them to form the usual adven- titious layer, and usually contain but a single involuntary muscle fiber Fig. 68. A pulp bloodvessel, showing the thin wall : C, blood corpuscles in the vessel ; Bl, bloodvessel wall showing nuclei of endothelial cells ; N, nuclei of connective-tissue cells in the body of the pulp ; I, intercellular substance, showing a few fibers. (About 200 X.) representing the media, while the walls of even the large veins are made up of only the single layer of endothelial cells forming the intima, and PULP. 91 are in structure like large capillaries (Fig. 68). This peculiarity of the bloodvessel walls is of great importance, as it renders the tissue specially liable to such pathologic conditions as hyperemia and inflammation. NERVE OF THE PULP. Several comparatively large bundles of medullated nerve fibers, con- taining from six or eight to fifteen or twenty fibers, enter the pulp in company with the bloodvessels and pass occlusally through the central portion of the tissue. These bundles branch and anastomose with each other very freely. Most of the fibers lose their medullary sheath before reaching the layer of Weil, in which position they form a plexus of non-medullated fibers ; from these fibers free endings are given off, which penetrate between the odontoblasts. In some cases these have been followed over on to the dentinal ends of the odontoblasts, but in no instance have they been followed into the dentinal tubules. THE FUNCTIONS OF THE PULP. The pulp performs two functions, a vital and a sensory. The vital function is the formation of dentin, and is performed by the layer of odontoblasts. This is the principal function of the pulp, and it is first manifested in the development of the tooth before the dentinal papilla is converted into the dental pulp by being inclosed in the formed dentin. After the tooth is fully formed the vital func- tion is not manifested unless the pulp is stimulated by some excitation affecting trophic centres and which causes the formation of secondary dentin. There are some exceptions where the formation is entirely local. The Sensory Function. — In regard to sensation, the pulp resembles an internal organ. It has no sense of touch or localization, and re- sponds to stimuli only by sensations of pain. The pain is usually localized correctly with reference to the median line, but, aside from that, is localized only as it is referred to some known lesion. If several pulps on the same side of the mouth and in teeth of both the upper and lower arches were exposed so that they could be irritated without impressions reaching the peridental membrane, and the patient were blindfolded, it would be impossible for him to tell which of the pulps was touched. The pain originating from a tooth pulp may be referred to the wrong tooth or to almost any point on the same side supplied by the fifth cranial nerve. The pulp is especially sensitive to changes of temperature, but is incapable of differentiating between heat and cold ; this fact is often made use of in differential diagnoses (see Chapter XVI.). The pulp is 92 DENTAL HISTOLOGY AND OPERATIVE DENTISTRY. also very sensitive to traumatic and chemical irritations, even when these are conveyed to it through the agency of the dentinal fibrils. Dr. Huber has suggested l that this transmission may be accomplished by the traumatic or chemical action upon the fibrils setting up metabolic changes in the odontoblastic cells, which act as stimuli to the sensorv nerves ending between the cells of that layer. Cementum. The cementum covers the surface of the dentin apically from the border of the enamel, lapping slightly over the enamel at the gingival margin (Fig. 69). It forms a layer, thickest in the apical region and Fig. 69. Gingival border of enamel, show the cem dentin ntum overlapping it: E, enamel ; C, cementum; D, (About 40 X.) between the roots of bicuspids and molars, and becoming thinner as the gingival line is approached. The cementum resembles subperiosteal bone in structure, but differs from it in the character and arrangement of the lacunae and in the absence of Haversian systems ; the layers, or lamellae, of the cementum also are less uniform in character than those of bone. The function of the cementum is to furnish attachment for the fibers of the peridental membrane which holds the tooth in its position. The surrounding tissues are never in physiologic connection with the outer surface of the dentin, except to form cementum over it or to remove its substance by absorption ; and when absorption of the dentin 1 Dental Cosmos, October, 1898. CEMEJSTUM. 93 has occurred on the surface of a root it is never repaired except by the formation of cement um to fill up the cavity and reattach the membrane. The cementum is intermittently formed during the functioning of the tooth, being added layer after layer over the entire surface of the root, the diiference in thickness of the tissue in the gingival and apical portions being chiefly, though not entirely, due to the difference in thickness of each layer in the two positions (Figs. 69, 70). The cementum on the roots of newly erupted teeth is thin, and on the roots of teeth of old persons is thick. This continued formation of cementum Fig. 70. Cementum near the apex of the root : Gt, granular layer of Tomes ; L, lacunas , b, point at which libers were cut oft' and reattached. (About 54 X.) is due to the necessity for change and reattachment of the fibers of the membrane. In the gingival portions, where the cementum is thin, the tissue is clear and apparently structureless, and usually contains no lacunae ; while in the apical half and between the roots the lacunae are numerous. In general, wherever the lamellae are thin, the lacunae are absent ; but where the lamellae are thick they are found. The canaliculi which radiate from the lacunae are not as regular as in the case of the lacunae of bone. Sometimes they are numerous, sometimes few ; they may extend from a lacuna in all directions, or they may be confined to one side, usually the side toward the surface of the cementum (Fig. 71). 94 DENTAL HISTOLOGY AND OPERATIVE DENTISTRY. Fig. 71. II. I). 1 ifi* - ■WmB •- - . .iE/.i^M^ X . */...•■<<*> / * I' fV;V. - < fpf^ ' r.-J-'S' Thick lamellae of cementum with many lacunae, filling an absorption in dentin: X, lacunae ; II, Howship's lacunae filled ; D, dentin. (About 250 X.) Fig. 72. Two fields of cementum showing penetrating fibers : Gt, granular layer of Tomes ; C, cementum not showing fibers ; F, penetrating fibers. (About 54 X.) PERIDENTAL MEMBRANE. 95 The cementum is penetrated through all its layers by fibers of the peridental membrane which have been imbedded in the matrix of the tissue and calcified along with it. The first layer, — that is, the one next to the dentin, — is usually structureless and shows no fibers in it, at least in its inner half. In ground sections the imbedded fibers often appear in a number of layers, while they are not apparent in the rest of the thickness. This is because just before and just after the forma- tion of the layers in which they appear the fibers were cut off and reattached, changing their direction, so that in the other layers the fibers are cut transversely or obliquely. This is illustrated in Fig. 72. These imbedded fibers are very numerous in some places. If properly stained, the tissue seems almost a solid mass of fibers. In ground sec- tions these have sometimes been mistaken for minute canals from the fact that they are not always as fully calcified as the cementum matrix, and shrinkage causes the appearance of little open canals. Hypertrophies of the cementum (formerly often called exostoses, or excementoses) are very common. The increased thickness may be of one lamella or of several lamellae in the region of the hypertrophy, or all of the layers from first to last may take part in it. Small local thickenings of a single lamella are seen in connection with the peri- dental membrane wherever a specially strong bundle of fibers is to be attached to the root to support the tooth against, some special strain. Peridental Membrane. The peridental membrane may be defined as the tissue which fills the space between the root of the tooth and the bony wall of its alveolus, surrounds the root occlusally from the border of the alveolus, and supports the gingivus. It has been referred to under many names, as pericementum, dental periosteum, alveolo-dental periosteum, etc. While this tissue performs the functions of a periosteum for the bone of the alveolus, it differs in structure from the periosteum in any position, so that any name including the word periosteum or implying a double membrane should be avoided. The peridental membrane belongs to the class of fibrous membranes, and is made up of the following structural elements : 1. Fibers. 2. Fibroblasts. 3. Cementoblasts. 4. Osteoblasts. 5. Osteoclasts. 6. Epithelial structures which have been called the glands of the peridental membrane. 7. Bloodvessels. 8. Nerves. The peridental membrane performs three functions : a physical function, maintaining the tooth in relation to the adjacent hard and soft tissues ; a vital function, the formation of bone on the alveolar wall and of cementum on the surface of the root; and a sensory 96 DENTAL HISTOLOGY AND OPERATIVE DENTISTRY. function, the sense of touch for the tooth being exclusively in this membrane. The fibrous tissue of the membrane is of the white variety, and may be divided into two classes, the principal fibers and the indifferent or Ftg. 73. £y*teULF* Diagram of the fibers of the peridental membrane : G, gingival portion ; Al, alveolar portion ; Ap, apical portion. (From a photograph of a section from incisor of sheep.) interfibrous tissue. The principal fibers may be defined as those which spring from the cementum and are attached at their other end to the PERIDENTAL MEMBRANE. 97 bone of the alveolar wall, to the outer layer of the periosteum covering the surface of the alveolar process, to the cementum of the approximating Fig. 74. Safe Longitudinal section of peridental membrane from young sheep, showing fibers penetrating cementum : D, dentin ; C, cementum, showing imbedded fibers ; F, fibers running to outer layer of periosteum covering the alveolar process ; F', fibers running to the bone at the border of the process ; B, bone. (About 80 X.) tooth, or become blended with the fibrous mat of the gum supporting the epithelium. They were so called by Dr. Black, not only because 7 98 DENTAL HISTOLOGY AND OPERATIVE DENTISTRY. they form the principal bulk of the tissue, but they also perform the principal function of the membrane, the support of the tooth and sur- rounding tissues. The interfibrous tissue, also of the white variety but made up of smaller and more delicate fibers, is found filling spaces between the principal fibers and surrounding and accompanying the bloodvessels and nerves. For convenience of description and study, the peridental membrane is divided into three portions : the gingival y that portion which surrounds the root occlusally from the border of the alveolar process ; the alveolar, the portion from the border of the process to the apex of the root ; and Ficx. 75. Longitudinal section of the peridental membrane in the gingival portion: D, dentin; N, Nasmyth's membrane; C, cementum ; F, fibers supporting the gingivus ; F 1 , fibers attached to the outer layer of the periosteum over the alveolar process ; F 2 , fibers attached to the bone at the rim of the alveolus ; B, bone. (About 30 X.) the apical portion, surrounding the apex of the root and filling the apical region (Fig. 73). The principal fibers spring from the cementum, the cementoblasts building up the matrix around them and then calcifying both matrix and fibers, in this way implanting their ends into the surface of the root. In Fig. 74 the fibers are seen passing through the last- formed layer of cementum. In most positions the fibers as they spring from the cementum appear as well-marked bundles of fine fibers. A short distance from the surface of the root they break up into smaller bundles, which interlace and are reunited into larger bundles, to be PERIDENTAL MEMBRANE. 99 attached at their other extremity to the bone, cementum, or fibrous tissue. To arrive at an understanding of the arrangement of the fibers of the peridental membrane, they must be studied in both longitudinal and transverse sections. In longitudinal sections of the membrane, in the gingival portion (Fig. 75), the fibers springing from the cementum at the gingival line pass out for a short distance at right angles to the long axis of the tooth and then bend sharply to the occlusal, 1 passing Fig. 76. Transverse section of the peridental membrane in the gingival portion (from sheep) : E, epi- thelium : F, fibrous tissue of gum ; B, point where peridental membrane fibers are lost in fibrous mat of the gum ; P, pulp ; F' , fibers extending from tooth to tooth. (About 30 X.) into the gingivus to support it and hold it closely against the neck of the tooth. These fibers are most numerous on the lingual side, where food is brought against the gingivus with force in mastication and tends to crush it down. In the middle of the gingival portion the fibers pass out at right angles to the axis and are blended with the fibrous mat of the gum on the labial and lingual sides, or are attached to the cementum of the adjoining teeth on the approximal sides. A little farther from the 1 In describing the direction and inclination of peridental membrane fibers they are always traced from the cementum to the bone, the angle with the horizontal plane being formed at the surface of the cementum. 100 DENTAL HISTOLOGY AND OPERATIVE DENTISTRY. gingival line the fibers are inclined slightly apically, passing over the border of the process to be attached to the outer layer of the periosteum. These fibers are specially large and strong. Just at the rim of the alveolus the fibers are inclined slightly apically and are inserted into the bone, forming the edge of the process. In transverse sections of the membrane in the gingival portion (Fig. 76) the fibers spring from the cementum in large bundles ; at the centre of the labial surface they extend directly outward, breaking up into smaller bundles, passing around bloodvessels and bundles of fibers, and blending with the fibrous tissue supporting the epithelium. Passing mesially and distally toward the corners of the root, the fibers swing around laterally and pass to the cementum of the next tooth. On the Fig. 77. Fibers at tne border of the alveolar process (from sheep): _D, dentin; C, cementum; F, fibers ex- tending from cementum to bone ; Itf, bloodvessel; B, bone. (About 80X.) approximal sides the fibers suddenly divide into smaller bundles, which wind in and out around bloodvessels, and bundles of fibers which pass into the gingivus and are reunited into large bundles to be inserted into the cementum of the next tooth. On the lingual side the arrangement is like that of the labial, except that the distance to which the fibers of the membrane can be followed before they are lost in the fibrous mat of the gum is usually greater than on the labial. In the occlusal third of the alveolar portion of the membrane the fibers pass, at right angles to the axis of the tooth, directly from the cementum to the bone. In this position the fibers are large and do not break up into smaller bundles, but the original fibers can be followed PERIDENTAL MEMBRANE. 101 Fig. 78. Transverse section of the peridental membrane in the occlusal third of the alveolar portion (from sheep) : M, muscle fibers; Per, periosteum ; Al, bone of the alveolar process; Pd, peri- dental membrane fibers ; P, pulp ; D, dentin ; Cm, cementum. 102 DENTAL HISTOLOGY AND OPERATIVE DENTISTRY. uninterruptedly from the cementum to the bone (Figs. 74 and 77). In the middle third the fibers are inclined occlusally, and this inclina- tion increases as the apical third is approached. In the apical third the inclination is greatest, and the fibers as they arise from the cemen- tum are very large and break up into fan-shaped fasciculi as they pass across to the bone. In the apical portion the fibers radiate from the apex in all directions across the apical region and spread out in fan- shaped bundles like those in the apical third of the alveolar portion. In a transverse section near the border of the alveolus (Fig. 78), at the centre of the labial surface of the root, the fibers are seen to extend directly out from the surface of the root to the bone of the process, ex- cepting where they are diverted to pass around bloodvessels. Passing around distally at the corner of the root, the fibers swing laterally so as to be almost at a tangent to the surface of the root, and are inserted much farther to the distal on the wall of the alveolus. A similar ar- rangement is noticed at the other corners of the root, though these tangential fibers are usually more marked at the distal than at the mesial corners. Studying the arrangement of the fibers with reference to the physical function of the membrane, it is seen to be the best that could be devised to support the teeth against the force of mastication and to support the tissues about them. In the gingival portion the fibers passing from tooth to tooth form the foundation for the gingivae between the teeth filling the interproximal spaces ; so that if these fibers are cut off from the cementum, by extending a crown band too far, or by the encroachment of calculary deposits beginning in the gingival space, the gingivus drops down and no longer fills the interproximal space. In the alveolar portion the fibers at the border of the process and those at the apex of the root together support the tooth against lateral strain, while those in the rest of the alveolar portion are so arranged as to swing the tooth in its socket and support it against the force of occlusion (Fig. 73). As seen from the transverse section, the fibers of the occlusal third of the alveolar portion are so arranged as to sup- port the tooth against forces tending to rotate it in its socket. CELLULAR ELEMENTS OF THE MEMBRANE. The fibroblasts are spindle-shaped or stellate connective-tissue cells which are found between the fibers as they are arranged in bundles. In sections stained with hematoxylin they take the stain deeply, and the fibers, which are unstained, are differentiated by the cells lying in rows between them. The number of fibroblasts in the membrane decreases with age. They are large and numerous in the membrane of a newly PERIDENTAL MEMBRANE. 103 erupted tooth, and comparatively small and few in the membrane around an old tooth. This is characteristic of fibroblasts in other positions. The fibroblasts are shown as they appear in a hematoxylin-stained section with low powers in Fig. 79, which gives part of the membrane in the gingival portion between two teeth. The cells are seen as spindle- shaped dots which mark out the fibers ; at F they are seen in a position Fig. 79. Fibers and fibroblasts from transverse section of membrane : F, fibers cut transversely ; F l , fibers cut longitudinally, showing fibroblasts. (About 80 X-) where the fibers are cut transversely. With higher powers these cells appear as in Figs. 81 and 90. The cementoblasts are the cells which form the cementum, and are found everywhere covering the surface of the root between the fibers Fi q. 80. j#£ i. Cementoblasts. (Drawing by Dr. Black.) which are imbedded in the tissue. While these cells perform the same function for the cementum as the osteoblasts do for bone, they are in form very different from the osteoblasts. The cementoblasts are always flattened cells, sometimes almost scale-like, and when seen from above 104 DENTAL HISTOLOGY AND OPERATIVE DENTISTRY. are very irregular in outline. This irregularity of outline is caused by the cells fitting around the attached fibers of the membrane so as to cover the entire surface of the cementum between the fibers. Fig. 80, from a drawing by Dr. Black/ shows several cementoblasts as seen when isolated by teasing. The cementoblasts have a central mass of protoplasm containing an oval nucleus, and short irregular processes which fit around the fibers as these spring from the surface of the cementum. Fig. 81 shows them in section perpendicularly to the Fig. 81. Transverse section, showing the cellular elements: Fb, fibroblasts ; Ec, epithelial structures; Cb, cementoblasts ; Cm, cementum; D, dentin. (About 900 X-) surface of the root, where they are crowded between the fibers. The cementoblasts often have processes projecting into the cementum like those from the osteoblast, but processes projecting into the membrane have never been demonstrated. In the formation of the cementum occasionally a cementoblast be- comes inclosed in the formed tissue filling one of the lacunae, in which position it becomes a cement corpuscle. 1 Periosteum and Peridental Membrane. PERIDENTAL MEMBRANE. 105 Fig. 82. H.B Pd.B, Border of growing process : Cm, cementum : Pd, peridental membrane : Pd.B, solid subperidental and subperiosteal bone with imbedded fibers ; Ms, medullary space formed by absorption of the solid bone ; H.B, Haversian-system bone without fibers ; Ptr, periosteum. (About 50 X.) 106 DENTAL HISTOLOGY AND OPERATIVE DENTISTRY. The osteoblasts of the membrane cover the surface of the bone, forming the wall of the alveolus, lying between the fibers which are built into the bone. In form and function they are like the osteoblasts in attached portions of the periosteum. They form bone around the ends of the peridental-membrane fibers, building them into the sub- stance of the bone. The bone thus formed over the wall of the Fig. 83. Pd.M. Pd.B. H.B. Penetrating fibers in bone : Pd.M, peridental membrane ; 0& 1 , osteoblasts of peridental membrane ; Ob 2 , osteoblasts of medullary space; Pd.B, solid subperidental and subperiosteal bone with imbedded fibers ; Ms, medullary space formed by absorption of the solid subperidental bone with imbedded fibers ; H.B, Haversian-system bone without fibers built around the medul- lary space. (About 200 X.) alveolus is like the solid subperiosteal bone, and is penetrated throughout its thickness by the imbedded fibers j but, as with the subperiosteal bone, it is constantly being penetrated by perforating canals, the solid bone being removed by resorption and rebuilt in bone with Haversian systems. This process is shown in Fig. 82_, PERIDENTAL MEMBRANE. Fig. 84. 107 Osteoclast absorption of bune over permanent tooth: Oc, osteoclasts; B, bone of CTypt wall; F, fibrous tissue of follicle wall ; A, ameloblasts. (About 62 X.) Fig. 85. ' J lPS* ■ :'m jc ■ * # ' ■ Osteoclasts: Oc, osteoclasts ; B, bone. (About 66X.) 108 DENTAL HISTOLOGY AND OPERATIVE DENTISTRY. a section through a growing portion of the process around a per- manent tooth. A higher power (Fig. 83) shows the penetrating fibers and the formation of Haversian-system bone without fibers, in the body of the process. The osteoclasts, or myeloplaques, are bone-destroying cells (Fig. 84) ; they act not only upon bone, but also upon cementum and dentin. They are oval cells, often as much as 30 microns in diameter, and con- tain many nuclei, — from two or three to fifteen or twenty. They are often called giant cells. The osteoclasts are not constantly found in the membrane, but make their appearance whenever calcified tissues are to be destroyed. In order for them to act upon the tissues they must lie in contact with its surface, and therefore the first step in absorption of the peridental membrane is the cutting off of the fibers imbedded in the bone or cementum. Where the osteoclasts act upon the surface of Fig. 86. Record in the calcified tissue of an absorption repaired : D, dentin ; Cm, cementum filling absorp- tion cavity. (About 40 X.) the tissue they produce bay-like excavations, in which they lie, and which are known as Howship's lacunae. These excavations are shown in Fig. 87, though the osteoclasts have disappeared. In Fig. 86, from a ground section, the basin-like excavations are shown filled with new-formed cementum, thus leaving in the tissue the record of an absorption repaired. In absorption of the roots of the temporary teeth the osteoclasts are found not only in the membrane and attacking the surface of the root, but all through the medullary spaces in the bone, removing the temporary alveolar process. When absorption is going on at one place on the surface of a root a compensating formation of cementum is going on at another, so that not all of the fibers of the membrane are cut off. This is illus- PEETDENTAL MEMBRANE. 109 trated by sections of temporary teeth that are ready to be shed (Fig. 87). Fig. 8.7. Cm 1 Root of a temporary incisor, showing absorption and rebuilding of cementum (from sheep) : G, gin- givus ; D, dentin ; Cm, cementum ; Ab, absorption cavity, showing Howship's lacunae ; Cm}, new- formed cementum. (About 50 X .) EPITHELIAL STRUCTURES OF THE MEMBRANE. The peridental membrane contains cellular structures of epithelial character which are so conspicuous that they demand consideration, though their nature and origin are not as yet fully understood. These structures were first well illustrated and described by Dr. 110 DENTAL HISTOLOGY AND OPERATIVE DENTISTRY. Fig. 88. Diagram of glands of peridental membrane. (G. V. Black.) Fig. 89. Fb.- Ec.~ -T). Epithelial structures of the peridental membrane (from sheep): Fb, fibroblasts; Ec, epithelial structures; Cb, cementoblasts ; Cm, cementum; D, dentin. (About 468 X.) PERIDENTAL MEMBRANE. Ill Black, in his work on the periosteum and peridental membrane, in 1887, and were called by him the glands of the peridental membrane. About the same time von Brunn l described what are probably the same struct- ures, and which he regarded as embryonal remains of the inner layer of the enamel organ, which he described as growing down over the sur- face of the root. These structures appear as cords of epithelial cells Fig. 90. Epithelial structures (from sheep) : Fb, fibroblasts ; Ec, epithelial structures ; Cb, cementoblasts Cm, cernenturn ; D, dentin. (About 700 X.) arranged in the form of a network winding between the fibers of the membrane, very close to the cementum and surrounding the root almost to the apex. Their arrangement is illustrated in Fig. 88, a diagram by Dr. Black. The meshes of the net are close in the gingival portion of the membrane, but grow more and more open in the alveolar portion. They are not confined to the membranes of young teeth or the temporary den- tition, as Dr. Black has shown them in the membrane of a tooth from a man seventy years old, though, like all of the cellular elements of the 1 Archivf. mikros. Anal, 1887. 112 DENTAL HISTOLOGY AND OPERATIVE DENTISTRY. membrane, they become less numerous as age advances. . These struct- ures are specially well shown in the membranes of the pig and sheep. Fig. 89 shows their appearance in a transverse section of the root of an incisor of a sheep ; here they swing out from the surface of the cemen- tum and back again in loops, winding in and out among the fibers. Studied with higher powers (Fig. 90), they are seen to be made up of epithelial cells with large oval nuclei which react to the characteristic epithelial stains. They are arranged in cords, though sometimes what seems to be a lumen of a gland tubule can be found (Fig. 91). The Fig. 91. Epithelial structures : Ec, epithelial cord, apparently showing a lumen ; Cb, cementoblasts Cm, cementum ; D, dentin. (About 500 X.) cords are invested with a delicate basement membrane, but no special relation to bloodvessels has been demonstrated. The attempt to show their connection Avith the surface epithelium has thus far failed. As the gingivus is approached (Fig. 92), they seem to swing out from the sur- face of the root and are lost between the projections of the epithelium lining the gingival space. There is evidence that these structures are, at least in some cases, of importance as the primary seat of pathological conditions of the membrane. PERIDENTAL MEMBRANE. Fig. 92. 113 Longitudinal section: Ep, epithelium lining the gingival space; Gg, gingival gland, so called , D, dentin ; A, Nasmyth's membrane ; Du, duct-like structure stretching away toward the gin givus from the epithelial cord, seen at Ec ; Cm, cementum, separated from the dentin by decalcification. (About 50 X.) 8 114 DENTAL HISTOLOGY AND OPERATIVE DENTISTRY. Fig. 93. Fig. 94. Young and old membranes (from sheep) : D, dentin : Cm, cementum ; Cm 1 , thickening of cemen- tum to attach fibers at the corner; Pd, peridental membrane ; B, bone forming the wall of the alveolus ; P, pulp. (About 80 X.) PERIDENTAL MEMBRANE. 115 BLOODVESSELS AND NERVES OF THE MEMBRANE. Bloodvessels. — The blood-supply of the peridental membrane is very abundant. Several vessels enter the membrane from the bone in the apical region. These arteries branch and divide, forming a rich network, from which the capillary vessels are given off. The arterial network is constantly receiving vessels which enter the membrane through Haversian canals opening on the w T all of the alveolus, and in this way the size of the vessels passing occlusal ly is maintained. Ar- terial vessels also enter the membrane over the border of the process. This double or triple supply of the membrane is important, as it main- tains the health of the membrane when the supply entering through the apical region is entirely cut off by alveolar abscess. While the arterial supply of the membrane is very rich, the capillaries in the membrane are comparatively few. This is, however, a characteristic of connective-tissue membranes. The nerves of the peridental membrane have not been sufficiently studied to be described in detail. Six to eight medullated nerve trunks enter the apical region in company with the bloodvessels, and they re- ceive other trunks through the wall of the alveolus and over the border of the process, but the manner of their distribution and the nature of their endings are not known. THE CHANGES WHICH OCCUR IN THE MEMBRANE WITH AGE. When a tooth is erupted the roof of the bony crypt in which it was inclosed in the body of the bone is removed by absorption and the crown advances through^ the opening. The diameter of the alveolus at that time is, therefore, greater than the greatest diameter of the crown, and the peridental membrane which fills the space is verv thick. By the formation of bone on the wall of the alveolus and the formation of cementum on the surface of the root the thickness of the membrane is reduced. In the young membrane most of the large bloodvessels are found in its outer half, forming a rather defined vascular layer near its centre. In the old membrane most of the bloodvessels are found very close to the surface of the bone, often lying in grooves in its surface. Both young and old membranes are illustrated in Figs. 138 and 139, which are taken from the temporary teeth of a sheep, one just after eruption and the other shortly before the time of shedding. CHAPTER III. ANTISEPSIS IN DENTISTRY. By James Tetjmax, D. D. S. The importance of antisepsis in dental operations has not been recognized as fully as the subject would seem to warrant. This has been in part due to the fact that dentists have been accustomed to the thought that cleanliness in the use of instruments would meet all the requirements of practice. This idea has been enforced by a general im- munity from unpleasant sequelae after operations, thus leading to a skep- ticism in regard to the value of antiseptic measures in the oral cavity. This immunity has been in part due to the fact that the fluids of the mouth were supposed to have a direct influence in preventing in- fection. This has never been proved through laboratory experiments, but clinical observation and long experience have demonstrated that injuries in the mouth ordinarily heal rapidly, even though these be made by infected instruments. It seems unreasonable to suppose that a fluid peculiarly subject to fermentation should have this effect, and this has led some to ascribe it to a vital influence. Miller l says of this : " It is a very fortunate provision that the gums in a healthy state offer so powerful a resistance to the invasion of the germs of most infectious dis- eases. For this reason a wound in the gums may be followed by scarcely any reaction whatever, while a similar wound on the hand with the same instrument may produce most disastrous results. It has been attempted to account for this fact on the supposition that the saliva has an antiseptic action, in evidence of which we are often re- minded that dogs lick their wounds, and that these heal rapidly. . . . . I doubt if there is anyone who would wish us to believe that the dead saliva has even the slightest antiseptic properties, in consid- eration of the fact that saliva, especially when it contains much organic matter, readily putrefies. If the saliva possesses any such property, it must be sought for in its living histological elements, — i. e. } in the living leucocytes or phagocytes." 2 1 Dental Cosmos, July, 1891. 2 For an elaborate study of this problem see " Experimental Study of the Different Modes of Protection of the Oral Cavity Against Pathogenic Bacteria," by Arthur C. Hugenschmidt, M. D., Dental Cosmos, xxxviii., p. 797. 117 118 ANTISEPSIS IN DENTISTRY. While it is true that there exists a degree of exemption from serious results, leading to indifference and careless management of cases, it is equally true that infection has resulted in the experience of almost every operator in dentistry. Prior to the period when Lister announced that all operations in surgery should be performed antiseptically, and made modern surgery possible, this ignorance was excusable ; but at the present time, with the accumulated knowledge in bacteriology, it should be impossible for any dental operator to neglect the procedures under this head considered absolutely essential for the general surgeon. The difficulties attending antisepsis in dentistry far exceed those in other branches of surgery. The dentist is necessarily obliged to meet conditions hourly that seem to preclude absolute freedom from sources of contamination. If he were to take the same precautionary measures now regarded as necessary for the surgeon, he would find practice almost impossible. While this is true, it does not follow that every effort should not be made to approach absolute surgical cleanliness. The usual methods employed to accomplish this, while valuable to a limited extent, are by no means equal to what could readily be secured without consuming much time or patience. The dentist is usually sat- isfied that he has fulfilled all antiseptic precautions when he has dipped his instrument in some antiseptic fluid, generally carbolic acid. Little or no attention is paid to the possibility of infection from rubber-dam, towels, hands, and the variety of instruments that enter into dental operations. Some of the latter, as, for instance, the separator, are more liable to carry infection than the excavator, the one generally regarded as most important. The appliances ordinarily in daily use are the rubber-dam, excava- tors, broaches, pluggers, clamps, ligatures, separators, drills, hand- pieces, napkins, and forceps. It is safe to assume that but few of these will receive any attention beyond ordinary washing. The rubber-dam is too often used as it is furnished by the manufacturer. If an attempt at cleanliness is made, it consists in washing the dam in cold or warm water, this being regarded as sufficient. When it is remembered that this is passed between teeth and usually forced up under gingival margins with ligatures, or clamps, frequently lacerating the surface, it becomes evident that the possibility of infection is always present. If infection does not occur from the rubber, it is almost certain to pro- duce a wound in a locality extremely favorable for the growth of patho- genic germs. The result is innumerable lesions that may extend to pericemental inflammations. The great increase in the past twenty- five years of gingival inflammations subsequent to operations in mouths of more than ordinary health must be partly ascribed to this cause. SOURCES OF INFECTION. 119 Excavators ordinarily receive the most attention, and yet, when their use is considered, they possibly require the least. It is rarely necessary to use the excavator outside of a cavity, where infection, if at all pos- sible, would do the least harm, for the continual washing of the cavity, as the operator proceeds, reduces the danger to a minimum. Broaches, and all instruments intended to enter the pulp canals, require the most careful attention, and this applies with equal force to drills ; yet it is feared that both of these, loaded though they are with septic matter, receive but indifferent care. When the dangerous possibilities which may result from this negligence are considered, it becomes a serious if not a criminal offence. The difficulty in making these instruments germ- free and in keeping them from becoming contaminated is fully appre- ciated ; yet the effort must be made, and it is not a difficult procedure, nor does it require a large consumption of time — an important item to the dental operator. Pluggers cannot be regarded as a source of infection. They are used solely in connection with metal, and therefore strict cleanliness is all that is absolutely required. It is fortunate that this is so, for these instruments require unusual care to protect them from rust. Hence immersion in an antiseptic fluid is deleterious and not re- quired. Separators — and under this head are included metal with screw attachments and wedges — require special attention, but probably receive the least. They should be made as nearly sterile as possible before their use upon a patient. Hand-pieces, of the various kinds in use, are probably the most difficult to keep thoroughly clean. While they do not come in direct contact with the tissues of the mouth, they may indirectly, by contam- inating the hands, produce unpleasant results. Frequent taking apart and boiling are essential, and should not be omitted. Napkins from the ordinary wash have been and are used with con- fidence that no bad results from use can follow. If the laundry is con- fined to the home, this may ordinarily be true, but the indiscriminate mingling of washes indulged in by the commercial laundryman is always a menace to health. Where napkins of the latter character are to be used they should be subjected to the sterilizing process. The chair occupied by a variety of patients may be a source of disease, and should be carefully cleansed, especial care being taken with the head-piece. The latter should be covered with a clean napkin, to be changed for every patient. The cuspidor, where the fountain is not used, is ordinarily an abom- ination, for here, if anywhere, will carelessness be manifest. There can be no excuse for this, as thorough daily scalding with boiling water and 120 ANTISEPSIS IN DENTISTRY. Fig. 95. Downie steam sterilizer. the use of antiseptics will keep it measurably free from unpleasant consequences. Glasses require to be thoroughly boiled both before and after use. Boiling should never be neglected with ejector tubes, either metal or glass, glass being generally used. Hard boiling in water for twenty minutes should be sufficient. The lancet is an instrument demanding especial care, as it may become a danger- ous source of infection. Before it is used the adjacent portions of the gum should be washed with an antiseptic. The forceps employed in extraction should be so constructed as to render the blades readily separable at the joint, and they should be boiled in soda bicarbonate solution for an hour. The recorded cases of infection from these instruments render this care imperative in all instances. Fig. 95 shows a convenient form of apparatus for sterilizing ordinary dental instruments by boiling soda solution. Oral Diseases and Their Transmission. The possibility of carrying disease from one person to another seems so self-evident that it ought not to require more than a word of caution, and yet it is clear that the attention given to this source of danger is by no means commensurate with the risks assumed constantly in practice. The peculiarly transitory character of much of dental practice precludes the possibility of any previous history of patients, and therefore every one should be regarded as a possible source of infection. Diseases the result of pathogenic bacteria independent of possible external infection are now in the main well understood, but by no means equally appreciated by medical practitioners, nor are they properly con- sidered by dental operators. Miller 1 states that "many facts favor the supposition that a considerable number of pathogenic micro-organisms may thrive in the juices of the mouth without showing in their vital manifestations any distinction from the common parasites of the oral cavity as long as the mucous membrane remains intact. If, however, the soft tissues have been wounded, as in extraction, or if the resistance of the mucous membrane has been impaired, these organisms may gain 1 The. Micro-organisms of the Human Mouth, page 275. ORAL DISEASES AND THEIR TRANSMISSION. 121 a point of entrance and thus become able to manifest their special actions." This fact, now well recognized, is being constantly demon- strated in the use of the various appliances that may, through careless handling, injure the mucous membrane. So much is this the case that a large proportion of gingival inflammations have undoubtedly had their origin from this cause. It has come under the observation of the writer that injuries thus received, although apparently unnoticed by dentist or patient, have resulted in the course of forty-eight hours in very disturbing pericementitis, confusing to the operator and very painful to the patient. The necessity for such antiseptic precautions here as are taken in general surgery is almost entirely overlooked. Before placing the coffer-dam, the clamp, or ligature, that portion of the month should be thoroughly washed with an antiseptic solution and an effort made to render the appliances equally sterile, or at least to inhibit develop- ment for a definite period. When the operation has been completed the same care should be extended to the tooth and contiguous structures. The evidence is abundant that many cases of pyorrhea alveolaris have had their origin from this careless indifference to accepted and necessary precautions. The mouth as a source of disease to the general system does not properly Belong to this article to discuss, but its importance cannot be overlooked. Dental writers have devoted much attention to this sub- ject. It is for the dentist to understand that he is, to a large degree, responsible for the general health of his patient as far as the mouth is concerned, and he should insist on prophylactic measures that will at least reduce this source of disease to a minimum. The constant danger of what Miller aptly calls " auto-infection " from the collection and propagation of pathogenic bacteria in the fluids of the mouth should suggest to the dentist constant efforts to effect the removal of all deposits on the enamel, gingival margins, tongue, and mucous membrane. This line of study will bring about in the future an entirely different dentistry as to hygiene and prophylaxis from that practised at the present time. The pulp of a tooth is not ordinarily regarded as a point of in- fection, and yet it is well known to be a serious menace to the health of an individual. Israel, quoted by Miller, 1 asserts that " the root canal furnishes a point of entrance even for the ray-fungus, actinomyces, and in one case the microscopic examination revealed the elements of this organism in the canal of a pulpless tooth. " When it is considered that some individuals have decomposed pulps in a number of teeth at the same time, and frequently a score of dead and broken roots, sending out their infectious material, it is not surprising that disease of a serious nature may supervene. While there is no record of cases coming 1 The Micro-organisms of the Human Mouth, p. 285. 122 ANTISEPSIS IN DENTISTRY. within the observation of the writer of pulps producing pyemia directly, it is a well-known fact, supported by a long list of recorded cases, that alveolar abscess, with its concentration of putrid material, is liable to be followed by blood-poisoning. There is no question that diseases of the digestive organs, of the lungs — in fact, of all the organs of the body — may be produced by infected material germinated in the mouth, and indeed, through sputum ejected, may affect individuals remotely situated. Miller, 1 in considering this portion of the subject, says : " We know that under certain circumstances saccharomycetes may directly colonize in the mucous membrane of the mouth, and that in the mouths of enfeebled individuals bacteria may occasionally obtain a foothold. The mucous membrane of the mouth and pharynx is especially sus- ceptible to the action of certain germs of infection (those of diphtheria, syphilis, etc.), and large portions of the mucous membrane and the sub- mucous tissue may be wholly destroyed by parasitic influences." There is a phase of this subject that requires more extended in- vestigation. Inflammations of the mouth are not infrequent where great swelling is present. This may be observed around the lower third molars with no explainable cause in dead pulps, overlapping mucous membrane, retarded eruption, or mal-presentation. It is evi- dently produced by bacterial invasion, but has not always yielded to antiseptic measures, and at times has resulted in abscess entirely inde- pendent of pulp devitalization. A recent report of three cases by Dr. John A. McClain 2 in the medical practice of Dr. M. G. Tull is interesting as indicating possi- bilities. The first case was an extensive swelling posterior to the lower third molar. He could not connect it with that tooth, and suspected auto-infection. He had cultures made with negative results. His theory w T as that it was diphtheritic ; and, although laboratory evidence was wanting, he determined to inject antitoxin. This injection was followed in twenty-four hours by an entire reduction of the swelling. All other efforts had previously failed to effect any result. Two other similar cases yielded to the antitoxin treatment in the same speedy manner. If this can be regarded as something more than a coincidence in practice, it may lead to an explanation of many similar anomalous pathological cases arising posterior to the third inferior molar, yet apparently not connected with it. Similar conditions have been the cause of much uncertain diagnosis and still more empirical treatment. The more the writer has considered this subject the more important it has appeared; and he is convinced that, when the proper prophy- 1 The Micro-organisms of the Human Mouth, p. 295. 2 International Dental Journal, October, 1900. INFECTION FROM MOUTH TO MOUTH. 123 lactic measures come into use for the prevention of tuberculosis, in all its protean forms, antisepsis of the mouth will be given primary importance. Infection prom Mouth to Mouth. Infection from mouth to mouth through instruments is a difficult matter to prove by cases, but theoretically there can be no cause for disputation. The question will always arise, Was the lesion occasioned by auto-infection or by transmission? The answer can rarely be given with the assurance desirable. In one instance, at least, in the writer's experience the origin was clearly traceable. This was in a patient of the better class, presenting for treatment in the clinic of the Dental Depart- ment of the University of Pennsylvania. Her teeth were remarkable for structure, regularity, and cleanliness ; gums perfectly healthy. Necrosis of the anterior alveolar plate was threatened when first seen, and finally resulted, in the entire destruction of the alveolar border and all the anterior upper teeth, but did not involve the maxilla. The history of the case as given was that a bicuspid had been extracted from the right superior region by a dentist notorious for his uncleanly habits. Not long thereafter the patient noticed a serious inflammation. These symptoms indicated a syphilitic infection, and the family physician was consulted, who insisted that no history of this disease existed and that infection must be the cause. The patient, through his treatment and that given locally, recovered, but was forced to wear an artificial sub- stitute. Cases of infection through extraction, either by the forceps or after- infection from the mouth, might be quoted almost indefinitely. Miller reports case upon case — in fact, the accumulation of these has become of serious moment ; and yet, in the face of undisputed facts, dentists will continue to extract teeth frequently without any precautions, or, at most, relying on simple washing of the instrument. Some German writers contend that antisepsis after extraction is wholly unnecessary, as the clot formed is a sufficient protection. This is certainly not true in all cases. It is not always the fact that a clot is formed, or when formed that it serves an antiseptic purpose. One of the most serious cases that has fallen to the writer to treat was that of necrosis of the superior maxilla involving destruction of the right side, taking in all the teeth from the third molar to the lateral, the floor of the antrum, a portion of the nasal bones, and half of the hard palate. This was the result of the extraction of the third molar by a specialist before the days of antisepsis; whether it was the result of infection is difficult to determine. In the opinion of the writer, no extraction should be attempted until the instruments used have been thoroughly sterilized by boiling. Before the forceps are applied the parts surrounding the tooth 124 ANTISEPSIS IN DENTISTRY. should be well washed with an antiseptic solution. After the extraction the socket should be syringed with sterilized water, followed by some powerful disinfectant. In view of the serious results probable in this operation there is no longer any excuse for injuries resulting from infection, and a suit for malpractice could be well sustained against an individual who had failed to observe the well-understood methods of antisepsis, while no intelligent practitioner could conscientiously appear on behalf of the defendant. External Infection. The danger to the operator from external infection from instruments is a constant menace; the constant use of these with general freedom from serious results, however, leads to a degree of carelessness not war- ranted by the ever-present danger from wounds. There is more real danger to the operator from this source than to the patient. All the excavators, drills, and broaches are hourly in contact with infectious matter, and it requires but a slight wound to produce any of the possi- bilities of blood-poisoning. The operator should be on constant guard in this respect, upon the slightest abrasion immediately taking measures to destroy all possibility of infection from germs that may have been introduced into the wound. This should at once be carefully washed and an escharotic employed, burning the parts. For this purpose zinc chlorid or carbolic acid is probably the best agent to use, followed by an antiseptic. The latter should be frequently renewed. Experience has demonstrated the value of turpentine in the various mechanical shops where this agent has been for many years in common use for wounds from rusted iron, the possibility of trismus resulting from such injuries being well understood. The writer has used this agent, after burning the wound, almost to the exclusion of other antiseptics. An illustration of the ever-present danger from wounds occurred to a friend of the writer's, one of the many young women who have graduated in dentistry in this country. She accidentally wounded her hand by a drill, and regarded it as of no moment. The result was severe blood-poisoning that for two years kept her hovering between life and death. After suffering from severe metastatic abscesses, she was finally restored to partial health, but with her constitution shattered and her practice ruined for the time being. Implantation and Transplantation. Previous to the recognition of the importance of antisepsis, the dentists of that period had a very natural objection to reimplanting teeth ; the practice of transplantation was then practically an unknown operation. The danger of the operation was appreciated, but the reason AGENTS USED FOB STERILIZATION. 125 was not then comprehended. When the study of bacteriology had ad- vanced to a science through the labors of Pasteur, Koch, and a host of investigators, the reasons for this fear were explained, and the condi- tions necessary to avoid unpleasant results being understood, the danger from infection was changed to absolute security. It is, moreover, to be ever borne in mind that but for this knowledge implantation and trans- plantation could to-day not be practised without the probability of serious results. A case illustrating this point occurred prior to the knowledge of anti- sepsis in the hands of a well-known dentist. He had removed three teeth and successfully reimplanted them for the cure of a violent case of neuralgia presumably due to calcific depositions in the pulp and about the external portions of the roots. Relief was so immediate that upon return of the pain another tooth was attempted. Trismus followed, resulting in the death of the patient. It is safe to assume that this unfortunate result could not have happened under the antiseptic care usual at the present time, even imperfect as it frequently is. To accomplish antisepsis in this operation the greatest care is neces- sary. In transplantation, teeth being procured from other mouths, the danger is necessarily much increased. The method, adopted by some, of immersing these teeth in various antiseptic fluids cannot be commended. Miller says of this : ] " It is generally accepted that the operator takes every possible precaution when he allows the tooth to lie for one-half to one hour in a 1 per cent, solution of carbolic acid, or in a 1 :1000 solution of bichloride of mercury. ... In order to reach bacteria that may have penetrated into the lacunae or chance vas- cular canals a much longer action of the antiseptic is necessary, and to be perfectly certain that Ave have accomplished our object we should have recourse to boiling water." Agents used for Sterilization. The possibility of injuring instruments has deterred dentists from using many of the agents recommended for the purpose of sterilization. Miller 2 made tests of various agents with indifferent results, with the exception of carbolic acid, trichlorphenol, and mercury bichlorid. The list tested included the following : Carbolic acid in 5 per cent aqueous solution and in pure form. Lysol in 5 per cent, aqueous solution. Trichlorphenol in 5 per cent, aqueous solution. Sublimate in 5 per cent, aqueous solution ; also in the strength of 1 : 1000 of water. Benzoic acid in the strength of 1 : 300 of water. 1 Dental Cosmos, July, 1891. - Ibid., page 520. 126 ANTISEPSIS IN DENTISTRY. Potassium permanganate in 5 per cent, aqueous solution. Resorcin in 10 per cent, aqueous solution. Hydrogen peroxid in 10 per cent, aqueous solution. Saccharin in concentrated alcoholic and aqueous solution. /3-naphthol in 5 per cent, alcoholic solution. Pyoktanin in concentrated aqueous solution. Absolute alcohol. Antiseptin in 5 per cent, aqueous solution. Zinc sulfate in concentrated aqueous solution. The essential oils in 5 per cent, emulsions and in pure form. The three previously named, carbolic acid, trichlorphenol, and mercury bichlorid, were the only ones that gave any satisfactory results, and these only partially so. In regard to the rest, Prof. Miller says : " They all fall far short of those already mentioned. The 10 per cent, solution of the peroxid of hydrogen came next to carbolic acid, but is considerably inferior to it. The essential oils, in emulsions as well as in pure form, utterly failed to produce the desired action." The results obtained by Miller are not wholly in accord with those of some others. Charles B. Nancrede, M. D., in an article 1 gives a list of agents which have " proved most reliable clinically, can be resorted to in any emergency, or are peculiarly applicable to meet exceptional indications : " Marked Inhibition. Complete Inhibition. Mercuric chlorid 1:1,600,000 1:300,000 Oil of mustard 1 : 333,000 1 : 33,000 Thymol 1:86,000 Oil of turpentine 1 : 75,000 Iodin 1 : 5,000 1 : 1,000 Salicylic acid 1:3,300 1:1,500 Eucalyptol 1:2,500 1:1,251 Borax 1 : 2,000 1 : 700 Potas. permanganate 1:1 ,400 Boric acid 1 : 1,250 1 : 800 Carbolic acid 1:1,250 1:850 Quinin . 1 : 830 1 : 625 Alcohol 1 : 100 1 : 12.5 At the time these tables were prepared one agent not mentioned was practically unknown as an antiseptic, — formaldehyd, or in solution known as formalin. Dr. Elmer G. Horton, B. S., assistant in bacteriology, Department of Hygiene, University of Pennsylvania, undertook, at the request of Dr. Edward C. Kirk, a series of investigations with formaldehyd, 2 the results of which are given, omitting the details of experiments : 1 "Treatment of Wounds: Antisepsis and Asepsis," Surgery by American Authors, Park, page 365. 2 Dental Cosmos, July, 1898. AGENTS USED FOR STERILIZATION. 127 " We employed the gas generated by heating over an alcohol lamp a pastil which contained five grains of paraform. The lamp was placed in a tin box of nearly one cubic foot capacity . . . (Fig. 96). Among the instruments employed in the tests were various chisels, excavators, and burs. These were boiled, shown by cultural method to be sterile, then either dipped into bouillon cultures or infected from selected cases found in the operative clinic of the Department of Dentistry, University of Pennsylvania. After infection each instrument was placed in a sterile tube and kept at incubator temperature (37.5° C.) for three hours. . . . In a single test with moi'st instruments we found sterilization complete. After the infection and subsequent drying the tubes containing the in- fected instruments were separated into two lots, one to be subjected to Fig. 96. Schering's formalin sterilizer. the method of disinfection and the others to be kept as controls, by which would be shown that no step other than the action of formalde- hyd destroyed the vitality of the germs. . . . After exactly ten or fifteen minutes, according to the experiment, the door was opened and the instrument quickly removed. . . . Each instrument (controls like- wise) was placed in a considerable amount of sterile bouillon and these cultures, together with the subcultures made from them, observed for at least one week. ... In all experiments a free growth developed from the controls. . . . The disinfection of instruments purposely in- fected in the clinics from cases of caries, pyorrhea, and gingivitis was satisfactorily accomplished in every case. . . . We conclude that infected dental instruments can be disinfected without injury in a closed space of less than one cubic foot, by an exposure of fifteen minutes to the 128 ANTISEPSIS IN DENTISTRY. formaldehyd gas generated from a pastil containing five grains of para- form by heating the pastil over a proper alcohol lamp." In an article on the "Uses and Limitations of Formaldehyd in Dentistry/' by Dr. F. W. Low, Buffalo, N. Y., 1 the effect of formal- dehyd gas is further given as shown by a series of experiments con- ducted by Dr. Thos. B. Carpenter, assistant bacteriologist to the Health Department of the City of Buffalo. Without entering into detail, the experiments consisted of two series, one of infected instruments and the other of clothing either of school-children, of nurses, or of the doctor in the presence of contagion, to determine whether they could be thor- oughly sterilized by placing them over night in a wardrobe exposed to the fumigation of the lamp used. The conclusion of Dr. Carpenter was that '"This apparatus can be relied upon, after an exposure of from ten to fifteen minutes, to destroy thin layers of the common, non-sporulating pathogenic organisms." In regard to the second series of experiments with clothing, he says : " It is evident, therefore, that twelve hours' exposure to the action of this lamp in' a closet of 15.8 cubic feet capacity is sufficient for effec- tive surface disinfection, the most resistant pathogenic bacteria being destroyed." A third series of experiments was undertaken with scaling instru- ments taken from the instrument-cases from several operators, including that of Dr. Low. The result of this elaborate experimentation is thus summed up by the author : " Every set, except the one where the whole case was fumigated over night, produced some cultures ; but not one set developed a culture of pathogenic organisms." "The Low lamp consists of an asbestos-lined tray, or box, sup- ported on legs (A), with an opening in the bottom to admit the chim- ney of the lamp, the purpose of which is to conduct the fumes of the formaldehyd gas into the tray and upon the instruments it is desired to sterilize. "The working parts of the lamp are shown in the illustration. An ordinary alcohol wick is drawn into the wick tube. To place the lamp (B) in operation fill it with wood alcohol, grain alcohol being incapable of generating formaldehyd. Adjust cone-shaped platinum coil so that it just touches the top of the wick. Light the latter; place on chimney, and after a few seconds' waiting blow out the flame. If the cone be in proper adjustment to the wick, it will be observed that the coil glows like a live coal, but there is no flame or dangerous heat. "Having the lamp in operation, as described, and the tray properly adjusted to set over it, as in illustration, instruments may be placed in the tray and allowed to remain for ten minutes, a sufficient time to 1 Dental Cosmos, February, 1900. AGENTS USED FOB STERILIZATION. 129 effect sterilization. When taken out they should be wiped dry with a surgically clean napkin or towel. "To stop the fumigation going on in the lamp, remove the chimney and slide the cage high up on the tube, so that the platinum cone no longer touches the wick, then allow it to cool before replacing chimney." Fig. 97. Low's formaldehyd lamp : A, for dental use ; B, for household use ; C, locked cage for public places. While it is not difficult for the average dentist to use formaldehyd as a disinfectant, it will probably be considered a useless expenditure of time, and, therefore, boiling in water and soda for at least twenty minutes seems the more feasible and is equally certain in the results. The dentist who aims to keep only aseptic instruments should have 9 130 ANTISEPSIS IN DENTISTRY. two sets in daily use. When through with one patient the instruments should undergo the boiling process in preparation for the next. At the close of the day all instruments used should be thoroughly boiled and dried upon aseptic napkins and placed in the case. The possibility of infection from tne latter must not be overlooked. The first and second set, therefore, used the next day for the first time should be cither boiled again or each instrument dipped into an antiseptic fluid. For this purpose the writer prefers a strong solution of hydronaphthol (8 grains to the ounce of alcohol) to the carbolic-acid solution ordinarily used. With this care all danger of infection can be removed and the dentist relieved of all legal responsibility. The combination sterilizer and hot-water heater for gas or alcohol, designed by Dr. George J. Paynter, seems to be a convenient arrangement for the office. The preparation of the hands previous to operations is most per- plexing to the conscientious operator, whether this be in surgery or dental practice. In order that dental operators may be able to arrive at definite conclusions in regard to what may be required of them in their daily work, the following quotation is given from JNancrede's article 1 on the care required in hospital surgical practice : " Sterilized water as hot as can be borne should be employed. This must, of course, be never cooled by the addition of any but cold ster- ilized water. . . . The nail-brush, best made of vegetable fiber, must be always carefully rinsed after use and sterilized by heat for each operation. . . . Although it is alleged that all soaps made by heat are sterile — indeed, that potash soap is an active germ-inhibitor in the pro- portion of 1 : 5000 — yet it is the part of prudence to combine with the soft soap 5 per cent, of hydronaphthol or thymol, to insure that the soap itself is free from germs. After thoroughly rubbing into the hands and arms and under the nails abundance of soap, the nail-brush and hot water must be vigorously used, especially beneath and around the nails, for from two to five minute, j. Next, carefully clean the nails and around them with a nail-cleaner. Removal of all grease can now be effected by ether or by immersion in alcohol, or best by alcohol contain- ing 5 per cent, of dilute acetic acid, which should be rinsed off thor- oughly with sterilized water, removing the last traces of soap. Finally, the hands should be immersed — not merely dipped — in a 1 : 2000 mer- curic chlorid solution for not less than three — preferably five — minutes. Instead of corrosive sublimate solution, ordinary mustard flour mixed in the hands into a thin paste with sterilized water, used with gentle friction for two or three minutes and then removed with sterilized water, will prove a most successful germicide." While the foregoing may serve as a basis for comparison, it would 1 Loc. cit. AGENTS USED FOE STERILIZATION. 131 be wholly impracticable in dental practice. It remains, however, that the hands of the dental operator should be the subject of constant care. Nails should be kept short and scrupulously clean. It seems to the writer that the use of a good potash soap and nail-brush, with bathing the hands in alcohol, will be amply sufficient unless working on a syphilitic patient, when more effective methods must be resorted to, and there can be nothing better than the mode described by Dr. Nancrede. The conclusions to which the writer has arrived from experience and study of the subject may be summed up briefly as follows : 1. Dipping instruments in an antiseptic fluid previous to operating, while beneficial, is not sterilization. 2. That boiling with soda is for the dentist the most convenient means of sterilizing instruments without injury, while the more recently introduced method of formaldehyd antisepsis is a dry process that does not rust or injure steel instruments and is also promptly effective. 3. That the ordinary methods used to effect sterilization in surgical practice are not possible in dentistry, but that every dentist is legally and morally bound to live as near to the rules of antisepsis as is possi- ble with the demands of a daily practice. CHAPTER IV. THE EXAMINATION OF TEETH PRELIMINARY TO OPERA- TION—METHODS, INSTRUMENTS, APPLIANCES— RECORD- ING RESULTS, ETC. By Louis Jack, D. D. S. The Operator. The attitude of the body of the dental operator has considerable influence upon the ease with which the various positions required in operating may be assumed, and also has some bearing upon the free- dom of his hands. The erect position should be maintained as far as possible and the preponderance of the weight should be sustained upon the balls of the feet. This secures equilibrium and enables movements to be made with little embarrassment. The shoulders should be held well back in order that the arms may not be cramped, and to permit the respira- tion to be carried on deeply and with quietness. For obvious reasons the breathing should be deep, slow, and always through the nose. The precise use of the fingers requires that in each application of the instrument a rest, as a fulcrum or base of action, should be used, and when force is to be applied a guard in addition is necessary to give security to the movement of the hand. The positions of the rest and the nature of the guard required in operating are various, depend- ing upon the situation of the territory of operation and somewhat upon the natural tact of the individual, so that a definition of them is scarcely required. Upon a careful application of the rests and guards depends the graceful and comfortable use of the instru- ments, and by means of them the hand passes by quick and easy grada- tion from the most delicate touch to the safe exhibition of considerable force. Each student should study and practice the use of the various rests and guards until by repetition their employment becomes invol- untary and appropriate to the situation. 1 The contact with the patient should be at as few points as possible and should be generally made with the fingers. Examination of the teeth and mouth in all their particulars is a 1 To aid in this study see American System of Dentistry, vol. ii. p. 44 et seq. 133 134 EXAMINATION OF TEETH. necessary preliminary to the treatment of any diseased or disturbed condi- tion which may appear. The importance of this procedure cannot be overestimated, as on it depends the formation of a correct diagnosis of departures from the normal state and it becomes a basis for the formulation of plans for the treatment required to restore the teeth and the related structures to a state of health, as well as to define the order in which the several operations shall be taken up, since an orderly pre- cedence in the treatment of individual teeth is frequently necessary. It is essential that the examination be most thorough, to prevent any failure to notice the least defect; since an unobserved slight lesion may become a deeper injury in a few months, and the consequences of an oversight may prove serious. Appliances used in Examination. The appliances required to effect thorough observation of every portion of each tooth to ascertain the extent of any lesion are of several kinds, viz, mirrors, magnifying glasses, explorers, floss silk, and wedges. The mieeoes should be both plane and concave. The plane mirror is important as a means to assist by the reflected image in determining the position of defects ; the concave as an adjunct to effect illumination, as it concentrates the rays of light and also may be used to produce an enlarged image. The enlarged image, however, is less sharp in defini- tion than the image of the plane mirror. Working to the Image. — The plane mirror is an important adjunct in all operative procedures connected with the teeth. Many situations in the mouth do not permit the direct reflection of the rays of light to the eye without assuming positions of the bocty and of the head of the operator which are awkward and embarrassing to free movement of the hand, as well as necessitating inconvenient and tiresome positions of the head of the patient. In addition, it frequently is impossible to secure correct observation of the progress of various procedures by direct vision. These difficulties may be overcome by the movements of the hand being directed by the image of the field of the pro- cedure on the mirror. This method of working to the image is at first difficult to the novice, since the images are reversed ; but by continued effort it becomes as easy to make correct application of movements by this method as by the direct rays of light. Further continued practice in this way renders the movements so completely under reflex control that the operator passes from a direct movement to a reverse one, and the contrary, without an apparent effort of the brain. This is equally true in all the various movements, even of those where the employment of considerable force is required. APPLIANCES USED IN EXAMINATION. 135 Fig. 100. * r a / Fig. 101. b The Quality of the Mirror. — These appliances should constantly be in good condition to insure clear definition in the image. The best kind of glasses are those in which the surface is covered by a deposit of Ft G . 99. pure silver. This furnishes a better reflect- ing surface and is more durable than is the so-called " silvering " with tin and mercury. Magnifying lenses of about II four diameters are useful to de- tect minute defects either in the teeth or in the condition of pre- vious operations upon the teeth. They are used either directly to magnify the parts, or else to mag- nify the image shown on the face of the plane mirror when direct rays of light cannot be caught. The latter method gives a clearer definition than the magnified image of the concave mirror. The magnifying glass may be the ordinary watchmaker's glass held before the eye by the muscles of the brow and cheek or the lens mounted as shown in Fig. 144. Such glasses are indis- pensable to the careful practitioner, since with their aid defects of the teeth and of operations may be detected which would escape obser- vation by other means. Explorers are, es- sentially, prolongations of the fingers ; they convey impressions by their vibrations to the tactile nerves, and are principally intended to be applied to parts where direct rays of light cannot reach. The forms required are simple and few. Their points should be delicate, to enable the smaller apertures and spaces to be entered, and are best when made Magnifying lens. Explorer. Self-contained socket. 136 EXAMINATION OF TEETH. of piano-wire, No. 18 B. & S. gauge, filed to acuteness and bent to a shape similar to that shown in Fig. 100. This form may be applied to all surfaces of the teeth, and but slight modifications are needed to explore posi- tions difficult of direct approach. At part a the size of the finer ones should be No. 25, and near the ultimate point, b, No. 30. The temper of this kind of steel gives sufficient stiffness and also permits slight bending to make modifications of the form to meet all requirements. The ultimate point may be sharpened and renewed at pleasure. The handles in which these instruments are inserted may be of wood, with metal sockets which should be of sufficient length to come into contact with the finger ; or they may be fixed in metal holders, in w 7 hich case the latter should be tapered to avoid weight and to give balance. Either form of handle should be round, to permit fractional rotary change of direction. Fig. 145 shows an explorer, w T hich consists of a socket, into which the wire point is secured by means of powdered shellac or powdered sulfur. The points maybe displaced and renewed when required. This socket fits into the usual cone-socket handles. Fig. 101 is a self-contained socket for the same purpose. These points may also be connected with broach holders that have a clutch actuated by a screw nut. Explorers of this kind may be re-formed by straighten- ing and then re-dressing between two emery-cloth disks in the dental engine, when the points can be shaped at will. Floss silk is used to pass between the approximal surfaces of the teeth at the places which are in too close contact to permit the ingress of fine explorers. In these positions floss silk may detect the presence of superficial softening of the enamel by the character of the friction or by the fraying of its fibers. It also is of use in determining the con- dition of fillings c.i approximal faces or the presence of a deposit of sali- A vary calculus at similar parts. The Dow electric lamp for mouth illumination with reflectors. Reflector A is jointed to vary the angle of reflection. Reflector B is for illumination of the fauces. Reflector C is for lateral illumination. THE EXAMINATION. 137 silk should be slightly waxed in order to bind the fibers. Entire reliance cannot be placed upon the use of silk, since it may in some cases pass slightly carious spots without the fibers being displaced, but it frequently furnishes indications for further procedures by which to establish certainty as to the state of approximal surfaces. Wedges are used when neither explorers nor silk give positive indi- cations of carious action but have raised doubts of the integrity of any part. They may be of wood where the teeth are not firmly fixed, when the space may be immediately made ; otherwise, where the fixation is firm, thin india-rubber or linen tape may be forced in. Transillumination of the teeth by the electric mouth lamp (Fig. 102) is extremely useful in cases where a question has arisen as to the condi- tion of an approximal surface. Superficial changes of the enamel may frequently be detected by this means, and it is particularly useful in deter- mining the condition of approximal surfaces at the margin of the gums. It is also of service in testing the vitality of the pulp. The Examination. The parts of the teeth most liable to carious action are those which most easily retain deposits of sedimentary matter composed of food debris, thickened mucus, and bacterial growths. These are the labial and buccal surfaces, where the mechanical relations of the lips and cheeks tend to retain sediment; the sulci, which by the direct force of mastication have food driven into them ; and the approx- imal surfaces. The latter are the most important to consider. The interproximal space is a serious predisposing cause of caries, be- cause the counteraction of the tongue and cheek in adapting the food between the occlusal surfaces of the teeth forces the finer particles of the food into the interproximal spaces, where it is retained by capillary attraction, assisted by the viscidity of these deposits, and by the apposi- tion of the cheeks with the buccal surfaces of the teeth. This space is usually triangular, the gum forming the base of the triangle. The point where caries usually begins is at the apex of this triangle, where there is the least movement and interchange of the contents of the space, as here the capillary force is the greatest, so that the fermentative processes of food decomposition are least interfered with. The technique of examination is as follows : After a cursorv in- spection of the denture with the mirror, the explorer is applied to the previously indicated surfaces, particular care being used in determining the condition of approximal surfaces, by introducing the instrument into the triangular space, the point being directed toward the acute angle. It should be drawn back and forth with a slight rotarv move- ment so as to impinge the point successively upon the whole approxi- 138 EXAMINATION OF TEETH. mal surface of each tooth. This movement should be made from the inner as well as from the outer aspect. In this manner the instrument will be brought into contact with every accessible portion of the inter- proximal surfaces. Then the sulci are explored and the buccal and lingual surfaces examined. The inspection is thus conducted from tooth to tooth. Next the lines of apparent contact are critically tested with the mirror for evidence of slow changes of structure as shown by discoloration or rapid alterations shown by a milk-like appearance of the tooth surface. Finally, all approximal surfaces which could not be explored are silked. To do this the floss is wrapped upon the index finger of the left hand, and with the right is drawn between the contact surfaces with a sliding lateral movement. Care should be exercised that no injury be done to the gingival margin of the interproximal space by suddenly and forcibly driving the floss into contact with it. This acci- dent may be effectually avoided by properly guarding and supporting the fingers by contact with the adjacent teeth. Practice gives facility in determining by means of the. silk the state* of the parts in contact with it. In the inspection of previous fillings, all margins, particularly those about the cervix and beneath the gum, should be critically inspected. Lastly, doubtful situations should be noted for subsequent examina- tion, to be made after separation. (The tests for pulp exposures are considered in Chapters VI. and VII.) The order of examination is best conducted by beginning at the median line of each quarter of the denture, progressing posteriorly with one kind of observation, and returning to the place of beginning with another kind of observation. The Chart Record. — The chart record should at the same time be carried on by the principal, or better an assistant, with the view of securing a complete record of each derangement, for guidance and for reference. The details of the record are indicated in a simple manner by symbols which are illustrated by Fig. 103, and explained by the glos- sary. These symbols may be combined, where required, to give fuller expression. From this temporary record important operations when executed may be transferred to a permanent record. The constitutional condition and the texture and apparent resistance of the teeth to caries and attrition ; the inherited tendency to diseases of the teeth ; the chemical reaction of the mucous and salivary secretions ■ the state of the general heath • the condition of the mucous membrane of the THE CHART RECORD. 139 mouth and throat ; the indications presented by the tongue ; the dietary habits and other hygienic relations ; the tendency to catarrhal affections ; the presence of the rheumatic or gouty diathesis — are all questions which Fig. 103. S-EX signifies : In the interproximal space. / " Attention— re-examine. // " Superficial softening. /// " A carious cavity. • " At the cervix, s " To separate, p " To polish. c signifies : Salivary calculus. ex " To examine. 1 " A pulp nearly exposed. 3 " A pulp probably exposed. 3 " A pulp fully exposed. □ " A devitalized pulp. enter into the prognosis and frequently largely determine not only the hygienic directions to be given to the patient, but also determine, in connection with the age and habits, the important question as to whether the restorative operations shall be of a permanent character or only of a temporary nature designed to preserve the teeth until restored normal functions may make it judicious to perform more enduring operations. The foregoing considerations with respect to the examination of the mouth and teeth sufficiently meet the requirements for beginning the rational treatment of dental disorders. CHAPTER Y. PRELIMINARY PREPARATION OF THE TEETH— REMOVAL OF DEPOSITS AND CLEANING OF THE TEETH— WEDGING— OTHER METHODS OF SECURING SEPARATIONS— EXPOS- URE OF CERVICAL MARGINS BY SLOW PRESSURE, ETC. By Louis Jack, D. D. S. Cleansing the Teeth. Before restorative operations are commenced upon the teeth all deposits of salivary calculus upon them should be removed and they should be cleansed of the covering- of partially inspissated mucus which even in persons of more than ordinary carefulness is liable to be found upon them. This film favors the admixture with it of sedi- mentary matter from food substances and frequently has so much con- sistence as to offer considerable resistance to its removal, and it pre- vents to a degree the contact of the naked brush with the teeth. Its presence is in every way detrimental to the preservation of the teeth, since it not only favors the adhesion of starchy matters, but also fur- nishes, wherever situated in connection with these food products, a favorable habitat for the development of bacterial forms responsible for the formation of the acid products that are the active agents of enamel solution. This deposit is most frequently formed on the inner and outer surfaces of the posterior teeth, where it invades the inter- stices and in some cases cover all surfaces which are not directly sub- ject to the friction of mastication. It should be thoroughly removed and all surfaces should then be carefully polished. The best means to effect this is to polish the parts with a mixture of pulverized pumice with glycerin. The glycerin binds the particles of pumice and permits its retention upon the polishing instruments. The persistence of the deposit is shown by the fact that when the pumice is applied it is a moment before the polishing implement comes into actual contact with the enamel. To be suitable for this purpose the pulverized pumice should have been elutriated or passed through a fine bolting cloth to remove the coarse and irregular particles which if per- mitted to remain might cause injury to the enamel surface. After the removal a vitreous surface should be given by quick friction with stan- 141 142 PRELIMINARY PREPARATION OF THE TEETH. Fig. 104. nic oxid (" tutty powder "), which also is better applied when combined with glycerin or rubbed up with vaselin. Salivary calculus is found precipitated at parts not subject to free friction, such as the buccal surfaces of the molars, the inner faces of the lower incisors, and it frequently invades the interstices. These deposits also should be displaced and the surfaces polished. The better appliances for the removal of superficial calculus are sickle-shaped scalers of various sizes and forms, which are inserted beneath the free margin of the gum, when the direction of the move- ment should be obliquely toward the occlusal aspect to avoid injury to the gingival attachment with the tooth. The consideration of the removal of deeply seated salivary calculus where some serious injury has been caused by its presence is treated of in Chap. XIX. Polishing- the Triangular Portion of the Interproximal Spaces. — When this is required an efficient means is to employ gilling twine of sizes proportioned to the space. This is applied by looping one or more strands with a piece of floss silk, w T hen the silk is drawn up- ward into the triangle and then is used to pull the twine into the space, which being armed with suitable powders is drawn to and fro until the absence of friction indicates that the surfaces have become smooth. The surfaces in contact may then be polished by means of German silver strips. Abbott's scalers. CARE BY THE PATIENT. Coincident with the preparation above described the patient should be given such instruction as will tend to maintain the state of cleanli- ness. The importance of this should be impressed as a necessary hygienic measure to preserve the teeth. This is to be accomplished by the use of suitable brushes and properly compounded powders. The detergent effect of powder is principally due to the particles becoming mixed with the film of mucus. This action breaks up the continuity of the film, which, with the accompanying sediments, is displaced by the friction of the brush. The correct use of the brush requires that it be placed with some degree of firmness upon the outer and inner faces of the teeth and then slightly rotated in a direction toward the occlusal aspect. The pressure drives the bristles into the valleys, and the rotary movement being away TREATMENT OF THE MUCOUS SURFACES. 143 from the gum avoids injury to that structure. This is the only efficient method of applying the tooth-brush, which should be the universal one. The application of this procedure in combination with the use of picks and floss silk should maintain a correct hygienic condition of the teeth, upon which, in the light of the present knowledge of the causes of solution of the enamel, depends the preservation of the teeth from that source of injury. It has been shown that when sound enamel becomes attacked, the potent cause is the fermentation of starchy deposits permitted to remain in contact with it. It should be understood that the use of the pick removes deposits from the cervical trir.ngle, and that silk is intended to sweep the more contracted portion of the interstice. Further reason for care is found in the fact that the mouth in an unclean condition becomes a favorable habitat for the development of germs some of which may have pathogenic properties capable of affecting the general health. It therefore becomes eminently the duty of the dental adviser to enforce correct hygienic conditions of the mouth. Much importance in this connection should be attached to the use of cleansing preparations having inhibitive action toward bacterial life. Those most serviceable contain hydronaphthol, which has considerable efficiency without toxicity. A three per cent, solution of hydrogen dioxide is also very applicable for frequent use. Formalin as an ingredient of a wash is also applicable, but must be prescribed with considerable caution. Treatment of the Mucous Surfaces. When the gums, the membrane of the mouth or of the throat are inflamed, treatment preparatory to operations upon the teeth should be directed toward restoring these parts to a normal state. Where the inflammatory condition is not expressive of derangement of the alimen- tary functions and is the result of some simple local irritation, the condition w T ill usually respond to the topical action of stimulant tonics. It is necessary here to discriminate as to whether or not the inflamed surface has been produced by neglected care of the mouth, which fre- quently induces a lax condition of the gum from the absence of friction or by the consequences attending the presence of bacteria. These may cause a deficiency of tone or disorders in other portions of the mouth and of the throat. Should these conditions be present the employment of disinfectant gargles and mouth-washes is indicated. The presence of salivary calculus may also induce inflammatory dis- turbance of the gums, and from the points of deposit this may extend by diffusion over a considerable area. In this connection deposits, either of calculus or of sedimentary accumulations, posterior to the lower third molars may induce serious diffuse inflammation of the contigu- 144 PRELIMINARY PREPARATION OF THE TEETH ous tissues, sometimes extending to the fauces. For this condition the mechanical removal of the deposits combined with an antiseptic spray will usually be restorative. For diffuse redness and deficient tone of the mucous surfaces a wash composed of potassium chlorate and quinin will prove sufficient in most cases, as follows : ]^. Potassii chloras, 3ij ; Quininse sulphas, gr. iij ; Sp. rectificatus, 3j ; Aquae, g v j. — M. S. For use as a gargle. A dessertspoonful to a wineglass of water, or directly upon the gum in full strength by means of a soft tooth-brush. The fresh ingredient has specific action upon the mucous membrane of the mouth. Concurrently with the local therapeusis the employment of massage of the gum with the finger, either naked or covered with a napkin, is of considerable value. When the conditions are catarrhal or are expressive of gastric derangement only general treatment with concurrent attention to the diet and correct hygienic relations will meet the requirements of the case. Coincident with the general treatment above indicated, the simpler operations upon occlusal surfaces may be carried on. In all cases of initial treatment for children or nervous patients it is important to begin with simple and, as nearly as may be, painless operations, to accustom such patients to the more or less disagreeable procedures and to elicit their interest and co-operation in what is being done for their benefit. Cavities on Approximal Surfaces. The preliminary treatment of this class of cases, on account of the limitation of space and the necessity for somewhat indirect application of the instruments and of the requisite force, necessitates the closest attention to every detail. Upon the care here taken depends the comfort, and furthermore, indirectly in many instances, the health of the person. The procedure of first importance is to produce a sufficient enlarge- ment of the interproximal space. In all cases, whether the teeth are in apparent contact or whether they may, from loss of substance on the approximal aspect, present sufficient room for the management of the various procedures, spacing is equally necessary. It is done in order that when the stopping procedures shall have been completed the natural SEPARATION OF THE TEETH. 145 relations of the teeth with each other will be restored. This relation, as before indicated, is one of apparent contact near the occlusal surface with a triangular space at the cervix. The mechanical basis of this arrangement is such that the function of comminution of food is better effected if there is no breach in the continuity of the occlusal aspect of the denture. The consequences of breaches of continuity, especially in relation to the posterior teeth, are often of serious import. Not only may the food be driven into the space, to the discomfort of the patient, but serious injury of the gum may follow, as in many cases the tissue becomes inflamed by the impaction of food in the enlarged interspace, which in- duces peridental disturbances and may occasion the ultimate loss of the affected tooth. It is also not unimportant to consider that the forms of the teeth have an esthetic value, and that the harmony of the features forbids the mutilation of their natural forms. Separation of the Teeth. Separation of the teeth is a procedure requiring care to avoid injury and to render the process comparatively painless. When the teeth are mobile, as in the case of children, the movement is more easily and more quickly made than when the alveolar walls are compact and when also the teeth are in close proximity. In the former case the arch easily expands and permits the teeth to yield ; in the other case the resistance requires more force to be used and the application of it for a longer period. In all instances the force and the material used should be adapted to the presented conditions and the movement should be sustained until the required space is gained, it being dele- terious to make repeated attempts to separate the same pair of teeth. When the proper precautions are taken there is no danger attending the process ; even the firmest structures of mature age permit sufficient spacing if it be slowly and steadily done. METHODS OF MAKING SEPARATIONS. The means by which these are effected are various and the choice is determined by the amount of space required, the time in which it must be accomplished, and the firmness of the supporting structures. Some regard must also be had for the peculiar susceptibilities of the patient to the pain which may be caused by the effort. These methods are — by immediate wedging, which may be made when the fixation of the teeth is not firm ; by the swelling of firmly impacted pellets of cotton or of tape, and by the resilience of strips of caoutchouc where the teeth are in general contact and where they are firmly fixed. Immediate wedging is more applicable to the front teeth, where 10 146 PRELIMINARY PREPARATION OE THE TEETH. usually only a small space is required, and is a valuable method of securing a separation of the front teeth to determine their condition and to permit polishing strips to be inserted for the removal of super- ficial discolorations and for the treatment of superficial softening. Here the procedure is to insert a wooden wedge between the incisors near the incisive edge, when it is forced by pressure or by percussion until a suf- ficient opening is effected, the space then being secured by another wedge of hard close-grained wood forced between the teeth at the cervix. This process in some instances is repeated by forcing farther the first wedge and again increasing the security by driving the cervical wedge. This plan is not applicable when the interspace at the neck is quite angular, since the fixing wedge cannot be made secure, as it then is disposed to advance against the gum. In this case one of the subsequent methods should be pursued. If the fixation of the teeth be not firm they yield by a slight enlarge- ment of the arch and by closing the neighboring slight spaces. Immediate separations may be effected by mechanical separators, notably the William A. Woodward (see Fig. 105), for the front teeth and Fig. 105. Fig. 106. EIII1IH Woodward's separator. Perry's separator in conjoint use with matrix. the Perry (see Fig. 106) for the bicuspids and molars. It should be stated that each of these is preferably to be used when some previous space has been made by other means, following which a considerable increase of space may be secured by these appliances. Separation by the Swelling- of Fibrous Materials. — These act by the capillary force of water upon the fibrous structure of the material, whether pledgets of cotton or tape. This means is also more applica- ble when the fixation of the teeth is not firm, and has the advantage of being painless and more readily tolerated by children and by persons who are impatient of pain or of any form of dental distress. Pledgets of cotton are more applicable where a partial preliminary opening of a carious cavity has been made, and are more appropriate for the posterior teeth. Here, when there is no danger of pulp exposure, the pledgets may be packed with considerable firmness. In some instances it is advantageous to saturate the pledget with thin sandarac SEPARATION OF THE TEETH. 147 varnish, which attaches the fibers, but the time required is much in- creased, as the cotton yields to capillary attraction only as it loses the resin. Tape is more useful for the incisors ; it should be of linen and may or may not be waxed. Its entrance is facilitated by an immediate pre- liminary application of a wooden wedge. Caoutchouc — India-rubber. — When a strip of india-rubber is drawn into a close interspace the ' middle portion is constricted to great tenuity. The action is by the resilience determining the two exposed ends toward the middle, with the result that at length the space attains the size of the thickness of the strip. It will be perceived that the physical force is that of two opposed wedges acting with constant power. The effect is such that it overcomes the greatest resistance to separation of the parts and therefore is the most effective means which we have. Caution is required in the use of this material both as to the thick- ness of the rubber and as to its purity. The pronounced resilience of pure rubber is generally painful, and in most instances greatly so. The resilience can be reduced by employing adulterated specimens of the material. The white-rubber tubing of the shops cut longi- tudinally into various widths effects the object with less rapidity but surely, and generally without pain. The strip is drawn into position by a sliding motion, care being taken not to force the piece into contact with the gum. To prevent the rubber being conveyed to the gum as the space enlarges, a small portion should extend slightiy beyond the occlusal surface. As this kind of rubber is more difficult to introduce when the contact is close and firm, a previous partial opening should be made with a piece of rubber dam. This method has the value of pain- lessness, and also does not usually necessitate a period of rest after the separation has been effected. Red Base-plate Gutta-percha. — When it is desirable to gradually effect considerable spacing between teeth, where the carious cavities are deep with well-defined boundaries but not involving the pulp, the method of Dr. Bonwill, of packing the cavities and the existing space with a sufficient mass of this form of gutta-percha, produces expansion by the continued force of mastication driving the material upward. This method also has value in some instances where it is desired to force the gum beyond the cervical margins, and may be an acceptable sub- stitute for aseptic cotton for this purpose. Securement of the Space. — Should soreness of the teeth have been caused by the separation, a period of rest should be given the parts until the distress has passed over. It is, however, important that large spaces should not be long retained, since in some instances alveolar resorption 148 PRELIMINARY PREPARATION OF THE TEETH. may be induced by the continuation of the changed position. An inter- val of two days usually suffices for the pericementum to recover from the disturbance, when the restorative procedures may be conducted. The retention of the space may be effected with gutta-percha or with the plastic cements, — the first being suitable when an open cavity appears ; zinc phosphate when from the smallness of the cavity gutta- percha may not be readily retained. Oxychlorid of zinc should be used when the cavities are shallow but sensitive, — the reason for which will appear later. It is generally advisable' to introduce a thin wedge of wood at the cervix and in contact with the gum to prevent the re- taining material from impinging upon this tissue and to give a base to support the introducing force. Exposure of Cervical Margins. — When cavities extend beneath the gum, which frequently is the case when caries has recurred above the cervical margins of fillings, it becomes necessary to force the gum somewhat above the carious border. This should be done quickly rather than slowly, otherwise in adult subjects the continued pressure may arouse diffused inflammatory disturbance of the contiguous tissues. Generally it is preferable first to cut away the gum between the teeth with a straight, narrow bistoury, and gently force red gutta-percha against the gum, gradually moulding it to the form of the depression. Cotton pellets for this purpose are not admissible unless they are anti- septically charged, for which purpose an admixture of aristol with the cotton is the most suitable, since not being soluble in water it better maintains the asepsis. Cotton may be conveniently charged with aris- tol by saturating it with a solution of aristol in chloroform and allow- ing the greater portion of the solvent to evaporate before introducing the pledget. The solution of aristol in oil of gaultheria may also be used for the same purpose. When hypersensitiveness of the gum tissues exists it is admissible to paralyze the sensation with a suitable solution of cocain previous to introducing the pellet of either gutta-percha or cotton fiber. A four per cent, solution of cocain hydrochlorid applied upon cotton to the sensitive tissues will speedily relieve the condition. Adrenalin chlorid, 1 : 1000, combined with a weak solution of cocain, may be substituted for the above. CHAPTER VI. PRELIMINARY PREPARATION OF CAVITIES— TREATMENT OF HYPERSENSITIVE DENTIN BY SEDATIVES, OBTUND- ENTS, LOCAL AND GENERAL ANESTHETICS— STERILIZA- TION, WITH A BRIEF CONSIDERATION OF THE PHYSIO- LOGICAL AND THERAPEUTIC ACTION OF THE MEDICA- MENTS USED. By Louis Jack, D. D. S. Hypersensitive Dentin. Dentinal hypersensitiveness frequently presents the most serious impediment to the procedures connected with the treatment of dental caries. This condition must be considered an exaltation of the normal sensitiveness of the dentin, and presents a wide range from slight pain on contact being made to so high a degree of sensitiveness as to be un- endurable. In the latter instance persons of the greatest capacity for tolerating pain will shrink from the most careful instrumentation. Im- mediately upon the opening of a carious cavity there usually are indica- tions of excitement of the vital elements of the dentin. This con- dition may be so slight as to present no obstacle to further procedures, or it may on the other hand be so excessive as to forbid all instru- mentation until a reduction of the sensitiveness has been effected. This altered state of the dentin has been considered by some as one of inflammation of the dentin. As the opportunity does not exist for the usual concomitants of inflammation as pathologically defined and which are induced by the alterations of the circulation of the blood, viz. heat, redness and swelling, with exaltation of nervous function caused by the additional supply of arterial blood, the term inflamma- tion is a questionable one to apply to a hyperesthetic condition of dentin. This manifestation is more logically explainable as a disturb- ance caused by changed relations of a tissue which is naturally pro- tected by the enamel from irritating influences. The relation of the enamel and the dentin is analogous to that of the epidermal coat of the skin and the rete mucosum. Pain caused by abrasion of the epidermis is immediate and acute, and occurs before the increased supply of blood increases the intensity of it. It is hence induced by 149 150 PRELIMINARY PREPARATION OF CAVITIES, ETC. the altered relation of the mucosum. The analogy is further borne out by the fact that in each instance a protective covering affords salu- tary relief. The normal sensitivity of dentin is not high, as is shown by an immediate examination of a surface exposed by accident, but after a few days the denuded surface manifests impatience of mechanical contact and of applications of cold, which proves that the altered rela- tions induce a condition of the part similar to the condition of the skin when the epidermis is broken. This appears to be the case in- dependent of the influence of chemical agencies, as exaltation of sensi- tiveness occurs when the fluids of the mouth are in a normal state. The same indications are presented when a non-sensitive cavity is pre- pared, as here, in case the cavity be not protected by a stopping, the same phenomenon subsequently appears. Generally also, in such cases, if a stopping is inserted without pre- viously effecting a coagulation of the surface of the cavity, pain arises upon reduction of temperature. This condition is designated as sec- ondary sensitivity, which is caused by the traumatism. In some cases of this kind the pain becomes so great as to require the removal of the stopping and the carbolization of the cavity. In extreme cases reflected pain in the other teeth may appear in consequence of the disturbed relations making an impression upon the nervous elements of the pulp. When exposure of the dentin has been brought about by caries, the sensitivity excited is liable to be much exalted above the normal, and is only prevented from giving constant indications of this condition by the presence of the carious matter, which, being a poor conductor of heat, in a measure protects the pulp from thermal irritation and from mechanical contacts. This accounts for the fact that while there may some- times be acute pain in the early stages of decay of dentin, the irritability and reaction of the pulp appear to become less as the caries advances. When the teeth are undergoing rapid decay the dentin is more sen- sitive than when the carious process is slow. As the color of the carious matter gives some indication of the rate of progress, we may from this indication form an impression of the probable degree of sensitiveness. When the carious matter is light, the action has been rapid ; when it is yellow or light brown it is less active ; and when it is dark brown or black, it has progressed very slowly. In some cases of the last character, when the parts are subject to friction, spontaneous cessation of decay takes place. The parts are then nearly devoid of sensitiveness. The process by which the dentinal tubuli become oblit- erated by calcific deposits is called eburnation. When the dentin be- comes exposed by attrition, that tissue is not as greatly irritated as it is by the progress of caries, since by reason of the gradual loss of sub- HYPERSENSITIVE DENTIN. 151 stance changes take place within the tubules b) T which their capacity to convey sensation is diminished or obliterated as the case may be. When the gum recedes, exposing the cementum, a very high degree of sensitivity is often excited, which is prone to decline by spontaneous changes of structure. There is often here the added influence of acid conditions of the mucous secretions where they flow out upon the teeth at this point, and where, too, the parts are not easily cleansed. It is a notable fact in connection with cervical hypersensitiveness that while it persists these parts are less liable to decay than when loss of sensitive- ness here takes place. The area of hypersensitivity usually is not evenly distributed throughout the carious cavity, but has its chief seat near the line of union of the dentin with the enamel, thus bearing out the law that sensitivity is greatest at the terminal end-organs of the sensory nerves, with the further qualification that the more minute the fibrillse the greater may be the acuteness of the sensitivity. This fact is illus- trated by the example of cavities in the occlusal surfaces of the molars, which manifest pain only at the margins ; is only less evident in the cavities of approximal surfaces, and is strongly shown in the shallow buccal and labial cavities, which present their whole surfaces near the line of juncture of enamel and dentin. In most cases of caries, the zone of highest sensitivity is immediately beneath the soft portion of the decay, and when this layer of dentin is cut away the pain becomes less, in some instances approaching the nor- mal. This statement, however, has force only in the milder manifesta- tions of this condition. The Effect of Acid Conditions of the Oral Fluids. — In the pre- vious chapter some allusion was made to the fact that an acid state of the oral fluids is detrimental to the teeth as promoting carious action, and that alkaline or even neutral states have a retarding influence. Here it must be considered as an axiom that no cause is so active as a primary influence in inducing excessive dentinal sensitivity as a con- stant slightly acid state of these fluids ; and, conversely, that a neutral or slightly alkaline state is non-irritating. These conditions should be kept in constant view in dealing with this subject. The degree of sensitivity of dentin is modified by a variety of other general conditions. These are — relative density of the structure, rapidity of the carious action, and the constitutional peculiarities of the person which are connected most directly with nervous impressiona- bility to disturbances of the tissues. The rate of progress of caries exerts considerable modifying influence over dentinal sensitivity. When caries is of slow progress the amount of organic tissue exposed to irritation is comparatively small, for the 152 PRELIMINARY PREPARATION OF CAVITIES, ETC. reason that the well-known salutary and protective changes of structure go on coincidently with the slow inroad. The slight irritation of slowly advancing caries to some extent exerts a stimulating influence toward inducing tubular deposits. On the other hand, when the carious pro- cess progresses with rapidity, reparative efforts upon the part of the pulp are paralyzed, the organic elements of the tissue become denuded to a greater extent, and therefore sensitivity is increased to a propor- tionate degree. As these fibrillar elements are the means of extending the irritation to the pulp of which they are the peripheral prolongations, it is evident how important a factor the active advance of caries is, and also to what extent the rapidity of the process increases the morbid concomitants of dental caries. It has been pointed out that the area of hypersensi- tiveness generally pertains to a narrow line at the outer limit of the dentin, but in rapid caries this line is a broader one. The anatomical element of the dentin concerned with its sensi- tivity is contained within the tubuli. While the exact nature of the matter in these tubules has not yet been certainly determined, it has been shown to have sufficient consistence to permit of extension, as in separating sections under the microscope what appear to be fibers have been seen. Also the same appearance has been presented in fresh specimens when the pulp has been drawn away from the dentin. It is not difficult in reviewing these facts in connection with the various conditions and phases of dentinal sensitivity to conclude that the exalta- tion is inseparably connected with an irritated state of the tubular con- tents. The variation in the degree of sensitivity of different teeth of the same mouth — of those which are side by side and in a similar degree of progress of carious action ; the profound fact, heretofore stated, that the dentin at a short distance beneath the decay is much less sen- sitive ; that in some instances sedatives modify the degree of pain, and that coagulants produce a marked impression upon the capacity of the tubular contents to convey sensation, force by inference the conclusion that in diseased conditions this anatomical element is largely concerned in conveying impressions to the central organ of the tooth. It is also undoubted that unusually high sensitivity of dentin is an inherent constitutional condition with some persons, and that it pertains to some families apparently as an inheritance, but may be explained in these instances as the transmission of acute nervous impressionability. In connection with this subject should be considered the further observation that the temperature sense of the teeth is various; that with some the application of ice makes no impression upon the teeth when in normal condition, while with others in the same condition the least cold induces pain. It would further appear that the degree of sensitivity TREATMENT OF DENTINAL HYPERSENSITIVITY. 153 when caries occurs bears some relation to the relative tolerance of the teeth to reduction of temperature. On these premises it is not difficult to account for the manifestation of acute sensitivity, and to build thereon an hypothesis governing the various conditions presented by dentin when it is subjected to the irri- tation of the carious process. These views have steadily gained sup- port with the advance of microscopic study of the tissues, and have supplanted the older view that the sensitivity of dentin is a result of mechanical vibrations extending to the dental pulp. Treatment of Hypersensitivity of the Dentin. Having considered the general principles governing hypersensitivity of dentin, we are prepared to enter upon a study of the treatment. This is to be considered under the following general lines : namely, the therapeutic, the chemical, the anesthetic, and the mechanical. Treatment of Slight Hypersensitivity. — The first requisites to be observed here are a calm manner and earnest sympathy, accompanied with the assurance that if severity of pain occurs, mitigating means will be resorted to. It is an important and laudable object to remove dread and secure confidence, which is attained among other means by select- ing at first the simpler and less painful operations. When confidence is secured, slight pain arouses the courage of the patient. The effect of the opposite course of indifference and harsh cutting alarms the patient, arouses apprehension, and greatly increases the nervous exaltation. In the simpler cases sharp instruments used with quick, light, and rapid movements are called for. It should in this connection be noted that cutting in this manner stimulates somewhat the nervous force of the patient, and if the movements are in very quick succession they appear to paralyze the part; the pain is thus lessened in comparison with deliberate and slow instrumentation. The movements of the ex- cavators should be in a direction away from the pulp rather than toward it, and the cuts should be by drawing the points instead of pushing them ; this is for the reason that the pressure in the latter case is greater than in the former. When the sensitiveness is so great as to interdict immediate excava- tion and formation of the cavity, some method of treatment of the sur- face is required to overcome or to confine it within a tolerable degree. The Therapeutic Treatment. — Under this head the available reme- dies are morphin, veratrin, and cocain, — each of them being applied with glycerin as a menstruum. It should be stated that neither have much immediate effect, and therefore they should be sealed in the cavity after the opening in the enamel has been prepared, and the softer caries has been lifted and peeled off. The closure should be effected by 13 154 PRELIMINARY PREPARATION OF CAVITIES, ETC. means of gutta-percha, or with what is probably better, a thin paste of phosphate of zinc laid over the dressing. After some days the pain will be found diminished in many instances. The therapeusis is effected by the absorption of these sedatives by the partially disorganized tissues. Another method of applying cocain is to secure the cavity from the entrance of moisture, and after desiccating the surface a saturated pledget of vapocain, a solution of cocain in sulfuric ether, is introduced. As evaporation of the ether takes place cocain is forced by osmosis into the tissue. In cases of subacute sensitivity this means frequently is efficacious, but is of little value in hypersensitive conditions. It is advantageous as preparatory to this line of treatment first to neutralize the acidity of the cavity with an alkaline solution, which may be either ammonia, sodium carbonate, or sodium dioxid, afterward removing the excess of alkali by thorough washing with warm water. Treatment of Hypersensitivity of Dentin by Electrical Osmosis. Within a recent period a means of treatment of this condition has become prevalent which has been designated by the terms cata- phoresis, electrical diffusion, and electrical osmosis. It has been demonstrated that the action of electrical currents conveys fluids, with the substances held in solution, from the positive elec- trode toward the negative electrode. Further, that an electrical current passing through a membrane accelerates the natural process of osmotic diffusion if the positive pole is applied on the side of a membrane or tissue from which the osmotic diffusion is taking place ; in case the situation of the poles be reversed, the osmosis is retarded or prevented from occurrence or is reversed. This action bears some analogy to that which takes place in electro-metallurgy when a metal in solution is conveyed from the anode (positive pole), and is deposited upon the cathode (negative pole). If the current be reversed the deposited metal is again taken up by the solution and is conveyed back again to the other pole. This is a law connected with the passage of electrical currents through fluids which are capable of con- duction. The following will illustrate the action which takes place : " If two compartments separated by a membrane are filled with a fluid and in each an electrode is placed, there is a streaming of the fluid through the septum from the positive to the negative pole, so that in time there is an increase in the negative side. This osmotic action, as is well known, occurs naturally between two fluids of unequal density from the lighter to the denser liquid, but if the anode is placed in the denser liquid DENTINAL ANESTHESIA BY ELECTRICAL OSMOSIS. 155 and the cathode in the lighter the natural osmotic current is not only overcome but is reversed." If a substance containing water, as a ball of wet clay or a piece of muscular tissue, have an anode connected with a current of sufficiently high potential attached to one side, with a cathode attached to the oppo- site side, the watery contents of the substance are conveyed to and appear in excess on the cathodal side ; at the same time the anodal side be- comes less damp ; also, if a capillary tube be filled with water and an anode and a cathode be similarly arranged, the water flows toward the cathode. As a membrane or tissue may be considered to be a series of tubes in close contiguity, it is apparent that the movement of fluids must take place through them in the direction the current is passing. These examples are an expression of electrical force. The applica- tion of this law of the passage of fluids from a higher to a lower elec- trical potential is the fundamental process which is employed in electrical diffusion of medicaments. The depth to which medicaments may be conveyed depends upon the conductivity of the tissue and that of the medicament which is being applied. " The cataphoric action of electricity has often been made use of experimentally to introduce drugs into the system through the skin. In man quinin and potassium iodid have been thus introduced and subsequently been detected in the urine." As early as 1859 Dr. B. W. Richardson used this process to pro- duce local anesthesia, and completely demonstrated its power in this direction. It has also been clearly proven that when a solution of cocain is applied to the skin, its characteristic action upon the mucous membrane will not here take place. But when the anode is wet with the solution and a galvanic current is passed through the epidermis to the cathode, placed upon an indifferent surface, anesthesia is effected over the surface covered by the anode and to an indefinite distance inward. This effect is not produced by the current alone, which has been abundantly proved by conclusive experiments, these having been fol- lowed by demonstrations confirming the above statement. When the medicaments so applied have anesthetic or analgesic properties their characteristic effects are produced. When this principle is applied to the transfer of medicaments it is found that they pass for an indefinite distance into the contiguous tissue along with the current from the anode toward the cathode, but with some degree of diffusion ; the diffusion depending upon the resistance of the tissue and upon the extent of the surface of the cathodal (nega- tive) electrode. 156 PRELIMINARY PREPARATION OF CAVITIES, ETC. GENERAL PRINCIPLES INVOLVED IN THE METHOD. The application of electricity requires the consideration of the ' general principles or laws governing its transmission. The source of this force is to be found in chemical transformation. Under the laws of the correlation of force it is capable of being con- verted into heat, light, magnetism, and mechanical power, and may be used to disorganize substances, when its action is called electrolysis. Its movements are constant in their direction, viz. from bodies of high to those of low potentiality. In perfectly conducting substances electricity moves with entire free- dom under any electro-motive force however small. In perfectly non-conducting substances electricity will not move under any electro-motive force however great. In imperfectly conducting substances electricity moves only on the exhibition of intense electro-motive force, the force varying according as the substance is a more or less indifferent conductor. Electricity has two elemental properties. These are denned as cur- rent strength, designated by the term amperage; and electro-motive force, which is termed its voltage. The active energy of electricity depends upon the first property, its distribution upon the latter. Since it must be assumed that few bodies are perfect conductors, this force or pressure is of that degree which may be required in any given case to move the active energy, the amperage, against the resistance it meets with. The unit of strength is the ampere. The unit of pressure is the volt. The unit of resistance is the ohm. The unit of power is the watt. A volt represents the electro-motive force (E. M. F.) required to impel one ampere of current through one ohm of resistance. 1 An ampere of current is so much as will deposit 0.00118 gram of silver per second when passing through a standard solution of nitrate of silver — or which will decompose 0.09326 milligram of water in one second. Hence the ampere is the measure of rate of flow of an electri- cal current, and in connection with the voltage measures the energy of the current. The unit of resistance (ohm) is that degree of resistance which will permit the passage of one ampere of current at one volt of pressure. The watt is the power exerted by one ampere of current at one volt of pressure. In the economic application of electricity its transmission is effected DENTINAL ANESTHESIA BY ELECTRICAL OSMOSIS. 157 through metallic conductors. The resistance of these is varied by the character of the metal, the cross section, and the distance. For certain purposes other substances are employed to effect greater resistance than the metals. The current strength flowing in a circuit is equal to the pressure divided by the resistance. The resistance equals the pressure divided by the strength. The pressure equals the strength multiplied by the resistance. In elementary terms : Amperes = volts -s- ohms. Ohms = volts -s- amperes. Volts = amperes X ohms. Watts = volts X amperes. It follows from the formula that the amount of power and the cost of producing it is the same whether the current is of large amperage at low voltage or of small amperage at high voltage. Thus an incandes- cent lamp may be supplied by 100 volts at ^ ampere or by 50 volts at 1 ampere — the result in each case being 50 watts. Comparative Illustration. — Given a current of 100 volts at fifteen amperes, and we wish to use only ^ ampere, the resistance to be put- in the circuit is found thus : 100 v -*- 2^ a = 40 o. In case we have 2-| amperes under 7 ohms resistance, it requires 17 J- volts to move this degree of amperage through the given resistance, thus : 2}aX 7r = 17}v. If one has a current of 110 volts, and de- sires to use a J-horse-power motor, the least amperage required is ly/o"? which is found by dividing 186 watts by 110. These examples make plain the means of determining the character of current required for any given purpose. Electrical force may be produced from its source in galvanic cells by arranging them in series or in multiple. If in series the voltage is the sum of the volts of the cells so arranged, and the amperage is that of each of the cells. If joined in multiple, the strength in amperes is the sum of the amperes of the cells, and the voltage is that of one cell. Fig. 107 * represents the arranging of cells in series, the positive of one with the negative of the next. In case each cell has a voltage of 2 and an amperage of 1 the electro-motive force of 5 cells will be 10 volts at 1 ampere. Fig. 108 2 represents the joining of cells in multiple. Here all the x See Dental Cosmos, December 1896, p. 998. 2 Ibid. 158 PRELIMINARY PREPARATION OF CAVITIES, ETC. positive elements are joined together and similarly all the negative to eaeh other. The voltage now is 2 and the amperage 5. Fig. 107. The former method of assembling the cells is designated as "high tension," the latter method as "low tension." When the source is the Fig. 108. + dynamo, high and low tension are produced by the strength or weakness of the magnetic field. For electrical osmosis the source should be from batteries in series, for the reason that in multiple the amperage would be too great when the voltage is of sufficient force to overcome the resistance. The degree of electrical energy tolerated by living dentin is exceed- ingly small, on account of the peculiar and intense pain excited by the transmission of electrical currents through the teeth. This is shown by the low initial voltage of the batteries used for the purpose, varying from less than 5 to rarely more than 20. But the initial passage of a current of as high electro-motive force as these Avould not be tolerable, and must therefore be reduced by suitable methods of effecting re- sistance. The apparatus used for this purpose is the controller, the purpose of which is through its resistance to diminish the energy of the current to sufficient weakness to meet the requirements of any given case. All forms are constructed on the principle of the use of materials which are highly resistant of the passage of electric currents. These substances DENTINAL ANESTHESIA BY ELECTRICAL OSMOSIS. 159 are water, carbon, graphite, and coils of wire of known high resistance, the most effective being of German silver. In the case of the latter the degree of resistance is regulated by the length and fineness of the wire, the cross section being reduced to the size which will conduct the cur- rent without excessive heating, and to that end it is graded with refer- ence to the initial amperage of the current. In comparison with silver as a unit German silver has a resistance of 13.92. The carbon and graphite controllers usually are constructed in the form of a broken ring — one pole of the battery being connected at one end of the ring, the other pole being attached to an index which travels over this annular disk. This method of construction gives a fine grada- tion of current with high resistance. It may be used in connection with a German-silver wire rheostat, where currents of great strength are used for reasons which will appear later. In the use of high-voltage cur- rents, such as the 110-volt circuit, it may be switched through the coils to a nearly definite low voltage by means of a rheostat, when the adaptation to the case may be effected through the graphite con- troller. In the arrangement of the apparatus to effect electrical osmosis the battery, the controller, the instruments of observation, and the patient are in series. In the analysis of the course of the current it appears that the patient is another element of resistance, and that dentin is more highly resistant than the other tissues. In other words, there are two resistances in the circuit — the controller and the tissues of the patient. The result of the resistance of the dentin, unless the initial voltage is small and is reduced by the controller to an infinitesimal degree, is the occurrence of pain, which takes place with different persons at various degrees of amperage. The approach to intolerance of the current is designated the " pain limit." This condition has been assumed by some observers to be caused by the evolution of heat in the dentin con- sequent upon the resistance of this tissue. This view is not now con- sidered to be conclusive, as the calculated elevation of temperature at -^ milliampere is not sufficient to account for the degree of irritation which occurs on increasing the rate of flow. This determination leaves two other hypotheses to account for the irritation : a, the ten- dency of the current to disorganize some of the anatomical elements of the canaliculi ; and b, the osmotic pressure of the migration of the medicaments. Here the student is not confused with consideration of the complicated forces which are in action connected with the electroly- sis of the cocain solution. 1 The pain limit is variable with different persons, and in different 1 See " The Foundation Principles of Dental Cataphoresis," Items of Interest, vol. xx. p. 345 et seq. 160 PRELIMINARY PREPARATION OF CAVITIES, ETC. teeth of the same person. With some it is reached with the first influx of the current at low voltage with a record of ■£$ milliampere, this low record indicating high resistance of dentin and permitting but- slow increase of the force until after cocain has diminished the sensitiv- ity of the irritated surface. With others the pain limit may not be reached with a voltage of 20 and a recorded amperage of T ^ to -^ milli- ampere. In respect of electrical irritation there must be taken into account also the high nervous sensitivity of some persons, as with these there usually appears greater susceptibility to electrical irritation. The following table of calculated resistances shows the resistance in ohms, and the liability to the generation of heat in the dental tissues in view of their density, or the tendency to disorganization as previously stated, and it suggests that care be used in the application of electrical force for the purpose under consideration. With 15 volts initial pressure at T 4 „ milliampere in circuit the ohms are 37,500. 15 1 tt \ < a 150,000. 10 A n < I it 25,000. 10 I tt 1 TO tt i a 100,000. 5 i a 4 To it I t it 12,500. 5 i it i TO tt t i it 50,000. As the resistance of the body including the dental tissues varies from 10,000 to almost 70,000 ohms, it would appear necessary that the con- troller should have at the highest point a resistance of not less than 400,000 ohms. This degree of resistance is required to obviate the effect of impulse which may occur in closing the circuit. Occasionally slight shock is felt at 500,000 ohms. The varying resistance of the current through the tissues depends upon the density of the dentin, the distance traversed, the condition of the surface of the skin, and the thickness of the adipose tissues. The average resistance of the patient as recorded by Dr. W. A. Price is about 25,000 ohms from cavity to hand, and the difference of resistance from tooth to hand and cheek to hand is from 3000 to 5000 ohms. He reports one case where the resistance from cavity to hand with a 40 per cent, solution of cocain was 28,500 ohms, which on placing the pad on the cheek was reduced to 23,000 ohms. Dr. Price further places the average resistance from hand to tongue at 9000 ohms, and from cheek to tongue at from 3000 to 7000. This would make the resistance of the dentin nearly 20,000 ohms. An exact determination of the resistance of the skin in any given case would enable a very close approximation for the dentin to be calculated. The condition of the cavity as to relative moisture and the degree of saturation of the pledget of cotton containing the anesthetizing agent DENTINAL ANESTHESIA BY ELECTRICAL OSMOSIS. 161 as well as the percentage of the medicament exert a considerable quali- fying control of the resistance, as appears from the experiments of Dr. Price. When a section of dentin partially dry on the surface had a resistance of 30,000 ohms, after being dried and saturated with a 40 per cent, solution of cocain the resistance was reduced to 4500 ohms. The principles here stated and the facts presented apparently demon- strate the importance of careful selection of the degree of voltage at the battery ; of the use of a relatively low amperage to the voltage ; of the necessity of controlling the current within the boundary of the pain limit ; of the importance of avoiding impulses of current by rapid advancement or by movements of or displacements of the anode ; and of attention to the maintenance of a constantly moist state of the anodal and cathodal contacts. These principles and facts have led to the application of galvanic currents for the production of a state of anesthesia of hypersensitive dentin ; and the results of experimentation in this direction have proven that the same effects have followed here as have occurred in the softer tissues. The extreme sensitiveness of the teeth to electrical currents and their resistance to the passage of electrical force were obstacles to the earlier application of this method of treatment in dentistry. The absence of means to control the current strength (the amperage) and to reduce the pressure (the voltage) to the capacity of the teeth prevented experi- mentation in this direction until within a comparatively recent period. It follows from the above statements that the current strength that is tolerable at the commencement of the application is so small as to be scarcely measurable in many instances. To produce this small current, either the battery voltage must be low or the resistance in the controller exceedingly high. Any form of battery which is constant when the amperage of the individual cell is from one-fourth to one-half of an ampere will have sufficient current strength. The E. M. F. may be 'from one to two volts per cell. The voltage required to produce the necessary electro-motive force in an application to the teeth to produce dentinal anesthesia varies from five to thirty. For children and where the teeth are apparently not dense, ten cells sometimes are sufficient, but generally fifteen to twenty are needed. The cells should be arranged in series and connected in a manner which enables the selection of any number to produce the re- quired E. M. F. for any given case and to permit an increase of cells during the administration. The most important condition of the electrical force for the purpose is that the amperage shall be inconsiderable, since high amperage is intol- erable to the teeth. As the most efficient results are produced when the ii 162 PRELIMINARY PREPARATION OF CAVITIES, ETC. recorded amperage is not over three-tenths of a milliampere, the use of a current of high amperage is unnecessary, and it is attended with distress. High voltage is equally painful, as the endeavor to force the current against the resistance of the dentin results in electrical irritation, as already described. The chlorid of silver cell is probably the one best suited for the purpose, as its electro-motive force remains practically constant under various conditions. The E. M. F. of each cell is about one volt ; the internal resistance eight ohms ; the strength one-fifth of an ampere. This battery on account of its constancy and durability is largely used in electro-medical apparatus. It is now furnished dry, and is more acceptable as being less troublesome on this account. The dry Leclanche battery is also one of the best forms, as it is an open-circuit battery. As long as the circuit is open there is no action in the cell and consequently there is no loss. At present these two forms of galvanic battery cell appear to be the kinds best adapted for the purpose of inducing electrical osmosis. The life of a chlorid of silver dry cell battery is stated to be 700 hours of cataphoric work under a high resistance of tissue, but it must be remembered that the continuance of energy of all forms of battery is varied by the resistance and the conversion of electrical energy into heat by the controller which regulates the amperage and the voltage. This principle applies to all sources of electrical force. The controller which at present appears best adapted to be interposed between the battery and the anode is the Willms controller, which, as before stated, should be constructed with a resistance at the highest point of at least 400,000 ohms. The gradations of resistance decrease from this through 112 contact points. These permit a very gradual reduction of the resistance as the switch is conveyed from point to point in the circle. This controller also has the advantage of being moderate in cost and easily procurable. An important adjunct of any apparatus is a reliable milliamperemeter. This should have a scale to record divisions of fortieths of a milliampere, from the fact that the amperage of the current through the dentin is fre- quently efficient at less than two-tenths of a milliampere. The milli- amperemeter also aids in detecting leakage of current, as where the indicated amperage exceeds four-tenths milliampere there is reason to suspect imperfection of the insulation of the tooth. In this case a longer period than usual will be required to effect the anesthetization, and the degree of this effect may be less. The use of the direct current generated by the dynamo is of ques- tionable utility as compared with the current from a battery. The DENTINAL ANESTHESIA BY ELECTRICAL OSMOSIS. 163 current from the dynamo is subject to changes of voltage and the amperage is liable to fluctuations consequent upon alterations of the load in the general circuit. This instability causes a series of pulsat- ing shocks upon sensitive dentin and the pulp, which react with the expression of pain. The possibility of the transmission of severe shock through accidental grounding or defective apparatus where such excessive voltage is used is another and sufficient reason why the steady and low-voltage current of a battery is preferable for this class of operations. TECHNIQUE OF THE ADMINISTRATION. At the present period cocain has been found to be the most effective anesthetic for obtunding dentinal sensitivity by electrical osmosis. It is used in strength varying from 12 to 24 per cent., and by some as high as 40 per cent, has been used ; li grain of one of the salts of cocain added to 5 minims of water procures a solution of 24 per cent. ; to 7-J- minims, 18 per cent. ; to 10 minims, 12 per cent. The salts of cocain which have been used are the hydrochlorid and the citrate. Each is efficient in the strength stated. The resistance of cocain citrate is for 12 per cent, solution 234 ohms ; for 24 per cent. 153 ohms. The resistance of cocain hydrochlorid is for 12 per cent, solution 80.85; for 24 per cent. 61.25. These provings indicate that the hydrochlorid is the better salt of cocain for the purpose. 1 The tooth to be operated upon is isolated, by means of a rubber dam and is ligated at the cervix to prevent leakage of current. If there are metallic fillings in the tooth, these should be covered with a coat of varnish carefully laid on and dried. This precaution does not always possess the value claimed for it, as the dentin beneath a metal filling, because of its density or lack of porosity, will not convey the current as well as the carious matter and the softer dentin of the fresh cavity. In some cavities where caries has occurred at the cervix above gold fillings, and which do not permit of complete isolation of the fillings, the cataphoric influence is not interfered with. The carious matter should not be completely removed and need only be partially dried. The cavity is loosely filled with a small pledget of lint saturated with the solution of cocain. The anode, the point of which is of platinum, is covered with a thin stratum of lint which is dipped in the solution and inserted in the cavity in contact with the pledget previously introduced. The cathode, which should be at least one and a half inches in diameter, is placed at a convenient place on x The writer is indebted for the determination of these resistances of cocain solutions, etc., to Mr. A. W. Schramm, of the University of Pennsylvania. 164 PRELIMINARY PREPARATION OF CAVITIES, ETC. the face or neck. The desired number of cells are placed in circuit with the controller at zero. All being ready, the switch is placed on the first contact point. At this moment, however great the resistance of the controller, a slight sensation is sometimes experienced, but at once the switch may be passed slowly over the contacts until some sign from the patient indi- cates that the current is being felt. Here it is retained until subsidence of the sensation occurs, when the resistance of the controller should be very gradually lessened. This process is continued, keeping con- stantly within the limit of pain ; at length the switch may be more rapidly advanced to the last pin. When this can be done without thrill, the indication is that anesthesia is complete. The switch is then carried back to the zero point, when the excavation may be conducted. Where it is necessary to remove the rubber (as the solution of cocain is strong) the preparation should be previously washed away to prevent any of it from being swallowed. The 'period of administration varies from eight to fifteen minutes in ordinary cases where the indicated amperage is from -^ to t 2 q- milli- ampere. When, however, the dentin is dense, as where denudation has taken place by attrition, a longer time is required to effect penetration by the cocain. Also where from any condition the indicated amperage at first is -fo milliamp&re or less, time and patience are demanded. The loss of time is more apparent than real, since there usually is a direct relation between the pain limit at very low amperage and high sensitivity ; what is apparently lost in the time of the application is gained in the after facility of instrumentation. The sphere of the action extends throughout the cavity, but to a somewhat less degree at the extreme lateral margins, and more particu- larly at the occlusal margin. Here usually no more than a normal degree of sensitivity is found, which appears to be due to the fact that in making the retentive undercutting this procedure may extend beyond the sphere of the complete influence of the cocain. The effect is most pronounced when the application is made directly to the carious matter. In this case the diffusion is greater than when the caries is freely re- moved, for the reason that in the latter case the current seeks the line of least resistance toward the pulp. It follows from this that when all parts of the cavity are equidistant from the pulp, the action should be more effective throughout upon the surface of the dentin. This is proven to be the case from the profound effect in cavities upon buccal and labial surfaces and in shallow cavities of occlusal surfaces. Besides the less diffusion of the cocain when the carious matter is removed, a degree of electrical force which in the former case is easily tolerated DENTINAL ANESTHESIA BY ELECTRICAL OSMOSIS. 165 becomes painful. These facts mak^e conclusive the importance of retain- ing some of the carious contents of the cavity. An explanation of the influence of the current is found in the prin- ciples and examples given on page 154. As the anode is put in con- nection with the lint saturated with the cocain solution the fluids of the tooth advance toward the pulp through the canaliculi, their place being taken by the solution of cocain. At the same time it is observed that loss of fluid from the lint occurs, necessitating additions to maintain the proper wetness, some loss of water taking place by evaporation. Conditions Influencing Tolerance of the Current. — As already stated, when the electrical force is brought into connection with the carious matter the irritation caused by the current is of trifling degree and soon subsides, indicating that the anesthetic effect has been produced ; but when the cavity is denuded of caries the above-stated degree of current force is not so tolerable, the irritation continues longer and does not subside in the same manner, but the effect upon the tissue is nearly if not quite as marked. The nearer the bottom of the cavity is to the pulp, the greater the irritation. Hence in this condition it becomes necessary to begin with a low degree of voltage. While in the one case fifteen cells may be selected, in the other ten cells are more satisfactory. To avoid the removal of caries the condition of the dentin as regards sensitivity should be tested at the line of its connection with the enamel. Some stress has been laid upon the necessity for rendering the solu- tion of cocain more highly conductive. This claim is probably more theoretical than practical in its character, since experience with the solutions given indicates that the conductivity is sufficient, and that the resistance is more to be looked for in the dentin than in the solution, and that when the tooth has become tolerant of the current at a com- paratively low voltage an increase of pressure of the current is suf- ficient to complete the anesthesia. The form of the platinum anode should be such as to permit its easy entrance into the cavity when its point is covered with a layer of absorbent lint. For all cavities in the approximal surfaces and in most occlusal positions an excellent form of anode is made by curling the end of a fine platinum wire (No. 25) into a flat knot, or forming it in a loop. On the loop a properly sized piece of lint may be gathered. This may be packed into the cavity and secured with additional lint when required. This method is a self-sustaining one. The connection between the free end of the anode and conducting cord is made with a spring clip, as shown in Fig. 110. 166 PRELIMINARY PREPARATION OF CAVITIES, ETC. For labial and buccal surfaces two or more small points to screw into a common handle are sufficient (see Fig. 109). These have to be Fig. 109. Dental anodes for cataphoresis. held in situ. A form and arrangement to make these self-sustaining offers an important field for inventive skill. Fig. 110. Snap and wire electrode. A convenient cathode electrode is shown in Fig. 111. In this the surface is recessed to receive a disk of amadou (spunk) or cottonoid, Fig. 111. Cathode for cataphoresis. one and a half to two inches in diameter, which retains an abundance of a solution of sodium chlorid to maintain contact. The surface is platinized to prevent corrosion. The reverse side has the usual socket to receive the conducting cord, which is placed in a projection intended to pass through an opening in the band which supports the rubber dam. It is indifferent where this electrode is placed ; the objects to be attained are to lessen the resistance as much as possible and to secure constant apposition with the surface with which it is connected. If the person be comparatively lean, the face before the ear is to be preferred. When there is much adipose tissue on the face, the usual negative hand electrode, covered with a small wet napkin to maintain close contact, may be better than the application to the face ; but in general the nearer DENTINAL ANESTHESIA BY CHEMICAL AGENTS. 167 the cathode is placed to the angle of the jaw, the quicker and surer is the result of the administration. The action of cocain administered in this manner is profound. The effect is primarily upon the contents of the canaliculi, as is shown in the cataphoric treatment of shallow cavities. After superficial anes- thesia has been established much lateral cutting will later elicit a degree of pain ; in deep cavities nearing the pulp, the effect extends to that organ. The recurrence of sensitivity takes place within a few hours. No injury appears to follow. This method of treatment is little required where the degree of hypersensitiveness is such as to yield to desiccation of the dentin or the application of carbolic acid combined with caustic potassa (" Robin- son's Remedy "). But when the pain attending excavation requires active treatment, such as the employment of zinc chlorid or general anesthesia, the cataphoric method is far preferable to either, and is nearly certain to give relief. The condition where cataphoresis is most required is when the impatience of the dentine to mechanical irri- tation is extreme. Usually in this case the condition extends deeply. The results of successful cataphoresis are marvellous, and it may be truly stated that no advance of recent years in the therapeutic treat- ment of the teeth is comparable to this. 1 Cautious excavation is required after cataphoric treatment, as in the absence of sensitivity indiscriminate cutting may needlessly encroach upon the pulp. In case exposure really exists the action of cocain does not prejudice conservative treatment of the pulp. When devitalization is determined upon, the anesthesia facilitates this procedure. As stated in Chapter XVI. cocainization may be then continued either cata- phorically or by instillation. Should arsenous acid be selected as the devitalizing agent, cocainization may be used as a preparatory measure to lessen arsenical irritation. The Chemical Treatment. Under this head are included the application of warmed air, the use of coagulants, notably carbolic acid or zinc chlorid, and, in combination with these, one of the essential oils, preferably oil of cloves, for reasons stated below. Warmed Air. — This method is of great value in subacute cases. It is especially serviceable for the cavities of incisors and biscuspids and others of easy access. The effect here produced is due to the depriva- 1 For further study of this subject, see " International System of Electro-Thera- peutics," Section C, p. 1 et seq., Peterson; also, "Foundation Principles of Dental Cataphoresis," by Dr. Price, Items of Interest, vol. xx. p. 345. 168 PRELIMINARY PREPARATION OF CAVITIES, ETC. tion of the tissue, to a greater or less degree, of one of its elements, viz. water, and it is more effective in teeth of dense structure, since the sur- face of these is more easily desiccated than the softer teeth. If it were possible to remove all the water of the tissue from the surface to the depth of the irritated part all sensitivity would thereby be overcome, but generally this can be only imperfectly done ; nevertheless, the benefit is generally considerable. This means is easily and quickly applied, and as it presents the simplest method in the cases where it is applicable it forms therefore the easiest and most available procedure for this purpose. The warmed air may be produced by heating the bulb of a warm- air syringe (Fig. 112) over a lamp or Bunsen burner, when a continu- Fig. 112. Warm-air syringe. ous stream of air is forced through the nozzle into the cavity. Some tact is required to deliver the heated air in a manner to cause the least pain by its impingement. If the nozzle be held too far away from the tooth the stream of air in passing through the atmosphere takes along with it so much of the surrounding cool air as to cause pain, and if held too close the heat is equally painful. In all cases the abstraction of the water, even when the degree of heat is well balanced, produces some Fig. 113. Electric warm-air syringe. unpleasant sensation, which soon passes away and after a few moments the case is reduced to a state of slight and simple sensitiveness. The DENTINAL ANESTHESIA BY CHEMICAL AGENTS. 169 blast should be gently applied at first at intervals of a couple of sec- onds ; when the pain induced by the abstraction of the water some- what diminishes, the force should be increased and made continuous, when in most cases the excavation may be continued. The air may also and preferably be heated by an electric warm-air syringe (Fig. 113), which has the advantage of maintaining an even degree of heat. As stated before, this means is of less use with soft teeth, and fre- quently fails when the teeth have a high grade of sensitivity which appears to be due to constitutional conditions, — where the sensitivity is not confined to the surface of the tissues immediately beneath the caries but pertains to the whole of the dentin. Preparatory to the use of heated air, the application to the cavity of absolute alcohol is serviceable, on account of its high affinity for water. Carbolic Acid. — This substance, while of little efficiency in con- trolling acute sensitivity, is of benefit in moderating that condition. Its efficacy is increased by adding to it a proportion of one-third of oil of cloves, which latter has some anesthetic influence. When other more active means are not admissible and the effect is not immediately satisfactory, a better result is produced by placing this combination in the cavity and sealing it in with zinc phosphate until a subsequent visit, as before described. On account of the feeble affinity of carbolic acid for water, the obtundent effect is facilitated by the previous partial desiccation of the surface of the cavity by warm-air blasts. Carbolic acid in combination with caustic potassa, equal parts of each (Robin- son's Remedy), is often of much service in subacute sensitivity. The preparation should be laid in the cavity in contact with the denuded dentin and should be allowed to remain until it deliquesces. Carbolic acid in combination with tannic acid is also serviceable when sealed in the cavity by an impermeable temporary stopping. Zinc Chlorid. — Of all substances, when not interdicted by proximity of the dental pulp, zinc chlorid is the most efficient of the topical remedies for the condition under consideration. Its action is explained by the double power of its affinity for water and its extreme coagulating effect upon albumin. It is evident that if the tissue be deprived of two of its elements the function of sensitivity must be impaired or destroyed. In the degree to which this action takes place the tissue loses its capacity for irritation. As zinc chlorid in concentrated solution is an active escharotic to organic tissue, it must be employed with caution. After paralyzing the vital resistance of the part its action is by combining in definite propor- tions with the albuminous elements of the structure. It has the fur- ther property of an excessive affinity for water, which enables one to 170 PRELIMINARY PREPARATION OF CAVITIES, ETC. arrest its action by sufficient irrigation to remove all traces of the salt from the cavity. Its active coagulating power renders it a valuable agent in excessive dentinal sensitivity where there is not close proximity of the pulp, and its safety is ensured by the facility with which any re- mains of the salt may be taken up with water. Unless employed in excess and too long continued the action of the zinc chlorid does not pass beyond the zone of the exalted tissue, which, as we are aware, generally is of limited depth. The cessation of the pain produced by it indicates the time for its removal, when usually the dentin will be found to be insensitive. There are instances, how- ever, when no apparent effect is produced, which can only be satisfac- torily explained on the ground that the vital resistance of the tissue is sufficient to overcome the coagulative power of the zinc salt. In general, zinc chlorid must be regarded as an entirely safe agent if used with discretion. It is more applicable to shallow cavities which are so situated, or are of such form, as to require much formative cutting at the margins of the cavities, as in buccal and labial surfaces and in the very superficial cavities of incisors and bicuspids. A warning, however, should be presented that as the pulp cornua of incisors frequently pro- ject near the surface, particularly in the young subject, considerable care is here required in any but shallow cavities of decay. If it were used in excess and its action extended there would always be danger, as its energies would not cease until the affinities of the whole amount were satisfied. In deep cavities the effect, particularly in soft teeth, would eventuate in the ultimate devitalization pf the pulp. It fol- lows, therefore, that it would be improper to seal up any quantity of this substance in a cavity. The action of zinc chlorid is terminated when the excess is removed and the cavity irrigated with water. The affinity it has for water quickly removes the excess and soon deprives the tissue of the remain- ing portion. When cavities are deep and it is found necessary to resort to this agent the surface of the deeper parts should be protected by an insoluble coating, after which the margins, where the sensitivity is acute, may be acted upon without detriment. Here it is requisite to remove the deep caries, desiccate the surface and make a coating with a varnish. For this purpose red gutta-percha rubbed in chloroform is applicable, since it may be deftly applied to any given part and when the chloroform has escaped is protective. To properly apply zinc chlorid it is highly important to isolate the tooth by means of rubber dam to protect the gum and to prevent the entrance of moisture. Its affinities for water are so great that even the vapor of the mouth dilutes it so much as to lessen its power. The DENTINAL ANESTHESIA BY CHEMICAL AGENTS. 171 form in which it is best to employ it is the saturated deliquesced salt, which is taken from a bottle containing the salt in excess. The fluid is introduced on a pledget of cotton and is permitted to remain until the pain occasioned by it has ceased. It will be found that there are two periods of pain : the first from its irritation of the fibrils in the bottom layer of the caries, and then again when it has reached the zone of exalted dentin a little beneath this ultimate layer of decay. It folloivs, if the caries has all been previously removed and the sensitive tissue interdicts further cutting, that but one period of pain is encountered. The cutting should therefore be deferred until after the second period of pain has passed. The disregard of this considera- tion has sometimes cast discredit upon the efficiency of this sovereign remedy. It is requisite that the chlorid be chemically piwe, and the fused form is preferable to the crystals of the shops. The paix attending the application is sometimes extreme for a mo- ment. This can be moderated by air-drying the cavity and dressing it with carbolic acid, which does not seem to prevent the action of the chlorid. To avoid the loss of time which may be occasioned by the slow action it is advisable, after securing the dam at the neck of the tooth by a ligature, to very tightly tie the free portion of the rubber a short distance from the tooth with a strong ligature, and after cutting away the excess of rubber some other service may be rendered. When the pain has ceased the case may be proceeded with, or the excess of chlorid may be thoroughly washed out and the cavity temporarily closed until a subsequent time. Another method of securing the action of zinc chlorid is to make a paste of zinc oxy chlorid and fill the cavity with -it. Even after crys- tallization of the paste takes place it contains a slight excess of the chlorid, which slowly acts upon the hypersensitive tissue. This method, however, is not adapted to deep cavities, and care must be exercised con- cerning its use in teeth of inferior grade. Zinc chlorid is an extremely valuable remedy when the previously described agents prove insufficient or are not indicated. Conditions which render Zinc Chlorid inadmissible. — It has been stated that the chief danger of its use consists in the liability of the coagulant and escharotic action reaching the pulp in deep cavities. This danger is further enhanced when the teeth are soft, as in this con- dition the penetration is liable to be greater than would be the case with dense dentin. The same caution must be observed when the structure is incomplete, as it is in the teeth of young subjects. Even here, as extreme sensitiveness is always found at the peripheral limits of the 172 PRELIMINARY PREPARATION OF CAVITIES, ETC. tubules, it is not difficult to limit the action to this part by the means above pointed out if care be taken in the required procedures. The Acids. — Chromic and nitric acids are of service in extremely shallow cavities of very high sensitivity. The former acts by coagula- tion of the organic elements of the dentin and the latter by decomposi- tion and solution. To apply these the adjacent tissues require to be protected. Each should be carried in small quantity upon a gold probe. Silver nitrate is applicable for reducing the sensitivity of dentin after the removal of superficial caries or when by abrasion or by erosion the exposed tissue is intolerably sensitive. It is, however, only to be used in the back of the mouth, on account of the discoloration which it produces. Antimony chlorid is applicable only to cases of exposed cemen- turn, where it is claimed that it is equally as efficient as silver nitrate, and has not the objection of discoloring the tissue. General Anesthesia. While some reluctance should exist as to the propriety of inducing general anesthesia, it sometimes becomes necessary to resort to this means of alleviation. Necessity for this election arises where the sen- sitivity is extreme, when the previous remedies have been inefficient, and when from the nature of the case zinc chlorid is inadmissible. The subjects should generally be adult persons of intelligence, who possess moral force and, having confidence in their adviser, are capable of giving the requisite indications of the progress of the anesthetic influences. Sulfuric ether is the most suitable anesthetic to be employed, and the operative procedures should be performed in the first stage, that of peripheral anesthesia. At this period, which is before the stage of excitement commences, dentin may be cut without the slightest pain being felt. This is an important consideration, since if the ad- ministration is continued into the period of excitement nothing can be done, and if it is conducted to a full degree the patient is not manage- able. Also the subsequent depression is to be avoided. While general anesthesia in the first stages is available for the relief of dentinal sensi- tivity, it is found, on the contrary, when resorted to for the removal of the pulp, as may occasionally be required in the most severe cases of congestion, that nothing short of profound anesthesia will suffice. When the first stage is reached, the patient being conscious and able to reply to questions, the cutting is commenced • as the pain returns a few more inhalations are given, when another part of the cutting may be proceeded with. This may be repeated until the cavity is formed. GENERAL ANESTHESIA. 173 Fig. 114. The catting should be quickly and deftly conducted. The amount of ether administered is far less than is required to induce full anesthesia, and the patient suffers far less depression than if the operation were performed without this means. There is also no danger of shock, since the patient is, or should be, intelligently concerned in the progress of the case. If the condition were carried into the second stage, when excite- ment exists and alarm is aroused in addition to the operative interfer- ence, there is liability to shock, which, being due to a profound impres- sion on the nervous system, is not liable to occur when the patient concurs in all the steps of the procedure. The time required to bring about a sufficient degree of dentinal anesthesia frequently is less than two minutes. The ether should be pure and should be given with a free supply of air mixed with the vapor. The ordinary custom of using the towel to envelop the face is questionable, since this method does not permit enough air to accompany the ether vapor. An invaluable inhaler for this purpose is the one invented by Dr. Allis (Fig. 114). This consists of an oval frame composed of a series of wires through which passes back and forth a continuous band of muslin. The layers of muslin are near each other, and still so far apart as to permit the free passage of the at- mosphere. The correct manner is to continuously drop the ether in small quantity upon the muslin to maintain it at an even degree of partial saturation. This appliance is one of value to the dental operator, as by it the anesthetic state can be more quietly brought about with less of the characteristic disturb- ances which attend the usual modes of applving sulfuric ether. The use of chloroform for the purpose under discussion is wholly inadmissible. The mechanical means consist in the use of temporary fillings, which may be either metallic or non-metallic. The metallic act by inducing, in consequence of the slight irritation of thermal conductivity, a consolidation of the subjacent dentin, which in time obliterates the tubules. The non-metallic act simply as a protective covering to the denuded dentin. Their action hence is more tardy than that which follows the use of the former. The metallic stoppings for this purpose may be composed of either tin foil or amalgam. Each of these requires cavities of reasonably good The Allis inhaler. 174 PRELIMINARY PREPARATION OF CAVITIES, ETC. retentiveness, therefore they are not applicable to shallow cavities 01 unsuitable form. The non-metallic may be either gutta-percha, zinc phosphate, or zinc oxychlorid. The two latter are the most desirable, as they adhere to any well-dried cavity, and having some irritating influence on the tissues tend to induce structural consolidation in addition to their protective action. They have, however, the disadvantage of suffering loss by chemical solution, and unless kept under close observation are delusive and in many instances are a deceptive means of preventing the recurrence of decay. In the employment of these substances due care should be exercised concerning the proximity of the pulp, in which cases the previously indicated means of shielding the pulp walls should be pursued. The chief disqualification of gutta-percha is its lack of resistance to attrition, and when in positions shielded from wear it may be attacked by low forms of bacterial life, which disintegrate it. Mechanical protection of cavities is most applicable to teeth of a low grade of structure and for young children who may not have the ability to tolerate the more active means needed to reduce dentinal sensitivity. For these cases gutta-percha stoppings when carefully introduced are a great boon, since they protect the tissues during the period of completion and consolidation of the dentin. CHAPTER VII. PREPARATION OF CAVITIES— OPENING THE CAVITY— RE- MOVING THE DECAY— SHAPING THE CAVITY— CLASSI- FICATION OF CAVITIES. By S. H. Guilford, A. M., D. D. S., Ph. D. General Considerations. — The importance of the proper preparation of a cavity for the insertion of a filling can scarcely be overestimated. Upon its being well done the success of the completed operation largely depends. As many fillings fail from lack of thoroughness in the pre- paration of the cavity as from any other cause. The operator should not be actuated by haste, but should be deliber- ate, careful, and painstaking. Each stage of the operation should be thoroughly performed in order that when completed the cavity may be in the best possible condition for the reception and retention of the filling. The operation is naturally divided into five stages : 1. Opening the Cavity. 2. Establishing the Cavity Outlines. 3. Removing the Decay. 4. Shaping the Cavity. 5. Perfecting the Enamel Margins. 1. Opening the Cavity. Every cavity to be excavated must first be opened, so that it may be approached and operated upon at all points. The particular manner of doing this will have to be determined by the extent of the decay and its position, but in all cases the opening must be as full and free as the conditions will permit. The accessibility of the cavity will depend upon its location. Upon the three exposed surfaces of a tooth crown (occlusal, lingual, and labial or buccal) access to a cavity is usually easy, but upon the unexposed surfaces (approximal) access can only be had after the teeth have been pressed apart. For methods of securing temporary separation of the teeth see Chapter V . A cavity upon an exposed surface, if small, can usually best be opened by the use of some form of exgixe bur. A few sizes each of the forms known as " fissure/' "inverted-cone," and "round" (or 175 176 PREPARATION OF CAVITIES. " rose-head ") are shown in Figs. 115-117. A spear-pointed drill is sometimes used, but is less serviceable on account of its tendency to be caught or broken in the irregularities of the cavity orifice. A modified form of fissure bur has found much favor in the opening of small cavities on exposed surfaces. It is made from an ordinary bur Fig. 115. Fig. 116. Fig. 117. Ill 111 li Fissure burs. Inverted-coue burs. Round burs. from which the head has been broken, by cutting spiral blades on the tapering neck of the shank. Being pointed, round, and tapering it easily effects an entrance into the cavity and enlarges the orifice grad- ually and symmetrically. It is shown in Fig. 119. In cavities of larger size, where decay has made more progress, the overhanging walls of enamel can best be broken down by chisels of suitable size and form. Where a straight chisel can be employed it will be found most efficient, but in positions difficult of access, one having a slight curve or angle may need to be employed. Figs. 120 and 121 represent both forms as well as the sizes usually preferred. The Fig. 118. Fig. 119. Fig. 120. Fig. 121. Cross-cut burs. Modified fissure bur with tapering point. Straight chisels. Curved chisels. width of the blade may vary from one-sixteenth to one-eighth of an inch, but wider ones than these will seldom be required. A chisel may be used with either hand pressure or mallet force. If the former, great care must be exercised to prevent its slipping and causing pain or possible injury. The best safeguard in its use is to place the thumb of the right hand on the tooth being operated upon or some adjoining one and use it as a fulcrum or pivot upon which the REMOVING THE DECAY. 177 instrument may move in a curve. By this means the motion of the chisel is regulated and controlled and all danger of slipping avoided. It will sometimes be of advantage to roughly pack the interior of the cavity with cotton or spunk to receive the impact of the instrument should the chisel accidentally be forced to the bottom of the cavity. The better plan, however, in most cases, is to employ mallet force for the cleavage of enamel unsupported by dentin. By holding the chisel between the thumb and three fingers of the left hand and resting the little finger of the same hand on an adjacent tooth for steadiness, a smart but light blow of a mallet in the right hand upon the end of the chisel will easily and painlessly cleave off portions of the enamel. In opening cavities of small extent or limited depth upon approxi- mal surfaces a round or inverted-cone bur will best F 122 serve the purpose, but where caries is more exten- sive and the surrounding enamel is unsupported by dentin the orifice of the cavity can be more advan- tageously enlarged by means of a delicate chisel (shown in Fig. 122) the blade of which is bent at a slight angle to the shank and all three of the edges of which are bevelled to convert them into cutting edges. This instrument will be found especially useful in opening cavities of medium or larger size on the approximal surfaces of the incisors, the point | | doing the cleaving and the side edges being used to Delicate three-sided smooth the enamel margins. chise1 ' use ™ for o opening cavities on After the orifice of the cavity has been sufficiently approximal sur- enlarged to afford a full view of its interior the next stage of the operation is entered upon — 2. Establishing the Cavity Outlines. In all cases, and especially for those on approximal surfaces, it is necessary to extend the boundaries of cavities not only to include all decayed or injured tooth structure, but also all such healthy tooth tissue as may be required in order to bring the outlines of the cavity to such points as will establish relative immunity from future decay. To this end, in cavities upon the approximal surfaces of biscuspids and molars, if of considerable size, the buccal wall should be extended to the approximo-buccal angle of the tooth; the lingual wall to the approximo-lingual angle, and the cervical or gingival wall to a point beneath the free margin of the gum. Thus extended, the buccal and lingual walls will be in such position as to be kept clean and free from food deposits, and consequently from decay. The gingival wall, extended beneath the gum margin, is protected and immunized by the overlapping gum tissue. 12 178 PREPARATION OF CAVITIES. Cavities on the approximal surfaces of the incisors and canines should in like manner be extended to include the entire area of possible future decay, but they do not need to be extended so far labially as to make the gold conspicuous. The lingual margins of these cavities may be freely extended lingually, both to insure necessary strength and to afford room for approach in the act of filling. In studying the size and form necessary for each cavity to possess, a mental picture should be drawn and the cavity shaped in accordance with it. 3. Removing the Decay. The character or consistence of the carious structure has much to do with the method and means employed for its removal. If it be of the semi-elastic or leathery variety so often found in the teeth of young persons, it can be most easily removed by means of spoon-shaped or round-bladed excavators, which being oval or circular in edge out- line and free from marginal angles, will lift and separate the layers without danger of injuring the underlying healthy dentin and with the infliction of a minimum amount of pain. Fig. 167 illustrates this kind of instrument in some of its forms, selected from the Darby-Perry set. In the dark, hard variety of caries, as also in the white, chalky variety, the different forms of burs and excavators will be found best suited for the purpose. In the removal of caries care should be exercised to inflict as little pain upon the patient as possible. To this end, in cavities of con- siderable extent, it is best, after the orifice has been sufficiently enlarged, to make a sweeping cut with an excavator around the cavity just below Ftg. 123. B-ojiifntfiunii IT I n Excavators. the enamel line, thus freeing the decayed portion at that point. Follow- ing this the remaining portion of carious dentin should be removed by placing the blade of the excavator near the bottom of the cavity and REMOVING THE DECAY. 179 makiDg draw-cuts toward the orifice. To cut in the reverse direction would produce uncomfortable pressure upon the most tender portion of the cavity, and possibly, by inadvertence, expose and wound the pulp. When burs are employed for the removal of caries it is safest to use only those more or less rounded on their circumference, such as the round or oval forms, for they more nearly conform to the natural outline of the cavity, leave no angular grooves in the dentin, and are not so likely to injure the subjacent healthy dentin. The varieties of bur known as the inverted -cone and wheel, while very useful for opening cavities, should not be used for the removal of caries in deep cavities, because of the irregularities of surface which their peripheral angles produce. Rapidly revolving burs in an engine handpiece are very apt to cause pain by the development of frictional heat. This may largely be pre- vented by lifting the bur at short intervals and allowing it to run free for a moment, which will prevent overheating the tooth and thus avoid unnecessary pain. Thorough excavation of the cavity and the removal of all carious dentin is absolutely essential to success. To allow any portion of it to remain and trust to the employment of germicides for its sterilization is running the risk of failure, for we can never be entirely sure of disinfection. Besides this, there is no good reason for allowing it to remain . By carious dentin is meant the remains or debris of the action of caries, — a product resulting from this disintegrating action upon both the organic and inorganic constituents of dentin. In nearly all cavi- ties we find two varieties of altered tissue. That nearest the surface is a mass of thoroughly disorganized and usually decomposed matter filled with micro-organisms. Beneath this and lying next to the healthy den- tin there is a zone or layer from which the calcium salts have been re- moved by the acid solvent, but which still retains its original form and vitality. This layer of decalcified dentin may be allowed to remain, especially in the bottom of a cavity, as it serves to protect the subjacent tissue from thermal shock, but as a precautionary measure it should be treated to an alkaline application or some germicide such as carbolic acid, mercury bichlorid, formalin (10 per cent, aqueous solution), or oil of cinnamon, before the insertion of the filling. Occasionally caries will be found to be self-limited. In such cases, through some unexplained change of conditions, the progress of caries has been checked and the layer of decalcified dentin re- stored to its previous normal condition. "Where this has taken place the restored tissue is usually of a darker color than ordinary dentin, and on this account may be mistaken for carious dentin and removed. 180 PREPARATION OF CAVITIES. It is, however, easily distinguished from caries by its hardness, and should in no case be removed except from the sides of a cavity, and then only when its dark color showing through the walls would prevent the cavity, after being filled, from having that clear and clean appear- ance which it should possess. With some practitioners it is the custom to prepare a cavity dry } because in this way the operation is more rapid and usually less painful. In such case the rubber dam is applied first of all and the operations of opening, cleansing, and shaping the cavity are all performed without the presence of moisture. Repeated applications of warm air from a syringe, at intervals during the operation, desiccate the dentin and di- minish its power of sensation. Others, in order to avoid the unpleasant- ness to the patient of having the dam in position for so long a time, prepare the cavity roughly in the presence of moisture, then apply the dam, dry the tooth thoroughly, and finish the operation. Whichever plan is adopted it is absolutely necessary, in all cases, to finish the preparation with the dam on and the tooth dry, for it is only after a tooth has been deprived of its moisture that we are able to decide whether all the niceties of preparation have been successfully carried out. Certain marginal and structural defects that are not noticeable while the tooth is moist are plainly revealed after it has been dried. 4. Shaping the Cavity. This is one of the most important of all operations associated with the stopping of a cavity, for according as it is properly or improperly performed success or failure will result. Too much stress cannot be laid upon its importance, nor too great care be exercised in its accom- plishment. Inasmuch as a filling is retained in place mechanically it follows that the cavity must be of such shape as to secure retention. To this end it should be larger within (at least at certain points) than at the orifice. An exception to this rule lies in cavities where the depth is greater than the diameter. In cavities of this character parallel walls will suffice, because lateral-surface contact is so great in proportion to the mass to be held in place that displacement could not occur. In larger cavities of moderate depth, however, the reverse is the case, and they will require the assistance of internal enlargement for the retention of the filling. To govern each of the conditions two rules may be formulated : 1. When the depth of the cavity is greater than the diameter of the orifice, parallel lateral walls will prove retentive. 2. When the diameter of the orifice is greater than the depth of the cavity, the latter will have to be someAvhat enlarged internally to retain the filling. SHAPING THE CAVITY. 181 Examples of the first class are found in the narrow but rather deep cavities which occur on the lingual surfaces of the upper incisors near the cervix ; in the pit cavities on the buccal surfaces of molars ; and in the small cavities found on either side of the enamel ridge on the occlusal surfaces of the lower first bicuspids. Examples of the second class are found in numberless places on any of the crown surfaces. In some cases cavities will be found of such form that when caries has been removed they will have a naturally retentive shape, but in the great majority of cases more or less sound tissue will have to be removed in order to give them the required form. To give a cavity a retentive form it is not necessary that its interior be enlarged throughout its whole extent, but it must be larger at two or more points, and these points must be opposite one another. Frequently it Avill be easier to enlarge the cavity at all points, and to this no objection can be urged provided too much sound tissue be not removed or the pulp be not too nearly approached. Too great enlargement tends to weaken the cavity walls and therefore should be guarded against. In shaping the cavity internally instruments should be employed that will leave the surface free from angles. Excavators for this pur- pose should have curved edges, and burs should be of a round or oval form. If grooves are required they should be made neither deep nor too near to the enamel, to avoid weakening the walls. At the cervical margins of cavities grooves and starting pits should be avoided when- ever possible, for they weaken the portion of the cavity which is sub- jected to the greatest strain in the introduction of the filling, both mechanically and by cutting oif the nutrient supply to the cervical margin, which tends to alter the resistive character of that portion of the tooth structure by devitalizing it. For the same reasons deep grooves or undercuts should not be made near the incisal or occlusal surfaces, for the strain of mastication will be liable to result in fracture of the wall if it is thus unduly weakened. In the process of shaping the cavity internally the enamel margins will naturally be assuming their proper form, but the final part of the preparation should consist in giving these frail portals of the cavity very careful and minute attention. The permanency of a filling will depend largely upon the strength of the enamel walls and their proper preparation. The enamel cap of a tooth when intact is exceedingly strong and capable of resisting great strain, but when its continuity has been broken by caries and it is left unsup- ported by dentin it is very weak and brittle. This is readily understood when we remember that enamel is composed of an aggregation of enamel 182 PREPARATION OF CAVITIES. rods or prisms in close juxtaposition, slightly joined together by a cementing substance, with their greater diameters perpendicular to the plane of the surface of dentin upon which they rest. When continuous, these rods mutually support one another and are thus capable of resisting great strain ; but when a lesion has occurred they lose support on the adjoining side and hence are easily separated in the direction of their length. Fig. 124 (after Black 1 ) shows this condition perfectly. A de- tached section of enamel prisms is represented at a, and at b is shown a portion about being separated by a chisel. Fig. 124. Showing enamel structure. This will explain Avhy enamel unsupported by dentin should not be allowed to form the margin of a cavity, for it will probably either be fractured while the filling is being introduced or afterward in mastication. On all convex surfaces of a tooth the enamel rods radiate outwardly, and by forming the margins of a cavity on these lines it will have a slightly flaring or trumpet-shaped orifice, which will not only afford the greatest strength but will admit of a better finish being given to the edges of the filling. In many cases it will be necessary to give the margins of a cavity more of an outward bevel than would be obtained by simply following the cleavage lines of the enamel rods. This can be secured by cutting away the outer ends of the enamel rods in an oblique direc- tion as shown at c in Fig. 124. No weakening of the border will result in such. cases, inasmuch as the shorter rods will still rest upon the dentin. If, however, the rods were cut so as to leave only their outer ends in place, as shown at d, they would have no substantial support, and would be liable to be crushed during filling or afterward. All cavity margins should have the outward bevel to a greater or less extent in order to secure the best and most permanent results. In cavities upon depi-essed or concave swfaces of teeth it would not Dental Cosmos, vol. 441. PERFECTING THE ENAMEL MARGINS. 183 Fig Cross-section of a bi- cuspid showing treat- ment of enamel in the sulcus. do to have the enamel margins formed on the lines of enamel cleavage, for this would make the margin of the orifice the most contracted por- tion and result in frail marginal edges. Fig. 125, representing a cross-section of a bicuspid tooth with a cavity in the sulcus, will illustrate this point : A shows the cavity orifice prepared on the lines of enamel cleavage, and b the dressing across the outer edges of enamel required to give the necessary strength. It may therefore be laid down as a rule that to secure the best results the line of the enamel wall from within outward should form with the surface of the tooth at this point an obtuse angle. 5. Perfecting the Enamel Margins. Beside the proper shaping of a cavity margin it should be made as smooth as possible. In accessible cavities upon exposed surfaces of teeth the final marginal smoothing or finish can best be effected by the use of a bur shaped somewhat like a fissure bur, but having a rounded end and being simply file-cut upon its surface instead of being bladed. Such a one is shown in Fig. 126. Its sides being parallel, no rounding of the cavity margins can occur when it is used with the end inside of the cavity. Any other form of bur with a short head would unavoidably give to the cavity margin either a concave or a convex surface, both of which would be incorrect. The buccal, lingual, and cervical enamel margins of a compound approximal cavity should never be finished with a round bur, even of the plug-finishing variety, but should be smoothed with suitable chisels, broad-faced excavators, or approximal trimmers, the latter being shown in Fig. 127. Fig. 126. Fig. 127. ? File-cut enamel finishing bur. Approximal trimmer. The practice of finishing enamel margins with sand-paper disks is very objectionable, as they are almost certain to give to the margins a 184 PREPARATION OF CAVITIES. rounded edge which cannot be filled and finished without leaving a feather edge of the filling overlying the enamel, which will eventually be broken off or flared up, leaving an imperfect margin. The Gem cavity trimmers, recently introduced, are probably the best instruments yet devised for giving to enamel margins the perfection of finish required for gold filling. They produce a smooth but unpolished, surface, to which the gold is readily adapted and along which it cannot slip or slide. Classification of Cavities. 1 I. Simple Cavities on Exposed Surfaces. Bicuspids and Molars. Incisors and Canines. A. Occlusal. D. Labial. B. Buccal. E. Lingual. G. Lingual. F. Incisal. II. Simple Approximal Cavities. Incisors and Canines. Bicuspids and Molars. G. Mesial and distal. H. Mesial and distal. III. Compound Cavities. Incisors and Canines. Bicuspids and Molars. I. Mesio-labiai. P. Mesio-occlusal. J. Disto-labial. Q. Disto-occlusal. K. Mesio-lingual. R. Occluso-buccal. L. Disto-lingual. 8. Occluso-lingual. M. Mesio-incisal. T. Mesio-disto-occlusal. N. Disto-incisal. 0. Mesio-disto-incisal. In the foregoing classification the cavities have been arranged pro- gressively from the simplest (A) to the most complicated ( T). I. Simple Cavities on Exposed Surfaces. BICUSPIDS AND MOLARS. Class A. — Cavities upon the occlusal surface are very accessible and in full view, enabling the operator to see every part of the cavity and affording him plenty of room in which to operate. Naturally those nearest the front, as in the bicuspids, present the advantage of greater 1 Following the suggestion of Dr. Black, in the above list the word Ungual is used for the same surfaces in both the upper and lower teeth, doing away with the word palatal. In the forming of compound terms, where the mesial or distal surfaces are included, these terms precede the others. Where they are not included and the word occlusal is used, it is given first place. SIMPLE CAVITIES ON EXPOSED SURFACES. 185 accessibility, but none of them are difficult to prepare and fill except under unusual conditions. Usually the first part of a bicuspid crown to become affected by caries is the fissure between the cusps. Sometimes it presents merely as a black line into which only the point of an explorer will penetrate ; at a later stage the cavity is more fully defined by the greater pro- gress of caries and the crumbling of the walls of its orifice. In the first instance the cavity is most readily and comfortably opened by means of the tapering fissure bur shown in Fig. 119. After passing it into one of the terminal pits of the cavity it may be drawn along toward the other, opening the fissure quite freely. Once open, the decay may be removed and the cavity shaped by a suitably sized round bur (Fig. 117). As the decay has usually progressed farther in the region of the terminations of the cavity than in Fig. 128. ^ ne S p ace between them, the cavity when fully formed will be oblong in shape and contracted in the centre. In Fig. 128, A shows this form, while B represents the same surface before being operated Cavity in sulcus of a bicuspid. ° r upon. In preparing the cavity no more sound tooth-structure should be sacrificed than is absolutely necessary, but every portion of decay should be thoroughly removed and particular attention be given to opening up the minor fissure terminations as shown at A A, b B (Fig. 129). When completed, the cavity should be very slightly larger within than without, the margins should present B no angles, but onlv a series of curves in outline, and the The fissure & ' # ' terminals. marginal edges should be slightly bevelled outwardly. Bicuspid cavities of this character vary in size according to the extent of decay, but the essential features in each case are very similar. The lower first bicuspid differs normally from all others of its kind in having no sulcus and consequently no fissure between the cusps. In- stead of the two cusps being separated by a sulcus they are united by a ridge of enamel. (See Chap. I., p. 35.) The only points, therefore, that invite decay upon the occlusal surface of this tooth are the two pits that are found one on each side of the ridge. These are to be filled separately. They probably represent the very simplest form of simple cavities to be found anywhere in teeth. The occlusal surface of an upper first or second molar presents two points liable to decay. One is a pit formed by the junction of two small fissures near the mesial margin, and the other is a fissure which runs between the disto-buccal, disto-lingual, and mesio-lingual cusps- 186 PREPARATION OF CAVITIES. Both are represented in Fig. 130. When limited in extent they should be opened in the same manner as a bicuspid fissure cavity, but when larger they may be opened by means of a chisel followed by a suitable bur. In these, as in all cavities in sulci, the fissures must be followed and opened up to their extremest limits in order to ensure success, while the margins and marginal edges must be so formed as to be strong, smooth, and bevelled. The general form of these cavities when prepared is shown in Fig. 131. It will frequently be found that these two occlusal cavities Fig. 130. Fig. 131. Fig. 132. Fig. 133. Upper molar fissure cavities. Upper molar fissure cavities prepared for filling. are joined underneath, while near the surface they are separated by a ridge of enamel and dentin. In such cases the ridge should be cut away and the two cavities converted into a single larger one as illus- trated in Fig. 132. If the ridge were allowed to remain it would almost certainly be fractured either in the operation of filling or subsequently by the force of mastication. The upper third molar differs from those anterior to it in having but three cusps and consequently but one central pit with radiating fissures. A cavity occurring here when properly prepared will pre- sent a triangular outline with rounded angles, as in Fig. 133. The terminals of fissures should always be finally finished with a round bur to prevent any possible angles and opportunity for leakage at those points. The lower first molar, as well as the third, having five cusps with intervening sulci, a cavity upon this surface will be pentagonal in out- line, as represented in Fig. 134. Extreme care should be exercised in preparing cavities of this character to insure that the fissures running between the buccal cusps are fully opened and cleared of every particle of decay and discolora- tion. Too often this is overlooked and caries supervenes. The lower second molar with its four cusps has two sulci inter- secting each other at a right angle. Decay usually begins at the inter- section and extends along the radiating arms of the fissures. If the cavity were prepared by cutting out the fissures only it would yield a crucial-shaped cavity with four sharp or nearly sharp angles at the intersection, as shown in Fig. 135. Owing to these angles of dentin and enamel the perfect filling of the cavity would be exceedingly difficult. The case may be simplified and better results in every way obtained SIMPLE CAVITIES ON EXPOSED SURFACES. 187 by rounding these angles and giving the cavity a form like the one shown in Fig. 136. Fig. 134. Fig. 135. Fig. 136. Lower first molar with stel- late cavity. Prepared. Lower second molar with crucial cavity. Not pro- perly prepared. Cavity in lower second molar. Correctly pre- pared. Class B. — Buccal cavities are seldom met with in the bicuspids except at the cervix. In this location they possess the same features as the similar class of cavities occurring on the labial surfaces of the incisors. Their treatment will be described under class D. The upper molars also are seldom found decayed on the buccal sur- face except at the cervical border. Cavities occurring at this point are usually narrow and long, following the outline of the gum. They can best be prepared with an engine bur of suitable form, and if occurring on the second and third molars a right-angle attachment may have to be employed to reach them conveniently. Decay at this point is often of the white variety, and as it so nearly resembles the natural color of the tooth extreme care will have to be exercised to include all of the decalcified portion within the limits of the cavity. A retentive form is most conveniently given to these cavities by slightly undercut- ting them in the direction of their length. In the third molars it is sometimes advisable to make an undercut or starting-pit at the distal end for the beginning of the filling. Sometimes a small cavity will be found at about the centre of the buccal surface of the upper molars, but far more frequently a cavity of greater extent will be found upon the same surface of the lower second molar. It originates in a pit at the termination of the fissure running over from the occlusal to the buccal surface between the two buccal cusps. Oftentimes the cavity is so large as to include the greater portion of this surface of the tooth. Its usual form and appearance are shown in Fig. 137. Not infrequently this cavity is compounded with one on the occlusal surface. In opening and preparing it a slightly undercut form is readily given to it. Class C. — Decay rarely occurs upon the Ungual sur- faces of molars on account of their smoothness and con- vexity and because they are more or less constantly rubbed by the tongue in speech and mastication. The evenness of this surface is, however, broken in the upper first and sec- ond molars by a fissure extending over from the occlusal surface and passing between the lingual cusps. (See Chap. I., p. 39.) This fissure Buccal cavity in lower sec- ond molar. 188 PREPARATION OF CAVITIES. is deeper and more pronounced in the first molar, but in each tooth it is generally the seat of caries early or later in life. In the majority of cases this fissure is decayed throughout its entire length, forming a compound cavity, but occasionally only the pit at its termination on the lingual surface is affected. Another point on the lingual surface liable to decay is on or near the mesio-lingual angle of the upper first molar, about midway between the cervical and occlusal margins. At this place is often found a supple- mental cusp, diminutive in size, and where it joins the main surface of the tooth a small fissure exists which invites decay. This additional cusp, when it does exist, is found only upon the first molar. It is shown at A in Fig. 138. (See Chap. I., p. 39.) Neither of these cavities presents any difficulties in prepara- tion except such as occur from their slight inaccessibility. Occasionally, though very rarely, the lingual surface of any of the molars may present a cavity of decay close to the gin- gival line and partly beneath it. Such cavities are doubtless caused by the retention of food debris beneath the free margin of the gum, and owing to their position they are difficult to treat. They should be opened and packed over-full with cotton and sandarac varnish or gutta- percha for a day or two, to press the gum away, after which they may be prepared and filled in the usual manner. INCISORS AND CANINES. Class D. — Cavities upon the labial surfaces of incisors and canines are usually found along the gingival margin, and are the result of the direct action of acids probably formed at this point. In the beginning, and when small, they are entirely exposed, but when of greater extent they frequently extend beneath the free margin of the gum. They are nearly always elliptical in outline and may consist of simple decalcified enamel still retaining the usual surface form, or they may possess the common characteristics of cavities in general. The opening and preparation of this class of cavities are not attended with any marked difficulties except that when they extend beneath the gum care will have to be exercised not to wound this tissue, as the consequent bleeding would obstruct the view and interfere with the progress of the work. This may be prevented by pressing and holding the gum away with a suitable instrument held in the left hand while the cavity is being prepared. Particular attention should be paid to the care- ful preparation of the cervical margin of the cavity and to its terminal points. The former should be made smooth and even, and the latter should be extended far enough to include any enamel that shows the least sign of acid alteration. Slight grooves or enlargements at the SIMPLE CAVITIES ON EXPOSED SURFACES. 189 base of the cavity along its upper and lower margins will give it a suf- ficiently retentive form. A second locality on the labial surface where decay is frequently found is anywhere between the central portion and the incisal edge, in pits and depressions that indicate imperfect development of the enamel. These pits or grooves extend in a nearly straight line parallel to the incisal edge, and are frequently the seat of decay. When quite shallow they may be obliterated by grinding the surface with a small corundum wheel and polishing, converting the surface at this point into a distinct concavity. When the I( ^_^ pits are deeper and isolated they may be filled separately, the result being a lesser degree of conspicuousness ; but when they are connected by a groove, as they usually are, they will have to be converted into a single cavity and Pitted i nC isor. filled. A common type of this defect is shown in Fig. 139. When these pits occur upon the incisal edge or in close proximity to it the choice lies between an unsightly gold filling, sections of porce- lain rods inserted into the pits, or their removal by grinding and the resultant shortening of the crown. Class E. — There is usually but one point upon the Ungual surface of incisors and canines that is liable to decay. It is in the pit at the junction of the basilar ridge or cingulum with the adjacent tooth surface. The incipiency of caries at this point presents only as a mi- nute cavity, the opening and shaping of which is readily accomplished with a round bur. Although the orifices of these cavities may be small, the dark spot that marks their direction is often continued quite a distance toward the pulp chamber. This black point should in all cases be followed to its termination and obliterated. As the depth of these cavities is greater than the diameter of their orifices, no special retentive shape need be given them. The orifice should always be bevelled and enlarged, if necessary, to include any neighboring fissures. When these cavities are of greater extent they are prepared and filled like others of similar size and form. Class F. — Cavities upon and confined to the incisal edge of incisors and canines are easily prepared on account of their accessibility. This particular surface should, and generally does, remain free from decay on account of the attrition to which it is constantly subjected ; but when defects in the enamel exist, caries sometimes occurs in connection with it. This surface often needs covering with gold to check abrasion in cases where, after middle life, the crowns (especially those of the upper teeth) have been shortened by excessive wear. Under these conditions 190 PREPARATION OF CAVITIES. the surface must be so prepared and shaped as to retain the gold that is to cover and protect it just as though caries had originally injured the part. In forming the cavity in the exposed dentin it is only necessary to cut deeply enough to afford a lodg- ment for the filling, but the orifice must be so enlarged and excessively bevelled as to reach to the marginal edge of enamel all around. This is done to protect the enamel from chipping or fracture in mastication. To afford the greatest security to the filling the cavity should be under- cut throughout its whole extent. When thus prepared, cavity or^n- the cavity in cross-section will resemble a double dove-tail cisal surface. as shown in Fig. 140. II. Simple Approximal Cavities. INCISORS AND CANINES. Class G. — Cavities upon the mesial and distal surfaces of the anterior teeth present only the difficulty arising from inaccessibility. To reach and operate upon these cavities, the teeth, if in normal contact, will usually have to be pressed apart either by gradual wedging or by immediate separation with a " separator." Even after this has been accomplished the cavity cannot be operated upon in a direct way as are cavities upon exposed surfaces, but will have to be approached from either the labial or lingual aspect of the crown. To do this, if the cavity be small, will generally necessitate an additional enlargement of the cavity toward the surface from which it is to be approached. As the lesser of two evils the enlargement is usually made toward the lingual surface, for in this way there will be no exposure of gold when the filling is completed. When the cavity is of larger size and the enamel wall on the labial surface has been weakened by caries it will have to be removed, and access will thus necessarily be afforded from that side. Whenever possible, however, undue enlargement of the cavity and consequent exposure of gold should be avoided. In ordinary cavities upon the approximal surface the frail walls bordering the orifice should be broken away with a small chisel, and after the decay has been removed by means of burs or excavators and the proper form given to the cavity, the margins should be carefully smoothed and bevelled from within outward with small plug-finishing burs or with the side-cutting edge ol the small chisel shown in Fig. 122 and here reproduced (Fig. 141). Anchorage is obtained in these cavities by flattening the cervical wall so as to form distinctly rounded angles with the labial and lingual walls respectively. Slight depressions should also be made at the labio- SIMPLE APPROXIMAL CAVITIES. 191 cervicoaxial and the linguo-cervico-axial angles for starting and securing the first portions of the filling. A shallow undercut in the dentin near the incisal border will also be necessary to serve as an opposite anchorage. Retaining grooves should never be- made in the labial or lingual walls of the cavities, as they would seriously weaken them. In approximal cavities of large size, where they extend from near the incisal edge to or beyond the free mar- gins of the gum, the difficulties of producing a perfectly formed cavity are greatly increased. While affording greater ease of approach on account of their size, the cervical border of this class of cavities is apt to be less perfectly prepared owing to its obscure location. When the cervical border extends beneath the free margin of Delicate three-sided the gum the latter should be pressed and held awav chisel, useful for . . . -in i* opening cavities on during excavating, so that the cervical wall may be approximal sur- plainly seen and operated upon throughout its extent. faces - Cutting of the wall should be sufficiently extended rootward as well labially and lingually to include any defects or checks in the enamel bordering it, and should be made entirely smooth and free from angles, for it is the most vulnerable border of the cavity after the filling has been completed. Should the cavity extend near to the enamel termination at the cervix, it will be best to still further extend it so as to pass beyond this margin ; for if a small portion of enamel be left there it will be liable to be broken away in the process of filling and thus render difficult the proper finishing of this portion of the approxiuial surface. So, also, if the cavity on account of its size should approach very near to the incisal edge, it is best to remove this frail corner and con- vert the cavity into a compound one. Where such a weak corner is allowed to remain it is very frequently broken away in subsequent mas- tication. Such a result is shown in Fig. 142. An accident like this is more likely to occur in thin, flat teeth where the plates of enamel meet- ing at the incisal edge have little or no dentin between them. Where doubt exists as to whether the corner should be ^ ,.,, riG. 142. removed or allowed to remain, it is well, after the cavity has been prepared, to test the strength of the corner by strong pres- sure upon it in the direction of the long axis of the tooth with a piece of orange-wood. If it resists this strain it will prob- straight ably resist the force of mastication, and if it break away under fracture - the test it will demonstrate that it would have been unwise to allow it to remain. If the corner be left as a border and support for the filling it should not be weakened by a deep retaining groove. Such groove or anchorage \fIQ. 142. o tension an- chorage. 192 PREPARATION OF CAVITIES. should be shallow, and as far removed from the incisal border as the conditions will permit. In many cases where the incisal wall would be seriously weakened by any attempt to use it as an anchorage or support for the filling, and where it seems undesirable to remove *it, an ex- cellent anchorage for the lower border of the filling may be obtained by cutting an extension upon the lingual surface in the form of an arm, as shown in Fig. 143. 1 Such extension, if made but little deeper than the enamel, will not materially Lineal ex- weaken the tooth and will secure the filling perfectly. Its position should be near the incisal edge, but not so close to it as to weaken the part. In the anterior teeth the relative difficulties between mesial and distal cavities are insignificant. BICUSPIDS AND MOLARS. Class H. — The preparation of small cavities on the mesial and distal surfaces of the bicuspids and molars, though simple in character, is usually most difficult of thorough performance. This is due entirely to their inaccessibility when the teeth are closely approximated. How to approach these cavities is often a matter of no small concern to the student or young practitioner, and the preparation and filling of them is generally more difficult than that of larger and more complicated cavities in exposed situations. To lessen the difficulty of approach it is important, whenever practicable, to create by wedging beforehand as great a separation as possible between the teeth. The greater the space gained the less the difficulty of approach. When conditions warrant cutting down to them from the occlusal surface, and thus converting them into compound cavities, it is the better plan to pursue, for, although this method involves the loss of more tooth tissue, it greatly facilitates the operation of filling by affording additional space and accessibility. When, however, the cavities are small and situated at the centre or toward the gingival margin of the approximal surface, they should be dealt with as are similar cavities in the anterior teeth, depending upon previous spacing for room in which to work. These cavities can usually be best opened and mainly prepared with a round bur. After the caries has been removed and the walls defined and prepared, the cavity may be made retentive in form by slight under- cutting throughout its entire circumference, or it may be enlarged at two opposite points only. The cervical wall can be shaped with an obtuse- 1 Dental Cosmos, vol. xxxvi., p. 198., and Dental Review, vol. ix., pp. 812 and 819. COMPOUND CAVITIES. 193 angle hatchet excavator as illustrated in Fig. 144, and the lower or occlusal wall be slightly undercut by an acute-angle excavator like Fig. 145. Fig. 145. 1 Obtuse-angle hatchets. Acute-angle hatchets. The sharp angles on the cutting edges of these excavators should be rounded before being used, so as to avoid the formation of angles in the cavity. As the enamel rods on this surface radiate outwardly at such an angle as to give the proper bevel to the orifice of the cavity, a careful following of their lines in the preparation of the cavity margins will be all that is necessary to give them the desired form and strength. Where simple cavities upon the approximal surface are large they may extend so near to the occlusal surface as to weaken it. When this is the case the enamel wall should be cut away and the cavity converted into a compound one of the approximo-occlusal type. 146. III. Compound Cavities. INCISORS AND CANINES. Classes I and /. — 3fesio-labial and disto-labial cavities occur from the near approach or union of simple cavities upon their respective surfaces. Cavities of considerable length up- on the approximal and labial surfaces are very apt to join one another by extension of caries. When they do not join they are usually separated by a narrow terri- tory of more or less impaired tooth tissue, and in such cases must be united to obtain a satisfactory result. Each cavity should be as nearly prepared as possible separately, after w T hich the intervening tissue should be cut away and the margins of the channel connecting the two be made as strong and smooth as possible. This channel will usually be of less width than either of the cavities, but not more difficult to fill on this account. Fig. 146 shows a front view of such a compound cavity. 13 Mesio-labial cav- ity prepared. 194 PREPARATION OF CAVITIES. Whether the cavity be a mesio-labial or a disto-labial one will not materially affect the manner or difficulty of operating. Classes K and L. — Mesio-lingual and disto-lingual cavities are formed in the same manner as those of classes I and J, except that in Fig 147 tnese cases the lingual surface is involved instead of the labial. Extensive caries in the region of the basilar pit or of the fissures connected with it often approaches so nearly to an approximal cavity in the same tooth as to demand the union of the two (see Fig. 147). The method of preparing and Mesio-lin- , . . guai cav- uniting the two is substantially the same as that followed in lty " classes I and J, just described. A mesio-lingual cavity is perhaps more easily prepared and filled than a mesio-labial one, for in its preparation the free cutting away of the intervening wall is permissible, Avhich affords increased room for operating. Fortunately, a lingual cavity rarely extends so far as to connect with both a mesial and a distal cavity. When it does, the joining of the three cavities very seriously weakens the crown at the point where the greatest strain occurs. Classes M and N. — -These classes include cavities upon either the mesial or distal surfaces connecting with a cavity upon the ineisal edge. They usually occur in consequence of the wearing away of the latter surface through attrition or from the necessitated removal of the ineisal corner on account of weakness. Both the approximal and ineisal cavi- ties may be prepared separately as described in classes F and G, after which they should be connected, the walls made strong and smooth and properly bevelled. A typical cavity of this class is shown in Fig. 148. In all such cases the labial plate of enamel should be preserved intact as far as possible for appearance sake, and if any cutting has to be done to increase the size or depth of the ineisal portion of ><) THE OPERATION OF FILLING CAVITIES. to conserving tooth structure, and when he has given it a shape to please him he can select, from the many, a special form of gold that will meet his requirements. There are certain principles involved in the packing of gold which must be borne in mind, and the operator should study these before introducing his filling. The first of these is force, and the direction and relation of that force to the object to be attained. If a given cavity is to be filled with non-cohesive gold the operator must take into consid- eration the strength of the cavity walls, and must determine whether by the wedging process which he will exercise in the effort to adapt the gold to the walls of the cavity he will run the risk of breaking them. Non-cohesive gold is usually introduced by what is known as hand pressure. Each layer of gold is carried to the floor and the walls of the cavity by a process of wedging, and the mechanical arrangement of each piece of gold should be such that no portion of the gold can es- cape when the filling is completed. It will be shown later on, when considering the various types of cavities to be filled, that in small cav- ities of simple shape the gold prepared in the form of tape is best suited, whereas in compound cavities or those of greater size the gold may be introduced in the form of compact cylinders or blocks. When it is desirable to use a combination of non-cohesive and cohe- sive gold, the former is generally introduced first and the cohesive is in- corporated with it by driving or forcing layers of cohesive into the non- cohesive. This is best effected by using single layers of heavy foil or rolled gold of a thickness equal to 20, 30, or 40 grains to the leaf. If the filling is to be made of but one kind of gold and that the cohesive variety, both hand pressure and percussion by means of the mallet may advantageously be employed. The operator who has learned to combine the two forms of gold and is not restricted to either method of packing is best qualified for the requirements which are presented in general practice. Perfect adaptation to the Avails may be effected by either method, but greater celerity and the attainment of equal excel- lence may be reached by combining the two. Plugging* Instruments. — In the selection of instruments for pack- ing gold the operator should have a sufficient number to meet his every need. They should be of such a variety of patterns that every part of every cavity, however remote, can be reached with ease. It is a mis- taken notion that a large number of instruments (if well selected) is confusing. The operator should study his instruments and know their uses as thoroughly as he knows the letters of the alphabet, and if this be done and they be arranged in an orderly manner in his case, the con- fusion will be manifest in their absence, not in the possession of them. For packing non-cohesive foil none are better adapted than the set shown in Fig. 182, made from patterns furnished by Dr. B. J. Bing. INTRODUCTION OF THE GOLD. 237 Fig. 182. R 9 10 \ OffifW i r f 11 12 14 15 16 11 Dr. Bing's set of pluggers. X This set should be supplemented by a small and a medium sized foot-shaped condenser (Fig. 183), for packing FlG 183 cylinders, mats, or blocks against the cervical wall. The handles of instruments used for packing non-cohesive foil should be of such size that they can be grasped firmly in the hand. When made of wood they are light in weight and agreeable to touch. Plugging instruments should have as few curves and angles as is consistent with the ability to reach all points in the cavity. As these are multiplied, direct force is sacrificed. The point of the instrument should be as nearly as possible in a line with the shaft. Deviations from this rule are sometimes necessary in order to reach all points in the cavity. Most plugging instruments have serrated points and are used for all forms of gold. As a rule these serrations should be shallow, and when cohesive gold is to be employed they should be only sufficient to prevent slipping, as gold that is quite cohesive packs as readily with smooth points as with rough ones. It is not definitely known when packing gold by percussion was first suggested, but the idea is quite generally accorded to Dr. E. Merrit of Pittsburg, who as early as 1838 used the hand mallet for condensing Foot-shaped condensers. 238 THE OPERATION OF FILLING CAVITIES. Fig. 185. Fig. 186. Fig. 184. Snow and Lewis auto- matic mallet. The Abbott mallet S. S. White electric mallet " No. 2. Founded on the " Bonwill." INTRODUCTION OF THE GOLD. 239 the surface of fillings which had been introduced by hand pressure. The first mallets used were of light weight and were made of wood or ivory. As the method became more general, heavier mallets were em- ployed, and those made of lead, tin, various alloys, and steel found much favor. Before the introduction of rubber dam for excluding moisture one hand of the operator was employed in holding the napkin, and it became necessary to have an assistant at hand to do the malleting. This led ingenious minds to discover some means of percussion besides the hand mallet, and several spring instruments known as automatic pluggers were introduced. The Snow and Lewis, the Foote, and the Salfnon found greatest favor, and all of them were good of their kind. The accompanying cut (Fig. 184) shows the Snow and Lewis Automatic Mallet as made at the present time. When pressure is applied to the point of the instrument a spring is liberated which throws a plunger forward with great force, which is expended upon the gold beneath the point. The impacting quality of this blow is not excelled by any of the mechanical devices in use. It is so constructed that a light or a heavy blow can be given at will. The operator will do well to adjust the instrument for light blows when using it in close proximity to frail or delicate wans, as there is more or less danger of fracturing them. Instruments of this class are not well adapted to packing gold in the posterior teeth of the lower jaw, as the blow is delivered at a more or less acute angle, and unless care be exercised when the operation is nearing completion the plugger point will slip from the surface of the filling and wound the soft tissues. Another instrument of this type devised by Dr. Frank Abbott (see Fig. 185) has a socket at either end of the hand-piece, the one giving a pushing and the other a pulling blow. The latter is serviceable for condensing gold upon distal surfaces. The electric mallet is one of the most ingenious devices em- ployed in dentistry. The first practical application of electro-magnetic force for dental malleting was made by the late Dr. W. G. A. Bon will. Its latest development is shown in Fig. 186. This instrument has found great favor among dentists for packing cohesive gold. Its blows are delivered with great rapidity and with such force that great solidity is attainable. A pair of electro-magnets transforms the electric cur- rent into electro-magnetic force, which is transmitted to the hammer. The electric current is furnished by a Bunsen or Partz battery, or the controlled current from a dynamo or storage battery can be used as the motive power. The direct dynamo current of 110 volts can be so modified by the use of a rheostat that its use may be employed, and the trouble incident to keeping a battery charged avoided. In the hands of a skilful operator there could be nothing 240 THE OPERATION OF FILLING CAVITIES. better for packing cohesive gold. The best results are obtained by its use when the gold is prepared in thin lam- inae or where a single thick- ness of heavy foil or rolled gold is employed. Considerable experience is necessary to enable the operator to use this instrument with satisfaction to himself and his patient. If the plugger point be pressed hard against the filling, the blows, which are delivered with great rapidity and force, become painful and dis- tressing and there is also danger of chipping the cavity walls. The better plan is to hold the point slightly away from the surface of the filling and allow the momentum which is given the instru- ment by the falling armature to complete the union of the various pieces of gold. The engine mallet (see Fig. 187) is intended for use upon the dental engine. It is made with a slip joint and can be applied in place of the hand-piece to nearly all of the dental engines in use, although it is best adapted to one of the " cord " engines because of the greater freedom of action. The instrument shown in the illus- tration embodies many improvements in con- struction which have been suggested by various operators since the " Bonwill mechanical mallet/' on which it is based, was introduced, and a point of relative perfection has been reached where are combined great efficiency with compactness and lightness in handling. It will be seen by the illustration that the essential feature of this in- strument is a revolving wheel having inserted in its periphery a hollow cylindrical steel roller. This constitutes the hammer. It gives a " spring," not a " dead " blow, as it is held to its position by a stiff steel spring. The roller revolves slightly in its socket at each contact with the plunger. When the engine is run at ordinary speed the small wheel revolves with great velocity, deliver- ing upon the head of the plunger as many as fif- Fig. 187. Engine Mallet. ;.whi INTRODUCTION OF THE GOLD. 241 teen blows per second. The force of the blow can be modified at will by an extremely simple contrivance, as follows : The interdigitations seen around the upper end of the sleeve are held together by means of a spring attached to the sleeve. Pulling the sleeve away from the head against the spring, and revolving it to the right or left, raises or lowers the head of the plunger. Upon releasing the sleeve the spring at once throws it back to engage w T ith the head, and the blow is heavier or lighter, according to the direction in which the sleeve has been revolved. The impacting power of the blow from this is great, and in the hands of an experienced operator a large quantity of gold can be con- "\\ > Fig. 188. \ ^ ] Varney's set. @ \@ AVebb's set. 11 Chappell's set. densed in a short space of time. When cohesive gold foil is employed smooth oval points may be used with most satisfactory results. The point should not be pressed hard against the filling, but a skimming or smoothing motion given to the instrument. The surface of the filling when thus packed has a polished or planished appearance as if done with a hand burnisher. Such fillings are usually of great density. There are other mechanical mallets intended for use on the engine which have what is known as a " cam " movement. They are not, 16 242 THE OPERATION OF FILLING CAVITIES. strictly speaking, mallets, for the instrument is pushed rather than driven forward by an eccentric. The Buckingham and the Holmes mallets belong to this class. They have not the same steadiness of motion as the ones previously described, and for this reason, among others, have not been in general use. In the selection of plugger points for power mallets the operator will do well to confine himself to those having more than one row of serra- tions and those which are smooth-faced. The serrations, if any, should be extremely shallow, and the corners of the instrument slightly rounded. Those of the foot-shaped variety are admirably adapted to power mallets, and as there is a great variety of patterns and sizes he will have little difficulty in meeting his every wish in this particular. A few points selected from the Webb, the Varney, and the Chappell sets will fill all requirements. The accompanying cut (Fig. 188) shows a good working set which has been selected from the three mentioned. Pilling — by Classes. (As arranged in Chapter VIII.) I. Simple Cavities on Exposed Surfaces. Bicuspids and Molars. Class A. — The small cavities upon the occlusal surfaces of the bicuspids and molars are among the simplest in form. They are shown in Chapter VII., Fig. 129. Cavities of this kind are quickly filled by means of non-cohesive foil in the form of tape as shown in Fig. 177. Such cavities are usually of regular shape and of a form re- quiring little if any additional shaping to make them retentive. A length of tape varying from an inch to two inches should be taken upon a wedge-shaped plugger point and carried to the bottom of the cavity, where it may be held for an instant with a point in the left hand ; the instrument in the right hand makes a fold of the gold and carries it into and against the walls of the cavity by a lateral mo- tion ; fold after fold is then carried into the cavity and pressed firmly in every direction. As it is always best to finish such fill- Fjg. 189. . . ings with cohesive gold, a strip of No. 20 cohesive foil should be wedged into the mass already in the cavity, and then all subsequent pieces malleted, to give the occlusal surface as great hardness as possible. A completed filling of this class is shown in Fig. 189. Perfect adaptation to the walls of the cavity is obtained by the use of the non- cohesive foil, and great solidity is only essential upon the surface. Cavities of this character, though of greater size, are found in the molars, as shown in Figs. 190-192, and may be filled in the same gen- SIMPLE CAVITIES ON EXPOSED SURFACES. 243 eral way. Mats of foil may be substituted for tape, and where the decay has progressed to such an extent as to involve a large portion of the occlusal surface, making, as is frequently found, large round and quite deep cavities, the gold may be introduced in the form of cylinders. In former times, when the dentist's only means of excluding moisture Fig. 190. Fig. 191. Fig. 192. Fig. 193. Fillings in molar fissure cavities. was the napkin, and when his ability to keep cavities free from saliva was for a limited time only, the use of cylinders was much more com- mon than at the present time when the rubber dam is generally em- ployed. Cylinders for such cavities should be hand-made and of No. 4 non- cohesive foil (Fig. 193). They should be long enough to extend above the margins of the cavity as shown in Fig. 1 93 and arranged around its walls. The first one is usually carried to that point in the cavity farthest away, and should be pressed with a foot-shaped instrument against the wall. Others are then put in place and wedged laterally until room is made in the centre of the mass for another cylinder, this in turn being wedged toward the outer walls, and the operation continued cav . until no more cylinders can be introduced. The cylinders ity with cyi- should then be condensed with great force upon their pro- truding ends, and finished with cohesive foil in the same manner as previously described. This mode of filling is best suited to deep cavities in which the walls are nearly parallel and yet sufficiently strong to endure great lateral pressure. In a cavity of unequal depth, where the central portion is quite deep and the sulci radiating from it quite shalloAV (see Fig. 194), it is well to use semi-cohesive foil in the central portion and cohesive foil in the radiating sulci. Such fillings require to be well anchored at the extremities of the fissures lest they be dis- lodged by sticky candy, which often adheres with great tenacity to the surface of the gold. The operator will do well in filling such cavities to confine himself to gold that is quite cohesive, except in the central portion as above indicated. Class B. — Cavities situated upon the buccal surfaces of the bicus- pids and molars are rather more difficult to fill because of the difficulty in getting the rubber dam beyond the cervical border of the cavity. Fig. 194. Filled stellate cavity in lower first molar. to 244 THE OPERATION OF FILLING CAVITIES. When this has been done and perfect dryness effected these cavities may be classed as simple ones. In small or non-elastic mouths it is often difficult to reach the second or third molars, hence the view of the cavity is somewhat impaired. In selecting the gold for such cavities the operator- must Fig. 195. ta k e j n ^ consideration the depth of the cavity. If it be shallow he will do better to start his filling in a retaining pit and fill throughout with cohesive foil. If, on the con- trary, the cavity be of considerable depth, he may fill the Buccal cavity bulk of the cavity with mats or tape made of non-cohesive in lower sec- f ^ an( ^ ag ^ e a pp roacnes the surface of the filling, incor- porate with it cohesive gold and finish his operation with the last-named variety. Such cavities are often advantageously filled throughout with Watts' crystal gold. This form of gold is easily seated and it has no tendency to rock or move in the cavity. A slight under- cut along the upper and lower border of the cavity is sufficient to hold the filling in place (Fig. 195). When these cavities assume larger proportions, as they frequently do in the lower molars, and become confluent with cavities on the occlusal surface, they should be filled after the following method : A mat or block of non-cohesive foil should be placed at the border nearest the gum ; this may be held for a moment with an instrument in the left hand. One or two other blocks may be laid against this, and, when they have been well fixed in the undercut, should be malleted thoroughly against the cervical border • the remainder of the cavity may then be filled with semi-cohesive or cohesive gold. The surfacing of all fillings should be done with gold which has been made cohesive by recent annealing. Class C. — Cavities do not often occur on the lingual surfaces of the bicuspids or molars except in teeth of very poor structure and in teeth from which the gum has receded to a point below the enamel border. Such cavities because of their inaccessible position are difficult to fill with gold, and, as a rule, some of the plastics are indicated. When the fissures on the upper molars become the seat of caries they may be filled with gold in the same manner as those in class B. It is usually necessary to pack the gold in these cases almost entirely by hand pres- sure because of the inaccessible situation of the cavity. Incisors and Canines. Class D. — Cavities upon the labial surfaces of the incisors and canines situated at or near the gingival border of the gum were formerly the source of much annoyance to the dentist when gold was the material selected for filling. The principal difficulty was occasioned by mois- SIMPLE CAVITIES ON EXPOSED SURFACES. 245 ture, either in the form of blood or serum from the wounded gum or mucus from the follicles situated along the mucous surface. Since the introduction of the rubber dam this difficulty has been greatly modified. But when the cavity extends somewhat above the nor- mal gum line there is more or less difficulty in keeping the rubber above the gingival border of the cavity. This is best done by taking a straight instrument the point of which has been made very sharp by rubbing it upon an Arkansas hone. The dam is then raised well above the cavity border and the point pressed firmly into the cementum and held with the left hand throughout the . Till Woodward clamp. operation of filling the cavity. A very neat and valuable device in the form of a clamp has been introduced by Dr. W. A. Wood- ward for this purpose. It is shown in Fig. 196. The dam should include not only the tooth to be filled, but several on each side of it. With the left hand it is stretched above the margin of the cavity, while with the right hand the two little points on the bow of the clamp are pressed firmly into the cementum above the cavity,. The clamp is then made secure by turning the set-screw. This clamp when well seated rarely moves, and the operator feels that this difficult operation has become a simple one. • There are cases, however, where the decay has followed the receding gum or extended beneath it to such an extent that the clamp cannot be used. To overcome this difficulty the gum should be slit and a " Mack " screw inserted to the depth of two or three threads into the dentin. The rubber dam is then drawn above this and held securely above the cavity. When the operation is completed the screw should be cut off with the wedge-cutters and nicely smoothed. When the slit in the gum has healed, the portion of the screw remaining will be concealed. Most cavities upon the labial surfaces are shallow and are best filled with cohesive foil or Watts' crystal gold. It is w T ell to fix the first piece securely in a small retaining pit and build each piece Fig. 19/. upon a sure foundation, As fillings upon the labial surfaces of teeth are usually conspicuous (Fig. 197), it is often desirable to fill such cavities with plat- inous gold, because the tint of the two metals in Labial finings!"" combination is more nearly the shade of the tooth. Especially is this true in teeth of yellowish hue. Class E. — As cavities upon the lingual surface of the incisors are usually confined to the laterals and most frequently are the result of imperfect development of the enamel in relation to the cingulum (see Chapter I., p. 25) ; they are small in size and easily filled. A tape of 246 THE OPERATION OF FILLING CAVITIES. non-cohesive foil, or a small mat of the same material, may be inserted into the cavity first, and the filling completed with cohesive gold as in other cavities surrounded by strong walls. Glass F. — As caries rarely attacks the incisal edge of the anterior teeth the operation of filling with gold is usually confined to artificially made cavities, with the view of arresting waste of tooth substance caused by attrition, or where for any reason it is deemed best to " open the bite." Great strain is often brought to bear upon fillings in this position, and too great care cannot be exercised in the shaping of the cavity and the subsequent packing of the gold. Cohesive gold is best suited to cavities of this description, and each piece should be freshly annealed, that there may be no doubt about the perfect union of each piece. It is well to start the first "Pic -i no x # x piece in a small retaining or starting pit and then fill all of the undercut before attempting to build the gold above the walls. As fillings in this position are subjected to great wear, the greatest hardness of surface attainable should be sought for, otherwise there will be battering of the edges and possibly flaking of the gold. Platinous gold is well adapted for this kind of fillings. Narrow strips of No. 20 or No. 30, well annealed and condensed with mallet force, will answer a better purpose than lighter foil (Fig. 198). II. Simple Approximal Cavities. Incisors and Canines. Class G. — In selecting the kind of gold and the form in which it should be prepared for fillings upon the approximal surfaces of the incisors and canines, the operator must consider the size of the cavity to be filled and the retaining hold which he is able to secure without sacrificing too much of the tooth structure. If the cavity be a small one, situated midway between the labial and lingual walls, and the surrounding borders be strong, a rapid and easy way of filling such cavities is to prepare the non-cohesive foil in the form of narrow tape. A leaf of foil cut into four pieces and folded with a spatula upon a napkin to the width of one-sixteenth of an inch, and then cut into lengths of three-quarters or one inch, is a good way of preparing it. An excavator of an angle of forty-five degrees, with the extreme point broken off, makes a very good instrument for packing such fillings. Space should previously be obtained, either by the slow pro- cess of wedging with rubber or linen tape or by means of the Perry separator. COMPOUND CAVITIES. 247 When the cavity is two-thirds filled it is well to use a few pieces of No. 20 cohesive foil, so that a dense surface may be given to the filling. Such cavities may be classed among the simple ones, and FlG -^ present no difficulties except their inaccessibility (Fig. 199). The operator should ever strive to conceal as much as pos- sible the gold in the anterior part of the mouth, and w T hen it is possible he should preserve the labial wall intact. This can often be done by cutting away a portion of the lingual wall and by packing the filling almost entirely from the under side of the tooth. Where a large portion of the approximal surface is involved, the retaining hold for the filling must be had at the cervical border and at the incisal edge. The first pieces of gold should be anchored in a groove or retaining pit near the cervix and the cervical border made secure before any other portion of the cavity is filled. The beginner will ordinarily do better to start such fillings with cohesive foil or W r atts' crystal gold. If the latter, he may then complete his filling with cohesive foil. Non-cohesive gold is rarely indicated in cav- ities of this description. The electro-magnetic mallet or the Bonwill mechanical mallet is well adapted for packing such fillings. Bicuspids and Molars. Class H. — Cavities of medium size situated upon the mesial or dis- tal surfaces of the bicuspids and molars and not involving the occlusal Fig. 200. surface may be filled after the same manner as small cav- I j ities in the incisors or canines. Operators who are not in r^L tne na ^it of using non-cohesive foil prefer starting such fill- I • | m S s m a sma H undercut or retaining pit and filling through- w"^ out with cohesive gold prepared either in narrow ribbons Approximal ° # # bicuspid or loosely rolled cylinders (Fig. 200). fimng " Such fillings, because of their position, must be packed largely by hand pressure, although the mallet may be used as the filling approaches completion. III. Compound Cavities. Incisors and Canines. Classes I and /. — Mesio-labial and disto-lab ial cavities in the incisors and canines are usually best filled throughout with cohesive gold. Each cavity independent of the others should have retentive shape, so that in the event of one filling being displaced the other will remain intact. As a rule it is better to fill the cavity on the labial surface first, because the first pieces of gold are more easily anchored in an accessible 248 THE OPERATION OF FILLING CAVITIES. cavity, and because also of the danger of displacing the gold in the approximal cavity when tilling the channel connecting the two fillings. Every possible care should be exercised in packing the gold in cavities of this description. The gold should be made thoroughly cohesive by recent annealing, and be used in pieces sufficiently small to prevent clogging. Such operations are more or less exposed to view, and the greatest degree of . artistic skill should be bestowed upon them to render them Mesio-labial # > r filling. as pleasing as possible to the eye. The original outline of the tooth should be restored with the gold, because it pre- sents a better appearance than a space between it and the adjoining tooth (Fig. 201). Classes K and L. — Cavities upon the mesio-lingual or disto-lingual surfaces of the teeth are filled in precisely the same way as those described under classes / and J. If the cavity be of con- siderable depth, non-cohesive gold may be used as part of Fig. 202 - the filling, but in any event the bulk of the filling should be made of cohesive foil (Fig. 202). Classes M and N. — Mesio-incisal ; Disto-incisal — Cav- ities situated upon the approximal surfaces of the incisors and becoming confluent with one on the incisal edge require great care in the matter of packing gold. It is often an advantage to have the cavity on the approximal surface unite with a natural or an artificially made one upon the incisal edge, because much better anchorage can be obtained in such cavities. Cohesive gold prepared in the form of ribbon or in pellets or cohesive cylin- ders, if loosely rolled, may be used. The better method is to fill the undercut at the cervical border of the cavity first, and then bring the gold toward the incisal edge as squarely as possible, keeping the mass on a line with the labial and lingual walls. The operator feels a sense of security when he is able to an- chor such fillings in an undercut or retaining pit on the incisal edge. In teeth with broad incisal edges there is ample opportunity to make a strong retaining hold, but where the edge is narrow a lateral cut into the palatal Mesio-mc^a, wall one-third back from the incisal edge affords a strong and secure hold for that portion of the filling. Operations of this class require great thoroughness in the packing of the gold. It should be very cohesive and when possible condensed with some form of mallet (Fig. 203). Class 0. — Mesio-disto-incisal. — Where both approximal surfaces and the incisal edge are united in one cavity, the better plan is to begin the filling at the undercut near the cervical border of the distal cavity, COMPOUND CAVITIES. '240 and build the gold squarely down as in classes M and N until the in- cisal edge is reached, thence across the incisal edge, then fill the mesial cavity after the same manner, uniting the three fillings at the mesio- incisal corner. It is better to insert such fillings with an electric or a mechanical mallet, as there is always dan- ger, when packing across the incisal edge by hand pres- sure, of pushing one or the other of the fillings out of the approximal surfaces. If no accident occurs in the pa c kins: of the gold a Mesiodisto-incisai . . fillings. filling thus made is very secure, for its form is like a staple and each portion helps to bind the others securely in the triple cavity. Non-cohesive gold should form no part of such fillings (Fig. 204)/ Bicuspids and Molars. Class P. — Mesio-occlusal. — The filling of this class of cavities offers no serious difficulties provided sufficient space has previously been ob- tained. As it is desirable to restore with gold the original outline of the tooth, sufficient space to do this in is a necessity, and the operator will soon learn that he can only accomplish good results in proportion as he recognizes the importance of this preliminary. The cervical border is the vulnerable point for recurrence of decay, and imperfection here in the matter of packing the gold means speedy failure of the filling, hence the importance of a perfect joint between gold and tooth. This may be obtained by using a roll or rope of non- cohesive foil. One end of the roll should be carried with a suitable plugger into the gingivo-linguo-axial angle of the cavity, and ex- tended across the gingival border into the gingivo-bucco-axial angle. Great care should be exercised at this point in reference to the gin- gival border. The gold should be first thoroughly matted down with a broad-faced plugger and then a few blows from an auto- matic or hand mallet should be directed upon it to insure perfect adaptation to this wall of the cavity. Subsequent rolls of non- cchesive foil may be introduced in the same manner until one-third or even one-half of the approximal cavity has been filled, after which cohesive gold should be substituted for the non-cohesive, and its use continued throughout the balance of the filling. Freshly annealed gold should be used upon the surface, that a compact filling may be the result. It is always better to insert too much rather than too little gold, as the operator can shape the contour according to his fancy or to the necessities of the case. The occlusal portion of the filling should be thoroughly condensed, 250 THE OPERATION OF FILLING CAVITIES. as much depends upon this for holding the filling in place. Great hard- ness is also essential to prevent battering in the Fig. 205. act of mast i ca tion (Fig. 205). Class Q. — Disto-occlusal cavities may be filled in precisely the same manner as those situated upon the mesio-occlusal surface. The difficulties Approximo-occiusai are slightly greater because these cavities are not so accessible. Cavities of this description can be greatly simplified by the use of the matrix. This little device converts compound cavities into simple ones, and when used with care and judg- ment facilitates the operation of filling to a wonderful degree. Experience has demonstrated that the only satisfactory method of filling cavities upon the approximal surfaces of the bicuspids and molars is to restore, by means of filling material, the original outline of the tooth. This is termed " restoration of contour." To do this success- fully requires artistic sense and mechanical skill of a high order, and an accurate knowledge of the topographical anatomy of the teeth. To the man who has these the operation is easy, but otherwise persistent effort alone will enable him to acquire the ability. The inexperienced operator will often do better if he confine himself in the beginning to but one kind of gold, and that of the cohesive variety. If this be done he should start the filling in a well-defined groove at the cervical border of the cavity, and then add, piece by piece, well-annealed foil until the filling is completed. Such a procedure is of necessity slow, but excel- lent operations can be made by this method. The beautiful and lasting operations of Yarney and Webb and others were made in this way. The matrix is best suited to disto-occlusal cavities. It is sometimes employed upon mesio-occlusal cavities, but, as a rule, obstructs the light and adds little to the convenience of the operator. The subject of filling with the aid of the matrix is treated in detail in Chapter XII. Fig. 206. Fig. 207. Fig. 208. Occluso-buccal filling. Occluso-lingual filling. Mesio-occluso-distal filling. Class R. — Occluso-buccal cavities are usually confined to the lower molars. If they be shallow it is better to fill throughout with cohe- sive gold. If, on the other hand, the cavity upon the occlusal surface be deep, non-cohesive gold may be used in part and then cohesive gold FILLING WITH TIX. 251 used to fill the channel connecting the two cavities. Such fillings are subjected to great wear and should be solid (Fig. 206). Class 8. — Occluso-lingual. — These cavities are nearly always con- fined to the first and second upper molars, and, as a rule, are best filled, with cohesive gold. The channel running into the lingual aspect of the tooth is not often deep, and non-cohesive gold is contra-indicated (Fig. 207). Class T. — Cavities upon the mesial and distal surfaces of the bicuspids often become confluent with those upon the occlusal sur- face, and it becomes necessary to fill them as one cavity. Such ope- rations are simplified by the use of a matrix upon the distal surface. A band matrix could be employed, but it obstructs the light somewhat and the operator will more frequently confine himself to a matrix upon but one side of the tooth. The filling should be commenced at the disto-cervical border, and after inserting a few mats or cylinders of non-cohesive foil proceed as in cavities described under class Q (Fig. 205). If these cavities be of considerable size the buccal and lingual walls are weakened and there is danger of their being broken away in the act of mastication. It is often well to truncate the cusps somewhat and build the gold well across the occlusal surface, allowing the strain to come directly upon the gold instead of upon the tooth structure. Filling with Tin. It is not definitely known when tin was first employed for filling carious teeth, but it has been used for at least a century and has found great favor with many. Prior to the improvement in the formulas of dental amalgams, tin was used more generally than at the present time. Tin possesses certain inherent characteristics which make it valuable as a filling material. Among these are great malleability, non -conduc- tivity, and it is thought by many to possess antiseptic properties. But while it has desirable qualities it has also some undesirable ones, such as softness, and when exposed to the secretions of the mouth it discolors, — which facts render it unfit for surfaces exposed to great wear in the act of mastication and upon surfaces exposed to view. The discolora- tion, hoAvever, is confined to the surface, and teeth filled Avith tin are not discolored in consequence of its presence. There are various methods of preparing tin for dental purposes. That which has found greatest favor in the past is in the form of foil. The tin used should be chemically pure. An ingot of the metal is rolled into ribbon and then beaten, after the same manner a? gold foil, into sheets of the desired thickness. As a rule it is not beaten as thin as the former. The foil best suited for most fillings is Xo. 10. 252 THE OPERATION OF hi LUX a CAVITIES. Pure tin, like pure gold, is cohesive, and fillings of great solidity can be made if the operator will exercise care in packing it. The best results are obtained by taking a third of a leaf of No. 10 foil and roll- ing it into a loose rope, then cutting it into lengths of half an inch or less and packing each piece with a view of making each part of the filling solid. Some prefer folding the sheet with a spatula after the same manner as gold foil, and then cutting into narrow tape. Equally good results are obtainable by either method. A more rapid but less satisfactory manner of introducing the fillings is to use the tin in the form of cylinders, not relying so much upon the cohesive properties of the metal. The directions for using gold in the form of cylinders will apply equally well for inserting tin foil. Shavings of Tin. — The cohesive property of tin is best illustrated when it is used in the form of freshly cut shavings from a revolving ingot of the metal. Any operator can prepare his own shavings and have them fresh daily or hourly, if necessary, after the following method : Take an ordinary corundum wheel two inches in diameter and one-half inch in thickness, such as is used in the laboratory. Make a mould of this in sand or marble dust, then melt in a crucible or ladle enough pure tin to fill the mould. When it has cooled mount accurately upon the mandrel of the laboratory lathe, and from it, with a sharp car- penter's chisel, turn shavings of great tenuity. When freshly cut, and before oxidation of the surface has taken place by exposure to the atmo- sphere, it will be found that the tin coheres with the same readiness that pure gold does. Broken-down teeth can be built up by this method, or by means of it surfaces may be contoured as with gold. The plugging instruments best adapted for tin filling are those hav- ing shallow but well-defined serrations and points not too broad. As the margins are approached broader points and condensers may be used, and the surface should be well burnished. The operator must not lose sight of the fact that while tin possesses many desirable qualities and is easily manipulated, it lacks hardness and is not adapted to surfaces where great attrition occurs. Its chief value is found in its use upon surfaces concealed from view and shielded from wear, and in the temporary teeth, where its greatest value is manifest. Tin fillings should be finished with the same care as gold ones, and the same directions will apply in all particulars. FINISHING FILLINGS. 253 Finishing Fillings. Much of the beauty and utility of a filling is imparted to it in the finishing. It is not enough that it be well made, it must also be well finished if the best results are to be attained. All fillings should contain rather more gold than it is intended shall remain, and this for the purpose of dressing down to such lines as will be artistic and practical. Fillings that are not well condensed cannot be given a fine finish. Solidity of the surface is an essential quality. After the last piece of gold has been well condensed it is well to give the surface a thorough burnishing for the purpose of getting a compact surface as well as to insure perfect contact with the margins of the cavity. The simple fillings upon the occlusal surface of the bicuspids and molars are best dressed down with small finishing burs, as shown in Fig. 209. These are fine cut and leave the gold with a better surface than when cavity burs are used for this purpose. The gold should be cut away until the margin of the cavity has been reached and until all overlapping of gold has been removed. The occlusion of the tooth of the opposite jaw should be noted, and, if it occludes unduly with the filling, enough should be taken from the surface of the gold to pre- vent it. When a uniform surface has been given to the gold, a suitable Fig. 210. Fig. 209. Plug finishing burs. .1 t! I Wood polishing points. wood point as shown in Fig. 210 should be mounted in an engine man- drel and dipped first in water and then in fine pumice powder and the surface nicely smoothed. A round-end burnisher may be used if the operator desires a polished surface, although it adds nothing to either the beauty or the utility of the filling. When fillings cover a larger portion of the occlusal surface the dress- ing down may be done with corundum or carborundum points, which if kept wet will cut more rapidly than burs and cause less heating. These are shown in Fig. 211, and are of many patterns and admirably adapted 254 THE OPERATION OF FILLING CAVITIES. to all parts of the filling. Those made of fine corundum and shellac, or corundum and vulcanized rubber, are more desirable than the coarse Fig. 211. 1 Corundum points. ones, which are liable to grind away the cavity margins because of the rapidity with which they cut. Fig. 212. Fig. 213. O © Felt polishing wheels. Fig. 214. Hindostan points. Fillings upon labial and buccal surfaces should be dressed down with fine corundum points or the Hindostan stones shown in Fig. 212 until the outline of the cavity has been reached. Any overlap- ping of the gold upon these surfaces gives a ragged appearance to the filling and detracts much from its beauty. Care should also be exercised in giving the filling the same degree of convexity that the tooth formerly had; in other words, the filling should accurately re- store the lost anatomical contour of the tooth. When sufficient gold has been removed the surface should be nicely smoothed with re- volving wood points charged with pumice powder and water, or a paste made of pumice and glycerin, after which the final finish may be made with flour of pumice, chalk, or oxid of tin, used by means of a revolving disk or wheel of felt or soft rubber (Fig. 213). The soft rubber polishing cup of Dr. John B. Wood is a valuable aid in polishing the con- vex surfaces of approximal fillings or those upon the cervical portion of labial cavities. It is shown in Fig. 214. As fillings upon the labial surface are more or less conspicuous at best, it is better not to give them a burnished surface. The dead or satin-like finish which is left by the flour of pumice is usually preferred. Dr. Wood's polishing cup. FINISHING FILLINGS. 255 Fillings upon approximal surfaces are more difficult to finish, and too great care cannot be bestowed upon them. An operator is often judged by the finish which he gives his approximal fillings, and justly so, as no class of fillings requires a higher degree of skill in the finishing. There is of necessity more or less overlapping of the gold in the insertion of a filling, and the removal of all excess is as important as any other part of the operation. For this purpose a great variety of instruments is supplied. Files and gold trimmers, as shown in Figs. Fig. 215. Plug finishing files. 215 and 216, are best adapted. The cervical border is one which should receive most careful attention. The gold should be filed and dressed down until the finest excavator or probe will not catch when drawn from the cervix toward the cutting edge. In addition to the Fig. 216. Curved finishing files. file and gold trimmer, strips of emery tape or sandpaper should be used until all margins are well defined. The operator should have at hand a great variety of these strips, some of extreme thinness and of various grits, of emery, of silex, and of buckhorn. When the filling has assumed the desired shape and all overlapping gold has been removed, the final finish should be given with linen or 256 THE OPERATION OF FILLING CAVITIES. cotton tape charged with pumice of exceeding fineness. If there are places where the tape cannot be made to reach, a soft-rubber wheel in Fig. 217. I I Approximal trimmers. the handpiece of the engine and charged with the same powder may be used (Fig. 218). Fillings in the bicuspids and molars because of their inaccessible position are often most difficult to finish, and for this reason should receive unusual care. If a matrix has been used at the cervical border, and has been made to fit the tooth perfectly at or near the gum, it will be found that the finishing process has been simplified in a great measure, because there is less overlapping of the gold at this point. Fig. 218. Soft-rubber disks. The pointed files, right and left, as shown in Fig. 216, are admirably adapted to dressing away any overlapping of gold at the cervical border. Fig. 219. Sandpaper disks. With these and the trimmers shown in Fig. 217 the general outline of the filling may be obtained, after which the emery and corundum tape may be used and the filling polished after the same manner as FINISHING FILLINGS. 257 described above. Disks of sandpaper and emery cloth and finer ones charged with cuttlefish powder (Fig. 219) are exceedingly useful in shaping and polishing the filling. Fig. 220 shows two forms of disk mandrels which may be satisfactorily used in carrying disks. Fig. 220. Morgan-Maxfield disk mandrel. Many approximal fillings in the bicuspids and molars extend to the occlusal surface. When this is the case the operator should pay special heed to the occlusion of the opposing teeth. If left too full the con- stant touching of an opposing cusp may batter the filling, or, if not securely anchored, dislodge it. A filling is not well finished until a delicate instrument can be passed from enamel surface to filling with- out catching. When this can be done, and dental floss is not frayed at the cervical margin, the inference is justified that no gold has been left overlapping. Repairing Fillings. Fillings somewhat defective are often susceptible of repair. The defect may sometimes be apparent in the finishing ; at other times it is the result of subsequent caries, and at still other times the result of a fracture of the tooth enamel along the border of the filling. The nature of the defect and the condition of the remaining filling must be taken into consideration before an effort to repair is undertaken. When the defect is due to insufficient gold at any point in the filling more gold may be added. It is well to first cut out a portion of the filling, making a distinct cavity of retentive shape. Cohesive gold is usually best suited to the purpose ; crystal gold often serves Avell in the repair of such defects. If the filling has been thoroughly condensed and the mass is solid there is little difficulty in adding more gold to it, provided the sur- face be clean. If it has been wet with saliva, the surface of the gold must be made not only dry but clean. It is well to wipe it with a pellet of cotton or paper saturated with alcohol or ether, after which the filling should be scraped with a suitable instrument. If the fill- ing be of considerable size and well anchored^ shallow retaining pits 17 258 THE OPERATION OF FILLING CAVITIES. may be drilled into it, which will make an additional hold for the gold which is to be added. Defects which arise from subsequent caries are perhaps more frequent in approximal surfaces at or near the cervical margin. These borders are vulnerable points for the recurrence of caries, and imperfect adaptation is not infrequently the determining cause of the beginning of such decay. To effect a successful repair in such localities ample space should be obtained, especially so if the repair is to be made with gold. If the decay has not extended beneath the filling, and sufficient space has been obtained, there is no greater difficulty in making a suc- cessful repair than in filling a simple cavity similarly located. If the operator is skilled in the use of non-cohesive gold, he will do well to prepare his foil in the form of narrow tape, and work it into the cavity fold after fold, allowing the loops to extend somewhat above the walls of the cavity. When the cavity has been completely filled the protru- ding folds may be well condensed and the filling finished in the usual way ; or the repair may be made with cohesive gold, the first piece having been made fast in a groove or retaining pit. Such repairs are often required in the bicuspids and molars, and large fillings otherwise good are saved by a successful repair at the cervix. The plastics are sometimes indicated in this class of cases, provided they be not so near the anterior part of the mouth as to be unsightly. Gutta-percha often serves a good purpose here, but in some mouths undergoes decomposition and is less reliable than gold. The oxyphosphates are contraindicated because of their liability to wash away after a few months. Amalgams are more frequently used, and nearly always serve well when thus employed ; but unfortunately the contact with gold produces discoloration, and an unsightly filling is the result. Whenever gold and amalgam are brought in contact in the same tooth, if the surface of each is exposed to the fluids of the mouth, the amalgam is almost sure to turn quite black. The discoloration of the surface of the alloy does not lessen its value as a preserver of the tooth, but its unsightliness is often too great to be tolerated ; nevertheless, utility enters so largely into the equation that the operator feels justified in using the alloy, because with it he feels sure of making a better repair. After the alloy has hardened it should be nicely dressed down and all overlapping of the material at the gum margin removed, when it should be smoothed and polished with the same care that other fillings receive. Fracture of one or more of the cavity walls is a common accident, and one which may be repaired if the filling has been securely anchored in portions of the tooth not involved in the fracture. Such accidents sometimes befall bicuspids and molars, especially the bicuspids, where fillings have boen inserted in each approximal surface, the two meeting REPAIRING FILLINGS. 259 in the fissure upon the occlusal surface. The buccal wall is sometimes the one broken away, sometimes the lingual. In either case the ability to successfully repair depends upon the stability of the approximal fillings and the anchorage which can be obtained at the cervical wall and in the exposed fillings. To restore with gold a buccal cusp or the entire buccal surface of a bicuspid might necessitate a show of gold which would be objectionable ; and a better plan would be to engraft a porcelain facing or an entire porcelain crown ; whereas such a restora- tion on the lingual surface would not be open to the same objections. Cohesiye gold alone is indicated for repairs of this kind. Watts' crystal gold when used in cases of this description has been most satisfactory. If the fracture extends above the margin of the gum the operation is much more difficult because of the danger from a flow of blood, and the additional difficulty of getting the rubber dam above the border of the fractured surface. This may be accomplished by filling for a few weeks with gutta-percha, when there will be recession of the gum caused by the pressure of the gutta-percha upon it. AVhen a similar fracture occurs in a molar, if the fractured surface does not encroach upon the pulp, and will admit of drilling retaining pits without danger to the pulp, there is no difficulty in restoring the broken portion with cohesive gold. Mack's screws are sometimes indicated in cases of this kind, since strong anchorage can be secured in this way without much loss of tooth substance. Fracture of the incisal edge of the anterior teeth is often a serious accident, because of the difficulty of repair and the unsightly display of gold when it has been accomplished. Large fillings situated upon the approximal surfaces of the incisors but not extending to the cutting edge, yet near enough to weaken the enamel overhanging, are especially liable to need repairs. The corner of the tooth breaks away, leaving the surface of the gold exposed, and the only hold the filling has is at the cervical border. In order to secure retaining hold for additional gold the operator must be careful not to displace the original filling. A wooden wedge should be inserted between the teeth and pressed home with sufficient force to hold the filling securely in place during the operation of repair. Sometimes a retaining pit can be made laterally into the sound dentin, or, by cutting a little channel through to the lingual surface and then deepening the channel at its ex- tremity with a round bur, a secure anchorage may be had for the fresh gold. Great care should be exercised in packing the gold, lest by inadver- tence the instrument should slip and push the original filling from its position. Fractured surfaces should receive prompt attention, for if left for a period of time disintegration of the dentin will set in and the 260 THE OPERATION OF FILLING CAVITIES. caries may extend beneath the filling and thus jeopardize or ruin the most thorough work. Eroded Areas. 'There is a class of cavities which has not been specifically treated in the foregoing chapter, partly because the lesions under consideration cannot, strictly speaking, be classed under the head of carious cavities, and they are of such a peculiar formation that no definite rule can be laid down as to the best mode of treatment. If the eroded area be narrow and confined to the cervical border of the labial surface, and in a mouth in which the teeth are not conspicuous, a filling of gold may be employed ; but not infrequently the eroded area extends over a considerable portion of the labial surface, and in such cases a filling of gold would be so inharmonious that it should be avoided if possible. Hitherto the operator has had little choice of filling materials, and has often been compelled, against his better judgment, to employ gold in these cases. The zinc phosphates have been almost as inharmonious in color as the gold, and their durability has been so variable that they could not be regarded as permanent in character. The same may be said of gutta- percha. Happily, the progress which is being made in porcelain inlay work promises something both artistic and durable. It is quite possible, with the great variety of shades of porcelain now being furnished, to match the tint of the natural tooth, and if care be exercised in the selection of shades and the contour given to the inlay these eroded areas may be covered and the tooth made to assume almost as natural an appearance as before the disease had attacked the surface. (For a detailed descrip- tion of porcelain inlays the reader is referred to Chapter XV.) CHAPTER XII. USE OF THE MATRIX IN FILLING OPERATIONS. By William Crenshaw, D. D. S. The matrix, as originally suggested and employed, was used exclu- sively between the molars and bicuspids, and consisted of curved pieces of thin metal of various kinds, which were braced with wooden wedges from one tooth to the other ; but now the matrix has been adapted to other teeth and other forms of cavities, as will appear in the further develop- ment of this subject. All forms of cavities occurring on molars, bicus- pids, and incisors, standing alone or together, excepting those cavities located in the occlusal surfaces of the first-mentioned class, and in the cutting edges and corners of the latter, are now subject to the use of the matrix as an aid in filling them. The large and difficult filling operations encountered between the molars and bicuspids, which in past decades so taxed the skill and vitality of the dentist, have been by various forms of device rendered easier of execution and more permanent and perfect in character. Matrices have been used more or less in one form or another for the past fifty years and some crude forms even longer. Dr. Louis Jack gave the profession thirty years ago the first practical idea and demonstration of the matrix and its possibilities, and his effort, more than all that had gone before, gave shape and impetus to the development of this important device. General Considerations. The limitations, no less than the possibilities, of the matrix are im- portant to understand, because, used indiscreetly, in locations which the judgment should forbid or in locations where it would be perfectly in place but for the unsuitable nature of the material employed, more harm than good may result from its use. To be able, therefore, to discern the proper class and location of cavities for the reception of the fillings, together with a knowledge of adapting the filling materials to the case in hand, are some of the requirements and demands on the operator who essays to use matrices. The matrix should possess as fully as possible the qualities of adapt- ability and fixedness to the teeth, at the same time provide for contouring and for leaving the teeth in proper position, and preserving the proper 261 262 USE OF THE MATRIX IN FILLING OPERATIONS. interproximal space. Further desiderata are that the matrix shall be resistant enough to stand the pressure of condensing gold against it, susceptible at the same lime of being shaped into whatever form needed, and capable of being removed from between the teeth without destroy- ing the form of the filling after that has been completed. The material of which the matrix is made depends somewhat on the location and class of the cavity to be filled. In many of the operations occurring between molars and bicuspids, particularly in the instances where only one tooth is decayed and only slightly so, slips of German silver or steel (36 to 40 gauge) may be inter- posed and used. In the instances where gold is to be the filling, and the cavity is of large size, the metals above mentioned, silver and gold plate, but of heavier gauge, and other substances may be employed. But in the event of the matrix band having to bear heavy tension, which tests the strength of it, as in the loop or band variety or any duplex form which separates the teeth, either decarbonized steel or phosphor-bronze, the ten- sile strength of which is equal to or beyond that of steel, should be used. Steel is somewhat unsatisfactory, because if bent often at one place it breaks, and it does not hold polish or plating well. Phosphor-bronze not only polishes and holds plating well, and does not corrode, but solders readily to gold, silver, German silver, steel, copper, and brass, and does not soften or amalgamate with the mercury employed in amalgam alloys. The matrix band should be closely adapted around the margin of the tooth cavity, and the cavity floor and walls coming up to the band should form as nearly as possible right angles with the band. This rule followed, with the employment of proper forms of instruments, will be found to insure well-condensed margins, and as full a contour as ordi- narily belongs to the tooth of its class ; and, in those instances where it is desirable, greater contour than belongs to the tooth may be produced. Those devices which when assembled are practically in one piece, and admit of easy application and steady fixedness on the teeth, with as little of obstructing parts as possible, are the ones with which the operator will ordinarily accomplish best results. The bands should not purposely stand away from the tooth. This is impracticable even if it were desirable, as there are no means for holding the band away from the tooth and at the same time having it secure from slipping and working loose under the operation of the filling. Occasionally in cavities occurring on the mesial side of upper first and second molars, and more frequently on both the mesial and distal sides of upper first bicuspids extending well under the gum, we encounter the concavity occasioned by the bifurcation of the roots, when of necessity the band stands off from the depression. The filling, however, whether of gold or tin-foil, is not better condensed at this point for that reason. GENERAL CONSIDERATIONS. 263 The failures made with the matrix result quite frequently from the selection of a wrong material. Take, for instance, any of the approximal surfaces of the molars or bicuspids in which the cavity extends beyond the margin of the enamel, presenting ideal conditions for the employment of the matrix ; prepare these cavities after approved methods, apply the matrix, and fill with any form of cohesive gold, and we have a filling beautiful in appearance, but more treacherous than beautiful, and one which will develop recurrent decay along the cervical margin sooner than would result from the employment of any other filling material placed in the permanent list. 'It will not matter what form of cohesive gold is employed, if heat sufficient to change its molecular arrangement has been applied in annealing the gold, it is practically impossible to adapt it, unaccompanied by linings, so as to secure moisture-proof joints, and therefore permanent results. Because, first, the tooth does not afford the resistance necessary to reduce the crystals of gold into adaptable laminae, and we have the crystalline gold resting on fibrous structure in the cementum and dentin, which together prevent the making of moisture-proof joints. Therefore this state of affairs, aided either by the seeping in of fluid at the base of the filling from the canaliculi and lacunae, or drawing in external moisture by capillary attraction from without, permits of recurrent decay. With cohesive gold, the result would be ultimately the same, with or without the matrix ; although the work would, should at least, be better executed without it. But with the cavity well prepared, and the matrix securely adjusted, the operation is inviting in appearance, and the operator is led into a snare and delusion when he essays to fill these points with cohesive gold exclusively. The objection here raised to cohesive gold does not apply to the same extent in adapting it to enamel walls, because in this tissue we have an absence of nerve-fibres, and a greatly denser substance against which to adapt the gold. While it is impossible to adapt cohesive gold to tooth structures so as to stop out moisture permanently, for the reason pointed out, there is that difference in the histological make-up of the tissue of cementum and dentin and enamel which explains the fact of cohesive gold being better adapted to enamel, and can be made to better prevent the leaking of moisture than in cementum margins. Again, decay cannot be so rapid in enamel margins, because of its inherent strength and re- sistance, due in part to the absence of nerve-fibres and to its greater density and hardness. The propaganda of Prof. Henry S. Chase — namely, that in propor- tion as teeth need saving gold is the worst material with which to do it — is true in its application to cohesive gold, particulary in cementum and dentin margins in connection with the matrix. But, substitute non- 264 USE OF THE MATRIX IN FILLING OPERATIONS. crystalline or soft gold in these margins, and we pass from the worst possible work done with gold, and made even worse by the employment of the matrix, to that which has proved the best possible — at least up to the present time. Cohesive gold is at its best in open cavities with strong enamel mar- gins, and is profitably employed in cervico-occlusal fillings in connection with soft gold and matrices to cap over the approximal wall of soft gold. Cohesive gold, on the other hand, is at its worst in connection with matrices when used at the cervical margins, particularly when the margin is located in cementum or dentin, because of the physical difficulties encountered in the adaptation of it, and the perishable nature of the margins on which it is laid. Again, in the employment of a carelessly formulated and com- pounded amalgam alloy packed into these cavities embraced by a matrix, depending too much on the matrix, as the tendency is, we have another instance in which the inefficiency of this device is made to appear. It should be made a rule of practice in employing the matrix to regard it simply as a mechanical device, the object of which is to simplify com- pound and other difficult cavities ; and not to depend on it to make good any of the essentials of the filling material. With this idea in view, and fortified by a knowledge of the essential characteristics of materials rather than matrices, we shall know where and when to employ them. The filling materials, too, must possess constancy of form, and susceptibility to that perfect adaptation which shall prevent the drawing in of moisture by ^capillary attraction, the result of which would be recurrent decay. An understanding of these characteristics is indispensable to the permanence of filling operations anywhere and everywhere, and by whatever method performed, and when they are thus understood, combined with the advantages afforded in the use of the matrix, the operator will accomplish his best results. The matrix should be used, therefore, for the ^purpose of simplifying the cavity, and never allowed to lead into the use of a treacherous and questionable material. The matrix is valuable in all those cavities of extreme decay involving the disto-occlusal, the mesio-occlusal, the bucco-occlusal, the disto-bucco, the mesio-bucco, and the disto-linguo and mesio-linguo occlusal surfaces of molars and bicuspids. In many instances the entire corners may be restored, as is intimated and included in the disto-bucco and mesio-bucco, the disto-linguo and mesio-linguo-occlusal surfaces. No method yet devised for filling these teeth is so satisfactory or productive of such results as when the matrix is employed, as it aids the adaptation of the material definitely and exactly in position. Its chief advantage is in having brought a cavity of compound and complex nature into simple GENERAL CONSIDERATIONS. 265 form, and so contributing to the mastery of the material that perfect adaptation and condensation is secured. A comparison of results at the cervical margin between fillings made of soft gold and those of the cohesive variety shows in so marked a degree in favor of the soft, even in operations where the matrix has not been used, that when this device is employed it places the standard of excellence of soft-gold work far beyond that of the cohesive. With the advantages thus accruing, soft gold in the form of cushions or cylinders may be perfectly adapted at the cervical aspect and as far up the wall as desired, capping over with a slab of cohesive which, when anchored in the occlusal surface, makes a handsome and lasting operation. Another treatment of these cavities is to place tin cylinders or cush- ions, which may be made by folding the cylinders upon themselves, and adapt at the cervical margin and up the cervico-occlusal wall to the top of the step D, Fig. 221, completing with the slab of cohesive gold or of amalgam for the remainder of the filling. (See Fig. 225.) The soft gold and the tin are practically the same in adaptation, due to the fact that in their manufacture the molecular arrangement is destroyed and becomes structureless, by which a closer and more perfect adaptation is possible. The matrix enables the operator to take advantage of this important quality ; and without thus simplifying the cavity, it would be quite impossible to confine, control, and condense these materials, and secure adequate solidity and adaptation to margins. The use of the matrix, therefore, not only enables the operator to place soft gold in a satisfactory manner at the points where it serves best, but also cohesive gold where it is best adapted — namely, at enamel mar- gins, and in that portion of the filling where it is most easily and perfectly adapted. Again, cohesive gold is placed in matrix work at that point where it best resists the attrition and stress of chewing, and the lateral wear between the teeth. Still another treatment of these cavities in connection with the matrix is with amalgam alloy. Assuming that the same care and pains have been taken with the preparation of the cavity for the amalgam as for the gold, the simplifying of it by the use of the matrix enables the operator to secure greater solidity and correspondingly better adaptation to the walls of the cavity. This material, used in connection with the matrix and cavity lining, places amalgam alloy on a plane not heretofore occupied by it. In the large proportion of cavities occurring in the class under consideration, this practice stands for much in the saving of these teeth. 266 USE OF THE MATRIX IN FILLING OPERATIONS. Cavity Preparation of the Major Class for Matrix Work. The subject of cavity preparation comes up in connection with the matrix as a matter of first importance. The form of cavity preparation ordinarily employed in cases of extreme decay of approximal surfaces of molars and bicuspids answers in some measure in matrix work. In the description of cavity preparation the terms depth, width, and length, as applied to the several walls of the cavity, should be limited, and apply to particular points, and particular points only. For instance, the depth of a cavity should mean from the point of decay toward the pulp, whether penetrating from the occulusal, mesial, distal, buccal, or lingual aspect of the tooth. The width should mean from side to side of the cavity, whether on the occlusal, mesial, distal, buccal, or lingual surface of the tooth. The length, the longest dimension, should mean the greatest length, in whatever direction it extends. The bottom of a cavity should be called the floor, as seen at A and d, Fig. 221. By reference to Figs. 221 and 222 the tooth shown represents a left lower Fig. 221. Fig. 222. Fig. 223. ' ^L-J D' "A" A B Cavity preparation of a molar Cavity preparation, showing Section of molar, showing the for the matrix. square corners. introduction of the cushion. molar, the decay of which penetrates from the mesial surface in the direction of the line leading from F, and we would say that the depth of the cavity seen at A and c was in that direction ; and that its width was bucco-lingual, from E to E, or from c on the buccal side to a point opposite on the lingual. This cavity, being a compound one, must have added together for its length, the floor of the step D, the axial wall F, and the floor A. The depth of the lingual and buccal walls is seen at c, and the depth of the floor at A. The axial wall and height of it is seen at F, and the floor of the step at D. In Fig. 221 is represented the cavity preparation, with which, in connection with the matrix and soft and cohesive gold, the operator is enabled to bring gold work in cavities of this class to a degree of per- fection rarely approximated without its aid. At the cervical margin of Figs. 221 and 222 it will be observed that CAVITY PREPARATION OF MAJOR CLASS FOR MATRIX WORK. 267 the floor of this aspect of the cavity, A, and the external wall of the tooth, B, form practically right angles, which is the angle, all things considered, with which to secure the best margins and best results. Beginning well up on the side wall at c, Fig. 221, passing down and along the base of the cement step and up the opposite wall, is a groove c, better shown in the sectional cut, Fig. 223, made with a No. 3 or 4 round bur, or Darby-Perry excavator, Nos. 11 and 12, designed as an anchorage for the base of the cervico-occlusal column, marked non- cohesive gold, Fig. 225. In this groove, which should be shallow and upon the floor surface, A, is condensed the gold. The groove extending up the side wall is not a necessity, though it may be incorporated in the cavity formation when the Avails are strong, but that portion of it along the floor should be employed. In the instances where the lateral walls are weak and the groove cannot be formed, the occlusal anchorage shown at D, Figs. 221 and 222, should be employed. In the formation of the side- wall edges, e e, Fig. 222, care must be taken to leave them strong enough to prevent fracture under the pressure of the matrix band. These walls should be beveled on the lines e e, Fig. 222, terminating in an obtuse angle with the external surface of the tooth, if practicable. Less than a right angle should not be depended on, if it can be avoided, as there is danger of fracture. In the formation of the cavity in Fig. 221, with the rounded corner Fig. 224. A— — B D Fig. 225. .--COHESIVE GOLD. -- G — --CEMENT. NON COHESIVE GOLD. Fig. 226. Cavity preparation, showing Section showing the plan of a Section showing the condensa- subdivisions of filling. matrix filling. tion of cushion k of Fig. 223. c, is seen the preparation suitable for amalgam or other plastic materials in connection with the matrix ; and for cushions and cylinders of foil if the cavity approximates the form seen in this and Fig. 222, and at F and H of Fig. 226. But these corners should be modified as nearly as possi- ble into the form seen at N n, Fig. 222, if the cavity is shallower from A to D, Fig. 222, than from F to H, Fig. 226. The square corners aid in better locking and binding the foundation subdivisions in the process of building in the filling — see Fig. 224. But when the cavity assumes the proportions seen at F to H, Fig. 226, the matter of square corners is not necessary, because when the distance 268 USE OF THE MATRIX IN FILLING OPERATIONS. from the top of the step, Fig. 226, to the floor is greater than from f on the axial wall to h on the matrix band, we have a form of cavity in which the cushions and cylinders bind and hold without the aid of square corners. It should be a rule of practice to put in cement steps whenever the dis- tance from the axial wall to the matrix band is greater than from the top of the step to the floor of the cavity, and bring the form of the cavity as nearly as possible into that shown in Figs. 223, 226, 227, and 229. Be- cause, first, it necessitates the use of less metal, whether of gold or tin ; second, it is better when finished, and more quickly filled to the top of the step, Fig. 227 ; and, third, it avoids the formation of the square corners, n N, Fig. 222, extending so deeply toward the pulp as to weaken the walls of the tooth. Fig. 228. Section showing cervico-occlu- sal wall built to top of step. G, groove for the grasp of the capping slab. Section of pulpless molar be- fore placing in the cement step. RF. Section showing the recon- struction of pulpless molar with cement step. In the introduction of the filling into the corners of Fig. 222, the method suggested is to carry in the cushion of soft gold or tin, as the case may be, and place in the corner at A with pluggers, Nos. 257, 258, or 259, Fig. 265, whatever size of these forms shall best suit the case, and partially condense it. In the opposite corner place in the subdivi- sion b, and then the subdivision c. Only this last introduction is carried straight down in the direction of the long axis of the tooth, while the other subdivisions, as seen in Fig. 224, are placed in diagonally and compressed in place. At this juncture hold down with a suitably shaped instrument, No. 174 or 175, Fig. 265, on one side and condense the other with the automatic mallet carrying a suitably shaped plugger, No. 18, Fig. 265, until adequately condensed. After this, change instruments about, and treat the opposite side in a similar manner. If the cushions are proportioned properly to the size of the cavity, two sets of each of these put into the subdivisions A, B, and c, Fig. 224, w T ill bring the wall to the top of the step, or nearly so. Fig. 221 represents the preparation of decay cavities, whether appear- ing on bicuspids or molars, the outer outline of which appears in Fig. 230 and comes under the head of the major class. All such decays CAVITY PREPARATION OF MAJOR CLASS FOR MATRIX WORK. 269 should as nearly as practicable be prepared after the suggestions of Fig. 221. In the formation of the cavity in Fig. 221, when the tooth is normal and its functions comfortably performed, care must be exercised to avoid too near approach to the pulp, particularly when the cavity is located in bicuspids, in which case we have a shallower zone in which to work than is found in the corresponding parts of molars. In the deeper cavities of bicuspids and molars, zinc phosphate should be used to bring the cavity into simple form, as seen in Figs. 225, 228, and 229. When these cavities are prepared after the suggestions and illustra- tions of the figures referred to and embraced by the matrix, not only is less material needed to bring up the cervico-occlusal wall to the top of the step, but additional advantages are gained in that the cavity is simpli- fied, the filling rendered easy of execution, and the character of the work improved. Oxyphosphate of copper cement, being more adhesive and less a thermal conductor, and possessing more of antiseptic property than the other forms of zinc cements, should be employed wherever practicable for step making. Its inky blackness perhaps is against its use in the anterior teeth, and farther forward than the molars. But it is also less irritant and is harder and stronger than any of the zinc phosphates. So that, in the instances where the cavity penetrates to or beyond the pulp, and compels the formation of a cavity as deep from the matrix band to the axial wall, as is shown in the pulpless tooth, Fig. 228, or as already cited, when the depth of the cavity from f to h, Fig. 226, is greater than the height of the step, the cement should be placed in posi- tion to bring the axial wall close enough to the matrix band to form the cavity into the proportions shown in Figs. 223, 226, and 227 when em- braced by the matrix. This class of cavities, when filled with gold, should be filled with soft gold cushions or cylinders to the top of the step d, Figs. 221 and 222, when, after forming the groove shown at G, Figs. 225 and 227, should be completed with cohesive gold and built securely in place. The anchorage, Figs. 221, 222, and 224 at d, indicate, what this should be. The procedure in the introduction of the soft-gold part, or of tin when that is used, in the major class, is seen at k, Fig. 223, and when con- densed, at l, Fig. 226. The introduction is in the direction of the long axis of the tooth and not diagonal, as shown in Fig. 224, though the diagonal introduction may be employed in special cases favoring it. The cushions thus introduced, rarely less in size and bulk than a size 3 cylinder, and generally much larger, do not fill up squarely out to their ends or to the lateral walls ; and the operator must look to these points, and level them up with small cylinders or their equivalent in cushions. 270 USE OF THE MATRIX IN FILLING OPERATIONS. The final condensing of this column as seen at I, Fig. 227, and before the cohesive part is begun, should be done by holding down the gold at one side of the cavity, while the automatic mallet condenses at the opposite, as suggested in the filling of the cavity of Fig. 222. The student must appreciate the importance of condensing first the soft and afterward the cohesive gold into the angles formed at E and N, Fig. 222, when that figure is embraced by the matrix. Pluggers Nos. 7 or 8, Fig. 265, of small treading surface are suitable for doing this part of the work. The cohesive gold should be used in narrow strips when the angle into which it must go is close and sharp. It is the purpose in engineering construction to secure the greatest possible strength from the arrangement of material entering into such construction. In the formation, therefore, of the anchorage for the fill- ings of the major class of the cervico-occlusal cavities, due regard must be given to the proportion of gold and enamel in making the anchorage head in the occlusal surface of fillings of this class. Just as it is possible to weaken a carriage wheel by having the tenons of the spokes so large as to weaken the hub, it is also possible to have the tenons so small and the hub so strong as from this cause to weaken the wheel. So also with the anchorage of this class of fillings ; the neck of gold going into the head of the anchorage may be so small, narrow, and shallow that the stress of chewing will cause it to break at this point. And yet the neck may be widened and deepened so much that the gold becomes stronger than is necessary, and the enamel on either side becomes correspondingly weak, and gives way under stress of mastication. The problem then is to proportion the neck of gold and the enamel so as to secure the greatest strength. Assuming the depth of the gold neck to be about its width, the rule of one-third gold in width and two-thirds enamel, one-third each side of the gold, answers the requirement. The Minor Class. While the principles inculcated by Drs. Webb, Black, and others in extension for prevention — extending the cavity margins well away from the contact point of the teeth — hold good in the larger proportion of cases, there are those individual instances presenting when the operator will not be justified in employing extension for prevention. Take, for instance, the highly developed teeth, with perfectly fused enamel through the sulci dividing the cones, lobes, and cusps of the molars and bicuspids, which from the excellence of their quality and the cleanliness of the patient almost entirely prevent caries ; it would be unwise and unneces- sary under these conditions to extend in preparation the borders of these cavities to the limits taught and endorsed in extension for prevention, and THE MINOR CLASS. 271 yet so necessary in many of the larger decays denominated the major class. The preparation of the minor class of decays, represented in the inner outline of Fig. 230, should be formed after the suggestions of Figs. 231 232, and 233. The student should comprehend the formation of both the major and minor class, as each must be prepared according to the supwstions made. The preparation, therefore, for the minor class may be enlarged to the Fig. 230. Fig. 231. Fig. 232. Bicuspid, showing the major and minor class cavity out- line. Side view, showing the out- line of the major and minor preparation. Transaxial section, showing anchorage of the minor class at line a of Fig. 231. proportions shown in the inner outline of Fig. 231, while the outer out- line of Figs. 231 and 233 would show the formation of the major class on the same tooth. Fig. 234 is a sectional cut showing the completed major class of the cervico-occlusal fillings, as adapted to and completed in the bicuspid. Fig. 232 is a transaxial section at the line A on Fig. 231 ; and at this point the anchorage for the minor class is seen in Fig. 232. The anchor- age can and should be made strong here under the buccal lobes of bicus- pids and molars, and similarly at the lingual sides. Above the anchorage, toward the occlusal surface, the cavity should be so modified as to come out on the occlusal surface, as shown in Fig. 233. Fig. 233. Fig. 234. Fig. 235. End view, showing outline of major and minor cavity preparation. Section showing the completed major class filling on bicus- pid. M, 2-grain cube of gold, show- ing relative size to the cav- ity in which it rests. The plnggers, Nos. 115 and 116 or 117 and 118, Fig. 265 — pairs in two sizes — are invaluable for tacking the cohesive gold into the condensed soft gold. Much of this part of the work must be done by hand pressure ; and it is important, in view of this fact, to prepare the gold in narrow strips, which should be annealed with electric heat to insure the strongest cohesion. 272 USE OF THE MATRIX IN FILLING OPERATIONS. In the filling of this class of cavities the matrix should be applied, and soft gold brought up to the anchorage shown in Fig. 232. At this point cohesive gold should be throughly condensed into the anchorages, and brought out, finishing the contour of the tooth. Care should be taken to bevel somewhat the occlusal surface of this filling to prevent the too positive impinging of the occluding tooth in the opposite jaw. The beginning of the cohesive on the condensed soft gold and the fastening of it there, in whatever class of cavities, depends on careful attention to several details: First, the operator must so conduct his operation as to control the saliva perfectly, keeping his work dry. Second, the matrix must be fixed and rigid in its application. Third, the pluggers should be kept freshly serrated, and of such forms as give direct entrance to and application of them at the point on the work. Fourth, the ser- rations should be clean and deep. Fifth, the gold should be clean and freshly annealed. Any of the forms of cohesive gold may be used, if the portions carried each time to their destination are small clean, and annealed. Small cohesive gold cylinders, Nos. \ and J, are easily used for this work, and the smaller ones should not only be employed to begin with, when this form is used, but as far as practicable throughout. The strips or ribbons, however, of cohesive gold when freshly annealed, and with all other conditions above enumerated complied with, give best results. The ribbon is tacked or pricked into the soft gold by interdigita- tion, and the union made with this or any preparation of cohesive gold, while not strong, is enough so, to enable the operator to reach his anchor- age points, where he may thoroughly secure the work. In making matrix fillings, if the matrix employed is of the band or loop variety and has no separating feature, in order to secure contour, and to have the fillings finish in the original form of the tooth, the teeth, if two are together, should have the cavities previously packed with cotton, long enough to produce mobility of the teeth so that they may more easily yield apart. This then gives opportunity to push the teeth apart still further, especially with those matrices provided with the separating feature, and so to gain room in which to shape the matrix band and to reproduce the contour of the tooth. Preparation of Gold for Matrix Work. In the soft-gold part of matrix work the form of the gold to be em- ployed is important to be understood. Large cylinders and cushions in comparison with those ordinarily used in cavities of given size are not only more safely and perfectly adapted, but more quickly done. This results from doubling and partly compressing the cushions, which, being further susceptible of compression, are still large enough to squeeze in place and bind as they are compressed, PREPARATION OF GOLD FOR MATRIX WORK. 273 In placing cushions into the bottom of large cervico-occlusal cavities of molars and bicuspids embraced by the matrix, it is important to start with those of sufficient size and density to bind as they are condensed, but it is not to be understood that the first such piece introduced must be fully condensed before other similar pieces are added. If this practice were followed, notwithstanding the fact that the first piece introduced binds as it is condensed, this is so only to a certain point of the conden- sation. Beyond this if we continue it, especially to that density which may be obtained against the resistance the tooth affords, it loosens, will tilt and rock, and is worthless. But if after placing in one cushion which the operator learns to proportion to the size of the cavity, and partially condensing it, he introduces another and carries the condensation to the point of the first, and still another, he may then mallet until the mass will yield no more; and the wall thus built will be steady, well adapted, moisture proof, and, therefore, impervious to leaking by capillary force. This comes of the fact that when three or more cushions or cylinders are carried down as described, the bearing up and down of the axial and matrix walls is sufficient to insure binding and steadiness. In the illustration, Fig. 223, will be observed at K a gold cushion entering the cavity between the axial wall F and the matrix band H. Fig. 236. Leaf of No. i gold foil, twisted ready for formation into cushions. The cushion is made of one-half of the gold twist shown at Fig. 236, and contains two grains of gold by weight. This cushion, when con- densed to its ultimate density, as by melting and hammering, is repre- sented in cube form and exact size at M, Fig. 235. A No. 4 gold cylinder, one-fourth of an inch long, contains one grain of gold by weight, and when this is condensed into cubic form it is one- half the bulk of the cube shown at M, Fig. 235. It transpires then that the large loosely-made cylinders of one grain weight are more difficult of satisfactory adaptation than those which contain the two or more grains, because the large loose ones lack the bulk and substance which is necessary to cause them to bind and lock in condensing. It will be seen further, by comparison of the 2-grain cube M, Fig. 235, with the proportions of the cavity in which it rests, that it reaches hardly half across the cavity, bucco-lingually, and that if this cube were elongated so as to reach across the cavity, its bearing against the axial wall and the matrix band would be lowered at least one-half, and there would not be sufficient bearing up and down these walls to hold the gold fixedly in place. This then demonstrates the difficulty of adapting gold 18 274 USE OF THE MATRIX IN FILLING OPERATIONS. or tin-foil at such points with cylinders or cushions containing less than enough material to bind and lock the mass in place in the process of con- densing. And if this be true, as is illustrated in Fig. 235, it is seen that the size 4 cylinder, containing only one grain, would be still more difficult to control, because it lacks in greater degree the bulk and substance sufficient to give the bearing up and down the walls necessary to the binding and locking in the process of condensing. Neither will the cylinders or cushions containing two grains or more in very large cavi- ties bear complete condensing, before adding other pieces without loosen- ing, for the reasons already given. In exceptionally large cavities of the major class, a sheet of No. 4 foil may be formed into a single cushion, and introduced to advantage. Such a cushion containing four grains would not build higher than is necessary to bind, even if it were formed into a rectangular parallelopiped — two cubes side by side, and extending from one lateral wall to the other, Fig. 235. The successful making of fillings with either gold or tin is not so much a question of securing the ultimate density of these materials, as that of securing adaptation of them to the walls of the cavity in such manner as shall prevent leakage beneath the filling. This result may be obtained with a compression or condensation of much less density than is shown in the melting of them, or as is obtainable against the resistance which the tooth offers. Formation of Cushions from Foil. The cushion of either gold or tin, rather than the cylinder, is a better preparation for matrix work, even when it is made from cylinders compressed or doubled upon themselves, because the cushion, made of foil, while soft enough to be adapted to the irregularities of the cavity, contains from twice to four times the amount of material which the loose cylinders do, and because of this fact, in connection with proper cavity formation, they are more easily secured in place. The student should appreciate the fact that until he succeeds in laying the foundation of soft-gold work in a manner to prevent its moving or shifting position in the process of condensing, he will have failed to secure the results within his reach. The employment of the cushion, therefore, rather than the cylinder, is urged as the best means to this end. The formation of cushions from the foil is as follows : Take a full leaf of No. 4 soft gold-foil, and with clean hands crimple and wrinkle it. Straighten this out, but leave the sheet undulated, when it should be loosely folded three to four times upon itself and loosely twisted. The twist thus made should be cut into from three to five pieces, Fig. 236, depending on the size of the cavity to be filled. The large cavities, FINISHING THE FILLING. 275 such as are seen in the approximal surfaces of molars, Figs. 221 and 222, will take a cushion made from the longer section of the twist shown in Fig. 236, which may represent one-half or more of the sheet of No. 4 foil ; while cavities of the proportions shown in Fig. 231 will take one-fourth or less. Smaller approximal cavities in the incisors will take from one-fifth to one-third of a half-sheet prepared after the manner of Fig. 236. The cushions prepared after these suggestions, when used for the large cavities of the molars and bicuspids, should somewhat resem- ble the illustration in Fig. 237. The preparation thus cushion formed from made is more desirable than the cylinders made of soft 2 ^ 1S e 0T ^ 0I ^ pa J foil, because it is more easily manipulated and with tsaUy compressed better results, and because the student learning to do this secures to himself a resource which enables him to prepare his cushions for all sizes of cavities, and is never at a loss for what is wanted when foil is to be had. But when this class of work is to be done with tin-foil, the cylinders, compressed or doubled, will serve best, since it is difficult to obtain a foil of tin light enough and soft enough to make desirable cushions. Tin-foil in cushions, made by doubling the cylinders upon themselves for the foundation portion of cervico-occlusal fillings, in connection with the matrix, works even more kindly, and adapts more easily than cushions made from soft gold-foil ; and if its use here is not forbidden by electrolysis, it is to be given first place as a tooth preserver, especially at the cervical margins, and as a non-conductor of the thermal changes to the pulp. Tin-foil and soft gold-foil laid together, and the two formed into cushions after the suggestions already made, may be used with results quite as beneficial for preservation of the margins embraced by the matrix as w r hen gold or tin alone is used, with the advantage of avoiding the danger of electrolysis of tin under gold. Finishing the Filling. No part of the work of making gold fillings, such as are included in the major class particularly, is more laborious than the finishing of them. Yet when the matrix has been properly adapted to the teeth, the finishing of the cohesive gold part may be lessened to the minimum. The more rapid and satisfactory finishing of the work following the use of the matrix is no small part of the advantage of this device, since the matrix gives not only the form of the wall which it embraces, but more than any other method yet devised saves filling material. This comes of the fact that when it is properly adjusted the cavity is converted into a mold so nearly the shape of the filling to be, that when it has been made very little work remains to be done in polishing. 276 USE OF THE MATRIX IN FILLING OPERATIONS. The first step toward polishing after removing the matrix is to go around the borders of the soft-gold portion of the filling with a blade burnisher, which should be kept highly polished and clean. In this operation the object should be to compress as much as possible by hand- pressure the soft-gold portion that may have bulged under the malleting. After this the Rhein trimmers, Nos. 31 and 32, should go over the borders, and should be held so that the blade shall rest equally on the filling and the adjacent external surface of the tooth. At this point, if the operation is between molars or bicuspids, the Perry or the Ivory separator is valuable, and should be placed so as to have the beaks impinge above the margin of the filling, and should be made to open the teeth only enough to pass in the thinnest strips and sandpaper disks. Care and skill are required in the handling of disks to avoid grinding away the contour of the filling, but the disk can be so held as to prevent this. The author finds, in removing the overhanging corners of the cohe- sive portion of these fillings, that the use of a stiff five-eighth inch garnet disk, held only to the corners and not permitted to pass in between the teeth, answers better than any form of corundum or carborundum wheels. After thus carefully shaping the cap or slab of cohesive gold at the contact points, and rounding them as the case permits and requires, flint strips and the " regular " grit, followed with the " fine " cuttlefish disk, completes the polish. The occlusal surface of cohesive gold is easily shaped with corundum wheels and polished with the cuttlefish disk, when these can be made to apply, or with leather wheels carrying pumice. There is no essential difference in polishing the major and minor class of these fillings, except in the extent of the work. Forms op Matrices for Molars and Bicuspids. A presentation of all the devices known' as matrices is not the purpose of this chapter, but only of those whose efficiency commends them. Fig. 238. DODDOD The matrices of Dr. Louis Jack. Fig. 238 represents the set of matrices devised by Dr. Louis Jack. This set of matrices is provided with concave surfaces for contouring the FORMS OF MATRICES FOR MOLARS AND R1CUSP1DS. 277 teeth, which indicates the high ideal of the originator of the device. They are made thicker and heavy at the base of the lateral edges, which aids in steadying them between the teeth, and they are provided with slotted edges, which engages a special pliers to insert and remove. i Fig. 239. (3) Loop matrices. Fig. 239 shows a set of loop matrices, which at times, and with teeth of slight constriction at the neck, answer well, but, like all of the loop variety, they require space at both sides of the tooth to admit of adjustment. Fig. 240. Brophy's band matrices. Fig. 240 exhibits a set of matrices devised by Dr. Truman W. Brophy, which, with the flexibility of the thin steel bands and under the action of the screw, may be made to aid the operator most acceptably. The band is not unlike the loop in the matter of passing between the teeth, and the teeth must yield apart to admit it. Still, with the thinness of the bands in this set, there is no difficuty in this particular. This form of matrix, however, is unsteady and difficult to fix rigidly on very short crowns, and particularly on those of decided conicality. Fig. 241 exhibits an improved loop matrix devised by Dr. S. EL Guilford, in which the lip feature is added for the purpose of having the band to catch below the cavity, without the necessity of forcing the band elsewhere around the tooth into the gum. This device, made in several 278 USE OF THE MATRIX IN FILLING OPERATIONS. lengths of bands, although tedious to adjust from the fact that three pieces must be handled, is otherwise valuable and serviceable. Fig. 241. Guilford's band matrices and clamps. Fiff. 242 illustrates Dr. W. A. Woodward's screw matrices. This form of matrix has valuable features in that the thin metallic ribbon constituting the matrix wall may be made as thin as No. 36 to 38 gauge, and yet possesses adequate tensile strength. The device is also valuable Fig. 242. Woodward's screw matrices. because in its use only one thickness of the ribbon need be carried be- tween the teeth. Again, it has the separating feature, which makes it additionally desirable, as this forces apart the teeth to start with, and the separation is continued as the operation proceeds, or as the exigency of the case demands. To Chapter XIV. in this volume, on Combination Fillings, by Dr. Dwight M. Clapp, the student is referred for the description of his matrix devices and their application. These matrices are quite as well employed for making gold and the plastic fillings as for the specific purpose of combination fillings. Fig. 243 shows illustrations of Dr. E. B. Lodge's matrix bands, ten- sion screws, and wrench. Those marked A are adapted to bicuspids and FORMS OF MATRICES FOR MOLARS AND BICUSPIDS. 279 molars of usual form, while those marked B are adapted to the same class of teeth, but of constricted necks and more pronounced bell-shaped crowns. C and D of this illustration show two forms of tension screws, and f and e the wrench for operating the screw d. Fig. 244 shows the Lodge device adiusted to the teeth. Fig. 243. QmmQmmm — «^ F@ Lodge's system of loop matrices. The bands of the Lodge matrix are made of German silver, and are provided with two eyelets in each, giving ample range of adjustment. Figs. 245 and 246 show a form of matrix suggested by Dr. A. C. Hewett, which, for simplicity and efficiency, meets a constantly occurring want. In the instances w 7 here the matrix is employed between the teeth Fig. 244. The Lodge matrix in position on the teeth. and it is braced by an adjacent tooth, and where no straining apart of the teeth is required, this device is admissible. But it should be braced with a wedge, ordinarily at the cervical edge. Fig. 247 is a form of matrix w T hich has been used by the author in extensive cavities occurring on the buccal surfaces of lower molars. 280 USE OF THE MATRIX TN FILLING OPERATIONS. The band which must be fitted to each case is made from No. 35 to 36 gauge German silver, and so cut that the projecting arms turned down on the occlusal surface of the tooth prevent it from carrying down with the wedge as the device is tightened. In the instances where the cavity extends beneath the gum the band can be provided with a lip to catch below the buccal margin. The dam can rarely be employed in these opera- tions, but fortunately it is not necessary for the first part of this operation. Fig. 245. Fig. 246. Fig. 247. The Hewett matrix held in position with the Parmly Brown clamp. The Hewett matrix held in The hand matrix used in position with the ordinary extensive buccal surface rubber-dam clamp. cavities on lower molars. When the lingual and buccal sides of these teeth are provided with ab- sorbent-cotton rolls, and especially when the saliva ejector is employed, the cavity can easily be filled to the top of the band with soft gold or tin, as suggested elsewhere in this chapter, before moisture shall interfere. If the capping for this filling shall be of amalgam, it can be finished within the time the absorbents protect. If the purpose is to finish with gold, the dam should at this juncture be placed over the band and tooth after the soft-gold part is brought to the top of the band, and the remain- der of the work finished with cohesive gold. Fig. 248. Fig. 249. The Hodson contour slip matrices. The Hodson matrix in position betAveen the teeth. Fig. 248 represents the contour slip matrices devised by Dr. J. F. P. Hodson. The device is a most meritorious one, with which the contour of molars and bicuspids can be fully restored, but can only be used between the teeth. Fig. 248 gives two views of the matrix ready to be slipped in place. These matrices are made preferably of thin annealed steel plate, forged or swaged on a leaden slab with an oval-end punch, giving them what- ever of concavity the case may require, they are then slipped in place, FORMS OF MATRICES FOR MOLARS AND BICUSPIDS. 28i which causes the teeth to yield apart. The gingival end of the device should be braced against the adjacent tooth with an orange-wood wedge until after the filling is inserted. The Hodson device is better adapted to amalgam work than gold, be- cause it does not possess the rigid fixedness in sufficient degree to remain securely in place for extensive gold operations. If the filling material used is a plastic the device is left in place. over night or longer, allowing the filling to set under pressure, which may be done readily, as the device shown in Fig. 249 is in no wise uncomfortable or troublesome to the wearer. When the adjustment of the matrix is properly made, it is unneces- sary in most instances, particularly in the uper jaw, to use the dam. Fig. 250 represents the contour matrix as devised by the author of this chapter. This device, which is of duplex form, is only used between the teeth, and acts in the three-fold capacity of matrix, separator, and rubber-dam clamp. The device is shown in position between two Fig. 250. Fig. 251. The Crenshaw contour matrix in position The contour matrix with one band between molars. turned out for removal. molars, the cavities of which have been prepared after the suggestions of Figs. 221, 222, and 223, and the manner of introducing the cushion. With this form of matrix the teeth may be drawn apart as with the sep- arator, and the fillings given the contour the teeth originally possessed. Fig. 251 shows the method of removing the matrix, as may be done when amalgam is used without lifting or unseating the filling. To do this the pin is withdrawn and the band embracing the unfilled tooth is turned out on the tension screw as a pivot. After this the band embrac- ing the filled tooth is lifted away from it, when the matrix may be removed from between the teeth. In amalgam work with this device only one tooth should be filled at a sitting, and after this filling has crys- talized and become fixed in the tooth the second one should be made. Fig. 252 shows how the operator may protect his work without the dam in the lower jaw by placing absorbent-cotton rolls on each side of the teeth, and how these are held in place by the matrix. The employ- 282 USE OF THE MATRIX IN FILLING OPERATIONS. merit of the cotton rolls gives time in which to insert amalgam and other plastic fillings before the rolls become saturated with saliva. In the same manner the cervico-occlusal colli ms of these fillings may be made of gold or tin cushions to the top of the step with the aid of the rolls and the saliva ejector, when the matrix should be removed, the dam put over the teeth, the matrix reapplied, and the operation finished with cohesive gold. Fig. 252. Fig. 253. The contour matrix holding absorbent cotton in position. The contour matrix in position between bicuspids. Fig. 253 shows the application of the short-bar matrix as adapted to bicuspids and between canines and first bicuspids. The bicuspid device is better adapted for use between molar and bicuspid than the molar one, although the latter may be employed at these points. Fig. 254. Fig. 255. The contour matrix in position between canine and first bicuspid, with bow brace attached. Enlarged figure of the anterior teeth matrix a and b, arms ; c, projection screw ; d, metal- lic ribbon. Fig. 254 shows the contour matrix in position between a canine and first bicuspid, in connection with the bow brace, which prevents the matrix slipping from between the teeth, as it is inclined to do on account of the bevel of the lingual side of the canine. Matrix fob the Anterior Teeth. In the effort to improve gold work in the approximal cavities of the anterior teeth by a method which practically does away with cohesive gold, the author offers the anterior teeth device. Fig. 255 shows the device enlarged, as it appears before being placed in position about the teeth, and with the lower part shown in section. MATRIX FOR THE ASTERIOR TEETH. 283 The arms a and b project through the loops formed on the ends of the metallic ribbon D, the thickness of which is 1 4 Q of an inch, and which may be passed between teeth of rigid contact. The parts A and B are separable, and when the tension screw c is turned in, the arm B is extended, which puts the ribbon D under tension. Fig. 256. Fig. 25, The metallic ribbon in position before crimp- ing. Fig. 258. The metallic ribbon adapted to tooth after crimping. Fig. 259. The holder applied for tensioning the ribbon. The holder applied for taking up slack in the ribbon. Fig. 260. Fig. 261, Application of the ribbon pressing the left cen- tral forward. Application of the metallic ribbon between the anterior lower teetb. Fig. 256 shows a lingual view of four incisors with the matrix ribbon in position before it has been adapted at the incisal edge. Fig. 257 shows the ribbon crimped and soldered, which Fig. 263. adapts it closely to the tooth at the incisal edge, and to the surface of the tooth beneath the ribbon. Fig. 258- presents a labial view with the device in position, and shows how cavities Fig. 262. Application of the holder pressing the lower right central forward. e, cervical, f, incisal, g, lingual, h, labial subdivision of approximal incisor filling. which extend through and open on the lingual face of the tooth may be floored and brought into simple form. Fig. 259 shows a means of taking up slack in the ribbon, if this 284 USE OF THE MATRIX IN FILLING OPERATIONS. should become necessary, by slipping the slitted arm astride of the ribbon, as shown in this figure. By this means, if at any time the tension screw should be run in to its limit, additional tension can be obtained without removing the ribbon. Fig. 260 is a view showing the cutting edge of the teeth and the crimp of the metallic ribbon. Fig. 261 is an application of the ribbon to the lower incisors. It must ordinarily be placed between the teeth before applying the holder. Fig. 262 shows the holder in position. Filling Approximal Cavities with Cohesive and Non-cohe- sive Gold with the Anterior Teeth Matrix. Fig. 263 shows an approximal cavity in a central incisor three-fourths filled by the aid of the matrix, after which the matrix is removed. The subdivisions of the filling, lettered E, F, and G, are made of soft gold, leaving the space marked H to be filled w r ith cohesive gold. The pro- cedure which best accomplishes this is as follows : If the cavity be a large one, take a No. 3 or 4 soft-gold cylinder and double it upon itself and again crosswise, making a firm cushion. Let this cushion be large enough to squeeze into place. Take a foot-shaped plugger with light serrations, Nos. 257, 258, or 259, Fig. 265 — whatever size of this form best suits the case — and press this first cushion into the undercuts of the cavity at E. After settling it by hand-pressure, take a suitable foot- shaped plugger, No. 257 or 258 answers well, in the automatic mallet, and, while holding down at the lingual side of the cushion, mallet the other, after which change the instruments about, and mallet the labial side. After this is done, treat the opposite end of the cavity at F in the same way, only the cushion going into this subdivision may occasionally have to be drawn into place with the throat of the instrument. When the F subdivision is condensed, use a No. 2 cylinder folded once upon itself, and introduce end-wise at G, which when condensed keys e and F in place. If the cavity be a large one it will require two of the No. 2 cylinders, and in some cases three, to bring this part of the filling to the centre of the cavity, which is necessary in order to securely brace E and F in place. The author cautions against using small soft cylinders w T ith which to make the key-block, because when condensed they do not build up high enough to obtain the necessary lateral bearing against blocks e and F to hold firmly in place. Neither should cohesive gold in any form be used here. It will be observed from the lines of the cavity division in Fig. 263 that the cavity is to be filled from the labial side, and that it extends THE HANDLES ADAPTED TO THE PLUGGERS. 285 through into the lingual face of the tooth, also that the matrix ribbon, which has been removed to show the plan of the filling, envelops and embraces the tooth in such manner as to floor the lingual portion of the cavity, as may be seen in Figs. 258, 259, 261, and 262. The action of the device not only moves the tooth forward to be filled as seen in Fig. 260, so that it may be got at easily, but transforms a dif- ficult cavity into one of easy, simple form. In the instances where the opening of the cavity is toward the lingual aspect with a labial wall to be preserved, the device operates with as much favor in filling from the lingual as from the labial — see Figs. 257 and 260. In these figures the action of the device will be seen to move forward the left central, and depress the right central and left lateral. When the filling is made from the lingual aspect, the lines of the sub- divisions of the filling, Fig. 263, would be reversed, and the key-block would be placed at H, with h occupying the position of G. Pluggers for Matrix Work. The point of a plugger is not all of its efficiency. The handle may materially enhance or handicap its performance, and the average student, unless guided in the selection of points and handles, is apt to get together in the selection of excavators and pluggers an incongruous combination, much of which will prove unsuited and unfitted for anything he is called on to do. Some of the forms of pluggers here suggested for matrix work may be found in the student's case. All included in the list of Fig. 265 are regarded as cohesive gold instruments, but several of these forms are ill adapted to that work and well adapted for soft gold. Many of the forms of instruments included in sets of soft-gold pluggers cannot be utilized in the execution of the soft-gold part of the matrix fillings set forth in this chapter ; and to assist the student in knowing which instruments shall be used to manipulate the cohesive, and which the soft, and the handles best suited to them, are pointed out and explanation of their uses made. 1 The Handles Adapted to the Pluggers. ]S T os. 7, 8, 10, 18, 115, 116, 117, 118, 207, and 208 should be placed in cone-socket handles Nos. 4 or 5, Fig. 264, according as the shank of the plugger point is small or large. These handles can be used for hand- pressure, but are designed especially for the hand-mallet, Nos. 174, 175, 248, and 250 should be placed in the cone-socket 1 The handles, pluggers, and numbers of same, are taken from the revised lists of the S. S. White Dental Manufacturing Company. 286 USE OF THE MATRIX IN FILLING OPERATIONS. handles Nos. 2 or 3, Fig. 264, according as the shank of the plugger point is small or large. Fig. 264. I 3 4 5 10 Handles for cone-socket points. 10a Nos. 257, 258, and 259 should be placed in the rubber handles No. 10 or 10a, Fig. 264, according as the shank of the plugger point is small or large. TEE USES OF THE SEVERAL PLUG GEES. 287 The Uses of the Several Pluggers. Nos. 7, 8, 115, 116, 117, 118, and 207, Fig 265, are for cohesive gold, and may be made to answer the needs of this work in conection with matrix fillings. No. 60 Parmly Brown plugger point, for cohesive gold, is of uni- versal application, and is best used in the electric or the engine mallet. Nos. 174 and 175, Fig. 265, are assistant pluggers, used to hold down Fig. 265. 1i ^i Vti 18 115 116 117 118 171 175 207 208 248 250 257 258 259 Condensed set of pluggers. when malleting ; and may be used for packing cushions in the cervico- occlusal column of molar and bicuspid matrix fillings. Nos. 248 and 250, Fig. 265, are for soft gold, and used for placing and compressing the cushions into the subdivisions E and F, Fig. 263, of the smaller class of approximal incisor cavities. Nos. 257, 258, and 259, Fig. 265, are for compressing the cushions into the subdivisions E and F, Fig. 263, of the larger class of approximal incisor cavities. The square corners at the toe of these forms should be rounded off. Nos. 10, 18, 208, 248, and 250, Fig. 265, are for settling and mal- leting soft-gold cushions in the cervico-occlusal column of molars and bicuspids, see Figs. 223, 226, and 227, and for carrying down and mal- leting the subdivision g, Fig. 263, and fillings of this class. A Matrix Auxiliary. [Dr. Alfred P. Lee, of Philadelphia, has devised a simple and practi- cal method of overcoming the difficulty often experienced in adapting the matrix to an approximo-occlusal cavity when the cervical portion of the missing wall presents a concave surface, due to the tendency of the roots to bifurcate. By the use of sheet copper, not more than 10 5 00 of an inch in thick- ness, in conjunction with the Ivory or similar matrix, an appliance is made which when removed after the filling has been inserted will be 288 USE OF THE MATRIX IN FILLING OPERATIONS. found to have kept the filling the desired shape, leaving no overhanging portions at the cervix to trim away. A piece of thoroughly annealed copper plate, large enough to cover the approxiraal portion of the cavity and extend, say one-eighth of an inch beyond the buccal and lingual margins, is pressed with cotton or bibulous paper pellets to conform to the concave root periphery at the cervix. The copper is then carefully removed and, if the cavity be for amalgam, the depression in the copper representing the cervical concavity is filled with hard wax until a convexity is obtained ; Transverse section of tooth at Both matrices in position on Shows copper plate with cervi- a point near cervical border of cavity. Outer line show- ing copper matrix in posi- tion. Dotted line represents degree of contour supplied with hard wax or solder. tooth crown. cal depression filled with soft solder and applied to cavity before adjustment of outer matrix. the copper plate is then placed in position, and around it a steel matrix is adjusted, and when fully tightened the free edge of the copper is burnished against the steel. When gold is to be inserted it is necessary to use something more stable than the hard wax, therefore the concave surface at the cervical margin of the copper plate is touched with zinc chlorid, and over the alcohol or Bunsen flame soft solder is flowed into the depression. Any surplus may be trimmed off with a disk. — Editor.] CHAPTER XIII. PLASTIC FILLING MATERIALS— THEIR PROPERTIES. USES, AND MANIPULATION. By Henry H. Burchard, M. D., D. D. S. The materials included in the heading of this chapter are — (1) Amalgam ; (2) Gutta-percha and its preparations ; (3) The basic zinc cements. History. — The introduction of the first member of the group was not prompted by any specific merit that it had been demonstrated to possess, but was due solely to its properties of easy introduction, com- paratively perfect sealing and prompt hardening, qualities which appar- ently recommended its wide and general use to those not possessing the requisite degree of skill for the successful manipulation of gold foil. Applied upon a basis of glaring empiricism, with an absence of technical skill, the material received the prompt and sustained con- demnation which its abuse had warranted. The steps and phases of this opposition of the trained and skilled against untrained and un- skilled operators may be read in the dental journals of from 1846 to 1878 and even after. It was commonly known as the " amalgam war." The first dental amalgam was that of Taveau, called " Silver Paste/' It was made of filings of coin silver (silver 9, copper 1), combined with sufficient mercury to make a plastic mass. It was presumably this alloy which was introduced into America by two charlatans named Crawcour, under the glittering title of " Royal Mineral Succedaneum." The discovery of the nature of the paste followed soon after its intro- duction, which was clearly prompted by the motives above stated. Thereupon followed a persistent and virulent attack upon the material and all who used it. Upon less than the merest shreds of evidence alleged cases of salivation and mercurial necrosis were recorded as due to the use of amalgam. That amalgam was still employed by the practitioners of France is evidenced by the presentation in 1849 of a formula for an amalgam alloy of pure tin and cadmium by Dr. Thomas Evans, an American dentist practising in Paris. An amalgam made from this alloy was found to shrink, and also to stain the dentin of teeth into which it had been introduced, owing to the formation of cadmium sulfid. It is note- 19 289 290 PLASTIC FILLING MATERIALS. worthy that Dr. Evans himself was the first to discover and make public the deficiencies of his amalgam. In America amalgam remained under a ban until Dr. Elisha Towns- end of Philadelphia, a practitioner of such great skill as to be safe from any imputation of lack of manipulative ability, introduced in 1855 an alloy of 44^ silver, 55^ tin. The amalgam of this alloy received an endorsement and application based more upon the eminence of its author than upon the results of actual clinical tests, and a reaction occurred which brought amalgam again under general condemnation. What was known as the " new-departure corps " had its birth shortly after this time. This was composed of a limited number of practi- tioners and metallurgists, who were impressed by the fact that gold as a filling material was not the panacea of dental caries, and that by inves- tigation alone could the proper place of amalgam be found in the dental armamentarium. It is due to this group of investigators to state that the history of the rational employment of plastics is the history of the "new-departure corps." It was undoubtedly due to it that plastics have come to be regarded as substances having definite physical and chemical properties which fit them for application as restorative and therapeutic agents for the relief of clearly defined physical and patho- logical states. As the properties of these agents become better under- stood, their employment more closely follows what is known as rational therapeutics. The use of any or of all of these several materials is founded so entirely upon their individual properties that a discussion of these properties must precede and govern that of their methods of manipula- tion. Nature and Properties of Amalgam. An amalgam is a combination of one or more metals with mercury ; it. is therefore any alloy into which mercury enters as a constituent. The word amalgam (Fr. amalgame) is derived from Gr. a/ia, together, yajueco, I marry ; or from cifia and fidXayfia, from ficddaaco, I soften — because of the softness and fusibility which mercury confers upon alloys. It is to be understood that amalgams are classified as alloys, and may be therefore members of any of Matthiessen's groups as follows : A chemi- cal compound in which the affinities are exactly satisfied ; one in which there is unstable chemical equilibrium ; a sub-chemical compound, or a mechanical mixture — although this latter is rare, as mercury exhibits some degree of affinity for all metais. There are two possible ways in which mercury brings about the solution of other metals : First, by a chemical affinity for the metals ; second, by lowering the melting-point of the solid metal, forming an NATURE AND PROPERTIES OF AMALGAM. 291 alloy whose melting-point is higher than that of a mean of its constitu- ents. The former is the explanation more in accord with the observed phenomena relative to the combination. Physical Properties of Amalgams. — As a class amalgams have defi- nite physical properties. First, that of hardening from a previous plastic condition ; and nearly all of them for some time subsequent to apparent hardening undergo change of volume and of form. The change of volume may be either contraction or expansion. Contraction and Expansion. — In contraction the mass tends to assume the form shown in Fig. 266. It has been shown by Dr. Black 1 that _ FlG - 266 - the extent of this contraction is due to several factors : 1. To the composition of the pri- mary alloy. All other things being equal, an alloy of 6a per cent, silver, 35 per cent, tin, represents about the fixed point where there is a minimum _ . ~~_ ~" 7 " T 7 r Diagram of amalgam shrinkage. of shrinkage. As a class, alloys con- taining less than 65 per cent, silver make amalgams which contract ; those containing more than 65 per cent, silver make expanding amalgams. 2. To the amount of mercury used in amalgamation. There appears to be a definite percentage of mercury which produces the greatest strength of an amalgam mass ; moreover, the percentage which produces the maximum strength increases the shrinkage of the shrinking alloys and increases the expansion of the expanding alloys. Surplus mercury in the amalgam mass can reduce neither the expansion nor contraction of the amalgam mass. While an excess or deficiency of mercury in- creases the shrinkage or expansion of an amalgam (according as the percentage of silver is 65 — or 65 +), these volume changes cannot be overcome by the percentage of mercury. An excess or deficiency of mercury weakens an amalgam. It would appear that the conditions which bring about the most perfect union of the metals produce the greatest changes of bulk in those alloys in which changes of bulk occur. An alloy the amalgam of which neither shrinks nor expands cannot be made to do so by changes in the amount of mercury employed. 3. A strong controlling factor has been found to be the evenness of distribution of mercury and alloy throughout the amalgam mass. An increase of the ratio of silver above 70 per cent, is followed by an enormous expansion of the hardening mass. It had always been noted that the amalgam made of a coin-silver alloy bulged from the walls of 1 Dental Cosmos, 1895, vol. xxvii. p. 637. 292 PLASTIC FILLING MATERIALS. a cavity inclosing it. This alloy contains, as stated, 90 per cent, of sil- ver. The appearance of an expanded amalgam is similar to that of ice at the month of an iron tube in which the water has been frozen. Copper amalgam is the only alloy tested by Dr. Black which under- went no change of form in hardening. " Flow " of Amalgam. — A property attributed to certain amalgams, that of spheroiding, has been shown by Dr. Black to be without exist- ence. The bulging of amalgams from the orifices of cavities was held to be due to the tendency of the mass to assume a spheroidal form, hence the term spheroiding. Tests showed the appearance to be delusive, the phenomenon being due to expansion and not to a spheroidal tendency. In addition to the properties of contraction and expansion the same investigator has discovered the property, hitherto unsuspected in amal- gams, that of flow. The property of flow — i. e. change of mass form, from molecular motion under stress — had been observed in the majority of metals, but as found in amalgams it has a unique expression. Instead of being limited to a definite degree, proportioned by the stress applied, it has been found that amalgams yield repeatedly to the same amount of stress when applied at intervals, as in mastication, or yield continuously when the stress is constant. The process appears to be without limita- tions. It is at zero in copper amalgams ; next less in amount with alloys containing 55-60 per cent, of silver with 5 per cent, copper and the remainder tin. It will be readily seen that this property exercises a great influence upon the integrity and adaptation of an amalgam filling. The notes quoted from Dr. Black were compiled from studies made of amalgams whose exact chemical composition had not been actually tested by the investigator. Later experiments x made with alloys pre- pared with the utmost care and exactitude by the investigator himself, gave widely different results (particularly as to the effect of adding a third or fourth metal to the basal alloy) in the direction of both flow and shrinkage. The first series of experiments which appeared to show an enormous increase of shrinkage and flow together with a lessening of edge strength, by the addition of a third or fourth metal (except copper, which the latest experiments still show to lessen flow and increase rigidity) were not confirmed when Dr. Black experimented with alloys made by himself, and an additional and unsuspected factor was taken into consideration, viz. the influence of heat upon the alloy. It has been noted by Dr. J. Foster Flagg 2 that alloys which were freshly cut possessed working properties different from the same alloys when " old cut/' or when aged. Dr. Black's observations appeared to confirm this, and his later experiments were directed toward deter- mining the cause underlying the change. Motion, which was said to 1 Dental Cosmos, December. 1896. 2 Plastics and Plastic Fillings. NATURE AND PROPERTIES OF AMALGAM. 293 bring about the change, was found to have no influence. After exhaus- tive and conclusive experiments it was ascertained that the change was due to a molecular alteration of the cut alloy, through a process of an- nealing or " tempering " — i. e. heat was the agent producing the change. The degrees of heat applied ranged from 130° to 212° F. It was found that the amount of time during which an alloy was subjected to the action of heat governed the extent of tempering ; for example, alloy subjected to a temperature of 130° for a given period, had the amount of amalgam expansion reduced a given amount ; if the heat were maintained for a longer period the expansion was corre- spondingly decreased. Each formula has its zero point beyond which tempering has no effect. In general terms, it was found that alloys in amalgams which expanded in hardening had the extent of expansion reduced by anneal- ing ; those which contracted had the contraction increased. Alloys which were without alteration of volume unannealed, shrank when annealed. The following tables will show the extent of change produced by annealing. It will be noted that the alloy of 72.5 silver, 27.5 tin, ex- hibits the minimum contraction after annealing. It will also be observed that less mercury is required to effect amalgamation in the annealed alloy. 1 Amalgams made from annealed alloys have both their flow and crushing stress slightly increased. I. Exhibit of Unmodified Silver-Tin Alloys. 2 FORMTIT,^. How prepared. Per cent, of mercury. Shrinkage. Expansion. Flow. Crushing stress. Silver. Tin. 40 60 Fresh-cut. 45.78 6 7 40.15 178 40 60 Annealed. 34.14 9 3 44.60 186 45 55 Fresh-cut. 49.52 4 8 25.46 188 45 55 Annealed. 32.13 11 1 28.57 222 50 50 Fresh-cut. 51.18 2 2 22.16 232 50 50 Annealed. 37.58 17 1 21.03 245 55 45 Fresh-cut. 51.62 2 2 19.66 245 55 45 Annealed. 40.11 18 17.53 276 60 40 Fresh-cut. 52.00 1 9.06 239 60 40 Annealed. 39.80 17 14.10 297 65 35 Fresh-cut. 52.00 1 3.67 290 65 35 Annealed. 33.00 10 5.00 335 70 30 Fresh-cut. 55.00 14 3.45 316 70 30 Annealed. 40.00 7 4.67 375 72.5 27.5 Fresh-cut. 55.00 42 3.92 275 72.5 27.5 Annealed. 45.00 3 3.76 362 75 25 Fresh -cut. 55.00 60 5.64 258 75 25 Annealed. 50.00 6 5.40 300 *For a full exhibit of this stupendous work of Dr. Black's, the reader is referred to his contributions in the Dental Cosmos for 1895 and 1896. 2 Black, Dental Cosmos, 1896, p. 982. 294 PLASTIC FILLING MATERIALS. II . Exhibit of Modified Silver- Tin Alloys. 1 Formulae. How pre- pared. Per cent, of mercury. Shrinkage. Expansion. Flow. Crushing stress. Modifying metal. Silver. Tin. 65 35 Fresh-cut. 52.33 1 3.67 290 65 35 Annealed. 33.00 10 5.00 335 66.75 33.25 Fresh-cut. 51.52 4 3.35 329 66.75 33.25 Annealed. 33.53 7 5.06 380 Gold 5. 61.75 33.25 Fresh-cut. 47.56 1 4.62 330 Gold 5. 61.75 33.25 Annealed. 30.35 7 6.07 395 Platinum 5. 61.75 33.25 Fresh-cut. 51.87 9 9.68 273 Platinum 5. 61.75 33.25 Annealed. 37.33 7 8.20 352 Copper 5. 61.75 33.25 Fresh-cut. 53.65 23 2.38 343 Copper 5. 61.75 33.25 Annealed. 35.60 5 3.50 416 Zinc 5. 61.75 33.25 Fresh-cut. 56.65 68 1.83 290 Zinc 5. 61.75 33.25 Annealed. 40.65 9 2.07 345 Bismuth 5. 61.75 33.25 Fresh-cut. 46.26 4.78 288 Bismuth 5. 61.75 33.25 Annealed. 23.67 6 5.58 308 Cadmium 5. 61.75 33.25 Fresh-cut. 57.57 100 6.40 225 Cadmium 5. 61.75 33.25 Annealed. 47.25 5 3.54 290 Lead 5. 61.75 33.25 Fresh-cut. 44.17 1 4.88 290 Lead 5. 61.75 33.25 Annealed. 32.76 10 7.18 276 Aluminum 5. 61.75 33.25 Fresh-cut. 65.00 445 Aluminum 1. 64.5 34.5 Fresh-cut. 46.98 166 12.60 198 Aluminum 1. 64.5 34.5 Annealed. 38.26 48 17.90 213 Edge Strength. — What is termed the edge strength of an amal- gam is the degree of resistance an edge or angle of an amalgam mass offers to force which tends to fracture it. Amalgams have heretofore been regarded as rigid crystalline masses, utterly devoid of malleability. The discovery of the existence of flow at once modifies all previous conceptions and data regarding edge strength, for it is evident that a corner or angle might not fracture and yet might flow under the stress of the impact of mastication, whereupon edge strength might be said to be great, and in reality be but slight. In view of the existence of the property of flow, edge strength must be measured as rigidity, the antithesis of flow, and a high crushing stress. It has been shown that contraction or expansion, and flow, are the influences which would disturb the maintenance of size and form of an amalgam filling ; therefore, a minimum of shrinkage and flow are the primary considerations in a satisfactory dental amalgam. Color. — One of the serious drawbacks to the wide employment of amalgam has been its objectionable color, both in its original state and furthermore when it has suffered discoloration through the formation of oxids or sulfids upon its surface. The silvery white of amalgam in its most acceptable condition is not so harmonious a color as the yellow of gold, which fact has led first to the restriction of the use of amalgams to such spaces as are not readily visible, where its original and subse- quently its altered color could not be a strong objection ; and, next, 1 Black, Dental Cosmos, 1896, p. 987. NATURE AND PROPERTIES OF AMALGAM. 295 has prompted a modification of the silver-tin formulae with the object of maintaining their original color. The discolorations are not alone upon the external surfaces of fill- ings, but frequently (and most frequently in improperly prepared and filled cavities) the discoloration affects the dentinal walls bounding the cavity (see Fig. 167). Fig. 267. Staining of tooth structure with amalgam (Bodecker) : e, enamel ; d, d, dentin ; b, border of cav- ity ; s, solidified dentin along the border of the cavity ; r, reticulum brought forth by the amalgam. (X 500.) As shown in the illustration the discoloration may be deep. This danger is increased by leakage, when putrefaction of the protoplasmic contents of the dentinal tubuli or decomposing albuminous substances generate H 2 S, and metallic sulfids are formed in marked quantities. 296 PLASTIC FILLING MATERIALS. This danger of dentinal discoloration is guarded against by interposing a barrier between the cavity walls- and the amalgam prior to the inser- tion of the latter. The influence of individual metals upon color will be discussed later. Thermal and Chemical Relations. — As a conductor of thermal in- fluence, amalgam is midway between gold and the basic zinc cements. As to the actual effects upon the vital tissues of dentin, it has never been demonstrated that amalgam exercises any specific influence, except that cadmium appears to cause, through the cadmium sulfid formed, a degenerative influence (Flagg), and copper has antiseptic properties (Miller, Fletcher). Chemically the dental amalgams are, to all intents and purposes, insoluble in the fluids of the mouth, the common solvent found in the oral cavity, lactic acid, affecting them but little. Classification of Amalgams. — Amalgams are divided into binary, ternary, quaternary, and so on, according to the number of constituent metals. The only binary amalgams employed in dentistry are those of copper and of palladium. Binary Amalgams. — Copper amalgam is made by adding freshly precipitated and washed metallic copper to an excess of mercury ; when solution is complete the surplus mercury is expressed through chamois. The plastic residuum is then packed into moulds to make small tablets of the usual form in which it is dispensed. A better method, which yields a product of greater purity, is to pre- cipitate the copper directly into the mercury by electrolytic process. This may be done conveniently by pouring a quantity of mercury into a suitable glass vessel — a small battery jar, for example — -and suspend- ing a thick plate of copper, by means of a wooden support, some dis- tance above the surface of the mercury. A saturated solution of cupric sulfate is then poured into the jar until the copper plate is com- pletely submerged. The cathode pole of a battery or other source of electrical current is then connected with the layer of mercury, and the anode with the copper plate. All that portion of the cathode electrode in contact with the cupric sulfate solution should be insulated with gutta- percha, and only the point which is in contact with the mercury left exposed. The passage of the current causes solution of the copper from the anode and deposits it in the mercury continuously as long as the foregoing conditions are maintained. The precipitation should be continued until the mercury is saturated, which will be evidenced by the appearance of the characteristic red color of the excess of copper at the cathode pole. When the saturation point has been fully reached the mass should be washed, first in dilute hydrochloric acid and then in water, dried and compressed as is usual with this amalgam when pre- NATURE AND PROPERTIES OF AMALGAM. 297 pared by the ordinary processes. This method was suggested to the writer by Dr. E. C. Kirk. In its typical form and condition, copper amalgam, when made plastic by heat, may be packed into matrices, such as cavities in teeth, where it sets quickly, undergoes no change of volume or form, and is devoid of flow. Therefore a cavity which has been sealed by it remains sealed. Upon its outer surface a coating of black sulfid quickly forms, which remains but does not penetrate the tooth struc- ture. The dentinal walls are commonly stained green through the absorption of the metallic salts. In improperly prepared specimens there is not a perfect chemical union between the metallic mercury and the copper. The presence in a filling mass of oxids of either of these metals establishes local electrolytic conditions which prevent the formation of the black sulfid coating and bring about the gradual dissolution of the amalgam mass. To recapitu- late : Copper amalgam is physically unchangeable as a filling material ; it brings about very offensive discoloration both of the dentin and of its own surface ; it is antiseptic. The second binary amalgam is that of palladium. Palladium is precipitated from a solution of its chlorid by iron or zinc, washed in nitric acid, and dried. To the precipitated metal, mercury is added, the combination being attended by the evolution of much heat (i. e. is an active chemical union). If an excess of mercury has not been used the amalgam sets quickly, does not alter in form, 1 and becomes black upon the surface, 2 but does not discolor the dentin. The addition of an excess of mercury retards the setting, and produces an inferior filling. Ternary Amalgams. — The base of all ternary amalgams is the alloy of silver and tin. The first of these was the alloy of Townsend, 44^ per cent, silver, 55^ per cent. tin. From this point the investi- gations and experiments radiated — it being found after many years of clinical testing that those alloys containing more than 50 per cent, of silver gave the best results. The formula given by Dr. J. Foster Flagg as affording the most stable alloy for amalgam — 60 silver, 35 tin, and 5 copper — was found by Dr. Black to be that giving the highest degrees of resistance to change of form, to flow, and to crushing. In view of Dr. Black's researches into the effects of annealing alloys it is evident that the ternary amalgam of the future will have a composition closely approxi- mating 72.5 per cent, silver, 27.5 per cent. tin. The binary alloys of tin and silver form the basis of all of the quaternary amalgams used in dentistry. 1 Tomes, Trans. Odoniological Society of Great Britain, 1872. 2 Bogue, Dental Cosmos, 1884. 298 PLASTIC FILLING MATERIALS. Quaternary Amalgams. — The metal additional to the basal alloy is added for the purpose of modifying the color or increasing the edge strength of the amalgam. The addition of copper 5 per cent, to an alloy containing over 60 per cent, silver increases the crushing stress and lessens both flow and contraction. The alloy is white when fresh, but in the presence of sulfur compounds discolors. The addition of gold (5 per cent.), as clinical records testify, aids in maintaining the color of the filling. It lessens shrinkage slightly (com- pare this and following statements with table No. II.), and appears to have little or no influence upon flow and crushing stress. The addition of platinum causes dark fillings and notably increases the flow ; the setting is slowed. The addition of zinc increases rigidity ; the amalgams expand for long periods after apparent hardening ; the crushing stress is moderately high — a direct contradiction of statements of several previous ob- servers. 1 Additions of bismuth, cadmium, lead and aluminum were made to the basal alloy, but all of them exhibited properties which exclude them from introduction into dental amalgam. Dr. Black 2 states that " alloys containing 5 per cent, of aluminum have their setting attended by the evolution of much heat ; an enormous expansion of the mass occurs ; the instruments used in packing are oxi- dized, and a distinct crackling of gas-disengagement is heard. " " The formation of aluminum amalgam is characterized by an exhibition of the affinity of aluminum for oxygen. Aluminum oxid is doubtless formed, which increases the volume of the amalgam mass." "Washing* of Amalgams. — Alloys which have been cut for some time, and mercury the purity of which is questionable, are found to be coated with oxids of the metals — in the case of mercury, with the oxids of contaminating metals. The advisability of washing the amalgam mass in some solvent which will remove the oxids is a mooted question. It has been stated that the washing of an amalgam mass increases its shrinkage (Flagg). On the other hand it has been observed that washed amalgams retain their color better. It is difficult to see how the washing could affect the integrity of the set mass unless oxidizing substances were left in it ; and this is clearly contraindicated by the maintenance of color in washed amalgam. The writer prefers wash- ing the plastic mass in chloroform prior to expressing the surplus of mercury. 1 It is to be recalled in this connection that Dr. Black's measurements are made with instruments of unequalled accuracy, those of previous observers with comparatively crude instruments. 2 Private communication. USE OF AMALGAM. 299 Use of Amalgam. It is to be understood that amalgam is to be employed only in those conditions and situations which clearly indicate it as the proper mate- rial. As a general rule, it is excluded from the ten anterior teeth of each jaw, although this rule is open to exceptions. Its anterior limit of application is usually regarded as the distal surface of the first bicus- pid. Its more general employment has been greatly reduced in many places since the introduction of what are known as combination fillings (see Chapter XIV.), and by improvement in the forms and character of artificial crowns. The first class of cavities to which amalgam is applied are those which extend beneath the gum margin ; the second, buccal cavities ; the third, compound cavities ; the fourth, approximal cavities ; the fifth, cavities upon the masticating faces of the teeth. These are the classes in which gold is most difficult of introduction and of proper shaping and finishing, in the order named. Amalgam should rarely or never be packed against dentinal or enamel walls without the interposition of a layer which will prevent either the discoloration of the dentin or the bluish appearance noted when amalgam underlies enamel. The shaping of cavities for the reception of amalgam fillings (see Chapter VII.) should be done with such care as will give assurance of the permanent retention of the filling and the perfect sterilization of the dentin before and during its introduction. The separation of the teeth, removal of gum overhanging cavity margins, and breaking down of frail enamel walls by means of chisels, precede the filling. The rubber dam is to be adjusted where and when possible, with such care that an exclusion of the fluids of the mouth is assured during the shaping, sterilizing, and filling of the cavity. As Dr. Black has shown, 1 much of the permanency of form of an amalgam mass depends upon the even distribution of the constituents ; it is evident that every aid to this end should be utilized, an important one being that the mass should be packed into a cavity having but one orifice, that for the introduction of the filling. With the data relative to dental amalgams which have been given, it is evident that a dental amalgam mass is by no means simple, but is a very complex body. If sufficient mercury has been used to effect solution of the alloy particles the mass will consist, first, of a quantity of a chemical amalgam — i. e. one in which the metals are united in atomic ratios — this being surrounded by one or more other distinct 1 Dental Cosmos, 1895, vol. xxxvii. p. 553. 300 PLASTIC FILLING MATERIALS. amalgams, each having its own time of setting and rate of contraction. If only enough mercury has been used to make a creaky mass the sur- faces of each alloy particle are covered by an amalgam of indefinite composition which acts as a cement binding the particles together. In this line the same experimenter has shown that mixing the alloy and mercury in a mortar by means of a pestle, wringing the surplus mer- curial solvent from the mass by means of heavy pliers, and packing the filling with steel burnishers are all influences which lessen the strength of the completed filling. The conditions are now a prepared and sterilized cavity ; any miss- ing wall required to give four sides has been replaced by a properly adjusted matrix (see Fig. 242, Chapter XII.). Fig. 268. Dr. Herbst's matrix. Matrices. — Matrices may be readily and quickly formed by cut- ting strips from a sheet of very thin steel which has been annealed Fig. 269. Fig. 270. Herbst pliers. and polished. By means of contouring pliers the matrix is given the correct contour, then wedged or tied into place. They must USE OF AMALGAM. 301 be so adjusted that they are immovably held during the filling ope- ration. A rapid method of forming a matrix is that of Dr. Wilhelm Herbst : A strip of German silver No. 33, wide enough to extend from the cervical margin of a cavity to its mouth, and long enough to more than embrace the tooth, is passed around the tooth (see Fig. 268) ; the strip is caught near its extremities by a pair of Herbst pliers (Figs. 269, 270) and drawn taut ; the pliers pinch the metal into close adaptation to the tooth walls. Held by the pliers the matrix is withdrawn, the line of junction touched with zinc chlorid solution, and soldered over an alcohol or Bunsen flame with soft solder. The matrix is replaced upon the tooth, the rubber dam applied, and the matrix pressed against the cervical margin of the cavity by means of a wooden wedge. The matrices of Guilford and those of Brophy (Figs. 240, 241, Chapter XII.) are operated upon a common principle ; the band which most nearly fits the periphery of the tooth is adapted, then drawn into close apposition with the tooth by means of the screw appli- ances. The matrix of Woodward is one of the most convenient. Its mode of application is shown in Fig. 242, Chapter XII. The Miller matrix (Fig. 271) is useful and adapted for the class of cavities shown in Fig. 272, as held in contact with cervical mar- Fig. 271 The Miller matrices. Fig. 272. gins through the action of the duplex spring leaflets. When necessary a wooden wedge is forced between the leaflets. (For other forms and applications of matrices see Chapter XII.) Mixing the Amalgam. — It is usuallv recom- Oilier matrix adjusted, mended that the proportion of mercury and alloy be determined by weight. An amount of alloy is first weighed, then weighed additions of mercury are added to it sufficient to make a plastic mass, when the two are to be mixed together; the relative amounts of mercury and alloy are to be gauged and recorded for each formula of alloy. With the " submarine " alloy of Flagg— 60 silver, 35 tin, and 5 copper— the 302 PLASTIC FILLING MATERIALS. ratio is equal parts by weight of filings and mer- cury. When a mortar is used for making the amal- gam, one of glass and having a glass pestle (see Figs. 273, 274) is to be preferred. Mixing in the palm of the hand is a dirty process, the hand and fingers becoming much discolored by the metallic oxids. Fig. 273. Fig. 274. Glass mortar. Glass pestle. A rubber mortar (Fig. 275) to be received in the palm of the hand has been devised by Dr. Genese. In view of deductions from Dr. Fig. 275. Dr. Genese's rubber mortar. Black's experiments this latter method of mixing is regarded as usually the preferable one. The filings are placed in the receptacle, the mercury is added, and the mass is triturated — if in a mortar, by the pestle, if in the rubber basin, by the forefinger guarded by a rubber finger-stall. When the USE OF AMALGAM. 303 amalgamation appears to be complete the mass is transferred to the hand and kneaded, then pressed into a ball. It is next enclosed in stout muslin, or China silk as recommended by Dr. C. E. Kells, Jr., and the surplus mercury expressed by wringing ; when no more mer- cury appears through the muslin, the button is removed : it should break with a clean, white fracture surface. Another method of mixing the filings and mercury is that of Fletcher. Filings and mercury are placed in a long glass tube which is shaken vio- lently until amalgamation is complete. The Packing- Operation. — Several devices have been invented for the purpose of carrying the amalgam to the tooth cavity, one of the Fig. % most simple being shown in Fig. 283, and another in Fig. 284. An- other excellent instrument is shown in Fig. 285, one end having ser- Fig. 277. rated points which engage the soft amalgam, the other a plugger head. Numerous methods have been advanced and advocated for the pack- ing operation. The one commonly followed is that of burnishing the amalgam. This has been shown by Dr. Black to weaken the mass. A small piece, rarely more than a cube of \ in. side, is carried to the deep- est and most inaccessible recess of the cavity and pressed against its walls by tapping, burnishing, or uniform pressure. Dr. Flagg's method is by tapping. Each successive piece of amalgam is tapped upon by the packing instruments until it combines with its predecessor and is per- fectly adapted to the cavity walls. The set of instruments shown in Fig. 279 are those by which this process is accomplished — Nos. 30-34 being packing instruments, while the others are shapers. 304 PLASTIC FILLING MATERIALS. A convenient and effective set of instruments for accomplishing the packing are shown in Figs. 280-282. Fig. 279. 30 31 32 33 34 35 36 37 38 39 40 Dr. J. Foster Flagg's amalgam and zinc filling instruments. Dr. W. G. A. Bonwill has advised a method which accomplishes the removal of surplus mercury and the even distribution of the mass, Fig. 280. Fig. 281. Woodson's double-end amalgam instruments. during the progress of the filling. Small squares of folded bibulous paper are caught in the jaws of pliers and laid upon the amalgam, when the exertion of pressure by means of amalgam pluggers or pliers forces out the surplus solvent and it is wiped away with the paper. The same end is also accomplished by the use of bulbous points of soft rubber. When through either method the cavity is more than half full, the remainder of the amalgam mass is wrung out to express more mercury, and the packing is resumed until the cavity is more than full. At the later stages of the filling the process of wafering is usually USE OF AMALGAM. 305 Fig. 283. followed. By means of chamois and heavy pliers (Figs. 283, 284) the amalgam mass remaining is compressed into a wafer, driving the surplus mercury through the pores of the chamois. The amalgam is put in a piece of chamois, and the chamois sack A is entered between the beaks B and c (the latter a roller) ; closing the handles of the instrument progressively squeezes out the mercury till any desired degree of dryness is attained. When the amalgam is squeezed to the requirements of the operator, the han- dles are released, and the spring opens the ap- pliance. The action is analogous to the finger and thumb movement in common use, but is much more powerful, and therefore more cer- tain and more uniform. Small sections of the wafer are laid upon the half-completed filling and tapped into a union with it. The cavity is more than filled, and at the completion of the packing the amalgam should cut as though nearly set. Another and excellent method where applicable is to shape small pieces of half-vulcanized rubber and cement them upon broken excava- Fig. 284. Mercury expresser. Flagg's wafering pliers. tors, and use them as pluggers during the later stages of the filling. The fluid cementing amalgam will have its surplus mercury expressed about the sides of the plugger. Still another method is to fill the cavity more than half full, then cut away the softened portion, and complete the filling with drier amal- gam. Fillings the initial portions of which have been introduced com- paratively dry are more homogeneous and are less likely to discolor and crevice than when more fluid amalgam has been used to begin the 20 306 PLASTIC FILLING MATERIALS. filling. An examination of an amalgam filling immediately after com- pletion will show the marginal portions to contain the softer amalgam, the harder being in the more central parts. The too common practice of placing in the prepared cavity sufficient amalgam in one mass to nearly or quite half fill it, is faulty. By no means can this method secure the accuracy of adaptation of filling material to cavity walls which is demanded of a correct filling. At the completion of the packing operation, unless the filling has been finished by wafering, the surface will be found still soft. It has been recommended l that small pieces of annealed No. 1 gold foil be burnished over the surface of the amalgam, until no more gold can be amalgamated by this means, when the filling will be found quite hard. The indefinite cementing amalgam has combined with the gold, for which mercury has a strong affinity, and formed a distinct amalgam upon the surface of the filling proper. As amalgams of gold are com- paratively soft, it is advisable to first fill the cavity more than full, apply the gold foil, then scrape the filling down to the cavity margins. Dr. Rhein's procedure is to fill the cavity with plastic amalgam and rub on the pieces of gold until no more gold is amalgamated. This gold amal- gam is permitted to remain. The surplus of mercury may also be con- veniently removed by absorbing it from the surface of the filling by pieces of sponge or crystal mat gold. An amalgam filling should be hard enough to resist cutting before the rubber dam is removed. In those situations where the rubber dam cannot be successfully employed, it is the accepted practice to prepare the cavity, sterilize it, when access is difficult sealing a germicide in the cavity for a day ; next adjust a napkin, and having mixed a submarine amalgam (one contain- ing copper and a high percentage of silver), the cavity is dried as well as possible ; a piece of the amalgam is then carried to the deepest recess of the cavity and quickly and forcibly compressed with a mass of bibulous paper. Another piece of amalgam is added and compressed, driving the surplus mercury from the amalgam. While the napkin is in position, a mass of temporary stopping (which see) is softened and placed in the remainder of the cavity. A knife blade passed over the edges of the amalgam will remove overhanging portions. At a subse- quent visit, the rubber dam is adjusted, the temporary stopping is removed, and the filling completed with amalgam. If the operator prefer, the rubber dam may be adjusted at once and the filling completed at one sitting ; the former method is, however, pre- ferable, as the cervical portion of the filling may be perfectly finished, and not be in danger of displacement, while the second section is packed. 1 Ottolengui's Methods of Filling Teeth, " Method of M. L. Khein." USE OF AMALGAM. 307 In cavities extending beneath the gum, and opening broadly upon a surface of a tooth where discoloration would be highly objectionable, the cervical half of the filling is made of a submarine amalgam and is completed with an amalgam containing gold, which will retain a better color. Should the external face of the filling be readily visible and not subjected to the stress of mastication, its outer surface is made of a wafer of an amalgam containing zinc, known as a facing amalgam. Copper amalgam is used, when used at all (and that is but seldom), upon the distal and buccal walls of third molars, in cavities extending under the gum line, which are difficult of access and to sterilize, and which cannot be properly dried. A cavity is prepared which need be but slightly undercut. A pellet of the copper amalgam is placed in an iron spoon (Fig. 285) held above Fig. 285. Heating spoon for copper amalgam. a Bunsen flame until globules of mercury appear upon its surface, when it is quickly crushed in a mortar and pounded until made into a paste. There can be no objection to washing the soft mass in aqua ammonia to dissolve and remove oxids which later form discoloring salts, and thus permit a chemical union of the metals which would be prevented by their presence. A napkin, or always when possible the rubber dam, is adjusted, and the filling inserted in sections. At the end of the oper- ation the filling should be firmly compressed with a broad -bladed spatula. In by far the greater number of cases in which amalgam was at one time used alone, it is now the accepted practice to place a lining of a zinc cement, and add the amalgam as a resistant and insoluble covering. In cavities which approach the pulp the same precautions are taken for the prevention of thermal shock as with gold. The most difficult class of cases in which to obtain satisfactory results with amalgam are those opening alone upon the approximal surfaces of bicuspids and molars. While it is true that amalgam may be manip- ulated in spaces impossible with gold foil even in soft cylinders, it is essential that sufficient room be obtained for the perfect introduction of the material and its subsequent trimming and polishing ; for polishing is quite as necessary an operation with amalgam as with gold. This space is obtained either through wedging or by cutting through the occlusal face of the tooth into the cavity. Space is to be obtained and amalgam packed in such a manner ijiat the amalgam at the completion of the operation shall exhibit no 308 PLASTIC FILLING MATERIALS. evidence of pastiness. To insure the removal of the excess of the sol- vent, gold foil may be burnished over it as already described until it requires some effort to cut the mass with a lancet blade. Amalgam when set is more difficult to cut and polish than gold ; the greater por- tion of the carving is therefore done at the same sitting as the filling, but should never be undertaken while the filling is soft. It should be in such a condition that it is necessary to carve, not smear, it into shape. A suitable cutting instrument of the form of Nos. 37 to 40 of Flagg's set (see Fig. 279) is passed first across the cervical border of the filling, removing any excess due to imperfect contact of the matrix with the cervical margin of the cavity ; next the lateral borders are carved, and then the masticating surface. The body of the filling is left full, so that after two days, when the filling receives its final dressing and polishing with cuttlefish disks, strips, pumice, etc., the filling will be reduced to correct contour. A polished amalgam filling will retain an untarnished surface when an unpolished one will discolor very objectionably. Many of the cases in which it was at one time the usual prac- tice to fill or restore almost entire tooth crowns with amalgam, Fig. 286. are trimmed down, shaped, and artificial crowns applied. One class of cases is fre- quently seen in which the indication is for an enormous amalgam filling rather than an artificial crown ; this is, the loss of the dis- tal half of the crown of a molar. As a rule the teeth are pulpless, or it is necessary Restoration^ lower molar with to devitalize the pulp. The appearance of amalgam. the crown after the removal of carious den- tin and cutting away frail enamel walls is seen in Fig. 286. A Herbst matrix is fitted, closely embracing all the margins of the cavity. The rubber dam is adjusted. It is of course understood that the root canals have been properly sterilized and filled. The posterior canal is drilled out for about \ in. and screw-tapped. A thin solution of zinc phosphate is mixed and the tip of a screw to fit the tapped root has its point dipped into the cement, and then quickly screwed into place. The amalgam is packed in larger masses than usual, using bibulous paper to compress it about the screw and into such scant undercuts as may be secured in the anterior portion of the tooth. The filling is completed with amalgam wafers. Such a filling should be well set before the rubber dam is removed. The upper surface is carved into cusps and sulci to occlude properly with the antagonizing teeth. The matrix should remain for twenty- four hours, when it may be split and removed. If the matrix has been exactly adjusted there should be no trimming of the margins required, USE OF AMALGAM. 309 no carving of contour, and no smoothing, the amalgam being ready for polishing strips. The occlusal surface is smoothed and polished with moosehide points and pumice, using a stiff brush to polish the sulci. Finishing". — The process of finishing hard amalgam fillings is simi- lar to that of finishing gold. For example : a compound cavity occu- pying the approximal and occlusal faces of a molar. A fine saw is placed in a frame as in Fig. 287, but set to draw-cut with its teeth Fig. 287. The Kaeber saw frame. pointing toward the frame. The blade, is passed above the cervical margin of the filling, engaging any projecting amalgam, which is then sawn off. It is just as essential with an amalgam as with a gold filling that the cervical edge should be exactly flush. The lateral margins of the filling are next carved smooth ; strips of emery cloth are passed into the interdental space and the filling smoothed and rounded, completing this portion of the operation with emery strips of the finest grit. Linen tapes or metal polishing strips are next charged with pumice and passed over the surfaces until they are smooth and the margins are perfect. The occlusal portion is polished by means of rubber or moose- hide points and pumice. Should it be a plain approximal filling, not a " contour," the saw is used to cut away surplus amalgam, and the polishing accomplished by means of disks and powders. Fillings upon the buccal surfaces of teeth are smoothed by means of disks and polished with rubber cups or disks and pumice. Gutta-percha. Origin. — The gutta-percha of commerce is the coagulated juice of the Isonandra gutta, a tree of the order of Sapotacece. The juice is found in all trees of this order, but some specimens are of much higher value than others. That from Borneo is regarded by manufacturers as being inferior ; it is the variety from which the name is derived — Malay, gatah or gittah, gum, and pertja, a tree. The gutta Tuban from Singa- pore is regarded as a superior variety. 310 PLASTIC FILLING MATERIALS. The mode of securing the juice is by tapping the cambium layer of the tree and catching the juice as it exudes. From this stage to its formation into sheets it undergoes several processes (see works on gutta- percha) ; it is possible that in some of these operations it may have its texture injured by overheating. " The purified gutta-percha probably consists of a hydrocarbon (pure gutta) having the formula C 10 H ]6 ; albane, C 10 H 16 O ; fluavile, C 40 H 64 O 3 ; and a variable compound named guttane. Pure gutta possesses all the good qualities of gutta-percha in a much enhanced degree, becoming soft and plastic on heating and hard and tenacious on cooling without being in the least brittle. The resins appear to be simply accessory components which have a decidedly detrimental effect when they pre- ponderate. Water, wood, fibers, bark, sand, etc., occur as mechanical impurities of gutta-percha." (Obach.) History. — Gutta-percha was introduced into dental practice as a fill- ing material about the year 1847. Soon after this a secret preparation was introduced by a Dr. Hill, which received his name. Numerous alleged analyses of HilPs stopping have been given, all of which are untrustworthy. It was found to subserve so useful a purpose that it received the tribute of wide imitation ; in fact, the white gutta-percha preparations of the present day had their foundation in this imitation. There is no entirely trustworthy evidence that the original was superior to the best of contemporary preparations. As at present employed as a filling material gutta-percha is in two forms, the first the well-known pink gutta-percha base plate, which is colored by the insoluble sulfid of mercury, the second the white prep- arations, made firmer in texture by additions of the soluble zinc oxid. The specimens of crude gum differ as to the amount of heat required to soften them to an equal degree. Dr. Flagg l states that the speci- mens requiring the greatest degrees of heat for softening, prior to the addition of the zinc oxid, afford the best dental gutta-perchas. The method of making the gutta-percha of dentistry is by softening a mass of the brownish-yelloAv gum on a slab which has been heated over boil- ing water, and driving zinc oxid into the softened mass by a process of kneading, using a wedge-shaped steel instrument as the kneader. It requires infinite patience and much time to distribute the powder evenly throughout the mass. Overheating the material at any stage of its manufacture or manipulation is ruinous to its texture. Classes. — Gutta-perchas are divided into three classes according to the temperature of softening : Low heat, softening below 200° F. Me- dium heat, becomes plastic at 200° to 210° F. High heat, 210° to 218° F. The low-heat specimens contain 1 part by weight of gutta-percha to 4 1 Plastics and Plastic Filling. GUTTA-PERCHA. 311 of zinc oxid ; in medium-heat the ratio is 1 to 6 or 7 ; and in the high- heat specimens the gutta-percha is almost saturated with zinc oxid. Physical Properties. — Gutta-percha is an almost perfect non-con- ductor both of heat and electricity. It is less hard and rigid than any other filling material. It contracts in hardening, i. e. cooling. Softened masses of it are coherent when dry, but not when wet. Its color may be made to resemble that of the teeth. To vital tissues it is the most bland, unirritating filling material known. After it has served as a filling for a greater or less period it is found to have increased in hardness and difficulty of softening, and its surface, and perhaps its substance, has become porous in variable degree. The increased hardness is observed in such situations as those in which putrefactive decomposition occurs ; that is, in places where there is an evolution of hydrogen sulfid ; the gutta-percha apparently undergoes a species of vulcanization. It becomes somewhat porous in those situa- tions where the formation of a solvent is active (lactic acid), which abstracts the soluble zinc oxid from the mass. The pink variety con- taining the insoluble mercury sulfid does not become porous, but wears with a comparatively smooth surface when subjected to attrition. Examining in detail these several physical properties it will be noted that gutta-percha has but one property in common with gold — its insol- ubility. Its rational employment is therefore in such situations and conditions as those in which the use of gold is contraindicated. Indications for its Employment. — First, in its several forms it is employed as a temporary filling material for both the temporary and permanent teeth. Owing to its non-conductivity it is employed near the pulp ; its insolubility recommends its use at the cervical margins of cavities, particularly in the buccal cavities of molars which do not extend to the masticating surface, where the non-resistance of the material would cause its rapid wasting. This is the most common of the situations in which gutta-percha is applied : very deep cavities upon the buccal surfaces of molars, extend- ing beneath the gum, and having ragged enamel margins, the orifice of the cavity being much smaller than its body. Owing to its non- irritating quality, the condition of the gum in contact with a gutta- percha filling remains normal. It is used in approximal cavities of the anterior teeth which have a similar form to those just described ; also in labial cavities, particularly when these teeth are in any degree loose. For example : in a cavity opening alone upon the distal wall of a canine tooth the carious process has almost invaded the pulp, the enamel walls unsupported by dentin still retain their form and have a good texture. Pink base plate is invaluable for the temporary filling of spaces after 312 PLASTIC FILLING MATERIALS. wedging and also the cavities to be subsequently filled with metal. A mass of the material may be packed into such spaces and be permitted to remain for months if desired, the gum in contact with it after its prolonged presence exhibiting no indications of irritation. Masses of gutta-percha may be packed in interdental spaces where there is not sufficient space for the introduction of contour fillings, with the purpose of having the teeth gradually separated by the impact of mastication ; the gutta-percha acts as a persistent and very gradual wedge. When it has been determined that an excavated cavity is unfit for the reception of a permanent filling, gutta-percha is the filling material par excellence. Although it is stated that gutta-percha shrinks markedly in harden - Fig. 288. Flagg's gutta-percha softener and tool-heater. ing, cavities in which it has been properly placed exhibit no evidences of softening after the material has been worn for months, or it may be GUTTA-PERCHA. 313 Fig. 289. for years. Particularly is this true when the pink variety has been employed and the method of introduction is correct. Mode of Softening-. — Gutta-percha should never be heated beyond a point which permits of accurate adaptation to undercuts and frail walls. The soften- ing should be gradual. Any heat in excess of this is not only harmful but ruinous. For its proper softening some device is necessary which shall permit of this type and degree of heating (see Figs. 288-290, 299). Fig. 288 illustrates the heater of Dr. Flagg. There are three metallic shelves, the highest of which receives the least amount of heat, and is designed for softening low-heat gutta-percha. The second shelf is for the softening of high-heat specimens. The lowest shelf and rack support the packing instruments, which are kept at a higher temperature than the filling material. Fig. 289 illustrates a device of Dr. L. A. Faught for the packing of gutta-percha. The heating wires connect at the bases of the instrument points, which are of aluminum, and sufficient heat is conveyed to the gutta-percha to maintain it in a plastic state during the packing operation. Instruments. — As a rule the instruments used in packing gutta-percha are too large and the material itself is used in too large pieces. If the cavity is of considerable extent, and usually it is, the filling should be introduced in four or more pieces. It is preferable to warm all the packing instruments so that the gutta- percha will remain plastic until perfectly adapted. Manipulation. — The rubber dam having been ad- justed, the cavity excavated and sterilized, the frail enamel edges broken away, without any particular object of margin form- ing, but to gain space, the cavity is dried for the reception of the gutta- percha. The field of operation should be dry, in order that each additional piece of gutta-percha shall adhere to its predecessor, which it would not do Dr ' ^ hfat'er 6160 ^ 10 if Wet A softened P ellet is taken U P on the P oint of a probe and placed in the most inaccessible portion of the cavity and tapped into accurate contact with the tooth walls (by Order of placing gutta-percha pellets. 314 PLASTIC FILLING MATERIALS. means of the corkscrew plugger No. 32 or No. 33), as shown in No. 1 of Fig. 290. A second pellet is added (No. 2) and similarly manipulated. The Nos. 3, 4 pellets are packed in the order shown in the figure. In adding the last piece broad-faced instruments are used, adapting the gutta-percha accurately to the margins of the cavity. The softened gutta-percha may be made to adhere better to the walls of the cavity if these be first coated with one of the lining varnishes. Another method of manipulation is to line the walls of the cavity with pellets until a cylindrical cavity remains. A cylinder of gutta- percha of that size is nearly softened and pressed firmly into the cavity by means of a broad spatula. Should the cavity be very deep, the pulp almost exposed, the por- tion of dentin overlying the pulp is to be covered by a thin pellet of low- heat gutta-percha softened sufficiently to permit of adaptation. A disk of pink gutta-percha base plate answers admirably for this purpose. The use of one of the lining varnishes, noted at page 257, especially the cellulose solution known as kristaline, previous to placing the pellets, will insure their adhesion to the cavity walls and prevent rocking or tipping of the mass of gutta-percha during the operation of its insertion. In order to secure the best results the kristaline solution should be thin when applied, and the solvent completely evaporated by blasts of warm air before any attempt is made to introduce the gutta-percha, for unless the varnish lining is fully hardened the pellets will not strongly adhere to the surface so treated. Dr. How's Improved Gutta-percha Fillings. — Dr. W. Storer How l has published a method of packing gutta-percha which is as excellent as rational, when the directions given are closely followed : "Many approximal cavities like C, Figs. 291, 292, may well be Fig. 291. Fig. 292. Fig. 293. —A" Approximal cavities. filled with gutta-percha, and such as C, Fig. 292, where a gold filling would show through the thin enamel front, can better be filled with suitable gutta-percha. The section, Fig. 293, shows the angles A, A', which should be given the enamel-edges when practicable, and in any case the enamel-margin should have a squarely defined angle at its surface border. " Cervico-labial or buccal cavities, as shown in Figs. 294-298, 1 Dental Cosmos, 1892, vol. xxxiv. p. 281. GUTTA-PERCHA. 315 admit of permanent gutta-percha fillings. Of course due attention Fig. 294. Fig. 295. Fig. 296. Fig. 297. Fig. 298. \ s J^iiij0 Cervico-labial and buccal cavities. must be given to the retention of the fillings by enlarging the interior walls of the cavities when they have not already such expansions. After suitably preparing the cavity, it should be made as dry as possible and so kept. The problem of conveniently and properly softening pellets of gutta-percha has been solved by the production of the ther- moscopic heater shown in Fig. 299, which approximates the exact size Fig. 299. Thermoscopic heater for gutta-percha. of the device. The heater is in this instance made of steatite, because of its heat-retaining property and the desirable physical qualities of its surface. The handle is of wood, at the opposite end from which, in the centre of the circular recess, is a small disk (J) of metal, fusible at about 212° F. On the heater near the metal a suitable number of gutta-percha pellets, as 1, 1, are placed, and the heater held over the flame of the annealing lamp or burner (as in the illustration) until the fusible metal melts, when the heater is placed on a piece of cardboard (or an empty foil-book), and the gutta-percha will be found to be prop- erly softened. The steatite plaque retains the heat long enough for an ordinary operation, but if the metal meantime loses its fluidity and so 316 PLASTIC FILLING MATERIALS. indicates a lowering of the standard heat, it may be quickly restored by a moment's holding of the heater over the flame, which will again fuse the metal. " When the flame is applied directly under the metal, as in the illus- tration, the material placed at 1 will, when the metal is seen to be fused, be at the heat of near 208° F., while the pellets at 2 will be heated to about 200°, those at 3 and 4 to near 194° and 180° respectively. Of course the location of the heat-source will produce corresponding varia- tions in the relative temperatures of the materials as severally situated ; but with a visibly definite standard such as the metal A, having a known fusing-point, the desired degree of heat may repeatedly be produced at any place on the receiving surface of the heater. A few seconds' contin- uance of the heater over the flame, after the metal has melted, will raise the surface heat to 212° or 215°, as the case may be ; but as a suitable indicator for a high-heat stopping, a button (B) of metal fusing at 230° is provided as a substitute for A, which is first melted and poured out on a piece of clean paper, the heater cavity being undercut so that when cold the metal cannot be shaken out. The boiling of a few drops of water in the heater cavity will likewise serve to indicate the proper temperature, but the fusible metal is in every way pref- erable. The best plan is to hold the heater over the flame until the F metal melts, set down the heater, blow hot air into the previously prepared and dry cavity until the tooth is sensibly warm, hold the heater again over the flame to melt the metal, and then with a suitable broad and cold instrument pick from the heater a pellet or group of pellets sufficient to a little more than fill the cavity, and by a quick, firm, rock- Trimming margins of ing pressure force the mass into the cavity as if it gutta-percha filling. were gought t<) take &n impresgion of the game# Then dip the instrument into ice-water, wipe dry, and hold it firmly against the filling for one or more minutes, after which with a keen- edged thin blade pare off the surplus, cutting from the centre obliquely toward the margin, as in Fig. 300, taking great care that the filling B shall be flush with the cavity margin at every point, as at A, A', Figs. 301 and 302. " Access to approximal cavities, as C, C, Figs. 291 and 292, will seldom permit the instantaneous mass-method just described, but in many such cases a warm, broad, flat blade, as stiff as the space will admit, can by repeated quick pressures be made to squeeze the soft mass into the cavity of the warmed tooth, and be instantly followed by a very thin strip of metal held tightly in both hands and wrapped with hard pressure over the filling around that side of the tooth, to both condense GUTTA-PERCHA. 317 and contour the plastic and produce the closest adaptation of the material to all parts of the cavity walls. " There is good reason for the belief that the common mode of suc- cessively introducing small pieces of imperfectly softened gutta-percha into a comparatively cold cavity, and employing instrument points more or less heated for packing the cooled plastic against one side of the cavity after the other, must in the nature of the case result in a leaky filling, such as gutta-percha is commonly said to make, whereas the defect is due not to the material, but to its inconsiderate manipulator. " In order to definitely determine whether or not suitably softened gutta-percha inserted by the mass-method will make a moisture-tight filling, some procelain teeth of natural size and forms were made, hav- Fig. 301. Fig. 302. Fig. 303. Fig. 304. ft! Fig. 305. Fig. 306. ■p A ' %- ing cut in them, prior to baking, cavities of the class shown in Figs. 291-298. These cavities have been filled with gutta-percha, leaving a surplus over the margins, as at a' a' ', Fig. 303, and when quite cool paring them flush as at A, A', Figs. 301, and 302, and after several days' immersion in dilute aniline ink, the fillings have been removed without a trace of color showing on the walls of either the fillings or the cavi- ties. The only exceptions have been where the margins were rounded, as at a, a/, Fig. 303, and the fillings not cut below them as shown, but left feather-edged, as at d, d' , Fig. 305. In these few instances discolor- ations were found under the laps, but in no case extending farther than to A' ', A f y Fig. 306. The tests prove that under conditions as nearly practically parallel as extra-oral tests can well be, gutta-percha fillings properly made will exclude external moisture. Obviously, it is better to pare the filling below the enamel-slopes, as in Figs. 304 and 306, than to leave it overlapping, as in Figs. 303 and 305. For a final finish use a rapidly revolved, lightly touching, cuttlefish-paper disk, followed by a wisp of bibulous paper or piece of tape wet with chloro-percha, applied for but an instant, to glaze the surface of the filling. " In the case of a very thin enamel front like that of Fig. 292, that part of the cavity C may be varnished with thin chloro-percha and dried with hot air just prior to filling it as before said. It might first be thinly coated with a tinted oxyphosphate or oxychlorid of zinc, which 318 PLASTIC FILLING MATERIALS. should be given ample time to harden before placing the gutta-percha. Indeed, it is a fundamental feature of good gutta-percha work that while one cannot operate too rapidly when the plastic is at its proper temperature, the preparatory and completing processes should be given as much time, care, and close scrutiny as more elaborate and often less enduring gold operations. There is furthermore room for the exercise of the artistic faculty in having at hand chloro-percha, or cellulose varnish of varied colors, with which, by means of a small brush, a gutta-percha filling as B, Fig. 294, and one in the like cavity C, may be given an inconspicuous shade, and the painting be renewed from time to time, if that be necessary by reason of wear. Fig. 307 is a sectional view of fillings like B, C, Fig. 294." Finishing' Gutta-percha Fillings. — If a gutta-percha filling has been packed with the proper amount of care and skill, it should require but little trimming. It should be undisturbed until cold. Its harden- ing may be hastened and intensified by holding ice-Avater in contact with it for a few moments. The portions overlying the margins are to be trimmed with extremely sharp lancets or by w r arm blades. Every cut should remove a little of the surplus material, never a mass of it, and should be made toward the cavity margins, never away from them. The filling should have been made so that no fulness is present to require reducing. It is a general practice to give a smooth face to a gutta-percha filling by wiping it with a tape slightly moistened, not wet, with chloroform. The surface produced by this means, although smooth, does not retain its integrity so well as when the surface is formed by cutting. The use of gutta-percha as a canal filling is discussed in Chap. XVII. Basic Zinc Cements. Zinc Oxychlorid. — The basic zinc cements employed in dentistry are the oxychlorid and the phosphate ; the oxysulfate should also be included. The oxychlorid is formed by the combination of calcined and pul- verized zinc oxid with a solution of zinc chlorid : ZnO + ZnCl 2 + H 2 = 2ZnClHO. This compound was introduced as a dental filling material about 1850, its hardness, whiteness, and apparent insolubility recommending it for that purpose. It required no lengthy period of time to demonstrate that as a filling material per se it was unfit for use. It disintegrated rapidly and was not free from shrinkage. Properties. — Freshly mixed, this material is irritating to vital tissues with which it is brought in contact ; applied close to or upon an exposed pulp it may be productive of a transient or a persistent irritation, BASIC ZINC CEMENTS. 319 or even inflammation. The extent of the irritation is largely governed by the fluidity of the cement paste, i. e. the amount of zinc chlorid present. It sets in fifteen minutes sufficiently to permit the packing upon it of an amalgam, and in half an hour a gold filling. After setting it is whiter though less hard than the zinc phosphate; it shrinks, particularly when used in large masses. It is a poor thermal conductor, and, like all bodies containing zinc oxid, is soluble in lactic acid — the usual sol- vent in the oral cavity. These several features are at present regarded as limiting the application of oxychlorid to — first, a lining material for carious cavities over which the insoluble filling proper is to be placed ; second, as a root-filling material (its use in this connection is discussed in Chapter XVII.). It is to be noted that the cement retains after setting an antiseptic power for a greater or less period. Use. — Zinc oxychlorid is usually employed as a lining material in teeth having what is known as poor structure — those in which caries proceeds to great depths without external evidence of the extent of invasion. After these cavities have been partially excavated it is found that further excavation and the removal of the deepest layers of the leathery dentin which appear to have retained sensitivity would prob- ably uncover the pulp ; it may be that the pulp has given subjective evidence of a mild attack of active hyperemia. In such cases the deepest layer of the partially disorganized dentin is permitted to remain and is subjected to the prolonged — fifteen minutes or longer — contact of hydrogen peroxid in the 25 per cent, ethereal solution (caustic pyrozone), 5 per cent, aqueous solution of formalin, or preferably a saturated solution of thymol in alcohol. The cavity walls are well dried with bibulous paper and the warm-air blast. Upon a mixing slab (see Fig. 308), a drop or two of the zinc chlorid is placed, and beside it a quantity of the zinc oxid powder. The powder is gradually incorporated with the fluid by means of a spatula until a creamy paste is made. A number of balls of bibulous paper are to be at hand. A portion of the paste is taken upon the end of an instrument and placed in the cavity, where it is quickly pressed into a layer against the cavity walls by means of the balls of bibulous paper. The walls are to be covered to a uniform depth of about one-sixteenth of an inch. The prompt application of the bibulous paper usually pre- vents any irritation due to the contact of the oxychlorid with the dentin overlying the pulp. Should the cavity be very deep it is advisable to protect the pulp by interposing a film of ethereal varnish between the oxychlorid and the dentin over the pulp. At the completion of the lining operation, the margins of the cavities are to be cleansed of the oxychlorid and the filling completed with the material indicated. 320 PLASTIC FILLING MATERIALS. Zinc oxychlorid as an obtunding agent in the treatment of hyper- sensitive dentin is of considerable value, and its use for that purpose is described in Chapter VI. The use of zinc oxychlorid as a canal filling, and the mode of using it, are discussed in Chapter XVII. The powder of this cement is made of zinc oxid calcined and pow- dered, to which have been added substances (borax, silica, etc.) which affect its properties but little if at all. The fluid is made by dissolving pure zinc or its oxid in hydrochloric acid to the point of saturation ; or, by making a solution of zinc chlorid 4 parts, water 3 parts, and filtering the solution. The use and effects of zinc oxychlorid as a pulp capping are dis- cussed in Chapter XVI. Zinc Phosphate. — These cements are nominally a combination of calcined zinc oxid with a syrupy solution of orthophosphoric acid : 3ZnO + 2H 3 P0 4 = Zn 3 (P0 4 ) 2 + 3H 2 0, although their actual composition is more variable than that of any other filling material. Both base and solvent commonly contain impurities — those of the base owing to lack of discrimination, or worse, in the source of the oxid. Many of the impurities of the phosphoric acid are due primarily to the well-known inconstancy of the acid itself, and others to the mode of its manufacture. Many of the specimens of powder are prepared from commercial metallic zinc, and therefore contain the impurities of that metal. Among the latter is arsenic, so that the presence of arsenic compounds in inferior cement powders is by no means impossible, which may pos- sibly explain in some cases the death of non-exposed pulps in teeth which have been filled with zinc phosphate ; but as recent chemical in- vestigation has shown that the arsenic when present in cement powders is in the form of an insoluble zinc arsenite, the danger of arsenical irrita- tion of the pulp from that source would seem to be a remote one. A common source of the glacial phosphoric (metaphosphoric) acid of commerce is from sodium phosphate, variable quantities of which are retained in the acid solution as acid sodium phosphate (dihydrogen sodium phosphate). This substance is soluble in water, and must there- fore greatly increase the solubility of any cement containing it. To properly make pure specimens of zinc oxid and phosphoric acid is a comparatively expensive operation — which will serve to explain the seemingly high cost of fine specimens of cement, and incidentally serve as a warning against the indiscriminate use of cheap cements. Making the Powdee. — A quantity of pure zinc oxid is luted in a BASIC ZINC CEMENTS. 321 sand crucible and kept at the highest forge-heat for hours. When cool the crucible is broken away and the vitreous mass of yellowish zinc oxid is reduced to a powder which will pass through a fine bolting cloth. This powder is placed in tightly stoppered bottles, for if exposed to the air it absorbs carbon dioxid and a portion of it is converted into the hydrated carbonate of zinc. This change may be noted in old powders by the effervescence due to the disengagement of carbonic oxid when phosphoric acid is added to them. Numerous substances have been added to the basal powder with the object of lessening the disintegra- tion, i. e. chemical solution, when used as a dental cement. Usually these additions are the oxids of other metals. The oxid of magnesium added to the powders causes the cement to set more rapidly ; the oxid of aluminum increases the rapidity of setting and makes a finer-grained cement, the central texture of which is, however, inferior. Cements of zinc oxid and phosphoric acid alone are apparently less soluble in lactic acid than when the oxids of aluminum and magnesium are added. Various other substances have been added which do not enter into chemical combination with the phosphoric acid, in the hope of confer- ring greater durability on the cement, but as yet but few of them have been shown to possess any value. The Fluid. — Phosphoric acid in its pure state is formed by hydrating phosphorus pentoxid : P 2 5 + 3H 2 = 2H 3 P0 4 . Much of the phosphoric acid used for cements is made by hydrating the glacial (metaphosphoric) acid, HPO s . The acid dissolves readily in water, being deliquescent when pure. Difficulty of solution is therefore an indication of impurity of the glacial acid. It requires a definite degree of heat to bring about the chemical hydration of the acid. At a temperature of 210° F. the union occurs, which is attended by the evolution of heat, the glacial acid being transformed into ortho- phosphoric acid. These acids are all hygroscopic. They will even ab- stract water from sulfuric acid. Impurities. — The commercial glacial acid is commonly, or as a rule, impure, containing variable amounts of sodium and magnesium phos- phates. These salts, particularly the dihydrogen (acid) sodium phos- phate, are permanently soluble in the phosphoric acid, and therefore give no evidence of their presence by the formation of precipitates. They are also soluble in water, which fact has a direct bearing upon the durability of cements made with the impure acid. It has been stated by writers that the acids of cement were occasion- ally the meta- and pyrophosphoric. A test of some of them said to be 21 322 PLASTIC FILLING MATERIALS. of these varieties showed none of them to give the reaction of the pyro- acid ; a few giving traces of the meta- acid. Precipitates which form in cement fluids are probably metallic phos- phates. The instability of cement fluids is notorious. Aside from the known or probable contaminations which they may contain this insta- bility is to be regarded as a distinctive feature of phosphoric acid. The Cement. — To make the cement, successive portions of the oxid are mechanically incorporated with the fluid until a stiff paste results. In five minutes a ball made of the paste glazes, and rebounds when dropped upon a hard surface. It breaks with a granular surface ; in fifteen minutes it is cut with some difficulty. If the cement fluid con- tain the acid sodium phosphate, an acid reaction may remain for hours or days. The atmospheric conditions markedly modify the properties. In warm, or hot and moist weather, the setting is more rapid and it may be sudden. In cold weather it is delayed. The greater the dilu- tion (the thinner the fluid), the more rapid the setting. In its freshly mixed state zinc phosphate is adhesive, losing this property in a great degree when set, if surrounded by moisture. It has a higher rate of heat conductivity than zinc oxychlorid. Uses. — Its legitimate field of usefulness is in situations and under conditions where its advantageous properties may be utilized and its disadvantages minimized. One of the principal facts to be borne in mind is the solubility of the cement in lactic acid, which is present almost always about the necks of the teeth, in approximal spaces, and along gingival margins. Its clinical use is therefore attended by the greatest measure of success when placed at a distance from such situa- tions — as, for example, in cavities opening upon the masticating sur- faces of teeth, where its great hardness is an element of advantage. Good specimens have been known to last for periods varying from three to eight years. Dr. Henry Weston has cited cases where an un- usually good zinc phosphate filling has lasted for ten years. As a filling material per se, zinc phosphate has but limited employ- ment except for the teeth of children, and as a temporary filling in the teeth of adults. Times and occasions will suggest themselves to every operator where gold, amalgam, and gutta-percha are contraindicated as filling materials ; in such cases zinc phosphate performs a useful ser- vice. Its great field of usefulness — where, indeed, there is no substi- tute for it — is in the filling of the greater portion of extensive cavities, which are then filled and sealed with gold or amalgam, by an inlay, or it may be by a partial crown. It is invaluable, and in most cases indispen- sable, as the retaining medium of fixed bridge work and of many forms of artificial crowns. Prior to placing the zinc phosphate filling in a cavity, it is a wise BASIC ZINC CEMENTS. 323 Fig. 309. Dropper. Fig. 310. Scoop. Fig. 311 precaution to line the latter with one of the quick-drying ethereal var- nishes, to protect the dentinal walls from contact with acid sodium phosphate which may be present in the cement. In some cases the placing of the cement in proximity to a non-exposed pulp is productive of marked suffering. Should the cavity be very deep it is the usual practice to place a softened disk of gutta-percha over the wall nearest the pulp. The rubber dam should always be adjusted before the insertion of a phosphate fill- ing, to insure dryness not only during the insertion, but during the period of hardening, at least fifteen minutes. Mixing of Cement. — This is an operation of equal, if not greater, im- portance than any other in the manipu- lation of zinc phosphate. Dr. Henry Weston has demonstrated how, almost entirely, the mixing of cement gov- erns its stability. Specimens of the same powder and fluid mixed after dif- ferent methods gave entirely different results, not only in the appearance but also in the hardness, texture, and solu- bility. The method of mixing set forth is that of the same experimenter. As- suming for illustration that an approx- imal cavity is to receive a contour filling, or a large occlusal cavity is to be filled, Fig. 308. Glass mixing tablet, with rubber feet. or an extensive cavity is to be three- fourths filled with cement : A drop, or, where a large mass of cement is required, two drops of fluid are placed upon a scrupulously clean glass (Fig. 308) by means of the dropper shown in Fig. 309, and Spatula. 324 PLASTIC FILLING MATERIALS. a mass of powder, in great apparent excess of that required, is heaped at a distance from it, taken from the bottle by the scoop (Fig. 310). A portion of the powder is drawn into the fluid by means of a stout spatula (Fig. 311), and stirred with a rotary movement until a thin paste is made ; another portion of powder is then added and is slowly and thor- oughly incorporated; more poAvder is added until the mass is as thick as putty and difficult to smear with the heavy spatula; the mass is scraped together, taken from the spatula, and rolled between the forefinger and thumb, which have been well scrubbed. The mass is now kneaded, then rolled into an oblong pellet. If for an occlusal cavity a piece about one-fourth the size of the cavity is set in the deepest portion and tapped into perfect apposition with the cavity walls by means of a burnisher. Other pellets are added, and the process is repeated until the cavity is exactly full, the burnisher form- ing the surface of the filling and outlining clearly every margin of the cavity. The filling should remain under rubber dam for at least fifteen minutes — longer when possible. A coating of ethereal varnish, a solu- tion of gutta-percha in chloroform, or melted paraffin as suggested by Dr. Bonwill, is applied to the surface and the grinding of the filling deferred for a day or two. Should the cavity be upon an approximal side of a tooth, a matrix is to be employed ; the most satisfactory and quickly adapted instrument for this purpose is one of the composition silver strips used for carrying polishing powders (Fig. 312). A strip Fig. 312. Polishing strip. as wide as the length of the tooth is to have one end rolled upon itself until it forms a cylinder more than one-sixteenth of an inch thick (Fig. 313, A). The strip is passed into the next interdental space and drawn Fig. 313. through until the cylinder (A) rests firmly upon the teeth ; the free end is noAV passed through the space into Avhich the cavity opens ; where it BASIC ZINC CEMENTS. 325 rests upon the lingual surface of the tooth it is burnished into contact with the edges of the cavity, forming walls to the latter (313, B). The cement is introduced as in the preceding case, and when the cavity is full the free end of the strip is drawn upon, compressing and round- ing the filling. Should the cement be an adhesive specimen or mixed thinner than described, the surface of the flexible mat- Fig. 314. rix is to be faintly oiled by means of olive oil. At the completion of the operation the cement should be exactly flush with the margins except at the labial aspect, and the surface of the cement should have such smoothness that polishing is not necessary. Cement fillings are polished dry with the finest of cuttlefish disks. The process of filling the body of any cavity is the same, except when the enamel walls are thin and frail. In the latter case, where space permits, it is preferable to line the walls with the oxychlorid of zinc, over which the phosphate is placed. Before inserting a veneer fill- ing of gold or amalgam, each cavity margin must be scraped free from cement. When orthodontia appliances such as rings or caps, or prosthetic appliances, crowns and bridges, are to be set it is preferable to use a cement prepared for that purpose, although it is the general practice to use the cement to which the operator is accustomed, mixing it thinner than for filling purposes. Wherever possible, it is advisable to operate under rubber dam, even while setting orthodontia appliances. The tooth is cleansed with chloroform — as, for ex- ample, when a ring or cap is set — to remove fatty mat- ters, and a layer of shellac varnish applied, which is then dried by the air blast (chip blower). Cement paste is formed, of such consistence that it will flow readily and yet not be watery ; the inside of the band or cap is filled with cement by means of an appropriate spatula (Fig. 314) ; a layer of cement is placed on the tooth where it is to be embraced by the band, which is then pressed into position and is to remain without disturbance until it is hard. The application of bands or ligatures should be deferred until the following day. As soon as the cement is hard the surplus is cut awav and the dam removed. Pointed spatula. 326 PLASTIC FILLING MATERIALS. Temporary Stopping. Preparations of this name are compounds of gutta-percha with various substances added to lessen the temperature of softening. As procured from the manufacturer they are of two varieties, the adhesive and the non-adhesive — or, to be more precise, the less adhesive. The former preparations, the adhesive, are usually made of gutta-percha (generally the pink base plate), Burgundy pitch, white wax, and chalk or zinc oxid. In the non-adhesive varieties the Burgundy pitch is omitted. The latter varieties are usually made of a pink color, to furnish a safe- guard against mistaking a filling of temporary stopping for one of gutta- percha. As the name implies, they are designed for temporary use, retaining dressings in teeth, to maintain space between teeth which have been wedged apart, until the attendant pericementitis subsides ; to press away gum tissue overhanging the margins of a cavity ; to fill excavated cav- ities for a few days. Unlike gutta-percha, most of these preparations cannot be permitted to remain for a prolonged period ; they usually become offensive, par- ticularly so when the hygiene of the mouth does not receive proper attention. To maintain space and press away gum tissue they are used as gutta-percha ; their lower heat of softening permits their application close to the pulp of a tooth without the painful response associated with placing hot gutta-percha in the same position. A prominent use of the material is the sealing of arsenical applications in teeth. As with any other material, it is necessary, in order to have the minimum of pain, to make the application and manipulate the stopping so that no pressure shall be exerted upon the pulp. Temporary stop- ping is inferior to zinc phosphate for this purpose, as the latter may be flowed into a cavity and over an arsenical application without causing the slightest pressure. Should the cavity of decay extend to or beyond the gum, a small conical piece of the temporary stopping should be softened and packed carefully against the cervical margin and gum, to act as a guard to the latter against contact with the virulent irritant arsenic trioxid. The arsenical paste on a minute pledget of cotton is laid upon the exposed pulp — if the latter be hypersensitive, beside it — and the remainder of the cavity and interdental space are filled with one very soft piece of temporary stopping. Temporary stopping, in cones, has been used as a canal filling (see Chapter XVII.) and as a filling for the bulbous portion of pulp chambers. Another important use of the material is the sealing of the occlusal cavities of teeth which are under treatment for septic pericementitis. OXYSULFATE OF ZINC. 327 Plugs of softened temporary stopping have been used for the arrest of alveolar hemorrhage ; also for the temporary setting of artificial crowns. Lining Varnishes. These are solutions of various gums and resins in alcohol, chloro- form, and ether, which are employed to furnish a non-conducting and impermeable film to cover the dentinal walls of excavated cavities. The first, sandarac varnish, is a thin solution of sandarac in alcohol. The second, a solution of virgin rubber in chloroform. The third a solution of hard Canada balsam, copal, or damar in ether. Another is the preparation known as Jcristaline, a solution of trinitro- cellulose in anhydrous amyl acetate. Before lining a cavity with zinc oxychlorid, a film of one of these varnishes, the quick-drying ones preferred, is applied, and when this is dry the cement may be inserted without causing pain. Varnishes have been used to furnish an adhesive surface upon w r hich to pack gutta- percha fillings. It is always advisable to varnish the walls of a cavity which is to receive a filling of zinc phosphate, to prevent the action of any free acid or acid salt upon the dentinal walls. Some of these varnishes are admirable non-conductors, and serve in that capacity under gold or amalgam fillings in a most satisfactory manner. They may be used to prevent the tooth discoloration due to the pres- ence of amalgam, particularly of copper amalgam. Zinc Oxysulfate. What is known as the zinc oxysulfate in dental parlance is merely a thin zinc oxychlorid containing zinc sulfate. A true zinc oxv- sulfate is made by mixing a saturated solution of zinc sulfate with uncalcined zinc oxid. It forms a white paste which sets quickly and attains about the hardness of an inferior plaster-of-Paris. It is bland and unirritating to exposed pulps ; is a non-conductor ; is faintly and persistently astringent. 1 Its principal use is as a pulp capping or protective. A thin paste is made, in which a disk of paper is dipped, then quickly and accurately laid upon the area of exposure. When hard (in a few seconds) a drop of fresh thin paste is flowed over the capping. The cavity may then be lined with zinc phosphate. As a pulp protector from thermal shock it is applied in a thin layer, and over it a lining of zinc phosphate is packed. 1 J. Foster Flagg. CHAPTER XIV. COMBINATION 1 FILLINGS. By Dwight M. Clapp, D. M. D. The use of more than one material for filling a single cavity was suggested by the observation of the condition of fillings composed of but one material and noting the effects of time and use thereon. If a large number of amalgam fillings in occlusal cavities are exam- ined, many will be found to have imperfect edges. One cause of this imperfection is, undoubtedly, the brittle character of amalgam, in con- sequence of which the edges have become broken. In other words, amalgam as a filling material lacks edge strength. Its dark, sometimes almost black, color also renders it very objectionable, especially if used in conspicuous positions. If the same number of gold fillings in occlusal cavities are examined, the edges will be found in better condition than was the case with the amalgam. One reason for this is, undoubtedly, because gold is not brittle, but possesses sufficient edge strength to withstand the force of mastication. Its color is also less unsightly than that of amalgam. For occlusal cavities, therefore, gold is regarded as the better filling material. If a series of occluso-approximal cavities filled with gold be studied, it will be found that the teeth are in much better condition on the oc- clusal surface than at the cervical borders of the fillings. Compare gold fillings with a series of amalgam fillings in this same class of cavities, and the condition of the teeth will be reversed : at least a much larger percentage of the teeth will be found in good condition around the ap- proximal portion of the fillings than was the case with the gold. Hence, the deduction is inevitable that, of these two materials, amalgam is the better to fill the cervical portion of approximal cavities. 1 The term " combination ' ' is adopted for the various fillings here described, in which more than one material is used, because it seems to be the most comprehensive. The putting together of different materials in filling teeth makes in no sense a chemical combi- nation, in which "any part of the compound is the same as any other part of it." Strictly speaking, the fillings are more "mixtures" than "combinations." According to the best authorities, however, the meaning given to combination makes its use here quite admissible. 329 330 COMBINATION FILLINGS. Zinc phosphate cement has many admirable qualities and is one of the most valuable filling materials known. It is easily worked, its color is good, its adhesiveness serves to bind tooth and filling together as the stonemason's cement unites the blocks of granite that he piles one on the other into one solid piece of masonry. As a tooth-saver it has no equal ; but its one great defect, its solubility in the fluids of the mouth, restricts, in a great degree, its usefulness when exposed to these fluids. From this it will be easily understood why it is often desirable to combine in one filling two or more different materials ; and it may be said with truth that the operator who selects his filling materials with the best judgment, and combines and uses them with the most skill, will save the greatest number of teeth. There would be just as much common sense and scientific reason for an electrician to make a dynamo entirely of copper, or a watchmaker to use nothing but gold in making a watch, as for a dentist to fill many of the cavities that come to him with but one material. It is an error to think that combination fillings are resorted to because more easily made than fillings of but one material, or that it indicates a lack of skill on the part of the operator who makes and recommends them. On the contrary, it is often much more difficult to make a suitable combination filling than one of any single material ; and the student will find that combination work will give ample opportunity for the employment of all the skill and ingenuity he may possess. Every operation must be made with the greatest amount of care and attention to minute details, or the object sought will be unattained, and the result be an inferior piece of work which will sooner or later cause grief to the patient and chagrin to the operator. It is impossible to describe all the combination fillings that have been found advantageous and useful, therefore only some of the most important will be considered in detail. The list is limited only by the perverse manner in which teeth decay, and by the ingenuity of the ope- rator to devise scientific and practical combinations to meet the cases presenting. It is to be understood in every instance in this chapter that the teeth are in proper condition to be filled without further treatment. If pulp- less, the roots are supposed to have been put in a healthy condition and filled. In cases of exposed, or nearly exposed, pulps, they are supposed to have been properly protected, and the teeth ready in every respect for the mechanical operation of inserting the fillings. Cement (Zinc Phosphate) and Amalgam. In Simple Cavities. — This combination is of the greatest service in saving badly decayed teeth that otherwise might have to be cut off and CEMENT AND AMALGAM. 331 Fig. 31-5 crowned, or perhaps lost altogether. The simplest cases where it may judiciously be employed are occlusal cavities. Many such cases are seen where there is little left but the enamel, which, however, is thick around the orifice of the cavity, and, if properly supported, will have sufficient strength to withstand the ordinary strain of mastication. Great care should be taken to remove the decay from every part of the cavity, being sure that none is left under the cusps or any part of the overhanging enamel. The edges of the cavity must be carefully trimmed, so that the filling can be finished flush with the external surface, in order not to leave any overhanging portion of amalgam to be broken off, as it certainly will be if so left, to the great injury of the filling. There are but few cases, even in occlusal cavities, where the rubber dam should not be used, at least for the final excava- tion and for putting in the filling ; for it is almost im- possible to be sure that all decay has been removed from a cavity unless it is dry. No filling should be allowed to get wet before it is all in place if it can possibly be avoided. It is much better to err by using the rubber dam too often than not often enough. Fig. 31 5 shows a cavity such as described. The cavity being ready, sufficient amalgam to fill one-third of it is prepared. Before introducing the amalgam, however, the cavity is filled two-thirds or three-fourths with rather soft cement, into which pieces of the prepared amalgam are crowded, forcing the cement into every portion of the cavity. The cement which has oozed out around the edges is then removed with an excavator, and the operation will have the ap- pearance shown in Fig. 316. The filling is then com- pleted in the same manner as an ordinary filling of amalgam in an occlusal cavity. The advantages of this kind of fillino; are many : The bulk of it is of cement, which does not change its shape perceptibly and is the best of materials when not ex- posed to the fluids of the mouth. The cement firmly removed; then unites the tooth to the filling, thus making a support to amalgam? 1 l tne ^ ra ^ wa U s as we U as a stopping to the cavity. The amount of metal is reduced to just enough for a cover- ing of sufficient strength to guard the cement, and the tooth will not be discolored by the amalgam, as is often the case in teetli of not very dense structure, and especially in the mouths of young patients, when not thus protected. The combination of cement and amalgam, as described above for Large occlusal cavity. Fig. 316. Section showing amalgam and cement. (Sur- plus cement must now be 332 COMBINATION FILLINGS. occlusal cavities, may be used in the same manner in simple approximal cavities in the molars and bicuspids, and even in the six front teeth, when the cavities are so situated that the amalgam does not show. When used in the front teeth the cement should be allowed to remain very near to the edges of the cavity. The amalgam need not be more in amount at this point than the thickness of an ordinary Fig. 317. Cement and amalgam filling in an incisor. The surplus cement has heen removed and the fill- ing is now ready for the finishing portions of amalgam : a, enamel ; b, cement ; c, amalgam. visiting card (see Fig. 317). For the front teeth very light colored amalgam should be selected, as color is of more importance than strength. In the temporary molars this combination can be used, frequently, with the greatest satisfaction, especially in those shallow approximal cavities where but little undercut can be obtained without exposing the pulp. The cement should be used quite thin, and the amalgam worked into it with a burnisher, or rounded instrument, forcing the cement to a feather edge at the margins of the cavity. In cases of this kind resto- ration of contour should not be attempted, as the force of mastication might serve to fracture the cement and dislodge the filling. In this manner many troublesome and difficult cavities can be successfully treated, and teeth made to last their allotted time that would otherwise be prematurely lost. In Compound Cavities. — A more extended description will be necessary for the treatment of compound cavities in the bicuspids and molars, especially where it is desirable to restore contour. In these cases a matrix is often a necessity. There are many matrices that may be used successfully, but, as they are described in other parts of this work, only one need be mentioned here. This is selected on account of being almost universal in its application. It can be made from any metal not acted on by the mercury contained in amalgam. German silver is inexpensive and seems to meet every requirement, and is, therefore, recommended. For ordinary use it should be from No. 35 to No. 38 gauge. If stiff it should be annealed, so as to be readily bent to the form of the tooth. It can be easily polished so as to reflect light CEMENT AND AMALGAM. 333 into the cavity, by drawing a narrow strip of it between two pieces of stationer's rubber (ink erasers). Place one piece of the rubber on a table, then the strip of metal held with pliers in one hand is placed on the cake of rubber, Avhile with the other hand another piece of rubber is held firmly down on the metal, which is drawn between the two until sufficiently bright. For ordinary cases, a piece is cut from the German silver, as shown in Fig. 318, A, wide enough to extend from the top of the tooth to a little beyond the cervical wall of the cavity, and long enough to a little more than cover the cavity laterally when tied in place. Sometimes it is necessary to make the matrix with a lip to extend under the gum, as shown in Fig. 318, B, or in some other irregular form, so that it can be Fig. 318. A, Matrix and ligature; B, lipped matrix. made to properly fit the cavity. Special cases may require a very wide or a very narrow one. The operator's ingenuity must devise the right shape. For tying the matrix to the tooth, coarse, well-waxed floss silk is the best. It is passed through the holes punched in the metal, as shown in Fig. 318, A and B. When these holes are made, the edges must be finished smooth, or the silk will be cut when drawn tightly around the tooth. The operator must use tact as to Fig. 319. how and where to make his knots in M*M^kfMm*7\ tying on the matrix. Usually, a good way is to place one end of the ligature, a, between the teeth, then to make a sur- geon's knot, as shown in Fig. 319. The other end of the ligature, b, is then forced between the teeth, and the knot tightened. This will bring the knot between the teeth and opposite the matrix and will hold the latter until it can be shaped and bent into place with a burnisher or other suitable instru- ment. The knot is again tightened, and the two ends of the ligature carried to the back of the matrix and a similar knot tied there. The second knot, when drawn tightly against the back of the matrix, forces it closely up to the cervical border of the cavity, and makes a firm resistance when the filling is being condensed. The silk is then wound WJfwm Manner of ligating the matrix. 334 COMBINATION FILLINGS. round and round the tooth and matrix until it nearly covers both, or at least sufficiently to insure its remaining in place during the operation. A knot may be tied each time the silk is wound around the tooth, or not, as appears to be necessary. Sometimes, when the sides of the tooth are sloping, the ligature has a tendency to slip off. This can usually be overcome by turning back, with tweezers, the two upper corners, as shown in Fig. 324. To saturate the ligature with sandarac or other sticky varnish will sometimes be sufficient to prevent the same tendency. Fig. 320 illustrates a simple and delicate, but very powerful, little FlG 32Q slip matrix which is of great efficiency ^ — ^ x . — ^ ^ — ^ in the treatment of occluso-approximal Mm%. _j^ ; m i / ^m^, cavities. They were conceived originally %-J w^- 3 jEL _J 8EIZJ ^ or tne pl ast i cs ; m which case they are left in place over night (the plastics thus setting under pressure), slipping out easily the next day away from the then hardened and perfectly contoured surface of the filling. "They are most easily made, even for each case (though in practice this is not necessary, as they may be employed over and over again), as follows: Suitable-shaped pieces, of a size to a little more than over- lap the cavity margins, are cut from thin . . . steel, ... all corners and burred edges smoothly finished ; a tiny hole is punched close to the middle of both the buccal and lingual edges, and it is then laid upon a piece of lead and swaged (not merely bent, be it remarked) into perfect concavity, greater or less as the individual case shall require, by tapping with a hammer a convex rod of hardened steel laid upon it ; my own instrument being a round-headed picture nail, case-hardened, polished, and with twisted wire attached at right angles to a handle. Any amount or shape of concavity required for each case can thus be produced in a moment, either newly from blanks kept ready or changes made in those used for other cases to fit the one in hand, about a dozen of different sizes and degrees of convexity being sufficient to select from, with little or no changes for all ordinary cases. The tapping having re-stiffened the steel somewhat, taken in connection with the impingement of the convex face against the approximal surface of the adjoining tooth, gives firmness and strength to these delicate little strips and a perfect hugging fit to the surfaces of the tooth being filled, especially at its cervical margin, that is most satisfactory," i When the cavity involves a large portion of the crown, or the mesial and distal surfaces, the matrix should be long enough to almost encircle 1 Dental Cosmos, June 1898, vol. xl. No. 6, p. 452. CEMENT AND AMALGAM. 335 the ton+h, the ends nearly joining against the sound remaining wall (see Fig. 321). In such cases it may be desirable to slit it one or more times, in order that it may be made to take the form of the tooth more easily (Fig. 322). After the tying is completed, a suitably shaped bur- nisher is used to form the matrix, by pressing it outward, to a proper contour. One of the desirable features of the matrix here de- scribed is the ease with which it is made to give just the right shape and contour to the filling. When used for gold fillings it yields enough so that with a little care in packing the gold can be forced beyond the margin of the cavity suf- ficiently to insure a flush filling when burnished, after removing the matrix. A matrix put on as described will have sufficient resistance for a gold filling ; for amalgam, cement, or gutta-percha it may not be necessary to tie it quite so securely. For compound fillings of cement and amalgam two methods, A and B, are here given. 7 , 7 1111 Matrix with marginal slits. A. Those cavities which, although large and involving much of the tooth, may have but small or comparatively small openings, especially if a matrix be used — and there are but few cases where the matrix is not advisable. If, after putting on the matrix, in this class of cavities, cement is introduced, and pieces of amalgam thrust into it, the cement will most likely be carried to the margin of the cavity at the cervical wall, and it will be found, after removing the matrix and finishing the filling, that a part of the external portion is of cement, and not being protected by the amalgam, would be washed out. To avoid this, a portion of the filling is made before the matrix is put on. Cement is put in, followed immediately by the amalgam as described for " occlusal cavities " with the added complication of the missing approximal wall. After sufficient amalgam has been put into the cement the portion of the latter which may have oozed out must be carefully cut away, so as to expose the entire outer edge of the cavity, including the cervical wall (see Ceme a J 1 t a 1 j n a 1 Jf and Fig. 323). ama gam ' After this has been done, the matrix may be tied on and the filling completed as though it were but a simple cavity. Sometimes it is well to leave the matrix in place until the amalgam is fully set. If this be done, care must be taken that no sharp edge or corner of it be left to wound the tongue or cheek. 336 COMBINATION FILLINGS. Fig. 324. a, Matrix ; b, amalgam packed against the matrix ; c, por- tion of cavity to be nearly filled with cement and fin- ished with amalgam. B. Cavities with large openings. The rubber dam and matrix having been adjusted, enough amalgam is packed against the matrix to form a shell of sufficient strength to make the approximal wall of the filling (see Fig. 324). This will leave a large portion of the cavity !|| } ' unfilled as shown in the figure ; in this space is placed cement, which is gently worked into the soft amalgam, but with care not to carry it through to the matrix. Before the cement be- comes hard more amalgam is put in, the sur- plus cement is removed, and the whole finished to look like an entire amalgam filling, while in reality it is only a shell of amalgam, perfectly fitting the outside of the cavity, cemented into place. If the walls of the tooth are frail, the cement will serve to greatly strengthen them. If, as some claim, large metal fillings alter sufficiently under changes of temperature to fracture frail walls, the danger is by this method reduced to a minimum, as the amount of metal is only just sufficient to give requisite strength. There is another class of cavities which may be described in this connection, presenting great difficulties in themselves, yet, with this simple matrix, they are often easily filled. It is those cases where decay has reached the alveolar border approximally, and extended on either the buccal or lingual portion of the tooth, or both, in such a manner that the dam cannot be made to stay beyond the cervical border of the cavity. If a liga- ture is used, it will draw into the lateral grooves of decay and be of no use (Fig. 325). The mode of treatment is as already described, with the exception that the matrix is adjusted before the rubber is put on. After the matrix is in place, it is but the work of a moment to put a Palmer clamp on to the tooth, and slip the rubber dam over clamp, matrix, and tooth. If the matrix has been carefully fitted there will be no trouble in keeping the cavity dry long enough for any ordinary operation. There are certain buccal cavities, also, below which it is difficult to retain the rubber dam. A very narrow matrix, adjusted with ligature and Matrix and clamp damp (Fig. 326), over which the rubber is placed, adjusted, ready for w iH often greatly simplify the operation. Modifica- dam . tions of this method may also be applied to the Fig. 325. Alveolar line be- yond which the liga- ture cannot be made to stay. Fig. 326. CEMENT AND GOLD. 337 bicuspids, and sometimes even to marginal cavities in the incisors and canines, with good results. Cement and Gold. This combination may be used, with but slight modification, in the same manner and in the same class of cases that have been mentioned for the use of amalgam and cement, cases under B excepted. The cement is, placed in the cavity, and, while soft, pieces of some of the so-called " plastic " golds are put into it, in the same manner as has been described for cement and amalgam ; the surplus cement is carefully cut away, and, after waiting for that in the cavity to become so hard as not to break or crumble under pressure, the pieces of gold placed in the soft cement are thoroughly condensed. For this pur- pose, de Trey's " Solila " Gold, Steurer's Plastic Gold, White's Crystal Mat Gold, and Watts' Crystal Gold are recommended. The filling can then be completed with the same or any kind of cohesive gold. Care must be taken to place a sufficient amount of the plastic gold into the cement to make, when condensed, a solid foundation upon which to build the rest of the filling. If too little gold has been used, it will " chop up " and not make a secure union with the cement. In some large cavities it may be found more convenient, after having filled the approximal portion with the cement and gold, to make a second mix of cement for the rest of the cavity, into which the gold is put as before. In some special cases it may be well to use foil in this manner, but, as a rule, the plastic golds will be found preferable. Too much stress cannot be laid on the desirability of this method for frail teeth, remembering always that the cement is the strengthening and supporting medium. The mason would not build a bridge pier of granite alone, or a house of bricks without mortar. However nicely the blocks of granite or the bricks might fit each other, it is the cement and the mortar that hold them together as in one piece. Especial attention is called to this combination of gold and cement for the six front teeth. In the teeth of young patients and teeth of low-grade structure there are often found large cavities which, if filled with gold alone, will in a few years, sometimes months, show discoloration around the fillings. Filled as above described, every vestige of decay having first been removed, a combination results which is the ideal preservative filling as far as present knowledge and facilities go. Pulpless front teeth that are much decayed can be improved in appearance and greatly strengthened by this method. Fig. 327 shows 22 338 COMBINATION FILLINGS. a cavity in a central incisor that can be filled to advantage with cement and gold. Fig. 328 shows a cavity in a central Fig. 327. Fig. 328. incisor with the pulp removed and but little of /I the crown remaining but the enamel. The greater / part of the cavity has been filled with cement into I ( which plastic gold has been put and condensed. ItpJ The filling can be completed with any cohesive bJM^m gold. °iSP^ I n compound cavities in molars and bicuspids, a, a, Fran enamel wails ; after the cement and gold have been put in, as b, gold surface made by described for cement and amalgam A, and the plastic gold condensed . ,. , /.,/.., i i . -, into cement. matrix adjusted, sojtjoil can be used to great ad- vantage at the cervical portion of the cavities, as elsewhere described for using soft and cohesive golds. Amalgam and Gold. Gold may be used in combination with amalgam — A, by allowing the amalgam to become hard before adding the gold ; B y by adding the gold while the amalgam is soft and finishing the filling at one sitting. A. Allowing- the amalgam to harden and then adding- g-old at a subsequent sitting will usually be done in compound cavities in bicus- pids and molars, for the purpose, principally, of overcoming the dark appearance of the amalgam. For instance, a filling involving the occlu- sal and mesial surfaces of an upper first molar will, in many mouths, show more or less, and, if of amalgam, be dark and unsightly. To avoid this, the cavity may be nearly filled with amalgam, leaving a portion of the occlusal surface and along the buccal wall (this being the part of the filling most likely to show) for completion with gold later. The matrix should be used as described for cement and amalgam fillings. It is a good plan to leave it in place, when convenient, until the amalgam is hard. Before adding the gold, it should be ascertained what part of the filling will show, and the amalgam trimmed and shaped so that the gold may form that portion of the filling that will be in sight. Fig. 329 shows a compound cavity in a molar partially filled with amalgam. The amalgam has been left until hard and the filling is now ready to be finished with gold. The figure also shows the cement lining under the amalgam. Suitable retaining places must be made in the amalgam to hold the gold in position, as there is no union between the two in this case, as there is when gold is added to unset amalgam. The gold being added makes a filling much superior in appearance to one entirely of amalgam. The gold will also make a better wearing material for the masticating surface, having better edge strength than the amalgam, and therefore AMALGAM AXD GOLD. 539 being less liable to be broken away from the walls of the cavity by the force of mastication, as spoken of elsewhere. Large amalgam fillings, when it is not necessary to have gold added on account of color, will be greatly improved if a channel is made with a small fissure bur between the amalgam and the enamel, and this care- fully filled with gold (Fig. 330). Fig. 329. Fig. 330. Fig. 331. Oecluso-approximal cavity Amalgam and cement com- Gold and amalgam corn- partly filled with amal- gam ready for completion with gold : a, a, amal- gam ; b, cement lining. bination with channel cut in occlusal margin for re- ception of gold : a, amal- gam ; b, gold ; c, channel burred out ready for gold, shows also cement lining. bination in incisor: a, amalgam ; b, gold. All amalgam fillings when gold is intended to be added, should be put in with soft cement, whenever possible, as described for " Cement and Amalgam " fillings. This will prevent much of the discoloration from the amalgam, as well as strengthen the teeth. Many front teeth can be saved and made to look well by filling with cement and amal- gam, as before described, and, after the amalgam becomes hard, cutting away that portion which is in sight, and filling with gold (Fig. 331). B. Amalgam and gold fillings, the gold being added while the amalgam is soft. These fillings will be indicated, usually, in com- pound cavities of the molars, and in the occluso-distal and sometimes even the mesial surfaces of the bicuspids. The amalgam will occupy not more than one-quarter or one-third of the approximal portion of the cavity, but sometimes in distal cavities of molars it may be good judgment to have as much as three-fourths of that portion of the fill- ing, amalgam. Xo operation requires greater attention to detail, or more neatness of execution, than where gold is used in conjunction with soft amalgam. If chips of the unset amalgam are left around the matrix, or in the folds of the rubber, or in any place where they may be caught up on the disk or finishing strip and rubbed over the surface of the gold while the filling is being finished, they will give it a coating of mercury and injure the appearance of the work. On the other hand, if the method given is followed carefully, no detail left out of account, no slovenly manipula- tion allowed to pass for neatness and tact in handling the materials, the 340 COMBINATION FILLINGS. fillings can be finished as soon as the last piece of gold is consolidated, without the least danger of mercury coating. In preparing the cavity for a filling of this kind, almost no tooth substance has to be cut away simply to get access to the cavity, to prop- erly start and pack the filling, as is often necessary if an entire gold filling is to be made. As a consequence, much valuable tooth substance is saved, for, so long as the decay is removed and frail edge walls are cut away, the amalgam can be perfectly packed, no matter how irregular the surface to which it is to be adapted. Of course, the excavation must be planned so that a filling of proper contour can be made, and walls cut back when by so doing future decay can be better guarded against. There will be many cases encountered, however, where, by this method, much of a tooth structure can be left, whereas if gold were to be used it would be necessary to cut, often causing severe pain, in order that the part might be properly filled. For the purpose of describing a simple combination filling of this kind, a cavity involving the occlusal and distal surface of an upper sec- ond bicuspid is selected as an example. In the first place, sufficient space must be secured for a filling of the right contour, and to allow for passing in a very thin strip for finishing the filling. It is best to secure this room by previous wedging. Space having been secured, the cavity is prepared with proper undercuts, and the walls of the approxi- mal part, to be filled with gold, made at as nearly a right angle to the matrix as possible. This is in order to facilitate packing the gold, it being very difficult to obtain a satisfactory margin if the walls form a very acute angle with the matrix. A matrix so adjusted that it will stand the pressure of putting in the filling without moving is an absolute necessity for this combination. It having been put on as described under the head of " Cement and Amalgam " fillings (page 333), enough amalgam is carefully packed at the cervical wall to fill one-fourth or one-third of that portion of the cavity. It should be thoroughly consolidated by using properly shaped instruments and sufficient force to drive it into every part of the cav- ity. It is a good plan to use small pellets of bibulous paper, forcing them against the amalgam with medium-sized instruments. The free mercury which rises to the surface should be carefully removed. It is well to put in considerably more amalgam than is to be left, cutting out the surplus, which method leaves a good surface upon which to begin with the gold. Before the gold is added, however, care should be taken to remove every chip of soft amalgam from the folds of the dam, or any that may be clinging to the matrix, or in any position where it might be brought in contact with the gold when finishing the filling. These chips will remain for a long time soft enough to coat AMALGAM AND GOLD. 341 the gold with mercury if rubbed against it, FlG - 33 -- therefore they roust be disposed of or an unsatisfactory filling will be the result. The proper amount of amalgam having been packed in the cavity, medium-sized pieces of some of the plastic golds before referred to are immediately added. The instruments used first on the gold should be as large as the cavity will accommodate, as they will break it up less and more readily carry the piece where it is wanted. I have found smooth slightly oval-faced instruments very efficient for start- ing the gold onto the amalgam, after which each piece of gold should be thoroughly condensed with smaller instruments As soon as the gold touches the amalgam it will absorb mercury, and sometimes several pieces of the gold will be entirely amalgamated. The surface of the filling will be- come very granular, and " chop up "to a certain degree as the first pieces of gold are used, and the instrument will cause a peculiar squeaky sound as it is pressed against the filling. The condensation must be very thorough at this point of the work, or the filling will be porous and the union between the amalgam and gold unsatisfactory. If the work is thoroughly done, however, the filling will be just as strong at this point as any other. As piece after piece of the plastic gold is added, the mercury will soon cease to penetrate it, and the surface become entirely gold. As soon as this stage is reached, and no more mercury is visible, any kind of cohe- sive gold can be used for the remaining portion of the filling. Fig. 332 presents some instruments that have been found especially useful in this work. The gold may be packed with hand or mallet pressure, or both. After the gold is all packed the matrix is removed, and the filling finished with sandpaper disks, strips, burs, and stones, in the ordinary manner. For finishing the amalgam portion of the filling only fine disks or strips should be used. The amalgam being yet in a granular condition, and not thoroughly hard, will be dragged from the edges somewhat and made slightly imperfect if a coarse grade of sand or emery paper be used. The gold will not break away from a filling made in this manner, even if there be no undercut in the tooth for holding it ; the union with the amalgam will be quite suf- ficient to retain it. The cavity must have the proper shape, Gold-pack- ing instru- ments. 342 COMBINATION FILLINGS. however, for holding in the filling as a whole, the same as if it were entirely of gold or amalgam. Cases may occur where it does not matter whether the amalgam and gold are firmly united or not ; then, instead of putting the plastic gold into the amalgam, soft foil may be used against it in the manner described for the combination of ''soft" and "cohesive" golds (page 345). Having become familiar with the simplest form of fillings of amalgam and gold, it will be well now to go a step farther, and take up some of the complications that constantly occur. Even the small amount of amalgam that is used will sometimes discolor a tooth slightly, especially if the buccal wall is thin or if the tooth is not of very dense structure. When there is danger of this discoloration taking place, it can be largely prevented by placing a medium-sized pellet or fold of Fig. 333. foil, known as "gilded platinum," against the buccal wall of the cavity before putting in the amalgam. This foil being faced with platinum, which has but very slight affinity for mercury, the amalgam can be consolidated against it with little danger of discoloration following. On the mesial surface of bicuspids and molars it will a, Amalgam ; b, not be enough, always, to put the gold and platinum foil gold extend- a g a j ns t the buccal wall ; more or less of the proximo- ing on the ° f > 1 buccal side buccal surface of the filling being exposed to view — i. e. guSmarg^ 6 not hidden b y the tooth anterior to it— it would look badly if made of amalgam ; consequently, in these cases the gold must be carried to the cervical wall, as shown in Fig. 333, the amalgam occupying a triangular space. Cement, Amalgam, and Gold. There are many teeth with very large cavities and frail walls, that can be rendered serviceable for years and made to look surprisingly well by the use of this triple combination. For instance, a molar or bicuspid having lost its pulp and a large portion of its crown, and occupying a conspicuous position, presents to the conscientious dentist a serious problem. He knows that if filled with amalgam it will be an eyesore to every one by its unsightliness. If filled with gold it would take hours, and exhaust both patient and operator, and there would be every probability of the walls soon breaking away and the filling com- ing out, testifying to the poor judgment of the operator in recommend- ing such a filling under such circumstances. If filled with cement it will have to be refilled often, and with each refilling would more than likely be somewhat weakened. The loss of contour by the wasting away of the cement will allow the tooth to change position, and its usefulness GUTTA-PERCHA AND CEMENT. 343 will gradually be lost, and the tooth sacrificed because the dentist did not bring the requisite amount of knowledge and skill to his aid to meet the opportunity offered. It is in saving such teeth as these that the reputation of the dental profession for skill and usefulness is in- creased, and honor and gratitude are accorded to the men who can accomplish it. The method of procedure will vary according to the size, shape, and position of the cavity. If small, a little amalgam can be put into the soft cement before putting on the matrix, as described for " Cement and Amalgam " A, the surplus cement removed from the entire edge of the cavity, the matrix adjusted, more amalgam put in, and gold added, as described for "Amalgam and Gold." In larger cavities, involving more of the crown, after having filled the approximal portion of the cavity with the cement, amalgam, and gold, cement should be put in a second time, into which plastic gold is carried, and the filling completed by building gold on to that which was added to the amalgam, and joining it to that which was put into the second mix of cement. In still larger cavities, the matrix can be put on first, amalgam packed against it to form the outer shell of the approximal side, as described for " Cement and Amalgam " B ; cement is then put into the body of the tooth, and into this gold is pressed (not amalgam) and afterward added to until it joins the amalgam, thus completing the metallic shell. From the specimen shown in Fig. 334 the matrix has been removed to better show the partially completed filling. It will be seen that the cement plays a very important part in this operation. It will preserve the color of the tooth though it may have been necessary to use a little of the gilded platinum, or to have the gold extend to the cervical border of the buccal corner of the cavity to support and bind firmly together the tooth and filling, yet it is pro- tected from external influences which would destroy it. Fig. 335 shows section of a filling of cement, amalgam, and gold. Fig. 334. Fig. 335. a, Amalgam and gold to form approximal shell of filling; b, cement and gold to which is to he added gold to complete the filling. a, Cement ; b, amal- gam; c, gold. Gutta-Percha and Cement. This combination is extensively used for what may be termed tem- porary work, in the teeth of young patients, in teeth of poor quality, and in badly decayed and frail teeth. 344 COMBINATION FILLINGS. It is generally believed that zinc phosphate will not last as well at, or just under, the gum margin in approximal cavities as will gutta- pereha ; although exceptions might be taken to such a general rule. It is the common custom to combine these materials, placing the gutta- percha at cervical margins, using the cement for the occlusal and con- tour portions of the filling. There is no doubt that fillings of these materials last much better when inserted with considerable pressure, thereby condensing well and making them solid. In accomplishing this, the matrix is of great assistance. It not only allows force to be used on the material while in a plastic state, but prevents its being crowded out of the cavity and up into the gum, and leaves the filling in such condition that but little shaping and finishing are necessary. Any suitable matrix — the one previously described in this chapter is recommended — having been adjusted, gutta-percha sufficient to fill the cavity a little below the gum margin is carefully packed into place with warm instruments. Sufficient heat must be used to make it thoroughly plastic, but great care must be taken not to burn or overheat the material. If the gutta-percha is overheated its physical properties and durability are very much impaired. All cavities where gutta-percha is used should be varnished with a thin coating of white resin or Canada balsam dissolved in chloroform. This will prevent the dragging away of the gutta-percha from the walls of the cavity in finishing, and will make the filling water-tight. Sufficient gutta-percha having been put in, the rest of the cavity is filled with cement. The matrix being in place and properly shaped, the operation is reduced, practically, to that of filling an occlusal cavity. It is of great importance that the cavities be kept dry, consequently the rubber dam should be used wherever it is possible to do so. The cement should be kept dry for at least fifteen minutes after it is put in, and then covered with varnish or vaselin to prevent the disagreeable taste due to its acid reaction, also to keep the filling for a still longer time from the saliva after the dam is removed. Recently there have been put on the market certain zinc phosphate cements that are in the nature of hydraulic cements. Fillings made of these should be allowed to get wet as soon as they are in position. Cement will wear better if smooth and well polished. A fine glossy surface can be obtained with an oiled burnisher when the cement is at just the right degree of hardness, i.e. when but slightly plastic. An excellent lubricant for instruments used to manipulate gutta- percha or cement is cocoa butter. A small porcelain druggist's jar into which it has been melted is convenient to have on the operating table. GUTTA-PERCHA AND GOLD—VARIOUS KINDS OF GOLD. 345 If a little of some of the essential oils, cinnamon or cassia, is added to the melted cocoa butter it will be much more agreeable and keep much better. Plastic fillings will rarely stick to instruments that have been rubbed on cocoa butter. If a shaving of it is placed on a completed cement filling it will instantly melt and flow r over the entire surface, preventing the disagreeable taste when the dam is removed, and will keep it from contact with the saliva for some time. Gutta-percha and Gold. For many years it has been the habit of some good operators to fill the interior of large cavities with gutta-percha, covering it with gold. Although this may not be objectionable practice in some cases, it cer- tainly cannot be recommended for general use. The principal objection to it is the danger of frail walls being fractured by the subsequent expansion of the gutta-percha. So many instances have been noticed where fracture has followed this combination that the fact seems well demonstrated that this danger exists. Again, there is no need of com- bining these two materials when zinc phosphate, which is so much better than gutta-percha for this purpose, is available and does not pos- sess the dangerous quality of expansion attributed to gutta-percha. Gutta-percha and Amalgam. What has been said in regard to gutta-percha and gold will apply equally well to gutta-percha and amalgam. Rarely, if ever, can this combination be used to so good advantage as can zinc phosphate and amalgam. Various Kinds of Gold in Combination. (A) The So-called Plastic or Crystal Mat Gold, with Other Forms of Gold. — Within a few years, preparations of gold other than that known as foil, or foil made into cylinders, ropes, and so forth, have been introduced and have become of great value in the filling of teeth. These golds are commonly known as " plastic gold." The term is, however, misapplied. The granular quality of these gold preparations, i. e. lack of fiber, is what gives them their peculiar and, for certain purposes, very valuable working qualities. To understand this charac- teristic, take a piece of White's " crystal mat gold" and place it upon a piece of blotting paper, then press the point of a medium-sized gold packer upon the centre. It will be observed that when the pressure is applied the gold is not inclined to curl up, but rests in its flat posi- tion, and the instrument has cut a. clean track in the gold, condensing only that which is directly under the point. The gold being without 346 COMBINATION FILLINGS. " fiber," so to speak, the particles not directly under the point are not drawn down as the pressure is applied. This is why this class of gold is so useful for starting fillings. Now take a cylinder made of gold foil, place it on blotting paper as before, and with the same instrument press on the centre of it. It will be noticed that the instrument does not make a clean cut through the cylinder, as was the case with the piece of mat gold, and, instead of remaining flat on the blotting paper, it is inclined to curl up. The fibrous quality of the foil is an advantage when a corner is to be built on to a tooth, or in any place where toughness of the material assists in its manipulation. By using these golds for starting cavities, the peculiar qualities just referred to will be exhibited. For illustration, we will take an extreme case — that of a shallow circular cavity in the buccal surface of a lower molar. This cavity is entirely without angles or undercuts, its walls flaring outward, the bottom being flat, or as nearly so as it can be made with a large bur (see Fig. 336). A piece of plastic gold a little larger than the cavity is placed in position, then with Fig. 336. Fig. 33/ Royce plugging instruments. a flat, very slightly serrated instrument (a, Fig. 332), it is carefully and gently worked into place and partially condensed, then a smaller instru- ment is used to condense around the edge. As only the portion of gold under the point is disturbed, this can be done quite readily without dis- lodging the whole piece. Soon sufficient force can be used to thoroughly condense the whole. Care must be used in selecting a first piece that it be not too large, but large enough, so that it will not chop up as it is being manipulated. After getting the first piece in place, the filling can be finished with the same or any other preparation of gold. If of the same, it is well to use oval points (Fig. 337) and work the gold toward the sides of the cavity with a sort of rotary motion, keeping the edges of the filling higher than the centre. This gold is very soft and takes a very sharp impression of the sur- VARIOUS KINDS OF GOLD IN COMBINATION. 347 face on which it is packed, as shown by the cross lines on the filling, a, Fig. 336, which are reproduced from those made in the cavity shown at b in Fig. 336. The lines across the bottom of the cavity were made with the sharp point of a hatchet excavator. This form of gold can be used to advantage, sometimes, at the cefvi- cal wall of compound cavities, provided a matrix has been tightly ad- justed. For starting fillings in approximal cavities in the front teeth it is sometimes invaluable, and it can be used in conjunction with any other form of gold, or interchangeably. If at any point in a filling the oper- ator sees a place where he thinks he can put a piece of plastic gold better than any other, there is no reason why he should not use it. Sometimes it is particularly useful to thrust into soft foil to make a sur- face upon which to build cohesive foil. It can be packed with either hand or mallet force, and with smooth or serrated instruments. (B) Non-cohesive and Cohesive Gold. — Strictly speaking, non- cohesive gold cannot be made cohesive by annealing, and can be used only on what is known as the " wedge " principle. " Soft gold," as the term is generally understood, is non-cohesive when used without anneal- ing, but when annealed it becomes cohesive. Softness and toughness are the qualities necessary to make tight joints between fillings and cavity walls, and good preparations of non-cohesive and soft golds have these qualities. Consequently, a method that will admit the use of these golds against cavity walls with a sufficient amount of cohesive gold added to insure strength and hardness, when strength and hardness are necessary, is desirable. An exaggerated illustration of stopping a cavity watertight with soft or cohesive gold is that of stopping a bottle tightly by using a velvet cork or a piece of hickory. It can be done with the hickory, but the time required to do. it perfectly, as compared with doing it with the velvet cork, is not unlike the difference between making a filling of soft and one of cohesive gold. Simple cavities, whether in occlusal or approximal surfaces, can often be half or two-thirds filled with soft gold in a very few minutes, and the rest of the cavity filled with cohesive gold. .A filling made in this manner is as good as, or even better than, one made entirely of cohesive foil, and the time required to do it is much less, as the soft gold can, on account of its softness, be used much faster than can the cohesive. In cavities of easy access the soft gold can be so manipulated as to be against the walls of the cavity at every point. Small cylinders, or any other form of soft gold, can be set around the edges, and the central portion of the cavity filled with cohesive gold. Care must be taken to carry the cohesive gold into the soft with instruments not too large, so that a mechanical union between the two golds is effected, as but little 348 COMBINATION FILLINGS. cohesion can be had between soft and cohesive gold. In large cavities, after the first pieces of soft gold have been put in place and cohesive gold worked in, the two kinds of gold can be used interchangeably. A piece of soft gold can be placed against a portion of the wall of the cav- ity, followed by a piece of cohesive, which is first attached to the cohe- sive portion of the tilling and then used to force the piece of soft gold to its place. Dexterity and tact in using these two golds together can only be obtained by experience, and carefully noting the characteristics exhibited under manipulation. In compound cavities soft gold plays a most important part. Fill- ings in these cavities fail, usually, at the cervical wall, and too much care cannot be taken in making them at this place as nearly perfect as possible. For this purpose it is now generally conceded that soft gold is much better than cohesive. A suitable matrix will greatly facilitate the operation and assist in obtaining the proper contour. The thorough packing of the gold will also be much simplified if the cavity is so prepared that the walls form no acute angles with the matrix, therefore attention to this point is important. A matrix having been properly adjusted — the one described under " Amalgam and Gold " fillings is recommended — one-half or two-thirds of the approximal portion of the cavity is filled with soft gold. For this purpose soft cylinders, ropes, pellets, or mats can be used. Great care must be taken in condensing the gold that it does not tilt under the instrument. The pressure should force the matrix away from the tooth enough to allow the gold to be condensed just a little over the edge of the cavity, so that when the burnisher is applied there will be sufficient gold to make a flush filling. When all the soft gold has been put in that the. case will allow, the cohesive gold should first be added in very small pieces in order to facilitate the driving of it into the soft gold, so as to make a strong union between the two. For this purpose very small cohesive cylin- ders or No. 3 or No. 4 foil will generally be used, but sometimes No. 30 or No. 60 foil or some of the plastic or crystal gold can be used. The filling can be finished with any cohesive gold, that kind being selected which the operator has found by experience he can best manipu- late under the existing conditions. He will also remember, as the work goes on, that a piece of soft gold laid against an exposed wall, and backed up with cohesive, as before described, will do much toward securing a good filling. (C) Soft, or Cohesive Gold, and Heavy Gold. — Fillings of soft or cohesive gold, or a combination of the two, should sometimes be finished with heavy gold. Nos. 30, 40, 60, and sometimes No. 120, GOLD AND TIN— TIN-GOLD. 349 can be used to advantage. These heavy golds — which are usually rolled, not beaten — make a very dense filling, and, when great strength and hardness are required, they are preferable to lighter grades. When a filling that is to be finished with heavy gold has been brought to the point where the thick gold is to be added, the surface should be as nearly level as possible, as it is difficult to adapt the heavy gold to indentations and irregularities. The instruments used should have the very finest serrations, if any at all. The gold can be put on by hand or mallet pressure, or by burnishing with oval points having very slight serrations, or with an ordinary burnisher. When done in this way'the burnisher is apt to become gold plated, and the instrument will stick to and drag away the gold. When this happens the gold plating may be removed from the steel by rubbing on a piece of ink eraser, on flour-of-emery paper. The most efficient way to keep gold from adhering to burnishers or instruments used for making burnished fillings is to hold them in an alcohol or gas flame until they are blued, repeating this as often as necessary. In using heavy gold great care is necessary that no portion of the piece added be left uncondensed. Hard pressure must be applied to every part of the gold, or it will flake off and destroy the good appear- ance, if not the utility, of the filling. Gold and Tin. Compound cavities are sometimes partially filled with tin and then finished with gold. At the present time it is a disputed question whether tin, if used as above suggested, will not be dissolved out, after a time, by the action upon it of the fluids of the mouth, leaving a cavity. It can be used exactly as described for soft and cohesive golds, sub- stituting the tin for the soft gold, or for a portion of it — for, as a rule, much less tin would be used than soft gold. When tin is used it can be made much more dense if it is packed with instruments as hot as can be used without causing the patient pain. If desired enough tin can be used to cover the cervical wall, followed by sufficient soft gold to complete one-half or two-thirds of the filling, the final finish being of cohesive gold. The matrix will be found of the same service as in the case of soft and cohesive gold. Tin-Gold. The term " tin-gold " has been applied to the combination of tin and gold when a sheet of tin and a sheet of gold have been laid one upon the other, and rolled, folded, or crimped together, being then used in 350 VOMBINA TION FILLINGS. the same manner as non-cohesive foil, depending on the " wedge " prin- ciple for holding in the filling. Various authorities recommend differ- ent proportions of the tin and gold to be used in this manner. All the way from one-quarter of tin to three-quarters of gold, i. e. the propor- tion of one-quarter of a sheet of tin and three-quarters of a sheet of gold to be folded or crimped together, to three-quarters of tin and one- quarter of gold. A convenient way of preparing " tin-gold " for use Fig. 338. Foil crimpers. Fig. 339. Crimped tin -gold. in medium-sized cavities is to take one-third of a sheet of No. 4 tin foil, upon which one-third of a sheet of No. 4 non-cohesive foil is laid. It is then placed upon crimpers (Fig. 338) and drawn into an evenly folded mass (Fig. 339). This is to be cut into lengths suitable to be used for the cavity in hand. These pieces can be doubled to make blocks, or rolled around a broach into cylinders, if desired. For larger cavities one-half, two-thirds, or even a whole sheet each of the tin and gold foils can be used. For very small cavities, one- quarter sheet of each may be sufficient. If it be a fact, as often claimed, that tin has peculiar preservative qualities as a filling material, it will be best to so crimp or fold the " tin-gold " that the tin will be on the outside, in order that it may be placed against the cavity walls. To obtain good results with this combination, it must be used with the same care and accuracy that are required for working gold. It is very tough and soft, and can be worked w T ith great rapidity by an expert. For method of using see chapter on Non-cohesive Gold, and work " tin-gold " as there described for non-cohesive gold. After a filling of " tin-gold " has been in for some time it will often be found to have changed in character, and instead of being a mass of malleable metal, as it was when put in, to have become hard and brittle, AMALGAMS OF DIFFERENT QUALITY— CEMENT AND ALLOY. 351 closely resembling amalgam, but, unlike it, will not stain or discolor the teeth. "Tin-gold" is recommended for use in the temporary teeth, in occlusal and buccal cavities of molars, especially in teeth of poor qual- ity, and in the mouths of young patients. Small approximal cavities in all the teeth may be filled with it to good advantage, when located w T here its dark color will not be objectionable. "Tin-gold" and Gold. — "Tin-gold" can be used in connection with gold in the same manner as has been described for the use of tin and gold, or soft and cohesive golds. Amalgams of Different Quality in Combination. For certain amalgams is claimed a greater preservative character than is possessed by others. But on account of very dark color or little edge strength l they may be undesirable for the surface of fillings, especially when contour is necessary, or when prominently exposed to view. In simple cavities it is very easy to fill nearly full with the amalgam deemed best for its preservative qualities, and to finish with that having superior color or edge strength as the case may require. For compound cavities fill about two-thirds with the first-mentioned amalgam, cutting away the surfaces and exposing the entire outer rim of the cavity, as shown in Fig. 329. The matrix is then adjusted and the remaining portion of the cavity filled with amalgam having the requisite edge strength for contour work. Cement and Alloy. Mixing alloys (such as used for amalgam) with cement has been recommended to a certain extent. This can be done by adding from 25 to 50 per cent, of the alloy filings to the cement powder and then mixing with the liquid, or the alloy may be worked into a thin mix of cement. The object of the alloy is to protect the cement, in a measure, from the fluids of the mouth, thereby making the filling more lasting. Another combination of cement and alloy which has proved of con- siderable worth, especially where it is impossible to secure proper re- tention for an ordinary amalgam filling, the combination having a very strong adhesive quality, is thus described by a well-known writer : " Ordinary alloy should be used, and not the recently introduced quick-setting varieties. On the mixing slab should be placed a quantity of zinc oxid powder and a sufficient quantity of the liquid. Now mix the alloy in the usual way, but do not express the mercury, unless in 1 See Chapter XIII. ; also writings of Dr. J. Foster Flagg. 352 COMBINATION FILLINGS. considerable excess, as a very dry mix is difficult to incorporate with the cement. Mix the cement as usual for use as a filling, and immedi- ately mix in about an equal quantity of amalgam, using a stiff steel spatula. The white metal or bronze spatula should not be used, as it is acted upon by the mercury. Now you have a stiff plastic mass, which may be rolled between, the thumb and finger into a convenient pellet and placed entire in the cavity, pressing carefully to place with smooth burnishers. A perfect contour may be built up without the aid of a matrix. " The mixture is extremely adhesive to the dry cavity walls, and no definite retaining shape is needed. Some of the amalgam may be saved unmixed with the cement, and can now be burnished over the surface of the combination filling, to which it adheres almost greedily, and thus a pure metallic surface, like a veneer, is given it which is as durable as an amalgam filling. Or a quick-setting amalgam may be employed for the veneering. " In color this combination is like amalgam, but is more granular in appearance, and in its working properties resembles stiff cement. When hard it takes on a metallic luster under the burnisher ; if sawed through it shows a metallic surface. It is less soluble in the oral fluids than oxyphosphate cement, but less durable than amalgam alone, except when veneered with amalgam as described. " Its advantages over amalgam are, first, its adhesiveness, which property makes it applicable to cavities in which, for any reason, a re- tentive form cannot be obtained ; secondly, the rapidity with which a large cavity can be filled, a valuable item where dryness cannot be long maintained, and making it unnecessary to employ the, rubber dam in many cases ; thirdly, the ease with which large contours may be made without using a matrix. " Its advantages over cement are its greater hardness and durability, but it is less agreeable in color, hence should be employed only in the posterior teeth. " CHAPTEE XV. RESTORATION OF TEETH BY CEMENTED INLAYS. By Joseph Head, D. D. S., M. D. Strictly speaking, the term inlay may be applied to any substance placed in a tooth cavity, but custom has restricted this term to fillings inserted as one piece. In primitive times teeth were filled by driving a solid piece of lead into the cavity ; gum mastic was also used in the same way ; and the green stone inlays in the central incisors of a human skull discovered at Copan, Honduras, probably antedate all historical record. Before describing the construction of inlays it may be well to con- sider their advantages and disadvantages ; for if they have no superi- ority over other fillings to counterbalance their inherent defects, inlays are without excuse for existence. Let us, therefore, first consider the main characteristics of the per- fect filling ; and then by a comparative table of various filling materials the good and the bad points of each may be justly examined. The characteristics of an ideal filling may be stated as follows : 1. Resistance to wear of mastication. 2. Resistance to action of oral fluids. 3. Harmony of color. 4. Exclusion of bacteria, and preclusion from growth of those that enter the margin. 5. Non-conductivity of heat. 6. Manipulation easy to patient. 7. Manipulation easy to operator. 8. Manipulation not destructive of healthy tooth structure. By a study of the table on page 370 cohesive gold will be seen to pos- sess over all other materials the sole, though important, superiority of greatest edge strength and resistance to the crushing force of mastication. True, it excludes bacteria from the cavity ; but experience proves that if the edges of a cohesive gold filling begin to leak and admit micro- organisms, the gold seems to be almost entirely lacking in the antiseptic power possessed by tin, amalgam, gutta-percha, and the cements. And 23 353 354 RESTORATION OF TEETH BY CEMENTED INLAYS. M 3 CO p O i— i W «! O CO O M H CO M P5 W H b o o g o GO w h^ w <) H Chips at edges ; crush- ing resistance excellent. P CD O X 08 a "3 • O_o3 IS M GO CD Is Is 03 3--° 03 CD P . Ph O CD <*H O 02 03 c ^, a'g CD*j M O CD .P -P eg 1.1 5" M Kl CD C73 03 p03o3 ^03 ■si 1 « 1 t» m « •£ CD CD eg co • # S2 CO CD -6 og 6 CD P P (H 03 si O o Ph cd" a "5 o S cuo 03 3 S o5 cd t; £ o gtJ) O P P O CD 03 CO 03 "eg P (H O CD—i ■81 P03 CD »3 tp W o 4 * 03 CD CD CD P P P -i , 3 .2 CD O eg ^2 CD nd P .p o Fh be 03 CD p P O P O 2 CD CD CD P 03^ p +s CD ^•O p CD cP > P^3 o3'o2 Ph "3 'E CD ol a "3 p "03 CD -P eg (H 03 03 CD CD CD P 03 HH> g CD *0 p iz; >> eg CO CO CD O ,_ .Pol p ^ CD .- t» O CD 03 03 CD CD t-i s 8 CD . P,| "£ 03 03^ Ph X W 03 ' '-" 03* °"3 IS 03 .* 03 03 P P. P H M© Ph ia o "P,P g @ 1 OS eg co w co" CD Q.CD bc-rt bb l >> Si bo 'ui P P 03^ cacg CD^2 o3 CD ^3 45 O CO P 03 ^5 (H O CD P o3 ft O Sfl 03-^ >> 03 o3 p _o '03 CD o3 O i2b p 03 is So 73 CD c p p eg CO CO CD C CD P P P a!. co A 73 03 So* O CD CD 03 •1 73 O Si Sh O O >> "3> p "CD "cf CD O CD >> u 'S P O CD o3 *03 CD ^3 CD p ,p p P O CD -P s p CD CD >> 3g ftCD CD CD CD P P >> t- og CD CD CD 8>8 Jo to « . o 2 P 03 O [3 O CD o "cd *3 O So «5 be 03 Qi P p" "co CD J3 ■P og 3 og 73 CD u eg 03 CD CD O CD ^ O ^ P 3 eg a "3 Ph 3, ^-OCD ^ « *5 P fc g I-9 CD* +3 05 ^ bc'> 03 "+3 ."tn CD ■s? ■go p1° ^2 sa S-o += p 03 P O CD >> c 03 5 03 S 03 ftCD CD CD CD CJ P © 1 a CD o3 P $££ O 03 CD w si O CD 3 FH CD > 03,-h CDS.-, 03 Or o3 ^a °rrH sal ^^ bo CD O P _o '03 CD 73 og O Og 03 CD O CD 6 ■A 03 "3 s ■ 6 03 ^2 ^j fH O > 6 CD P 3 P 1— l 03 03 a O f-l o3 CD «4H o p o o 03 CD P SH O "o CD p«.S bO'tH o3 03 CD d pj_2 CD CD Ph "ol CD ^3 !M O >> _0J 08 ft O eg eg 1 O O 03 03 CD © P O . "SiS CDS P 03 ■0 i*s P P 03 P CJ hi "P §3 03, fH co «t-i og CD O 03 O CO fe o O CD e S" P P < fe CD O P eg . .So CD O .<5p O s ~' ^^ p -p p p O O e O 1? H P s s >> P o a i i 1 . > CD -2 P ft p ft -JOT II^S X\%( in a>*» 03 w f O^H o3 eg Am Tt-aqjo ; )AI UOT I'BXndTU BK *8 INLAYS COMPARED WITH OTHER FILLINGS. 355 while it resists perfectly the action of the oral fluids, it so utterly lacks the other ideal attributes, as already enumerated, that with front teeth, soft teeth, and teeth of nervous patients its manifest disadvantages more than counterbalance its advantages. Soft gold is open to the same objections, but it has the advantages of resistance to wear, resistance to oral fluids, and, to a less degree, exclusion of bacteria. Tin has to a marked degree the good and bad attributes of soft gold, but it turns black. Amalgam bulges under mastication, chips on the edges, rusts, and leaks ; but it often prevents decay, by filling the dentinal tubules with its oxide. When rusty it is a moderately poor conductor of heat. It is easy of adaptation both for operator and patient, and calls for a manner of manipulation that is conservative of healthy tooth structure. It is therefore often available where gold is not. Oxyphosphate of zinc has all the advantages lacking in cohesive gold with the exception of color, and lacks all the advantages that cohesive gold possesses. Its edge strength is solely due to its great adhesion. It wears under mastication, dissolves in the fluids of the mouth, and usually absorbs bacteria ; but, on the other hand, it prevents the growth of germs, is a non-conductor of heat, has better color than gold, is easy of insertion for patient and operator, preserves weak walls, and does not require undercuts. The same may be said of oxychlorid of zinc, except that it causes pain to sensitive dentin and exposed gums. Gutta-percha, in a similar way, with the exception of color, possesses the good points lacking in cohesive gold, and lacks the good points pos- sessed by cohesive gold. It loses shape and wears under mastication, has feeble resistance to fluids of the mouth, has poor color, and leaks micro-organisms ; but, on the other hand, it inhibits from further growth the germs that enter, is a non-conductor of heat, is easy of insertion for both patient and dentist, and has a manipulation that tends to conserve frail though healthy walls. When we come to inlays we have a filling in which the good points of the cement are combined with those of amalgam, gold, or porcelain in such a way as to insure the advantages of both in the largest degree, and to reduce to a minimum the disadvantages of each. When a cavity is lined with a thin zinc cement squeezed out by the insertion of soft amalgam, this amalgam afterward having as much as possible of its mercury removed and the edges of the metal burnished to the cavity margins, an inlay of amalgam is to all intents and purposes made. This treatment takes away from the amalgam three of its objec- tionable features, conductivity of heat, lack of adhesion to the cavity, 356 RESTORATION OF TEETH BY CEMENTED INLAYS. and discoloration of adjacent tooth structure, while the adaptation of the plastic metal to the tooth margins can be quite as perfect as though no cement were used. So in using the principle of the inlay with amalgam three distinct advantages are gained without any counteracting disadvantages, all of which would seem to indicate that whenever possi- ble zinc cement should be used under amalgam. When an inlay of gold is cemented into a cavity with oxyphosphate of zinc all the advantages of cohesive gold and oxyphosphate of zinc are obtained, excepting that the line of cement remaining at the margins may in time prove a source of weakness. But experience has taught us that where this line is sufficiently fine to prevent capillary attraction, thus preventing a constant wash and change of solvent saliva, the mucus held in place by capillary attraction will act as an effectual bar against harmful destruction of the cement. Except in the fine line above men- tioned, such a filling compared with the ideal filling possesses excellent resistance to mastication and to the action of oral fluids, it has power to restrain the growth of bacteria that may enter, it is a non-conductor of heat, and is easy for the patient, while the manipulation involves no greater labor or loss of tooth structure than is entailed in the use of cohesive gold. The two possible objections that can be raised against the filling are bad color and an edge protected by a soluble cement. Hence — given a firm tooth structure that can bear the mallet without danger of being crushed, a dentin not sensitive to thermal changes, and a patient not too severely prostrated by the necessary malleting — a cohesive gold filling is superior to a gold inlay, inasmuch as the cohe- sive filling may have edges that perfectly exclude bacteria, even though it has no antiseptic action. Though the inlay largely inhibits from growth the germs that enter its margins, it nevertheless does allow them to enter ; and the filling that keeps out the germs entirely must be held superior to the filling that admits germs and then inhibits or destroys them. Unfortunately, in the soft, sensitive teeth of nervous patients the manipulation of cohesive gold does not result in the exclusion of decay germs. The tooth margins are powdered or weakened in some way by the manipulation or apposition of the gold, and the entering germs cause rapid decay, the cohesive gold not having the antiseptic power of restraining them. The thermal shocks, and the overwrought condition of the patient that sometimes lasts longer than can be avoided, both tend to produce unhealthy conditions of the mouth and consequent tooth dissolution. In such a mouth the inlay is indicated, as the patient should not be made to undergo the malleting ; and since the germs of decay will probably enter under any circumstances, it is necessary to use a filling the action of which will inhibit or prevent their growth. In approximal cavities where the filling does not show, and where PORCELAIN COMPARED WITH OTHER MATERIALS. 357 great resistance to the percussive force of mastication is necessary, the gold inlay is usually to be preferred. Its sole objection is the fine line of cement that connects it with the cavity walls ; but if the gold inlay be properly prepared, burnished, and finished as hereafter described, this line of cement may be rendered so microscopic as to become prac- tically no longer a source of danger. In other respects the gold inlay, when not visible, approaches very nearly the requirements of the ideal filling, having the advantages of perfect resistance to mastication, pre- clusion from growth of bacteria, non-conductivity of variations in tem- perature, easy manipulation, firm adherence to cavity walls, and an adaptation not usually so expensive to tooth structure as is the ordinary insertion of a gold filling. We shall now speak of the porcelain inlay, which in labial and buccal cavities fulfills more nearly than any other the characteristics of the ideal filling. Such a filling may possess color that really matches the tooth. It excludes germs of decay and precludes from growth those that enter. A porcelain inlay is a non-conductor of heat, it adheres to cavity w T alls, its manipulation is easy to the patient, and is conservative of tooth structure. The only real objection to labial porcelain fillings is the fact that great skill and patience are required in their insertion. Where, however, porcelain inlays have to withstand heavy strain in mastication, as in Figs. 363, 368, and 369, they are liable to chip on the edges. This objection, therefore, renders them somewhat less serviceable than gold inlays for non-visible approximal cavities in molars and bicuspids. For while the porcelain is sufficiently strong to withstand the crushing force of mastication, the chipping of the margin tends to accentuate the weak- ness already found in the solubility of the cement, which is its sole defence against bacteria. If such chipping occurs on the masticating surface of the molars or bicuspids, the fractured margins can be cut out with a fine in- verted cone bur, filled with creamy phosphate cement, and this cement, squeezed out with sponge gold which is finally condensed. This gives the porcelain an edge strength equal to gold. Thus with care and patience the porcelain inlay acquires the advantages of gold, cement, and porcelain, while it has none of the usual disadvantages. The Porcelain Inlay. — The work of making and manipulating por- celain inlays remains to be considered. Pieces of porcelain matching the natural tooth have, in times past, been ground to fit the cavities and then held in position with cement. This class of work, however, is hardly feasible except in labial cavities on the surfaces of the front teeth. An excellent method for obtaining good adaptation is to proceed as follows : A piece of tin-foil should be lightly burnished over the prepared cavity, as in Fig. 340, b, and the edges thoroughly outlined either with a burnisher or a plug of cotton 358 RESTORATION OF TEETH BY CEMENTED INLAYS. lightly pressed into the cavity, making the foil appear as in Fig. 340, e. The foil within the line of demarcation is then cut out and glued to the surface of a piece of porcelain that matches the tooth, as in Fig. 340, d, the porcelain is ground away up to the edges of the tin on all sides, and a moderately good fit is thus secured (Fig. 340, e). . This method, however, is superseded by recent discoveries ; but for those Fig. 340. a b c d e a, Defect at gingival margin ; b, cavity prepared ; c, mark of edge on tin foil ; d, tin foil cut out and glued to artificial tooth ; e, piece of porcelain ground and cemented into the cavity. who are interested historically Fig. 348, illustrating the steps of the operation, may prove of value. Ready-made porcelain inlays have been kept in stock for years at the dental depots. These stoppings are of different shapes and sizes, and are intended to be ground to fit the cav- ities and finally to be cemented in place (Fig. 341). Some, however, instead of being ground to fit the cavity, require the cavity to be ground Fig. 341. ©0 0© 0000 OOOOOOoa oooolCS'i Porcelain cavity stoppers. to fit them. Dr. George H. Weagant has devised a set of instruments suitable for this process (Fig. 342), consisting of five trephines, of con- secutive sizes, made of copper charged with diamond dust. These instruments are intended to cut pieces of porcelain out of an artificial tooth that matches the color of the natural tooth, and the cavity in the natural tooth is prepared with one of Dr. How's inlay burs (Fig. 343) THE PORCELAIN INLAY. 359 corresponding in size to the trephine. This method has several serious objections, one of the principal being that, in order to give the cavity Fig. 342. Fig. 343. # • © © o @ I Dr. Weagant's diamond trephines. Dr. How's inlay burs. Fig. 344. a circular shape, much sound tooth structure is usually sacrificed. Take, for example, the decayed spot shown in Fig. 344, a. This would have to be enlarged as in Fig. 344, 6, — a very serious objection. As early as 1882 Dr. Herbst advocated glass fillings. These were made by taking impressions of the cavity in wax and making two moulds in some such material as plaster or asbestos. The ground glass was then flowed into the first mould, in which most of the shrinkage occurred. The partly formed filling was then removed and placed, in the second mould, when more glass was added until the filling was complete. Even with this crude method the results were fairly satisfactory, although the margins were far from perfect and the glass was permeable to such an extent as to blacken ; nevertheless, fillings were made that preserved the teeth for years. In 1887 Dr. C. H. Land made mechanically perfect edges possible by devising the metal matrix. He used both gold and platinum, but found the latter preferable, as platinum could be adapted with a facility equal to gold, and allowed the use of a high -fusing tooth body much stronger and less likely to deteriorate than bodies capable of being fused on gold, which of necessity require so large a percentage of glass that they, like the fillings of Herbst, lacked permanence of gloss and color. From this discovery of Land dates all effective porcelain filling. Before this, pieces of porcelain had been ground to fit labial cavities, with fairly good results, and pieces of natural enamel from extracted teeth had been inserted in a similar fashion, but the accurate adaptation of porcelain to approximal cavities was impossible until the metal matrix was evolved. 360 RESTORATION OF TEETH BY CEMENTED INLAYS. At present the advocates of porcelain fillings are represented by two distinct parties : those who advocate a low-fusing porcelain that can be melted in a gold matrix, and those who advocate a porcelain of a fusing- point and resistance at least equal to Close's continuous-gum body, Fig. 345, 1 I f ! 1 1 12 3 4 5 6 Diamond points, Nos. 1 to 6 ; a, copper disk charged with diamond dust. necessitating the use of platinum for the matrix. It is claimed by the advocates of low-fusing porcelains that gold can be more perfectly adapted as a matrix than platinum. This, if true, is a very important advantage. But, on the other hand, those advocating high-fusing porcelains believe that they can get as perfect an adaptation with platinum as with gold, and that their porcelains have a better color, are stronger, more durable, and more easily manipulated, thus giving to the work a far wider range than seems possible with any low-fusing bodies yet devised, for porcelains seem to have strength and durability in direct proportion to their fusing-points. In this connection we should remember that when brilliant men of the past, through long series of experiments, were perfecting the process of continuous-gum work, they would undoubtedly have adopted the low-fusing bodies had they found any that would melt on gold and remain permanent. That they finally resorted to platinum and made durable porcelain bodies at their present fusing-points would seem to indicate that low-fusing porcelains are unable to withstand the solvent action of saliva and the force of mastication. The preparation of the cavity for either high-fusing or low-fusing porcelains is identical. The cavities should be free from undercuts. If these are unavoidable through extensive decay, the cavity should first be filled with oxyphosphate of zinc. The edges should be sharp and smooth, and where they are approximal there must be sufficient separa- tion to allow the metallic matrix to be withdrawn without distortion, as THE PORCELAIN INLAY. 361 success is impossible with a distorted matrix. The final polishing can be best accomplished with a set of diamond points (Fig. 345), or with Arkansas stone points, a variety of which can be had at any of the Fig. 346. Fig. 347. ^t1 Fig. 348. Fig. 349. Fig. 350. Fig. 351. I dental depots. The separation may be obtained with rubber, cotton, or tape. Approximal cavities between front teeth may be sometimes advantageously cut freely away from the back, as in Fig. 367, a, b, c, d. 362 RESTORATION OF TEETH BY CEMENTED TNLAYS. When the fillings are between bicuspids, the lingual walls should be cut unsparingly whenever it is necessary. Where the filling is to stand the A, Outline of labial cavity ; B, platinum foil large enough to be readily held immovable by the first and second fingers during the formation of the matrix. force of mastication the walls at the edges of the cavity should be at right angles to the grinding surface, as in Figs. 363 and 368. The prepara- Fig. 353. A, Outline of cavity in distal aspect of lateral incisor : B, platinum folded over cutting edge to insure immobility and to give outlines of tooth so that a perfect contour of porcelain may be obtained. tion of the cavity being completed, if high-fusing porcelain is to be used the matrix must be made with rolled platinum one one-thousandth THE PORCELAIN INLAY. 363 of an inch in thickness. If found desirable, thinner platinum may be used for small cavities ; but the firm burnishing required usually re- duces the foil of one one-thousandth of an inch to one three-thousandth Fig. 354. A, Cavity in anterior approximal surface of first molar. or one four-thousandth of an inch on the margins, where excessive thickness of the metal is objectionable. Foil thinner than one one- thousandth of an inch seems to lack sufficient body to stretch properly without tearing. This platinum, if annealed in a Bunsen burner or blowpipe, will be harsh and unfit for use, but when annealed in a muffle of an electric furnace it becomes soft and tough. It is most essential that the platinum should be absolutely soft. The platinum is placed over the cavity and pressed with spunk or bibulous paper as far as possible without tearing. This gives us the greatest possible amount of metal with which to form the mould. The edges will now have become distinctly outlined, and from this time the platinum should be held ab- solutely immovable or good results cannot be obtained. When the edges have become outlined, they should be gone over carefully with a ball bur- nisher, Figs. 346 and 347, and made sharp and free from wrinkles, the metal then spun down into the cavity as far as can be done without danger of tearing. Should wrinkles occur, they must be smoothed out, before they reach the edge, with the spatula shown in Fig. 349. When this has been done the metal should be boldly swaged to the bottom of the cavity with bibulous paper. This can frequently be accomplished with- 364 RESTORATION OF TEETH BY CEMENTED INLAYS. out the metal tearing, but if tears do occur, they are quite harmless, as they cannot reach the edge where the foil has already been adapted. Where the labial cavity extends under the gum, the large piece of foil extending immovably well up on the gum and swaged down on the cavity with bibulous paper will form an arch, and press and hold the gum back, so that the upper margin of the cavity will be defined in cases that at first seem absolutely hopeless of success. The soft, unbur- nished platinum takes a beautiful impression, but when the metal has been burnished or swaged it becomes elastic ; if therefore the matrix be moved during its formation, an accurate impression is impossible, for the elastic platinum when distorted cannot be forced back accurately into position Fig. 355. A, Posterior approximal cavity in second bicuspid; B, edge of platinum extending over first bicuspid to insure mobility. until it has been reannealed. When complaint is made against platinum by the advocates of gold matrices, it probably arises from the fact that they try to work the platinum in the same manner as gold. The matrix when finished should be carefully removed and heated to redness in order to destroy all organic material, as such material will tend to destroy the true shade of the porcelain. In labial cavities the piece of platinum should be cut sufficiently large to extend beyond the two adjacent teeth, and the metal should be moulded to the three teetn by pressure with cotton and bibulous paper. The metal is then held firmly upon the two adjacent teeth by the first THE PORCELAIN INLAY. 365 and second fingers, as in Fig. 352, when the general directions for adjust- ing the matrix to the cavity may be readily carried out. The large piece of platinum has two great advantages : it conduces to immobility of the metal during the formation of the matrix, and it gives the entire labial form of the tooth, so that an accurate idea may be obtained of the desired contour of the filling. In corners of centrals, as in Fig. 353, the platinum should be folded well over the labial and lingual surfaces of the tooth ; then it should A, Outline of approximal cavity ; B, flap of platinum that had been cut away and turned back to facilitate the removal of the matrix. also be bent over the cutting edge, forming a sort of cap, beneath which shows the entire contour of the tooth, and by means of which entire Fig. 357. A, Outline of cavity as formed in platinum matrix ; B, clamp holding platinum immovable while the matrix is being burnished into place. immobility may be obtained while the cavity margins are being defined and the matrix formed. The same principle applies in forming a half cap from a large piece 366 RESTORATION OF TEETH BY CEMENTED INLAYS. of platinum for the approximal cavities of bicuspids and molars. The platinum should extend, as in Figs. 354 and 355, from grinding edge to cervical margin, and along the sides of the adjacent tooth. This can be firmly held with the index and middle fingers of the left hand, while the right hand presses the metal with cotton partly into the cavity. . The margins and floor of the matrix may then be defined with a burnisher. It is most important that the greater part of the grinding surface of the tooth shall be outlined in making this mould, as by this means a truss effect is produced that will prevent the distortion of the sides of the matrix when it is either being taken off the tooth or when the porcelain is being fused. In mesial cavities the metal must be pushed away from the operator and the matrix held by means of the index and middle fingers, as in Fig. 354. In distal cavities the metal is pulled toward the operator, who works around and beyond the hand, holding the platinum as in Fig. 355. Fig. 358. Position of fingers : left lower bicuspid. When, as sometimes occurs, the adapted platinum is dovetailed around the teeth, so as to render its removal difficult or impossible with- out distortion, the outer edge of the platinum cap may be split with a sharp knife from the gum line, just beyond the cavity margins, as is THE PORCELAIN INLAY. 367 shown in Fig. 356. Fig. 357 shows a method of obtaining immobility of the matrix by a clamp that sometimes proves useful. Figs. 358 and 359 show the position of the fingers when manipulating the matrix on the lower teeth. This, of course, should be doue while the matrix is held motionless in the cavity. It is sometimes advisable, in order that perfect immobility may be obtained, first to pack the matrix full of bibulous paper or cotton. When this is done and the packing removed there will be no difficulty in teasing out an undistorted matrix from the cavity. The color of the filling must next be decided by means of a shade ring. The basal color of nine-tenths of all porcelain fillings is light yellow, and white added according to necessity will in a large number of cases be all that is required to obtain a perfect match. Whatever tint is desired, the basal color should be first ascertained, when the correct toning material may be added with comparative ease. The thoroughly mixed body, being wet with distilled water and dried with blotting-paper Fig. 359. Position of fingers ; right lower bicuspid. or muslin to the consistence of dough, is placed in the matrix on the point of the brush or spatula (Figs. 350 and 351), and settled to the bot- tom with a rub of the rough handle on the pliers that hold the platinum, more porcelain should be added until it comes to the edges, which should be kept scrupulously clean. After the filled matrix has been carefully dried by turning it face downward on a piece of soft muslin, it is placed in an electric or gas furnace, as the case may be., and baked until a gloss appears. 368 RESTORATION OF TEETH BY CEMENTED INLAYS. This baking will cause it to shrink about one-fifth of its bulk. The partially filled matrix must then be removed, allowed to cool and filled up to the edges with porcelain paste, and baked again. A third addition of porcelain may or may not be needed. After baking, the filling may be taken from the furnace almost immediately, as practically only very large pieces need to be cooled slowly, although theoretically a gradual cooling will make the porcelain tougher. The platinum should now be stripped off, care being taken to pull it away from the edge. Should it be pulled off toward the edge, chipping is likely to occur. If small portions of platinum stick to the porcelain, they can be peeled off with a sharp, tempered, pointed instrument. In large or difficult cavities a double burnish is sometimes available. It is done as follows : The first addition of porcelain to the matrix is not allowed to come to the edge. This is baked and cooled. The matrix is put again accurately into the cavity, held immovably and the edges reburnished. But with the ordinary cavity, the theoretical advantage of the second burnish is more than overcome by the danger that the matrix may not be accurately put back into the cavity before the second burnishing is begun. The filling is now ready for insertion. Undercuts may be carefully made in the cavity and grooves made in the porcelain, by using a thin copper disk (Fig. 345, a) charged with diamond dust, so as not to mar the edges. This is usually, if the proper method is employed, a safe and easy procedure with the smallest fillings. The disk and porcelain must be kept thoroughly wet during the cutting of the grooves. The inlay should be so held that the edge adjacent to the intended groove may be buried in the skin of the finger ; the groove can then be fearlessly made by the swiftly revolving disk that cuts only the hard porcelain and pushes back the yielding tissue of the finger without inflicting injury. If the porcelain is blackened by the powdered copper, the discoloration may be readily removed by a strong jet of water thrown upon it. If, however, the undercuts are not deemed feasible or sufficient, the gloss from the under side should be removed with a sandpaper disk or Avith hydrofluoric acid. The kind of hydrofluoric acid to be used is called commercially " white acid," and it can be prepared as follows : to the ordinary hydrofluoric acid, carbonate of ammonia should be added to saturation. This should be evaporated to one-half its bulk in a lead dish, refilled with hydrofluoric acid to its original bulk and once more evaporated to one-half its bulk. The liquid can then be poured into a gutta-percha bottle and kept free from air or moisture. This will make a frosted surface, while the ordinary acid will give a smoother etch. For etching the following method should be pursued : the face of THE PORCELAIN INLAY. 369 the filling should be imbedded in a piece of soft base-plate wax, leaving free the porcelain that is to enter the cavity. A drop of acid is then placed upon the porcelain and left there for about one minute, when wax and porcelain may be washed in water and the filling removed from the base plate. The under side will be frosted and the cement will adhere to it fairly well, but not so well as though efficient grooves had been obtained. The filling and the cavity should next be washed in alcohol and thoroughly dried. The rubber dam may often be put on with advan- tage just before the filling is inserted, although the thorough dryness of the tooth thus obtained will at first tend to make the filling appear too dark. The method of inserting the filling is as follows : creamy, slow-set- ting oxy phosphate of zinc, corresponding in color as nearly as possible to the tooth, should then be placed in the cavity, and the filling, picked up by means of a little cement on the spatula, be pressed home. The porcelain should be held in position for a minute or two until the oxy- phosphate has lost its elasticity ; for, however perfectly the porcelain filling may have been fitted, if it does not go accurately into place the edges will be as imperfect as though an ill-adapted matrix had been used. As before mentioned, a creamy, slow-setting cement is essential, and up to the present time the Harvard cement seems best to satisfy these requirements. When the filling is finally in position the setting of the cement may be hastened by a blast of hot air or a hot instru- ment applied to the porcelain. When the cement is wiped away and the tooth cleaned, paraffin or varnish should be flowed over the filling, in order that the cement may set for six hours before it is exposed to the action of the saliva. On the following day the edges may be ground with an Arkansas stone or polished with sandpaper. It is better for finishing that the edges should be a little too low than too high. If, however, the porcelain is too high it can be ground down and still give good results; but the original gloss is in most cases to be preferred. Having described the general operation of putting in a porcelain filling, a few cautions may not be out of place before describ- ing the special operations. Labial cavities should be made deep if good color and adhesion are desired. Overfusing is one of the great causes of poor colors, as the more the porcelain is like glass, the more the cement beneath will destroy the color. A bar of porcelain running into the tooth makes a much stronger anchorage than a platinum pin, as the platinum may stretch and it always tends to weaken the substance of the body. In large contours excessive contraction may be avoided by adding one 24 370 RESTORATION OF TEETH BY CEMENTED INLAYS. part in four of a colorless high-fusing powder to that part of the mixed enamel which is to be used for the first baking. The unfused particles extend across the matrix in every direction, making what is practically an internal investment. The slight lightening thus occasioned is entirely overcome by the second coat, and the proper contour is obtained in fewer bakings. When handling small fillings, the pliers and cavity may be advantageously kept wet up to the time of insertion, as capillary attraction will prevent the filling being dropped and lost. To place a tiny filling on the operating-case in the same relative position that it will take in the tooth prevents mistakes as to which side should go in first. In addition to the classification — labial, buccal, approximal, contour, etc. — porcelain fillings are to be considered in regard to their position in the mouth, viz. fillings that keep their color when cemented into place, and those that will be darkened by the consequent shadow. Unless these classifications are understood, many a well-matched porcelain inlay will end by appearing dark and unsightly in the mouth. Color varia- tions are met similar to those that are seen upon examining a piece of window-glass. The surface may be nearly colorless while the edge is dark green. The color of porcelain fillings is dependent upon the per- fection with which the light is reflected to the eye of the observer. For instance, in a perfect light, yellow porcelain is yellow, because all of the other rays that make up light are absorbed and only the yellow are reflected to the eye. If the light be gradually decreased, fewer yellow rays will be reflected, and the color will become darker; when there is no light reflected the porcelain will appear black. The more perfect the front and side lights in porcelain fillings the less will be the shadow variations in color. Take, for example, a simple labial cavity, as illus- trated in Fig. 360. If this extend into the dentin sufficiently deep to prevent the color of the oxyphosphate of zinc or of any other cement shining through it, and if it be not overbaked, the correct color of the porcelain will be given. If, however, we place this well-matched material on the approximal surface of the tooth, as in Fig. 361, with an adjacent tooth shutting off direct reflection, and thus allowing only indirect rays to meet the eye of the observer, the color will be lost in shadow, and from having been a perfect match, or nearly so, the shade will assume a dull lead color. Also, if in Fig. 360 the labial cavity should penetrate entirely through the tooth, through the lingual enamel, the inlay would present a problem of almost insurmountable difficulty ; for nearly all of the direct rays would pass through it and would be lost in the shadows of the mouth, while the side lights would be shut off by the non- transparent but necessary zinc cement. This difficulty may be over- come by placing two fillings, one on the lingual and one on the labial THE PORCELAIN INLAY. 371 surface. The oval inlay running through the entire tooth substance is mentioned only as an illustration of the greatest amount of color varia- tion to be met with; and the nearer that a porcelain inlay approximates to this condition the greater will become the tendency of the color to be lost in shadow. Take, for further example, the two fillings shown in Fig. 362. In each illustration the fillings go evenly through the labial and pal- atal walls of the enamel, and yet if both fillings are made of material that matches the tooth substance the corner inlay will look well, while the halfmoon-shaped filling will be dark. If, however, b does not go through the lingual wall and the cement extends entirely behind it, its color will be nearly, if not quite, as good as that of the corner, it having almost assumed the classification of the simple labial cavity before mentioned. The difference in the shades of these two fillings may be explained as follows : The corner (a) is illuminated by side light from the cutting edge, while the halfmoon-shaped filling (b) is shut in on four sides, on three by cement and on the fourth by the adja- cent tooth. It must be further noted with reference to the corner (a), Fig. 360. Fig. 361. ihat if it is looked at from directly in front, or from the direction of the arrow X toward the cement, the color will be good ; if, however, it is looked at away from the cement, as indicated by the arrow Y, the color will be lighter or darker according to the intensity of the light ; but the true color will not be seen. This, however, is not a serious objection, as the filling is usually seen from directly in front, and the occasional side views are equally divided between good and bad lights. We may, therefore, feel that a corner inlay which does not include more than a third of the tooth's cutting edge is an inlay favorable to the obtaining of a good match. Buccal fillings in bicuspids and molars are as easily matched as the simple labial cavities, for they come under the same conditions of light reflection ; but all approximal inlays, from the posterior surface of the canines back to the molars, show the same falling off in color, and unless allowance be made for this falling off disheartening results will be the outcome of otherwise careful work. There will be a darkening of the inlay in direct proportion as the cement shuts off the light and throws a shadow into the body of the porcelain. See Fig. 367. 372 RESTORATION OF TEETH BY CEMENTED INLAYS. Those not effected are simple labial cavities, corners of centrals and laterals, and cusps of canines and bicuspids. Those most affected are tips of centrals and of lateral incisors, and approximal and halfmoon-shaped cavities running through the lingual enamel. The broader the adjacent teeth the greater will be the shutting out of light and the consequent darkening of color. Tips of central and lateral incisors running entirely across the tooth are so subject to the shadow variations from cross light, side light, top light, and bottom light, that the restoration of more than a third is not advisable. When half of a tooth has been carefully matched and cemented into place, the tip may look very well in good daylight, but at night it may turn dark ; also in an artificial light shining from above the tooth and cement line show very dark while the porcelain seems snow-white. And now let us consider how we may partly conquer these shadow variations. Halfmoon-shaped cavities, as in Figs. 361 and 362, may be filled on the lingual wall with gold, an absolute match thus being made possible, but, generally, shadow variations can be best overcome by a judi- cious lightening of the filling. And now, having described the process of using high-fusing porcelain for inlays, the next consideration will be the modifications necessary when the low-fusing porcelain is melted in a gold matrix. The best of the low-fusing bodies are now said to keep their color and texture in the mouth indefinitely, to be strong enough for all necessary wear, and to retain their color in fusing, — which would indicate that the low-fusing materials have greatly improved during the last eight or ten years. Of these the Jenkins' body seems the best. Porcelains capable of being Fio. 363. Fig. 364. Large cavity in molar tooth involving approximal and Showing restoration of broken lateral grinding surfaces. Restored by porcelain inlay. incisor by porcelain tip. melted in a gold matrix are of two classes : those that are sufficiently low-fusing to be melted in a bare matrix, and those that melt so near the fusing-point of gold as to render necessary the investment of the gold matrix in order to prevent its being warped by the fire. In porcelains of the first class the method of procedure is very similar to that in which the high-fusing porcelains are fused in a platinum matrix. The No. 30 THE PORCELAIN INLAY. 373 gold foil is placed over the cavity margins in a manner similar to that prescribed for the use of platinum ; and then, instead of burnishing or spinning it in place, it is pressed into all parts of the cavity by means of spunk or cotton. The metal is so soft and ductile that this can be accomplished in a manner impossible with platinum ; and it is this easy manipulation of the gold that makes the sole advantage of the low-fusing over the high-fusing porcelain bodies. The gold matrix is then teased out of the cavity. This must be carefully done, since, being more easily adapted, it is also more easily distorted than the platinum. The proper mixture of porcelain is placed in matrix and the baking is performed exactly as with the high-fusing materials, the only marked difference in the working being that low-fusing bodies tend to spheroid and lose contour. This can be remedied by mixing with the paste a small quantity of similarly colored high-fusing porcelain. When such porcelains are used as require the gold matrix to be invested, the matrix must not be torn on the bottom at all, for in such event the porcelain will tend to run through into the investment instead of drawing away from the crack, as it does from a platinum matrix where no investment is used. The gold matrix must be dropped bottom side down into a paste of asbestos and alcohol, which is allowed to evaporate. Then the porcelain may be flowed into the matrix little by little, to minimize warping. The method described by Dr. J. Leon Williams 1 is as follows : " The thinner the gold can be used, the more perfect the fit of the finished inlay. A proper set of instruments for shaping the gold form and for manipulating the porcelain paste is an important matter. I have devised for these purposes the set of instruments shown in Fig. 372. They are all double-end instruments. Nos. 1, 2, 3, and 4 are designed for fitting the gold form to the»cavity, while Nos. 5 and 6 are for manipulating the porcelain paste. The gold should be cut out to represent roughly the shape of the orifice of the cavity, but consider- ably larger. Fig. 366 shows the proper shape for such a cavity as is shown in Fig. 367 at a. It will greatly facilitate the shaping of the gold form if a notch be cut out of the gold as shown in Fig. 366, and at the same time decrease the chances of breaking through the gold in forcing it into the shape of the cavity. It should first be introduced into the cavity without annealing. The cut edges will then slide over each other as the centre of the gold is forced to the bottom of the cavity. . . . Then, with the cotton or spunk tightly packed in the cavity, take instru- ment No. 2 and most carefully burnish the gold around the entire edge of the cavity. This instrument will be found well adapted to reach every part of the margin. It will generally be found best to hold the cotton-wood back a little from the margin of the cavity when one is 1 Dental Cosmos, November 1899, vol. xli. p. 1087. 374 RESTORATION OF TEETH BY CEMENTED INLAYS. burnishing, with an instrument held in the left hand, and with this instrument (preferably a ball burnished) also press the cotton-wool well Fig. 365. 1 into the cavity. This holds the gold form well in place and prevents rocking while the edges are being bur- nished. " Most operators have found the removal and imbedding of the gold to require the most delicate manipulation, and by the methods heretofore described one is never quite certain whether or not this part of the operation has been successfully performed until the inlay has been completed and tried in place. All of this uncertainty may be THE PORCELAIN INLAY. 375 avoided by the following procedure : Slightly warm and roll up in the fingers a small ball or pledget of hard white wax, such as is supplied for crown- and bridge-work. The ball of wax should be just a little larger than is necessary to fill the cavity completely; that is to say, it should slightly project over the margin of the cavity all round. The wax should be quite stiff when introduced into the gold form as it lies in the cavity of the tooth. Now take the broad, thin burnisher, shown Fig. 366. Fig. 367. Sheet of gold or plat- inum, notched and ready for adaptation to cavity. c d Right superior central, showing two large approximal cavities to which access is obtained by cutting freely from the lin- gual walls : a, tooth with cavities prepared ; b, porcelain inlays for same ; c, tooth showing lingual surface ; and d, labial surface after cementing of inlays. in No. 4, Fig. 365. and press the ball of wax firmly into place. To pre- vent the burnisher from sticking to the wax, it should first be dipped into French chalk or pulverized soapstone. In such cavities as are shown in Fig. 367, at a, broad polishing tape, dusted with French chalk, may be used for pressing the wax ball into place ; but great care should be exercised not to pull the tape the least in one direction or the other, as one would do in polishing a filling. This would rock the gold form and mar the fit. The pull should be steadily and equably from both ends of the tape, the object being to press the wax everywhere firmly over the edges of the cavity. A stream of cold water should now be thrown on the wax, and then the wax and gold form should be quickly removed. If this part of the operation is done with ordinary care, the finished inlay will always be found to fit perfectly. To facili- tate the quick removal of the form, care should be taken to prevent the wax overlapping the gold much at any point outside the margin of the cavity. To prevent this and also to assist in securing proper imbed- ding of the gold matrix it is well to let the margin of the gold project as much as possible beyond the edges of the cavity. " The matrix may now be imbedded without the slightest fear that its shape will be changed. For imbedding material I use plaster and marble-dust. When the investment is sufficiently hard the wax is thor- oughly melted out with a stream of boiling water. The investment is then dried and brought to a full red heat with the blowpipe. It is then allowed to cool, and is ready for packing. Now. the first step 376 RESTORATION OF TEETH BY CEMENTED INLAYS. in the packing of the porcelain paste is the all-important one to prevent the porcelain shrinking away from the walls of the matrix. This may always be accomplished easily with porcelain of any make if the follow- ing instructions are carefully observed : Mix the porcelain paste to the consistence of soft putty, and with the upper point shown in No. 6, Fig. 365, place a ring of this putty around the entire circumference of the cavity Fig. 368. Fig. 369. a h c Showing bicuspid with cavity involving approxi- Canine tooth showing at a, large cavity, and mal and grinding surfaces : a, tooth with at b and c, large porcelain inlay restor- cavity prepared ; b, porcelain inlay ; c, inlay ing contour of tooth, cemented in place. leaving the centre quite free or empty. In melting a porcelain paste it naturally shrinks toward the largest mass of its own body, or toward the centre of the mass. If, then, this centre be removed we should naturally expect the mass to shrink toward the circumference, and this is precisely Avhat happens when manipulated as directed. The matrix always comes out from the first baking with the porcelain everywhere firmly melted to the walls of the matrix. Nor will it start from this position at any subsequent baking unless it is very much overheated. "After each packing of the porcelain paste, a small camel's-hair brush with a fine point should be moistened (this is best done by drawing it between the lips after the manner of water-color artists) and drawn around the margin of the matrix to remove all overhanging particles of the paste. If this be not done, the margins of the inlay will often be found ragged, and a perfect margin is the most essential feature of a porcelain inlay. If gum-water be used for mixing the paste, it will be found necessary to remove these overhanging particles with great care, as the tendency naturally is for the gum-water to cause the particles of powdered porcelain to stick to the gold or platinum margin of the ma- trix. In building up the inlay for restoring lost corners of teeth and for general contours the work will be much facilitated if, after the first baking has been carried through as above described, to secure perfect union with the walls of the matrix, a small piece of solid porcelain be placed at the point representing the highest point of the contour of the inlay. These pieces of porcelain may be made by crushing old porce- lain teeth in an iron mortar. Care should be taken to use a piece small enough so that the outer edge will not show through when the inlay is THE PORCELAIN INLAY. 377 completed. Corners like the one shown in Fig. 369 may be produced in tliis manner without much difficulty." Dr. Williams's method of separating the gold matrix from the porce- lain, and grooving the inlay and cementjng it into the cavity, need not be dwelt upon, the subject having already been fully discussed. In summing up the advantages and disadvantages of the high-fusing and low-fusing bodies it will be seen that the advocates of the low-fusing materials claim the sole point that gold is more easily adapted as a matrix than platinum ; while the others claim that porcelains of high- fusing bodies are known to be permanent, to keep their color under firing, to contour without spheroidal tendency, to dispense with the use and consequent restrictions of an investment, and to furnish a process so simple and reliable that fillings may be constructed with greater certainty of good results and with more rapidity. There are three classes of furnaces that can be used for fusing por- celains — gas, gasoline and electric. The gas and gasoline furnaces are noisy, odorous, and dirty ; but seldom, if ever, get out of order. On the other hand, the electric furnace is clean, silent, and beautiful ; but it has only a limited life. Even in experienced hands its wires will burn out and need mending once or twice a year, and with the inexperienced it may easily be rendered useless in a few seconds. Nevertheless, in spite of this drawback, the electric furnace is to be preferred to the others, while the gas and gasoline furnaces are suitable only for the laboratory. The only feasible gas furnaces for high-fusing bodies are those which have a platinum muffle, in which the fusing porcelain can be thoroughly protected from the gas, for fusing porcelain cannot keep its color if subjected to the products of combustion of carbon. The two most practicable gas furnaces for high-fusing bodies are the Downie (Fig. 370) and the Midget Land. Either of these properly manipulated will fuse continuous-gum body within three minutes. They work on the blowpipe principle, and necessitate either a pressure- reservoir or labor with the foot-belows. Two gasoline furnaces are available — the Brophy and the Turner furnaces, and these are worked by gasoline blowpipes — very odorous and in careless hands dangerous. The electric furnaces are based on the principle that platinum wire submerged iu fire-clay will become red-hot when a current is passed through it. The fire-clay stores up this heat indefinitely, so that any degree of temperature below the fusing-point of platinum may be obtained. This fusing-point is said to be about 4500° F. The best furnace for high-fusing bodies that require a temperature of from 2500° to 3000° F. is the Hammond electric crown furnace. (See Fig. 371.) The gas outfit of Dr. Jenkins is neat and effective ; in fact, as a gas out- fit it is almost ideal, but can only be used for low-fusing bodies. The little 378 RESTORATION OF TEETH BY CEMENTED INLAYS. electric oven made by Ash (Fig. 373) is perfect for low-fusing bodies, and wherever a current can be secured this little furnace is to be strongly recommended. Its only drawback is that it cannot be mended, and that if a burn-out occur it must be sent to the manufacturer for a new coil of wire. It has not sufficient power to melt the high-fusing bodies quickly and well. The Gold Inlay. — As previously said, the gold inlay has practically perfect edge-strength, and therefore is sometimes to be preferred to the Fig. 370. Downie gas crown furnace. porcelain inlay in the back of the mouth, where its color is no objection and w T here its power of resisting mastication is of prime importance. The gold inlay is easy to make. The cavity should be prepared along the lines previously mentioned. Then soft gold plate, 36 gauge, should be held immovably over it and burnished, and swaged into posi- tion. Small tears at the bottom are of little consequence. When the matrix has been fitted, while it is still in the tooth, moss fibre or sponge gold should be packed quickly and firmly into it up to the edges, and to the proper contour. If this gets wet during the process, GOLD INLAY. 379 no harm results. The edges, however, should be left clean. The filled matrix should be removed and 22-k. solder flowed over all, keeping the Fig. 371. The Hammond furnace No. 1. Fig. 372. Dr. Jenkins' miniature gas furnace edges still clean. The filling should then be cut out, leaving a small margin of the gold plate at the edges. It is then placed in the tooth 380 RESTORATION OF TEETH BY CEMENTED INLAYS. cavity again, wedged immovably, and burnished on the edges a second time. If more sponge gold is needed for contour, it can be added and Fig. 373. Ash electric oven. soldered fast. The edges can finally be filled to full contour with 22-k. solder. It is polished, undercut, and set with cement in the usual manner. Fig. 374. Showing details of the process for making cast filling for incisor: a, pest with plate adapted; b, restored contour in wax ; c, the contour invested ; d, cast contour detached ; e, e, the finished restoration. Dr. C. L. Alexander's method l is described by its author as fol- lows : " My method consists in detail of burnishing platinum over the surface to be restored ; the holes for retaining posts having already been 1 Dental Cosmos, October 1896, vol. xxxviii. p. 850. GOLD INLAY. 381 made, can easily be located and the posts adjusted therein. Then by heating a little modeling compound over a spirit lamp, and pressing it firmly down over the surface and allowing it to cool, w T e can remove the platinum sheet and posts in correct relation to each other. We now invest and solder the posts with pure gold. The piece is again placed upon the tooth in the mouth, and after carefully trimming and rebur- nishing an impression is taken, and when an occlusion is needed it Fig. 375. Fig. 376. Restoration of bicuspid by cast filling. Front and back view of an incisor restoration, and cast filling for molar. is made at the same time by the patient closing the teeth together before the impression material has become hard. The metal founda- tion will be drawn out by the impression compound when it is removed from the mouth. Each side of the impression thus secured is filled with any good investing material and placed in an articulator. After heating and removing the impression material, the contour of the tooth may be restored by building up with wax. Over the wax surface thus Fig. 377. Foil matrix invested. Cast filling for molar. formed gold or platinum foil is burnished; if the former, it should be very heavy, say No. 60. A suitable portion of the wax being left uncovered, the work is cut away from the model and invested, with the exception of that part of the wax left uncovered by the metal. Through this opening the wax is boiled out, leaving a matrix lined with metal, which acts as a carrier for the fused gold ; 20- or 22-carat gold solder 382 RESTORATION OF TEETH BY CEMENTED INLAYS. should be used for this purpose. When pure gold is used, of course the matrix must be lined with platinum throughout. When removed from the investment, the easting is finished and cemented to its position in the tooth. "In bicuspids and molars it will frequently be found more con- venient to stamp up the cusps, using pure gold, 35 gauge." The pieces made as described by Dr. Alexander may be used as abutments for bridge-work. The gold inlays are, of course, to be cemented into place with great care as regards asepsis, dryness, and apposition. They have a great advantage over the porcelain inlays in that their edges can be burnished into place while the cement is soft ; and therefore when they are being given their final polish with the sandpaper disk, the disk should always be run toward the margins, so that a feather edge will be formed, which, with the burnishing men- tioned, will make an almost absolute joint possible. A Hard-Rubber Inlay. — Some dentists advocate making cemented inlays of hard rubber approximating the tooth in color. These inlays are feasible only where a perfect impression can be readily taken of the cavity, the filling being then made by the method usually followed in vulcanite work. The rubber inlay is noted only as a curious fact, and is not enlarged upon or recommended, for its color is not equal to porce- lain, nor is its edge strength equal to that of gold. As we have not only other materials that will produce better results, but also materials that can be manipulated in the time required merely for the vulcanizing of the rubber, it does not seem advisable to enlarge upon a process that appears to have no practical value. MAKING MATRICES UPON MODELS FOR PORCELAIN INLAYS. There are many who take impressions of the cavities intended for porcelain inlays, which impressions are run out in plaster or oxyphos- phate of zinc. On the models thus obtained the matrices are formed, and the porcelain fillings finished according to shades selected when the impression was taken. This has the advantage of saving much time for the operator, as the work of construction may be done by an assistant in the laboratory. As good results are claimed, the process should be given a fair trial ; but on theoretical grounds the expansion of the plaster, or the contraction of the oxyphosphate of zinc * used for the mould would tend to cause inaccuracy in adaptation of the edge. Most inlay workers find it sufficiently difficult to get perfect adaptation when the matrix is burnished to sharp enamel edges, and, except in labial cavities, to get the exact contour. Also, the colors often require 1 Wet oxyphosphate of zinc usually expands j dry oxyphosphate usually contracts. MAKING MATRICES UPON MODELS FOB PORCELAIN INLAYS. 383 such nice calculation that an assistant, not having seen the mouth, could hardly mix them satisfactorily. While good results have been obtained by giving the matrices for filling to an assistant especially trained in the art of fusing and mixing the porcelains, thus proving that such time-saving methods are practicable, the average dentist should not attempt the art of inlays with the idea of saving time; probably there will always be sufficient factors for failure if he works directly from the tooth cavity and gives his entire personal skill to the completion of the filling. With porcelain inlays the question of artistic color effect is paramount, and only through the most subtle discrimination can the best results be obtained. 1 Wet oxyphosphate of zinc usually expands; dry oxyphosphate usually contracts. CHAPTER XVI. THE CONSERVATIVE TREATMENT OF THE DENTAL PULP^ DEVITALIZATION AND EXTIRPATION OF THE PULP. By Louis Jack, D. D. S. As the dental pulp by its supply of nutritive pabulum maintains the vitality of the dentin and increases the resisting power of the tooth, it is important when this organ becomes exposed to agencies which threaten its destruction, to attempt its preservation when the condi- tions are favorable to that object. A further reason for maintaining the vitality of the dentin is that when the pulp becomes devitalized the loss of cohesive force which occurs as a consequence leads sooner or later to the fracture and ultimate loss of the tooth — this final result being delayed in proportion to the inherent strength of the tooth and the period of life at which devitalization takes place. The treatment of teeth when the pulp has been approximately reached by the invasion of dental caries has been previously consid- ered (Chapter VI.). Here will be set forth a rational line of treatment when the carious action has encroached upon that organ. Normal Characteristics and Pathological Tendencies of the Dental Pulp. The minute anatomical elements of the dental pulp are given in Chapter II. The salient features of these elements which have to be kept in view in connection with treatment are — (1) The minuteness of the apical foramina, which restricts the efferent circulation when the vascular phenomenon known as " determination" occurs. (2) The ultimate nervous distribution immediately beneath the odon- toblastic layer, forming a plexus which renders the whole surface of the organ highly sensitive when the blood supply is increased as the effect of irritation. (3) The arrangement of the capillary circulation in loops which arise from the vertical vessels. This relation of the vessels lessens the tend- ency to inflammatory diffusion. 25 385 386 CONSERVATIVE TREATMENT OF THE PULP. (4) The absence of lymphatics, which deprives the pulp of the power to remove inflammatory effusions or to convey insoluble medicaments. It should be noted that the pulp in a normal state is not a highly sensitive organ, but is rendered exquisitely so by the irritation from external chemical and infectious influences incident to its exposure. And it is under all conditions so extremely impatient of compression that a severe shock of that kind renders recuperation nearly impossible. This is probably due to the liability of disconnection of the pulp with its walls at some point on account of its feeble attachment to them. The pathological tendencies of the pulp under irritation are — (1) To hyperesthesia. (2) To circumscribed hyperemia under slight irritation. (3) To congestion or mechanical hyperemia under increased irrita- tion whicji terminates at length in stasis by the restriction of the circulation. (4) To proliferation of the deeper tissues as the result of latent con- gestion attended by fatty degeneration of cells and the development of dentinal nodules — pulp stones. An important consideration connected with the treatment of the pulp is the indication presented by a state of the teeth designated as the "temperature sense." This is a variable condition with different individuals, some being able to apply the coldest water in the mouth and to crunch ice without pain, whilst others whose teeth are sound are disturbed if cool water is brought into direct contact with these organs. When irritation of the pulp occurs the temperature sense is exaggerated in the individual tooth. This variation from the normal, as determined by a comparative test of the sound teeth, becomes an important diag- nostic indication, as will appear later. A further pertinent consideration bearing upon the various condi- tions of the exposed pulp, as shown by the symptomatology, is here in place. It has already been indicated that when the exposure of the pulp to irritation has been slight — that is, where this organ has been measur- ably protected from exterior influences by the covering layer of incom- pletely decalcified dentin — the pulp is ordinarily but slightly affected. When the denudation has become complete and the amount of pulp surface in contact with the carious matter has become considerable, and further, when by the solution and displacement of the carious matter the influence of the contents of the mouth is direct, the disturb- ances of the pulp become progressively increased. In the light of pres- ent knowledge of these injurious influences the causes of their operation must be attributed to infection of the pulp by the various minute organ- isms which have their habitat in the mouth. The pulp tissue becomes infected in the degree to which it is exposed and in proportion to its PATHOLOGICAL TENDENCIES OF THE PULP. 387 Fig. 378. power of resistance to the pathogenic character of these forms of life. It is axiomatic that the activity of inflammatory processes is usually in proportion to the degree and the kind of infection. Therefore it must be held here as elsewhere in surgical procedures that the existence of infec- tive influences and their control have to be kept clearly in view. This consideration enables us to understand the causes which render conservative treatment inoperative, in cases in which there has existed for a considerable period the opportunity for active invasion of the pulp by micro-organisms. When these deleterious influences have long con- tinued, the deeper tissues of the pulp, as before stated, become involved ; the chief factors producing the disturbed state eventuate in a suppura- tive condition. This state of the organ clearly indicates invasion by pyo- genic germs, the inflammatory processes attending this condition being superinduced by the peculiar irritation caused by the infection. This results in some instances in stasis followed by gangrene ; in other cases, where the arterial tension has not been great, in suppuration. The cha- racter of the suppurative process, rarely, is a circumscribed abscess of the pulp, the more common form being by progressive and destructive ulceration of the organ. Fig. 378 (after Arkovy) shows the phenomenon of invasion of the pulp by micrococci. 1 In the treatment of an organ which cannot be brought under ocular inspec- tion, the chief guides to determine its state are the apparent conditions — viewed in con- nection with the symptomatology of the case under treatment. The above-stated anatomical relations, physiological qualities, and pathological tendencies have an interesting bearing upon conservative treatment of the pulp. Exposure of the Pulp. — As an indication of the tolerance of the pulp to the approach of caries it is a common experience that after solution of the enamel has taken place, caries of the dentin proceeds until the pulp is nearly reached by the destructive process with little or no signs of irritation, as evinced by pain, appearing. It is the excep- tion that even persons of high nervous sensibility are cognizant of the influence of the carious process upon the pulp previous to actual encroachment. In the earlier stages of exposure the elements of the organ involved 1 In this connection see Micro-organisms of the Human Mouth, by W. D. Miller, pp. 293-295. Invasion of pulp by micrococci. 388 CONSERVATIVE TREATMENT OF THE PULP. are its peripheral nerve filaments, which are hyperesthetic from the hyperemic state of the organ immediately adjacent to the point of encroachment. At this stage the pulp becomes impatient of cold, and may indicate the nature of the lesion by reflex pain in other branches of the trigeminus. Later on, unless these conditions are subdued by treatment congestion of the organ takes place, when objective symp- toms in the organ itself may be elicited. This is shown by some sore- ness upon percussion, accompanied by much pain on the application of heat. These indications point to a greatly increased blood supply. Dila- tation of the arterial vessels of the apical region occurs, and the blood being unable to enter at the foramen is distributed to the peridental membrane. These manifestations indicate that the point of danger has approached. Soon thereafter congestion becomes so far estab- lished that prospect of successful conservative treatment vanishes. When patients are under frequent observation and have regular and periodical care taken of the teeth the pulp exposures which occur should be found in the hyperemic state, and if placed under treatment early after the carious action has approached the pulp, the prognosis should be favorable. But when neglected cases appear the history of which is obscure, and where the patient is forced to seek relief by the occur- rence of objective symptoms as narrated above, accompanied by local pain and pulsation, the indications point to devitalization and extirpa- tion as the suitable recourse. The exposure of the pulp is often discovered in the treatment of ordinary cavities in a somewhat unexpected manner, no indications appearing until the part is uncovered ; or a variety of subjective or possibly objective indications may be elicited which plainly point to this condition. At the commencement of the treatment to restore the lost tissue in any given carious tooth, except in very small cavities, the proba- bility of encroachment upon the pulp should be a supposition, and each step should be made with reference to this probability. The destruc- tion of the dentin is frequently surprisingly deep, or the cornua of the pulp may be acutely pointed and liable to be unexpectedly encountered. Therefore, in what may seem simple cases, cautious approach should be made toward the bottom of the cavity. Method op Opening the Cavity. The opening of the cavity should be effected by instruments which will not easily enter it, and the softer caries removed in a manner which will not induce pressure of the carious matter upon the pulp. For this reason, in the removal of the caries the excavation METHOD OF OPENING THE CAVITY. 389 should be first carried on at the sides of the cavity, and also along the margin of the cervical wall in approximal cases. Then the carious matter nearest the pulp should be carefully peeled off without pres- sure and without irritation. In this manner a pulp may be uncov- ered and the cavity cleansed of carious matter without contact being made with the pulp. To do this is the acme of skilful preparation. The instruments for removing caries should be of thin edge, very sharp, and always having cutting surfaces which are rounded, since angular or square-ended excavators are liable to make exposures un- necessarily. It is important that the direction of movement of the ex- cavators should be from the cervix toward the occlusal part — in other words, by drawing cuts instead of pushing ones. The difference in the excitement of pain between these two methods of cutting is surprising, and can only be appreciated by those who have experienced the com- parison upon their own teeth. The probable reason for this is that the force of the pushing cut is necessarily greater, and this may induce com- pression of the caries or of fluids against the pulp. It causes more pain at the moment, and cleansing in this manner is followed by greater after-irritation. Patients will at the time complain of reflected pain being caused by incorrect manipulation. It is obvious that every mode of procedure which increases the local irritation in the preliminary procedures of a pulp treatment must be deleterious in its results. The danger of making accidental exposures and of forcing the instruments upon the pulp are increased under push cutting. It is also clear that the use of burring instruments upon the pulp wall of cavities is questionable, since the infliction of some com- pression by excavating in this manner is nearly unavoidable. Here an interesting question appears : A cavity may be sufficiently deep to cause an exposure ; it has been carefully cleansed of caries, and the cornua are not apparent. It is then necessary to determine whether there is a real but minute exposure or whether there is a safe amount of healthy dentin to protect the pulp beneath the stopping material. One method is to cross-hatch the cavity by a very fine explorer. This is effected by holding the instrument very lightly and passing it gently over the surface in parallel lines in two directions. If the pulp has been reached, the instrument at the point of encroachment will lose its resistance or will drag the point of the cornu, as the case may be. While there may be no visual evidence of exposure, the certainty of it is frequently shown during the preparation of the cavity or the test- ing by a peculiar expression of the face of the patient, different from that manifested by the cutting of the most exquisitely sensitive dentin. This change of the countenance, accompanied by a slight start of the 390 CONSERVATIVE TREATMENT OF THE PULP. features, may oceur without the recognition of pain. This indication sometimes appears previous to the removal of all the caries ; it is then probably caused by some tension of the apex of the cornu produced by the disturbance of the carious dentin. The Diagnostic Value of the Reaction of the Pulp to Thermal Tests. Allusion has been made to the effects caused by reducing the tem- perature of the teeth. To make this subject clear it is necessary to con- sider the reaction of the dental pulp to thermal changes in its states of health and of disease. The normal rate at which the pulp of sound teeth reacts to cold applications varies with different persons from 22 to 66 degrees F. below the blood heat, the reaction to heat varying from 20 to over 55 degrees F. above the blood temperature, these tests being the extremes of the writer's observations. The degree of heat reaction may be designated by the + sign and the cold rate by the — symbol. These ascertained extremes may be taken as representing the range of tolerance in any individual case. The significance of ascertaining the normal rate of thermal irritation of the teeth is important in connection with the treatment of any case. When a healthy rate of + 144° - 32° F. is compared with one of +' 124° — 76° F. this at once is apparent. In the one case, the range of tolerance is 112 degrees; in the other, 48 degrees. Hence it is obvious that the determination of the normal rate is essential as a basis from which to consider the value of the thermal reaction of any given disturbed pulp. It is also evident that where the range of tolerance is considerable the probability of favorable treatment is greater than when this is small. Where the normal range is found to be below 50 degrees F., unless the other conditions are very favorable, conservative treatment of the pulp becomes questionable. The normal rate is easiest found by exposing the lower incisors to a continued discharge of water from a small-aperture syringe. The most suitable kind of syringe is that having a large aperture for charging and a small one for discharging. 1 The tests are begun at a temperature of 80° F., reduced succes- sively by diminutions of ten degrees until slight pain follows the tests. The continuation of the stream of cold water is necessary to enable the effect to reach the pulp through the dentin. With some per- sons the response is so quickly shown as to indicate that the dentin is responsive. 1 The best for the purpose is a modified form of the Laskey syringe. REACTION OF THE PULP TO THERMAL TESTS. 391 A large proportion of persons manifest distress between 40° and 60° F. Intolerance of heat is determined in the same manner, except that it is frequently necessary to isolate the tooth by applying rubber dam, since the gum usually begins to be pained at 130° F. In all cases in which the cementum is exposed isolation is required, since the cemen- tum may react at slight variations from blood heat. To secure exact- ness in any case isolation is better than an open test. When disturbance of the pulp occurs from the extended progress of caries the reaction of the pulp to changes of temperature is usually marked, and the variation from the normal rate is indicative of the degree of disorder of this organ. The response occurs to temperatures both below and above the normal rate. When the irritation of the pulp consequent upon its exposure is slight, the reaction is principally to cold, the degree apparently depending upon the extent of the hyper- emia. When the reaction to heat is marked, congestion of the organ is threatening. Disorders of the pulp appear to excite other anatomical elements of the teeth, as is indicated by reaction to cold and heat being more immediate than is the case with the sound teeth. A more exact degree of temperature reaction may also be secured when this condi- tion exists. It is essential in making tests that a carious cavity be closed by a pledget of wet cotton. This is sufficient to exclude the disturbing effect of the hypersensitive dentin, since water is a nearly absolute non-con- ductor. Examples from practice to illustrate : 1. Cavity rate, + 110° —80°, when protected as above + 130° - 60°. Here the normal rate was 4- 131° - 58°. 2. Cavity rate, + 108° - 90° ; normal rate, + 134° -65°. 3. Cavity, 4- 120° - 50° ; normal, 128° -48°. The following table of normal rates shows the variation between the point of heat reaction of the pulp and the degree of its reaction upon the abstraction of heat of different persons. + 152° — 41° + 150° — 40° + 144° — 48° + 144° — 32° + 140° — 48° -f- 140° — 46° + 140° — 46° + 140° — 32° + 140° — 56° 4- 134° — 58° -f 134° — 65° 4- 134° — 60° 4- 133° — 66° 4- 131° — 63° 4- 130° — 55° 4- 130° — 72° 4- 128° — 48° 4- 126° — 64° 4- 124° — 76° 4- 124° — 60° 4- 122° — 75° 4- 120° — 72° + 118° — 74° 392 CONSERVATIVE TREATMENT OF THE PULP. The normal averages of table — 9 cases from + 152° to + 140° average -f 143.3° — 43.2° = 100° range of tolerance ; 7 cases from + 140° to -f 130° average + 132.3° — 62.7° = 69.6° range of tolerance ; 7 cases from + 130° to -J- 118° average + 123° — 67° = 56° range of tolerance. Occult Cases of Reflected Pain. Cases difficult of diagnosis sometimes appear in which the question arises whether the pain is caused by a hyperesthetic pulp, by the influ- ence of malarial poisoning, or by a gouty condition. When the origin depends upon the two causes last named the teeth are not subject to thermal irritation ; also from these causes the occurrences of pain are not confined to the evening, as usually is the case with teeth in the early stages of disturbance. The stages of pulp exposure are divisible into three periods — (1) of quiescence; (2) of subjective symptoms, and (3) of objective manifestations. (1) Quiescence may continue in many instances for a considerable period after caries has reached the pulp where the situation is such that the force of mastication cannot cause compression of the contents of the cavity. Notwithstanding constant saturation of the gelatinous covering, and the presence of the micrococci concerned in producing the caries of the dentin, excitement of the pulp may not occur. The fact should not be overlooked that some persons escape odontalgic symptoms notwithstanding such progressive alteration of the pulp tissue takes place as to result in gangrene of the orgau. (2) Usually, however, after a period of quiescence of a longer or shorter duration there arises a train of subjective disturbances brought on by the continuance of chemical irritation and by the presence of fluids in the cavity, these influences becoming accelerated as the area of exposure becomes increased. The pain which occurs in this stage is reflected to one or more branches of the fifth pair of nerves. Flashes of pain occur to the teeth of the other maxilla, to the eye, or the supraorbital region, the most common region affected being the nerves of the ear, pain in this organ being probably the most general form of reflection which occurs. The exacerbations take place usually in the evening and at first entirely remit in the daytime. The pain in this stage will fre- quently pass away as the pulp is relieved from pressure and chemical irritation. In this stage the surface of the pulp does not present indications of being inflamed. From the lack of continuity of the symptoms it is a reasonable inference that the hyperesthesia observed in this condition is due to impressions made upon the point of encroachment and is con- TECHNICAL TREATMENT OF THE UNCOVERED PULP. 393 fined to the nerve fibrils distributed about the capillary loops involved, and thereby induces the reflected manifestations, the nerve fibrils being in this stage the anatomical element chiefly implicated. (3) Objective symptoms comprise those manifestations which, after the subjective ones have continued for some time, become localized in and about the affected tooth. These are : some soreness of the peri- dental membrane ; extreme sensitiveness to heat, accompanied through- out with dull, heavy pain in the tooth, and at length pulsative throbs. This order of statement is the usual sequence in which these indica- tions appear. They are the result of the extension of the disturbance to the deeper circulatory elements of the tissue. When this condition appears on the presentation of a case, or when in the course of the treatment it becomes apparent, the prognosis usually is rendered unfavorable to recuperation. The Technical Treatment op the Uncovered Pulp. Accidental Exposures. — These, which happen in the preparation of cavities, if produced by clean (aseptic) instruments where compres- sion has been avoided, require but simple treatment. The pain is relieved by the application of tincture of calendula one part, to four of water. When the bleeding ceases, the point of exposure should be antiseptically dressed and capped in the manner to be described. If the injury has been slight, the cavity may be at once filled with a metal, having regard to the strength, the placement, and the fixation of the cap used to defend the part from compression. Here the fixa- tion may be made by covering the cap with a broad block of gold foil ; after adapting this to the margins of the pulp wall of the cavity the filling may be proceeded with. In case of doubt a metal of less con- ductivity may be used, such as tin or amalgam. A metal filling is better in these cases, since the slight thermal irritation tends to the ultimate recovery. (See Chapter VI.). Treatment of Recent Exposures. — When the pulp has been fully uncovered, as previously described, the cavity should be washed clean with tepid water, be securely protected from the fluids of the mouth with rubber dam, dried, and lightly filled with a pledget of lint sat- urated with a mild disinfectant. On account of the invasion of the zone of dentin immediately beneath the caries by bacteria and micro- cocci, it is recognized that some means of sterilization must be adopted. This being necessary in the treatment of ordinary cavities, it is evidently here more demanded. On account of the impatience of the pulp to medication it is important to be careful in the selection of the sterilizing agent. The choice should be between hydronaphthol, acetanilid, and 394 CONSERVATIVE TREATMENT OF THE PULP. formalin : the first in the strength of 1 to 300 parts water ; the second, 1 to 200 parts; the third, not stronger than 1.5 percent. The saturated pledget of cotton may remain in the cavity during the procedures of the preparation of the dressing paste, the selection of the cap, etc. When these preparations are complete the cavity should be again dried, the drying being finished by a few puifs of warmed air. The point of exposure and the adjacent dentin are now touched with lint, filled with carbolic acid and oil of cloves, equal parts. The effect of this is to coagulate to a superficial degree the point of exposure. This practice is largely empirical. It may be avoided in cases where no disturbance has previously existed ; but where there are evidences of irritation it seems indispensable. The application of carbolic acid in this manner should be for a moment only. As carbolic acid has a very feeble affinity for water and as the topical touch is but momentary, it probably does not invade the tissue to an appreciable degree. It will also be observed that the com- bination possesses anesthetic properties. The student will not fail to hold in view that the treatment is appli- cable to cases in which it is evident the pulp tissue is not under much irritation. The condition should be one of hyperemia of the organ and gives indications of this by the existing hyperesthesia. Congestion should not have taken place, neither should inflammatory indications exist. Therefore the inference is that after the carious matter is removed the surface of the dentin and the point of exposure may be sterilized and the vital force of the pulp be given the opportunity to overcome whatever slight bacterial invasion may have reached that organ. Here the case must rest upon the well-established fact that the tissues have considerable power of mastering the influence of non-pathogenic germs as a factor in the process of recuperation. Treatment of Old Exposures. — In the conditions which exist where denudation has taken place to a considerable degree and where irritation has long continued, the disturbances which have arisen in consequence of the extension of the disorder to the larger bloodvessels and the attendant alteration of most of the anatomical elements of the pulp, the chances of establishing quiescence are slight. In the earliest stages of objective disturbances when the constitu- tional conditions are favorable an attempt may be made at conservative treatment after the inflammatory conditions are subdued by antiseptic treatment, accompanied by the use of resorbents and counter-irritation upon the gum. CAPPING THE PULP. 395 Capping the Pulp. A prominent feature in the conservative treatment of the pulp is the means to protect it from pressure, in agreement with the established fact that there is no irritation so fatal to the normal functions of the pulp as compression, and no condition from which it recovers with so much difficulty as this. Therefore all means directed toward its con- servation must conform to the necessity of preventing the least degree of compression. The means employed to prevent this form of disturb- ance have given this method of treatment the common appellation of " capping the pulp." Another principle of equal importance connected with the foregoing is that the capping material should be brought into immediate apposi- tion with the pulp. This is for the reason that if the least space be permitted to exist between the capping and the exposed point this space will fill with effused fluids, and the putrefactive changes which take place in these fluids induce the formation of gases with consequent compression. METHOD OF CAPPIXG. Various methods of capping are practised, such as laying on the part disks of paper or asbestos rendered antiseptic in various ways ; using disks of paper coated on the side to be placed next the pulp with " chloro-percha " or other plastic matter ; flowing over the exposed point a coating of oxysulfate or oxychlorid of zinc, being careful with the latter to use a formula of the fluid element in which the zinc chlorid is only in sufficient proportion in relation with the water that the union with the zinc oxid is not active. In connection with this method it has been common to mistakenly employ the strength of the fluid which is used when the formula is adapted for temporary fillings. When this method is used the coating is flowed over or laid in a cap on the pulp, and when somewhat " set " the cavity is temporarily filled with a more resistant material laid upon it with great care. With all the precautions which may be taken these dressings are somewhat complicated and are not applicable to small cavities or those difficult of access. In these cases the writer has generally depended upon the use Fig. 379. of a dressing composed of carbolic acid and ^, ^-^ gk ~ p. oil of cloves equal parts combined with zinc ^0 HP w |J W P B Oxid to form a plastic paste of Such consist- Weston's dental cavity caps. ence that when it is laid upon the pulp it will yield as it is adapted to the part, without producing pressure, and will flow out around the margins of the metal cap when this is used to con- vey the dressing. 1 Weston's caps should have the hole on the surface closed. 396 CONSERVATIVE TREATMENT OF THE PULP. The composition of the dressing is based upon the considerations that the menstruum is antiseptic, and possesses some anesthetic value. It also remains unchanged within the space and in time becomes, from the dissipation of the menstruum, somewhat firm in its character. The therapeutic action of the menstruum when combined with the zinc oxid is mild, and is employed for the reason that it is slowly given up by the oxid, and therefore makes an acceptable dressing. The Cap.- — In all cases where metal fillings are selected it is essential to use a metal cap. The methods where this is used are simpler and better under control than when dressings are made without this appli- ance. The reason for this is that the avoidance of compression is more certain. The caps are best when made of aluminium, for the reasons that this metal is a resistant material and caps of it are easily formed. When the outer filling is to be of gutta-percha or of the mineral cements, caps may be formed of concave disks of pure tin. The tin and aluminium caps are stamped from the plate by the hollow punches of the hardware shops, by which means various sizes of round and elliptical ones may be made. The effect of punching them upon the end of a block of wood gives the suitable concavity to meet the require- ments. For ordinary purposes they should be quite thin, but when gold fillings are made over them the thickness and the concavity should be such as to enable them to sustain the force applied. In cases where there are indications of approaching congestion, or where it is probable that the exposure is not recent, the dressing should have added to it a portion of guaiacocain. Placing- the Cap in Position. — Placing the cap in position is a step in the treatment requiring care. It should be assured that it is of suf- ficient size to pass well beyond the borders of the ex- posed organ, and in the approximal cavities it should cover the pulp wall of the cavity without intruding upon the marginal walls. If there is a single exposure it should be round ; if two cornua are exposed, either two caps should be laid or one oval one employed, as may best suit the case. In molars, usually, where two points are exposed, two caps are generally best ; in the bicuspid, one oval one under the same circumstances. The cap should be inserted edgewise in such manner that as it is laid in place the excess of dressing may flow out at the margin toward the operator. This is to prevent undue pressure, and to avoid air being included beneath the dressing, w T hich would prevent complete apposition of the dressing with the pulp. In cases of easy access the cap may be laid in place with fine-pointed CAPPING THE PULP. 397 pliers — notably the Bogue pliers ; but in the majority of instances it is preferable to previously eoat the convex side of the metal with wax, when, with an instrument adapted to the case, it may be carried into position and then placed in the manner described. It should next be pressed into position with sufficient force to bring the margins in contact with the dentin. Any excess of dressing should be taken away by light touches of an excavator, and when the cavity is to be filled temporarily it is better to fix the cap in place by flowing over it a little chloro-percha, which, Avhen dried, prevents disturbance of its position in the filling procedure. Care should be taken that when the pulp is found exposed in a de- pression, as occurs sometimes in the molars, this depression should be filled nearly or quite to a level with the floor of the cavity by taking a little of the dressing upon a suitable instrument and carefully filling this point ; otherwise, when the cap is placed, the paste may not find its way into contact with the pulp. At the moment of placing the cap, as the paste is yielding under the gentle pressure of forcing the edges of the cap into contact with the dentin, a little pain will sometimes be observed ; but unless the paste is too stiff no compression of the pulp should be caused. Filling the Cavity. — Whether the cavity shall be filled temporarily or permanently depends upon the prognosis. This, as will be perceived, is based upon the constitutional conditions and the state of the pulp at the time of treatment. For those of small experience in this line of treatment it would not be safe to attempt the permanent stopping of the cavity, except in acci- dental exposures and in cases where the history of no previous dis- turbance can be elicited and where the thermal reaction is slight. Even in the latter class it is generally best to delay permanent closure by a conductor of heat until after an experience of a year or more with a non-conducting stopping. At the end of this time the filling may be nearly all removed, care being taken not to disturb the cap, when with suitable precaution a metallic filling may be inserted. In the majority of instances it is safest to fill the cervical part with gutta-percha stopping, carrying the material over the cap, and then to complete the filling with zinc phosphate. In this way, with an occa- sional renewal of this temporary work, cases may be carried forward from ten to fifteen years. They may, however, be closed permanently and safely after an experimental trial of five years where no irritation has appeared. In many instances recovery takes place by secondary deposits of 398 CONSERVATIVE TREATMENT OF THE PULP. dentinal tissue the exact character of which has not been made out. The writer has observed a multitude of cases in practice when the open- ing at the point of exposure has become occluded by bony tissue. In some instances this has occurred in two years, in others after longer periods. In one instance a lateral incisor became protected by this formation, but in consequence of mistaken diagnosis of another condi- tion causing pericementitis, a drill was passed through the new tissue to the living pulp. This new opening healed again. In the same mouth another incisor also recuperated in the same period. In some cases when entire quiescence has been maintained for many years the pulp will be found not to have undergone any protective changes. It is not remarkable, however, that pulps may remain in a state of quiescence for a long period, when it is considered that in slowly- advancing caries the pulp will often be exposed for a long time without the occurrence of any signs of irritation, unless, by the position of the mouth of the cavity, the pulp has been subjected to the pressure of food. It may be concluded that, whether the pulp becomes protected by secondary deposits or acquires complete quiescence, conservative treat- ment in these cases has considerable advantage over immediate devital- ization. Still, in this connection in order to avoid embarrassments the necessity exists for careful selection of subjects to be treated in this manner, and also for proper analysis of the apparent condition of the pulp itself. To aid in this discrimination the following summary of conditions should be held in mind ; (a) Where no previous observable disturbances can be elicited. (b) Where the tooth has been impressed only by the application of low temperature. (c) Where, in addition, reflected pain in related parts has been observed. (d) Where the tooth has become much subject to impressions by heat. (e) Where continued objective disturbances appear, such as soreness to touch, or local pain of spontaneous character accompanied by pulsa- tion. Classes a, b, and c may be considered as amenable to treatment, and also, problematically, class d if taken early. Class e must, in view of the principles stated in this section, be eliminated from the field of con- servative treatment ; and where cases in the other divisions apparently amenable subsequently take on disorders coming within this classi- fication they usually have passed beyond the reach of palliative treat- ment. CAPPING THE PULP. 399 It is important here to consider the influence of the physical endow- ments of the patient upon the conservative treatment of the pulp. For some persons this treatment is followed by the happiest results ; no intolerance of the operation appearing, and even cases somewhat un- promising doing well. Again, with others, any case, however simple, goes down the scale to class e in spite of every care. The first constitutional condition favorable to success is that of soundness. As to what are called temperamental indications, when the subject is of good health, the lymphatic should alone be excluded and more particularly the bilio-lymphatic. These latter do not respond to pulp treatment in any conditions which occur to them ; and in reference to their exposed pulps the probabilities are that in the sluggish condi- tion of the parts involved the organ is early invaded by bacteria, and such changes have quickly taken place in the anatomical elements of the pulp as to render all chances of successful treatment valueless. The most promising cases are those for persons of active temperaments, with good circulation, thin skins, healthy gums, and limpid oral secretions. After-treatment. — It is not unusual for classes a, b, and c to require after-treatment. For this reason close observation for some time should be maintained. It is presumed that the judicious operator has made careful selection of the cases to be conservatively treated and that he will early decide from an analysis of the evident conditions whether the prognosis is promising or not. As previously indicated, some of the apparently favorable cases will not yield to treatment for the reason that the actual condition of the pulp may not be made out. Part of the difficulty here is occasioned by the indefinite character of the state- ments of the patient, who should in all cases be instructed to return for consultation if painful response to cold appears or if reflected pain should occur. If these conditions supervene, it is a sign of needed care to avert increasing disturbance. A most marked form of reflected pain is felt in the ear, and this frequently occurs previous to the aggravation of the temperature reac- tions. So much importance should be attached to this symptom of pulp disturbance that the first question asked a patient appearing with pain, or on approaching a suspected pulp, is, Have you had any pain in the ear of that side ? As reflection to the ear often occurs in advance of similar pain in other branches of the fifth pair, it becomes important to maintain close observation of this indication. In this state, sedation combined with counter-irritation is required. In any case where the tooth has been impressed by cold, either before the treatment or afterward, an application should be made to the gum over the tooth, of tincture of aconite root two parts, chloroform one part. The mode of application is important. A pledget of cotton or 400 CONSERVATIVE TREATMENT OF THE PULP. muslin to cover an area of one-half by three-fourths of an inch should be filled with the prescription, then squeezed out nearly to dryness between folds of a napkin to prevent an excess flowing over the mouth and with the saliva entering the fauces, to which it is extremely irritating as well as unnecessarily medicating the patient. Before the pledget is applied the surface of the gum should be cleansed of the coat of mucus cover- ing it, otherwise the remedy will fail to come in contact with the mem- brane. It is equally important that dryness of the surface be secured. This application should be maintained for from twelve to fifteen seconds. If allowed to remain too long upon the part, vesication takes place. The general after-treatment consists in the repeated application of aco- nitum as above directed, the repetitions not being made at the same point more frequently than at intervals of forty-eight hours. When it is desired to increase the counter-irritation, the gum may be scarified very superficially by quick, light movements of a small scalpel. The patient should be instructed to avoid subjecting the tooth to extremes of tem- perature in either direction. The control period of conservatively treated cases is usually within the first fortnight after the capping. It is important that treatment be given at the beginning of the dis- turbance, when a few applications may suffice. Neglected cases, from the tendency to pulp disorders, are liable to pass beyond the curative stage. The interesting phenomenon is frequently observed that when the heat rate rises the pulp at first becomes more intolerant of cold. In case the pulp continues to respond to the remedy the range of tolera- tion should increase in both directions. Examples: No. 1, W. H. J., + 108°- -73° ; 112°- 76° ; +120° -74°; 124° -74°; 128° -67°; + 130° - 66°. No. 2, I. A. W., + 120° - 84° ; + 120° - 86° ; 128° - 86° ; + 124°-76° ; + 134°-70° ; + 140° - 67° ; + 142° - QQ° • + 142° - 64°. It sometimes becomes necessary to open the cases and recap. This usually occurs when in reviewing the case it is considered that some oversight has befallen. There may have been two exposures. The cap may not have completely covered the exposed part. There may have been some compression from forcing the cap, or it may have been displaced during the after-procedures. Most careful records of all cases should be kept, with a relation of the condition and of the controlling symptoms. These records should be methodically preserved in a book kept for this purpose. Should sub- sequent irritation occur, a new diagnosis may be formed from the recorded facts and the new conditions. The record of conservatively treated pulps should be carried forward to the examination chart at each recurring periodic examination of the teeth. It is better that they be marked in CALCIFIC CHANGES IN THE PULP. 401 symbol with red ink, to prevent the unnecessary removal of temporary fillings and to explain the reason for their presence and thus avoid the accident of unnecessarily uncovering the pulp in such cases. Calcific Changes in the Pulp as related to the Operation of Pulp Capping. When loss of substance takes place slowly, either by carious action or by attrition, a notable calcific growth takes place in the pulp cham- ber opposite to the point of waste in the direction of the radiant course Fig. 382. Secondary dentin, resulting from irritation of the dentinal fibrils by caries (Black). A, Diagram of an incisor having a decay in the labial surface, a, and a deposit of secondary dentin at b. The point from which the illustration B is taken is shown by c. B, Illustration of the tissue of the secondary deposit in A : a, primary dentin ; b, secondary dentin ; c, seems to be a blood- vessel that has become calcined ; d, an irregular fault having some resemblance to the lacunse of bone ; e, pulp chamber. It will be noted that there are irregular deposits of granular matter in the substance of the secondary dentin, and that the tubules wind about them. of the tubules (see Fig. 382). If the loss of substance from the ex- terior progresses with sufficient slowness encroachment upon the pulp does not take place. The pulp chamber may become obliterated by the progressive deposition of calcific matter, which has tke designation of secondary dentin. The morphological character of the secondary deposit is histologically irregular, being frequently of mixed character, presenting some of the characteristics of dentin and also containing cemental cells with radiant and anastomosing canal iculi. For this reason deposits have been designated as osteo-dentin. In the earlier years of life opportunity does not offer to study these changes of structure, as the usual progress of caries is too rapid, but in advanced life they are common, it being not infrequent to find complete 26 402 CONSERVATIVE TREATMENT OF THE PULP. obliteration of the pulp cavity as well as of the canal of the root (see Fig. 383). In some instances nodules of calcific material appear un- Fig. 383. Calcification of the dental pulp (Black). At A is shown the outline of a lower molar with a cavity at b. The pulp chamber is much reduced in size and filled with calcific material, as shown in B. a, a large granular mass of calcific material, which is very transparent but finely granular. A very few irregular lines are seen in the centre, which slightly resemble dentinal tubes ; 6, an erratic growth of irregularly formed and unusually transparent dentin ; c, line of the growth of dentin from the floor of the pulp chamber : the growth from other directions is so perfectly regular as to leave no markings ; d, margin of the cavity of decay ; e, a bundle of cylindrical forms of calcific material extending down into the root canal. These extended to the apex of the root. attached to the walls of the pulp cavity (Fig. 384). These increase sometimes by external development and in other cases by the coalescence Fig. 384. A, Outline of a lower molar, with a large carious cavity at a; b, pulp chamber. The shaded por- tion, c, was occupied by cylindrical calcifications. B, Illustration of the cylindrical calcifica- tions. X 100. (Black.) of several contiguous nodules. Again, several nodules inhabiting the pulp chamber may increase in size without becoming fused, and, accom- CALCIFIC CHANGES IN THE PULP. 403 modating themselves to each other as development progresses, they at length completely fill the cavity, from which they are severally removed with great difficulty. , It is remarkable that while in some instances pulp nodules become the cause of producing violent pain by their pressure upon the nerves of the pulp, in the majority of cases substitution of the normal tissue takes place until nearly complete occlusion of the pulp cavity is affected without the occurrence of pain. Small pulp nodules are not infrequently found in pulps otherwise perfectly normal, but generally they are evidence of continued irritation of a mild form usually attending the progressive slow advancement of caries of the tooth. But this is not necessarily the case, since some of the most violent attacks of dental neuralgia have arisen from the pres- ence of nodules in perfectly sound teeth. The diagnosis of the existence of pulp nodules as the cause of pulp irritation is not easily made out. The determination of the condition usually can be reached only by the process of exclusion. As they do not occur early in life while the teeth are undergoing ordinary develop- ment, they may be looked for only after middle life. The pain is dull and reflected, and the paroxysms are frequent. There is sensibility to cold, and rarely pain appears on percussion. When the teeth are sound, the disturbing one will usually be determined by the tem- perature tests. An important differentiation from the usual irritation of ordinary pulp disturbance from exposure or the thermal irritation caused by the approximation to the pulp of large metal fillings, is that the disturbance from nodular irritation is not rapidly progressive and that the irritation may continue without marked exacerbations or subsidence for consider- able periods. Treatment is useless which does not include drilling to the pulp and devitalizing it. The difficulties involved in treatment by devitalization are liable to be attended by great pain, since when the pulp chamber is much occupied by nodules the action of the devitalizing agent has not free course. In these cases the remains of the pulp between the nodules and the walls of the chamber are attenuated, and when irritated by the arsenous acid give expression to an excessive degree of pain. 1 The Influence of Pulp Exposure, and the Effect of Conservative Treat- ment of the Pulp upon Calcific Depositions. — Allusion has been made to calcific deposits occurring on the walls of the pulp chamber as the result of peripheral irritation. Here, as stated, these accretions only occur when the degree of irritation is slight and of long continuance. The examples of this which have been given in dental literature are 1 For the form and extent of nodular calcification see American System of Dentistry. 404 CONSERVATIVE TREATMENT OF THE PULP. conclusive as to the ability of the pulp at all stages of its existence to take on this action when the conditions are as stated. On the contrary, when the disturbances are active the formation of calcific deposits on the walls of the pulp chamber do not take place, or if in the earlier progress of decay they have commenced, as the progress of the destruc- tive action approaches the pulp this change is suspended, and in some instances resorption of the secondary deposit takes place. It is apparently in this manner that the pulp becomes denuded under the influence of thermal or traumatic irritation in cases in which there was no evidence of exposure at the time of the preparation and filling of the cavity. This result would appear to be related to the principle that secondary structures and tissue of repair are liable to resorption as the result of irritation or disturbances of nutrition. The frequent occurrence of secondary dentin following the conserva- tive treatment of the pulp and in some instances occurring spontaneously over exposed pulps, raises important considerations connected with the subject. The writer has had many instances come under his observation in which secondary dentin has obliterated exposures, both in his own cases and in those of others. The influence of the tendency to nodular deposits upon the results of conservative treatment does not appear to be detrimental unless the pulp chamber becomes largely filled with them. The pulp at the period of life when calcific deposits usually take place is not so sensitive as it is at an earlier age, and therefore, unless senile conditions appear to be present or imminent, the existence of such deposits should not be inim- ical to the preservation of the pulp. The writer, who has had frequent cases of pulp devitalization after conservative treatment, has rarely ob- served " pulp stones " in these cases. It is an important consideration that when calcific deposits take place beneath fillings where the pulp has been nearly exposed, or where they have followed conservative treatment of the pulp, they are liable to resorption on the occurrence of irritation of the pulp from any cause which brings on an increased blood supply. This* is more remarkable since there are no lymphatic vessels in the pulp. This change can occur only by the development of osteoclasts on the surface of the pulp. Of this development there have been several recorded instances where the dentin has suffered resorption until the enamel has been encroached upon by the process of denudation, and when favorable conditions were established a deposition or formation of secondary dentin has occurred. EXTIRPATION OF THE PULP. 405 Extirpation of the Dental Pulp. The removal of the pulp is necessary when there has existed such a degree of disturbance of this organ as to render conservative treatment inadmissible. Also when the pulp has become denuded by attrition or by fracture of the crown and also where the roots are required to serve the purpose of bases for the attachment of artificial crowns and abut- ments of bridges. To facilitate the immediate extirpation of the pulp the employment of cocain has, within a recent period, come into use to effect anesthesia of this structure. For this purpose cocain hydrochlorid is dissolved in a solution 1 to 1000 of adrenalin — 1 grain to 5 minims of this strength being of sufficient activity. The application may be effected — (1) By instillation. (2) By the pressure method. (3) By cataphoresis. The choice of method depends upon the situation, the direction of approach, and the state of the organ. It is necessary in each case, by either method, as a preliminary, that the carious matter be removed and the tooth and such adjacent ones as may be necessary be enclosed in a rubber dam to prevent the escape of the solution into the mouth. Instillation is more applicable to exposures by attrition or fracture, and where there is direct approach or where the rubber dam cannot be applied ; also for the obtunding of a remnant of pulp in canals where the pressure method or cataphoric applications have not reached the apices of roots. To effect instillation a drop of the solution is placed upon the exposed pulp, and after a moment is lightly pricked into the surface of the organ. This conveys the solution into the tissue; as pain is manifested the instillation is interrupted and successively reapplied as it may be tol- erated. In most single-rooted teeth a few minutes is sufficient to permit the complete removal of the pulp. If the approach is direct or can be made so, the extirpation is easily effected with a Gates-Glidden drill of proper size for the case. The Pressure Method. — This consists of laying over the exposed sur- face of the pulp, after it is carefully and broadly uncovered, a small piece of amadou (spunk) saturated with a solution of cocain in either adren- alin solution, .001, absolute alcohol, or chloroform. The cavity is then closed with a piece of unvulcanized rubber. The next step is to effect pressure through this directly toward the pulp with a broad instrument so adapted in size that it will not meet with impediment, and yet not so 406 CONSERVATIVE TREATMENT OF THE PULP. small as to exert force upon the center of the rubber. The degree of pressure should at first be slight, and be gradually increased as the cocain exerts its effect upon the pulp. The force is exerted by successive steps, diminishing when pain follows, but maintained until the sensation ceases. At length, when no pain is produced by excessive pressure, the rubber and spunk are removed, when the pulp is immediately removed by the usual means. This operation is done quickly, to avoid the return of sensitivity. Those who pursue this plan state that it produces nearly uniform results and enables the canal and pulp chamber to be filled immediately. The indications are that the cocain overcomes the sensitivity of the surface of the pulp, and that pressure paralyzes the tissue by the com. pression to which it is subjected. Were the cocain conveyed to the apex, as when it is instillated, pain would not so soon return. Should the paralyzation of the pulp fibers in the canals be not com- plete, instillation may then be pursued as previously described. When the pulp is too highly sensitive to permit complete exposure to the cavity, a drop of adrenalin and a one-fifth-grain tablet of cocain are inserted, then make light and even pressure, gradually increased until the pain ceases. The pulp may then be completely exposed, and the usual solution may be applied with sufficient force, as described above, to effect complete anesthesia of the pulp. Obtundation by Cataphoresis. — The pulp may be readily anesthetized by cocain, as described for the treatment of hypersensitivity of the dentine by cataphoresis, and is in some cases, and for highly nervous persons, more acceptably than by the previously stated methods. The requirements are that insulation be perfectly secured ; that the voltage be low at the commencement and be gradually increased as the pain limit permits. When the pulp can* be uncovered and fully exposed, the process may be continued or completed by the pressure method or by instillation, as may be most applicable. When the pulp is removed after complete anesthesia by either of the methods above considered, the root canals may be immediately filled by any substance which may be conveyed to the apex and perfectly occlude the canals. It sometimes occurs that some bleeding takes place at the end of the severed vessels. This may be stopped by an applica- tion of adrenalin. The methods above defined have the advantage over the previous general practice of devitalizing with arsenous acid, as being more promptly effected, with much less pain in congested cases, and with the added advantage of avoiding any danger of causing discoloration of the teeth. There is also the further important consideration, that after-disturbance of the apical region, frequently following the use of arsenic, is avoided. R Acid, arsenosi . . . gr. xx R Arpenosi .... Morphica acetatis . . gr. xxx Cocainse hydrochl. 01. caryophylli . . . q. s. Eugenol .... M. et ft. pasti. M. et ft. pasti. DEVITALIZATION OF THE PULP. 407 Devitalization of the Pulp. There arise conditions which require devitalization of the pulp. For this purpose no agent has been found so acceptable as arsenous acid. The formula for use may be as follows : • gr. . aa • q. s. When arsenic is applied to a living; pulp which has not been in a state of disturbance, and therefore is in the condition of quies- cence considered in the section on conservative treatment of the pulp, little or no excitement of the organ takes place. If the paste be carefully applied in such a manner as to avoid pressure the pulp does not usually become excited and promptly succumbs to the chemical force of the arsenic. When on the contrary the pulp is in a condition of active congestion, such as is presented by cases of prolonged exposure, and where congestion has supervened as the consequence of futile attempts at conservation, violent further excitement of the pulp is nearly certain. In this condition the pulp resists the absorption of the arsenic and repeated applications are likely to produce no better results. The failure to discriminate between the different conditions of the pulp accounts largely for the variation in the action of the same formula upon the exposed pulp. It becomes important, therefore, to reduce the state of hyperesthesia of the pulp and to relieve the congestion in many instances before commencing the devitalization. The relief of congestion requires, first, the disinfection of the surface of the pulp and of the dentin contiguous to it. The most efficient agent for this purpose, generally, is formalin, which after the first slight pain produced by it is almost immediately soothing. Formalin owes its value as a disinfectant to its extreme diffusibilityand in the strength applicable does not appear to be coagulative in its action. The strength should for this purpose not be greater than 2 \ per cent. As formalin is composed of 40 volumes of formaldehyd with 60 of water, the above- stated percentage of formaldehyd is produced by adding 1 volume of formalin to 14 volumes of water. For the relief of ordinary congestion of the pulp cocain offers the best means, since it has direct and positive action over the capillaries, which has generally been adduced to account in part for its anesthetic influence, as by lessening the supply of blood in the capillaries it there- by reduces the stimulation of the nerve fibrils. In cases of known con- gestion as determined by the symptomatology when there is no effusion 408 CONSERVATIVE TREATMENT OF THE PULP. of lymph or pus from the exposed surface, the pulp is bathed with a strong solution of cocain and is then covered with a deep cap filled with a paste of cocain and oil of cloves hermetically sealed in for several days, when usually the arsenical paste may be used with much -lessened danger of irritation. An excellent method where delay is allowable is to cover the pulp with a metal cap filled with a thin paste of eugenol and cocain covered by a very stiff mixture of zinc oxide and eugenol. This filling when wetted becomes sufficiently dense to remain for some weeks. In these cases, and indeed in all cases, an excellent formula for de- vitalization will be found in the combination of 10 grains of arsenous acid ground well with 20 grains of cocain. A very minute portion of this is taken upon a small pledget of cotton previously charged with oil of cloves or carbolic acid, which is laid upon the exposed point and then sealed in hermetically, care being taken to avoid compression by arching over the dressing a suitable cap, or by flowing over the dressing a soft paste of one of the mineral cements. Too much care cannot be taken concerning the protection of the gum from escape of the arsenical prepa- ration, since serious destruction of the gum and alveolus maybe produced by the exuding of the arsenic. When there is evidence of the exudation of pus, this is checked by the application of deliquescent zinc chlorid or by washing with pyrozone. Usually in such cases the surface of the pulp has become necrotic by the suppurative process and will not be so repel Ian t of the arsenic as in ordinary cases. The time usually required for the action of the arsenic to reach well toward the apex of the roots is from four to six days. This, however, depends upon the quantity of the preparation applied and the resistance of the pulp tissue. As the aim should be to procure the nearly com- plete death of the pulp by one application, the longer period is preferable as entailing less difficulty and the expenditure of less time than when shorter intervals are allowed. The Safety Pocket. Instead of applying the arsenical pellet to the pulp, it is preferable in congested cases to insert it in an opening drilled nearly to the pulp at the cervical region of the cavity. This method is based on the principle that the chief seat of disturbance of the pulp is about the region of ex- posure. Therefore the more remote the application be made from the region of the exposure, the less the liability of arsenical irritation and the more prompt the action. 1 1 This depression was called a safety pocket by Clowes, who appeal's to have been its originator. PRECAUTIONS TO PREVENT DENTINAL DISCOLORATION. 409 A not uncommon degree of soreness of the pericementum occurs after arsenical devitalization. This rarely follows the use of cocain as above described, which leads to the conclusion that some of the arsenic has entered into the circulation of the region. Hence it is advisable when practicable t ) follow one application with cocain when necessary to com- plete the treatment. When the application is made to an entirely quiescent pulp it will often be found that at the end of one or two days a broach may be passed to the end of single-rooted teeth, when the pulp may sometimes be removed. In these cases, if the pulp be not then extracted, it will be found in some instances that at a subsequent period the organ has apparently recovered its sensitivity. The explanation of this is that the arsenic apparently paralyzes the nerves of the pulp without having acted deeper than the surface. In this case the application should be repeated for a lengthened period without disturbing the tissue. On removing the dressings if the broach cannot be passed to the end of the canal either of two courses may be pursued ; the application may be repeated without removing the devitalized portion, or a strong solution of cocain may be carefully instillated until it is conveyed to the apex of the canal by means of a broach. This procedure is best effected by isolating the tooth with rubber dam and then filling the pulp chamber with the solu- tion of cocain, which may be conveniently conveyed forward by gentle advancements and withdrawals of this instrument. The best form of instrument for this purpose is the Swiss broach tempered a little beyond a spring temper. A matter of considerable importance in connection with the instru- ments used in these manipulations is that they be either such as have not been previously used or that they be thoroughly disinfected previous to use. If an instrument of this kind is indiscriminately used, having probably been infected by some purulent case, septic disturbance of the tissues at the apex is brought about. The safest course is to use a new broach suited in size and stiffness to the case in hand. Precautions required to Prevent Discoloration of the Dentin. It sometimes occurs where arsenous acid produces much irritation of the pulp that the violent congestion occasions disorganization of the blood corpuscles, resulting in the distribution of the hematin throughout the dentin. This most unfortunate result is liable to follow the applica- tion to an already congested pulp when the application is made without first subduing this condition. It is also more liable to happen when under these circumstances the pulp has not been completely denuded of the carious matter. 410 CONSERVATIVE TREATMENT OF THE PULP. The removal of the ultimate layers of earious matter is important to permit the pulp to bleed and thus to deplete the engorged vessels. It is also necessary to avoid making an arsenical application until the assurance is reached that the bleeding has completely ceased, else subse- quent bleeding may induce discoloration. In addition the bleeding or any other kind of effusion prevents direct contact between the pulp and the arsenical paste. These general directions apply also to the employment of pow- dered cobalt as a devitalizer. The difference between the action of cobalt and arsenous acid is due to the variations in their respective solubility in the fluids of the pulp — cobalt having a low rate of solu- bility. For this reason this substance requires a longer interval, at least a week being necessary for its action to extend into the canals. In anterior teeth a shorter period should be chosen. With this substance it is of extreme importance that the application be made directly to the pulp. The method is as follows : A pellet of cotton the size of a pinhead is saturated with any of the essential oils ; it is then dipped in the powder and laid upon the pulp. The previously stated precautions are taken to prevent pressure of the pellet of cotton upon the pulp and to protect the cavity from the ingress of moisture. In these procedures connected with the removal of the pulp the use of alcohol is an important aid, since on account of its affinity for water it much aids, in addition to its cleansing properties, in the procurement of dryness of the parts. Desiccation of the pulp chamber materially assists in all the delicate procedures connected with the treatment of this class of cases. It lessens the pain of the remaining living portion of the pulp, and by giving firmness to the devitalized part makes more easy the removal of the dead tissue. It also facilitates the action of the disinfectants which may be employed to prevent rapid changes in the organic contents of the canal. The process of desiccation may be much facilitated by the concurrent injection of warmed air. It should be emphasized that in all procedures connected with the treatment of pulps undergoing devitalization the teeth should be isolated by the use of rubber dam. This is necessary not only to facilitate observation and secure dryness but to protect from mouth infection. The removal of the dead pulp tissue is effected by small barbed broaches which are passed between the pulp and the walls of the canal. When these reach the apex the pulp may in most instances be wound upon the instruments by a gentle rotation. When this does not take place because of the loss of consistence of the tissue, it is broken up by constant rotation of the instrument and removed piecemeal. The dis- PRECAUTIONS TO PREVENT DENTINAL DISCOLORATION 411 placement of the shreds is best effected by wrapping the broach with a few fibers of cotton dipped in alcohol. Previously to this, free communication must be established between the cavity and the pulp chamber, as well as such a formation of the lines of approach to the canals of the root as will give free access, not only for the removal of the dead tissue, but as well to facilitate the complete closure of the root canals to the apices to prevent the ingress of organic matter from the adjacent tissues. Minute directions for the form of approach to the various canals and the related procedures will be found in the next chapter. CHAPTER XVII. THE TREATMENT AND FILLING OF ROOT CANALS. By Henry H. Burchard, M. D., D. D. S. Pathological Conditions. The modes of treatment of the pulp chambers and canals of teeth containing non-vital pulps, or those in which the pulp is absent, are determined and governed by the pathological conditions present. These conditions may be broadly divided into aseptic and septic ; i. e. those which have not been invaded by micro-organisms, the others those in which the pulp or its remnants furnish the soil in which the develop- ment of micro-organisms has taken place. The first class includes those cases in which the pulp has been inten- tionally devitalized en masse, and also those in which the organ has undergone a process known as mummification, or dry gangrene. This latter condition is occasionally found as a consequence of traumatic death of the pulp without exposure, and sometimes as a sequel of attempts at conservation of exposed pulps by capping them with zinc oxychlorid. The septic cases may be divided into classes according to the depth of invasion of septic organisms ; they range from superficial ulceration of the pulp, to its disorganization through putrefaction, and the infection of the tissues beyond the apex of the root. Immediately upon or even before exposure of the dental pulp, its surface, and subsequently its substance, is invaded by several of the many forms of organisms which find a habitat in the human mouth. The first of the septic cases are those in which organisms have invaded the coronal portion of the pulp and destroyed part of its sub- stance — through a process of ulceration. Such cases become aseptic through the removal of the pulp en masse, provided no organisms be carried into the canal during or subsequent to the removal of the pulp. The second class of cases comprises those in which septic organisms have invaded the pulp along the direction of its veins and destroyed the mass of the organ through a process of suppuration. In these cases 413 414 THE TREATMENT AND FILLING OF ROOT CANALS. it is not uncommon to find the tissues of the apical region affected in some degree presumably by infection with the waste products of the organisms, a transitory pericementitis occurring which ceases when the dead pulp sloughs from its vital connection at the apex. The succeed- ing stages of the infection are those of moist gangrene and putrefactive decomposition of the pulp tissues, and later of the contents of the tubules. Following upon these conditions are affections of the cemen- tum and the pericementum in the apical region, resulting in an inflam- matory process in these parts. All of these stages of infection and decomposition may be found in the pulp at one time, the suppurative process preceding that of putre- faction. Cultures made from a gangrenous pulp (see Fig. 385) l showed Fig. 385. 4 " 5 Micro-organisms found in cultures from a gangrenous pulp. the smaller cocci and diplococci (5) nearest the apex of the root (c, Fig. 385, 1) where suppuration was in progress ; the larger forms and more varieties were found in the necrosed and decomposing portions of the 1 Miller, Dental Cosmos, July, 1894. PATHOLOGICAL CONDITIONS. 415 pulp (4, 3, 2). The cases of gangrenous pulps exhibit a mixed infec- tion, several varieties of cocci, bacilli, and spirochetes being found. 1 Cases are occasionally seen in which the pulp of a non-carious tooth has been devitalized in consequence of a blow, injuring the vessels as they enter the apex of the root ; the same effect is not rare as a conse- quence of too rapid or extensive movement of teeth in regulating. The pulps in such cases are probably destroyed by thrombosis of the vessels at the root apex. The death of the pulp may not be detected for years ; when evidences of albuminous decomposition are discovered, a growing opacity and changing color of the tooth may be detected. In other cases alveolar abscesses may form and discharge at some point near the tooth, or it may be at some distance from it. It is presumed that the organisms which have effected this decomposition of the pulp resulting in the suppurative process have found their way to it via the blood current. It is within the experience of every dentist that the products of decomposition occurring under these conditions afford a suitable soil for the development of virulent micro-organisms as soon as the tooth is opened to the air. The several conditions described are to be regarded, for purposes of treatment, as definite pathological states. The treatment is to be directed to the attaining of such conditions as shall insure the retention of the tooth with an entire absence of pathological manifestations. Rational therapeutics should govern each procedure. Cases in which the Pulp has been Intentionally Destroyed and Re- moved en masse. — As this procedure usually has been determined upon in consequence of suppuration or inflammation of the pulp, the septic organisms, the staphylococci, streptococci, and bacilli, have followed the course of the inflammation, i. e. along the veins. The organisms of putrefaction, if present, have affected but in very limited degree the most external portions of the pulp, so that the color of the dentin is unaltered except to a very slight depth. After the removal of the pulp the contents of the tubules are chemically unchanged, and the canals contain no organic matter, except the blood which may have escaped in consequence of tearing away the pulp. There may also remain odonto- blasts which have become mechanically detached during the operation. Provided no organisms have been introduced during or subsequent to the operation of extirpation, the canals are aseptic. If proper anti- septic precautions have been taken, sterilizing and isolating the tooth to be operated on and also the instruments employed, no infection occurs. These are the cases in which immediate root filling is to be recommended and may be practised with success. 1 See Fig. 397. 416 THE TREATMENT AND FILLING OF ROOT CANALS. Pigment. Fig. 386. S + hemoglobin. C0 2 ,NH 3 ; H 2 and H 2 S fatty ucts. prod- lf the septic process has invaded the pulp extensively the pulp tissue, as its destruction progresses, be- comes the seat and soil of putrefactive decomposition involving also to a vari- able extent the contents of the dentinal tubules, and the color of the dentin un- dergoes a series of changes. 1 The ap- pended figure (Fig. 386) gives a graphic diagrammatic representation of the serial decomposition of an infected pulp. The albuminous constituents of the pulp un- dergo fatty transformation ; next putre- factive decomposition attended by the evolution of hydrogen sulfid, ammonia, and other end products. According to the Aromatic and extent of invasion and its variety, waste products are formed (ptomains and al- lied substances) by the organisms which act as irritants to the vital tissues, until, when the apical but still vital portions of the pulp become the soil for the de- velopment of pyogenic organisms, the tissues of the apical region are affected. Usually in the later stages of pulp sup- puration the tooth becomes sensitive upon percussion. Succeeding this state of affairs is a period of delusive quiet, during which the apical tissues, although doubtless affected by the toxic substances present, exhibit but slight subjective symptoms. The remnants of the pulp are undergoing progressive decomposition, as are also the contents of the dentinal tubules. After a variable period, governed by the virulence of the organisms present and the inherent resistance of the vital tissues of the apical region, these latter succumb, poisoned by the toxic sub- stances formed in contact with them, and an inflammatory action arises ; this may be subacute, evidenced by sensitiveness upon percussion and a deepening of the gum color overlying the apex of the root, constituting a condition known as subacute pericementitis ; or, if the attack be more severe, or the resistance lessened, the symptoms are more violent ; there is a pronounced hyperemia, quickly succeeded by the evidences of marked inflammatory action. The tooth, owing to the effusions in the pericementum, becomes elevated and exquisitely sensitive to touch ; the color of the gum deepens, and heavy throbbing pain is complained of; acute pericementitis is in progress. In more severe cases marked 1 See Chapter XX. on Bleaching. Ptomains. Peptones, Pus. THERAPEUTIC AGENTS. 417 oedema of the gum and it may be of the face arises ; the pulse increases in volume, tension and frequency ; febrile action, with a temperature as high as 103° or 104° may occur; in other cases distinct evidences of septic intoxication may appear, and indeed even septicemia or pyemia 1 may result at a later stage. The severity of the inflammatory action is no doubt governed in part by the variety of the infecting organisms, and again by the physical condition of the individual attacked. Judging from the mode of prog- ress and attack, the staphylococci are the offenders where the inflam- matory action is circumscribed, and the streptococci in cases which exhibit a tendency to spread along the course of the fascia and produce phlegmonous inflammation. 2 Schreier 1 has found the almost invariable presence of a diplococcus in this condition, probably the diplococcus pneumoniae. Individuals presenting any of the several manifestations of struma, inherited or acquired, suffer from a debility of general vital processes, and may have the inflammatory action run a riotous course (see Alveolar Abscess, Chapter XVIIL). As a rule, when a tooth has been the seat of subacute pericementitis for a lengthened period, or of acute septic pericementitis for from twenty-four to forty-eight hours, there is more or less death of cellular elements in the inflammatory effusion, pus forms, and alveolar abscess is established (see Chapter XVIIL). In cases of subacute pericementitis, even those in which pus forma- tion is not evident, the tissues of the apical region are assailed by the products of putrefactive decomposition, which latter process may prove difficult to overcome, the tissues rebelling at each attempt to close the outlet to the escape of gases which irritate them. Each phenomenon mentioned as accompanying the stages of septic infection and albuminous decomposition forms an item for consideration in the therapeutic measures to be applied. Therapeutic Agents. The natural and true inference from what has been stated is that the class of therapeutic agents to be locally employed in any of these condi- tions are all included under the general order of germicides, antiseptics, and disinfectants. The one distinguishing feature that all of these substances have in common is the power — differing in degree in each — of destroying patho- genic organisms or rendering innocuous their waste products ; their other properties differ widely, so that the agent for application to spe- 1 See case of Dr. E. T. Darby, Proc. Odontological Society of Pennsylvania, 1892. 2 See case reported by Dr. E. C. Kirk, Proc. Odontological Society of Pennsylvania, 1892. 3 See Dental Cosmos, vol. xxxv, 1893, p. 617. 27 418 THE TREATMENT AND FILLING OF ROOT CANALS. cific disease conditions is selected with a regard to which shall best and most completely attain a definite end. According to the effects produced upon albumin the agents under consideration may be placed in two classes, coagulants and non-coagulants. In the former class are in- cluded salts of the metals and alcohols ; in the latter, many of the essential oils. Mineral acids and the alkalies act by chemically destroying the albumin. The metallic salts which have been employed or tested as germicides in pulp canals are the chlorids of zinc and of aluminum, the bichlorid of mercury, the bichlorid of gold and sodium, the sulfate of copper, and the nitrate of silver. The salts of copper, silver, and gold are not adapted on account of the discolorations produced by them. Mercuric chlorid is open to the same objection ; thus the only metallic salt having general application is zinc chlorid. The alcohols employed are the ethylic (commercial) alcohol ; phenylic alcohol, i. e. carbolic acid, and creosote, with the coal-tar derivatives, the cresols. In this connection formalin — a 40 per cent, solution of the gas formaldehyd in water should be mentioned very favorably ; in dental practice it is reduced to a strength of 3 to 5 per cent. Preparations of iodin, bromin, and chlorin are all powerful anti- septics and disinfectants. Bromin is inapplicable owing to its irritat- ing effects and offensive odor ; chlorin is employed in the form of hypochlorites ; usually in the solutions called electrozone and meditrina, electrolytic products of sea-water. Labarraque's solution of sodium hypochlorite appears to have fallen into general disuse, as have also the hyposulfites. The usual form in which iodin is applied is as the tincture. Iodin trichlorid is said l to be five times as strong as mercuric chlorid as an antiseptic. The essential oils recommended as antiseptics for employment in canal and dentin sterilization are those of thyme, cinnamon, cassia, myrtle, and eucalyptus. The alkalies employed as sterilizing agents are Schreier's alloy of po- tassium and sodium, called Kalium-natrium ; sodium carbonate and so- dium dioxid. The mineral acids which have been recommended are hydro- chloric and sulfuric, the latter by the method described by Dr. Callahan. 2 The gases oxygen and chlorin, in statu nascendi, are employed as sterilizing agents, the former extensively. When these are applied as bleaching agents, the sterilization is coincidently accomplished, as pointed out in the chapter on Bleaching. Oxygen is liberated from aqueous and ethereal solutions of hydrogen dioxid and solutions of sodium dioxid. 1 Langenbach, quoted by Miller, Dental Cosmos, vol. xxxiii. p. 342. ' Proc. Ohio State Dental Society, 1894. THERAPEUTIC AGENTS. 419 Iodol, iodoform, and kindred substances are not employed as germi- cides per se, but for other therapeutic properties possessed by them, e. g. their supposed capability of maintaining sterilization after the more powerful antiseptics have been employed as germicides. Aristol, dithymol biniodid, is another member of this group, which owing to its chemical composition is theoretically preferable to the others. It contains twice the quantity of iodin in loose combination, and in addition has as its base a powerful antiseptic, thymol. These agents are supposed to act as antiseptics in consequence of setting free iodin when brought in contact with albuminous substances. It has been demonstrated that iodoform is not a germicide (organ- isms growing about it), but it appears to lessen or destroy the effects of toxic substances generated about it as the result of albuminous de- composition. The final antiseptic to be mentioned is the mechanical removal of infected tissues. Zinc chlorid forms, when brought in contact with albumin, a dense and almost colorless coagulum of zinc albuminate. Placed at one end of a capillary tube containing albumin, it diffuses rapidly through the solution, coagulating it throughout. 1 Carbolic acid forms less dense coagula, and creosote still less. Mercuric chlorid and silver nitrate form complete coagula also. It may be well in this connection to call attention to an observation made by Dr. Kirk, in an essay read before the First District Dental Society of New York, that coagulation is a chemical process, as illustrated in the union of mercuric chlorid with albumin. The metallic salt does not act by catalysis, but there is a distinct quantitative relation between the coagulant and the coagulable material, the process ceasing when the quantitative relation of these bodies is chemically satisfied ; if an excess of HgCl 2 be employed, a definite amount of the salt combines with albumin to form an albuminate of mercury suspended in a solution of the chemical excess of HgCl 2 . If an excess of the albumin be employed, an albumin- ate of mercury is formed suspended in a solution of albumin. The albu- minate of mercury when brought in contact with an easily decomposable sulfur compound may be reduced by the formation of mercury sulfid and the albumin be restored to its primary condition, 2 which would seem to indicate that HgCl 2 is an unreliable germicide where putrefac- tive decomposition is in progress giving rise to H 2 S. Formalin readily and quickly affects both albumin and gelatin, con- verting them into a tough coagulum which maintains its form and 1 Prof. James Truman, Proc. Academy of Stomatology of Philadelphia, Dec. 1894. 2 Abbott, Principles of Bacteriology, 3d ed., 1896. 420 THE TREATMENT AND FILLING OF ROOT CANALS. appears to be persistently antiseptic for certain varieties of micro- organisms. The essential oils act as antiseptics without coagulation, having markedly less germicidal action than the agents above mentioned. Placed in root canals they diffuse through the dentin, maintaining a prolonged antiseptic influence ; their absorption into the dentin pro- duces some degree of discoloration in that tissue. These oils differ in antiseptic power. Oil of thyme and oil of cinnamon stand at the head of the list, oil of cloves and eucalyptus being- far below them in the antiseptic scale. The antiseptic value of oil of thyme is dependent upon its active principle, thymol, which is separated from the oil by fractional distillation and further purification by treatment with soda and then by hydrochloric acid. Thymol has high therapeutic value not only in con- nection with pulp-canal sterilization, but of the infected pulp itself. Attention was first directed to the value of thymol as a sterilizing agent for infected pulps by Hartmann, 1 and his observations were subsequently confirmed by experimental tests made by C. Rose. 2 Thymol appears to possess the valuable property of destroying the infecting organisms without at the same time injuring the vitality of the cellular elements of the pulp tissue, as the investigators cited have re- ported numerous cases of recuperation of badly infected pulps under treatment by thymol applied in substance. The alkalies employed as antiseptics saponify the fatty matters formed in the course of albuminous decomposition, and dissolve albuminous sub- stances with which they are brought in contact. The first of these, the alloy of potassium and sodium, 3 when placed in contact with decom- posing pulp tissue abstracts the elements of water from it, and sodium and potassium hydroxids are formed, which have the power of saponi- fying fats and dissolving albumins. Sodium carbonate has similar properties, but acts less energetically. Sodium dioxid under the same conditions forms sodium hydroxid, nascent oxygen being set free, which acts as a germicide and also decomposes the coloring substances in the dentinal tubules, acting as a bleaching agent to the dentin. Solutions of hydrogen dioxid are decomposed into water and nascent oxygen in contact with the putrescent canal contents ; the liberated oxygen acting as an oxidizer. The mineral acids when employed subserve a double office. Sul- furic acid placed at the mouth of fine canals unites with and decom- poses the calcium salts of the dentin, forming calcium sulfate, easily removable with the fine canal scrapers ; its second office is that of an 1 See Deutsche Monatsschrift f. Zahnheilkunde, vols. i. and iv., 1892. 2 See Dental Cosmos, vol. xxxvi., 1894, pp. 41 and 362. 3 Schreier's preparation (see Dental Cosmos, vol. xxxv.j 1893, p. 22). MATERIALS FOR FILLING THE ROOT CANAL. 421 effective germicide, destroying all organisms with which it is brought in contact. Materials for Pilling the Root Canal. The materials employed to hermetically seal the apical foramina of sterilized canals are in the condition of solids inserted en masse or in successive portions ; or they are pastes applied alone, or upon some medium which acts as a vehicle. Another class are ordinarily solid, but are brought to a condition of fluidity before inserting them. The properties which should be possessed by a satisfactory canal filling are as follows : Impermeability — it should hermetically seal the apical foramen, effectually preventing the egress of pathogenic organisms or their waste products from the canals to the tissues of the apical region and vice versa, and it should prevent transudations from the apical tissues into the pulp canals. It should be unchanged by the influences about it ; be unirritating to the soft tissues ; and possess sufficient plasticity to permit of its ready adaptation to the walls of the space it is designed to fill. It should be at least aseptic when applied, and pref- erably antiseptic : it is to be esteemed in the degree that it maintains this latter quality in combination with the other desiderata stated. The solid materials which have been employed for this purpose are gold foil, shredded tin, gold, copper and lead points ; carbon points saturated with creosote, wood points dipped in creosote and partially car- bonized cotton wool have been used for this purpose. The readily oxi- dizable metals have not found favor owning to the possibility of dentinal staining following their employment. The plastic materials employed are softened gutta-percha cones and the zinc oxychlorid cement. The latter and also other pastes are frequently employed to fill the meshes of a wisp of crude cotton wool or asbestos fiber, these latter being the vehicle for carrying the paste into position. It is to be remembered that when cotton fiber is kept in prolonged contact with zinc chloric!, the cellulose undergoes a chemical change : it is converted into a pectous substance called amyloid, which is a colorless colloid, unchangeable in the conditions existing at the apex of a pulp canal. Cotton itself may be included among the plastic root fillings. The fluid substances employed are solutions of red gutta-percha base plate in chloroform, constituting the so-called chloro-percha, which contains in this case vermilion ; if made of white gutta-percha it contains zinc oxid and a variable amount of other mineral substances. The other members of this class are salol and paraffin, made fluid by heat before insertion and becoming hard when cool. Gold was the first material adopted for the purpose of canal filling, being introduced in this connection by Dr. Maynard over fifty years 422 THE TREATMENT AND FILLING OF ROOT CANALS. ago. Properly adapted, it may be made to hermetieally seal the apical foramen. It is difficult to manipulate, and its removal after the type of adaptation required is wellnigli impossible. Tin has the same virtues and is open to the same objection, which in fact obtains when any metal is forcibly driven into the apical portion of the canal. It is held, how- ever, and with a measure of good reason, by those who have advocated the employment of metal for this purpose, that when a pulp canal has been thoroughly sterilized and filled, the necessity for the removal of the root filling will never arise. The degree of confidence expressed in this opinion has not yet served to override the caution of conservative operators, so that metals have an extremely limited employment in this connection. The plastic materials most frequently recommended and which sta- tistics and general experience demonstrate to serve most acceptably as canal fillings, are the oxychlorid of zinc and gutta-percha. The zinc cement when in paste form may be readily adapted to any accessible canals, and it maintains during and for some time after set- ting an antiseptic action. The peculiar and specific influence exerted by this material upon the albuminous constituents of the tooth may be seen as a not infrequent sequel to its employment as a pulp capping. Many of such teeth whose pulp chambers have been opened some years after the capping operation are found to have had their pulps changed to a dry tough mass which has not been the seat of septic invasion ; moreover, the normal color of the dentin of such teeth has been main- tained, showing that no extensive chemical decomposition has occurred in the contents of the tubules. As a canal filling it becomes very hard, remains white. Its removal when indicated may be accomplished by repeated applications of sulfuric acid after the Callahan method of open- ing canals. When freshly mixed the oxychlorid paste is markedly irritating to vital tissue with which it is brought in contact, and considerable irrita- tion to the apical portions of the peridental membrane not infrequently follows its use as a canal filling. This irritation, which may be produc- tive of much pain, is due to the diffusion of a portion of the zinc chlorid through the apical foramen before it has entered into chemical combina- tion with the zinc oxid of the powder used in forming the cement. This irritative action, though closely similar in its symptomatology to the early stages of septic inflammation of the apical tissues, does not terminate in suppuration, but subsides after a time varying from a few hours to a day or two, complete resolution taking place in all cases where the canal fill- ing has been judiciously performed. This chemical irritation from the uncombined zinc chlorid may be avoided by first placing a minute pledget MATERIALS FOR FILLING THE ROOT CANAL. 423 of cotton at the apex of the canal, saturated with a mild antiseptic — e. g., creosote, carbolic acid, or an essential oil. When the meshes of cotton are filled with the paste made thin, the zinc chlorid acts upon the cotton, converting it into amyloid ; so that if a pellet of cotton moistened with a sedative antiseptic be placed in the apical portion of a root canal and the thin paste placed over it, the filling of the apex after the chemical action noted consists of the un- changeable impervious amyloid and not of cotton. Long thin gutta-percha cones are readily made plastic, but the adaptation of the material to the walls of the canal is less intimate than is that of the oxychlorid of zinc. It is unchangeable in the conditions under which it is placed, and is the most bland and unirritating of filling materials. Its removal after proper placement is difficult but by no means impossible. The gutta-percha compound known as temporary stopping has similar properties, but is less tough in texture. The last of the plastics introduced is a resinous substance called the balsamo del deserto. It is probably an exudation from one of the varieties of pine or fir. Its virtues and employment were first described by Dr. W. H. White of Silver City, N. M. His experiments indicate 1 that the resin has a pronounced antiseptic action ; the antiseptic value of the material is enhanced in practice by the addition of from 3 to 5 per cent, of oil of cassia, which combination is that which is now furnished by the supply houses. It adheres to wet surfaces, and is perfectly non-irritating to soft tissues with which it is brought in contact. It remains unchanged when employed as a canal dressing. Dr. White finds that the roots of temporary teeth which have been filled with the material suffer no interference with the resorption process because of its presence. Thin solutions of gutta-percha in chloroform (chloro-percha) have wide employment as fillings for fine and tortuous root canals. These solutions may be carried into any canal which will admit the finest broach. They shrink in hardening, so that a canal filling of such a solution does not hermetically seal the cavity when the material is hardened. The solution is usually employed in combination with the gutta- percha cones. Dr. R. Ottolengui l recommends a method which may be followed with advantage : A number of pieces of floss silk about an inch long are saturated with chloro-percha and dried ; these are then thrust in a chloro-percha canal filling while it is fluid. Should it ever become necessary to remove the filling, the projecting end of one of the pieces of silk is caught, and the entire filling may be withdrawn. 1 See International Dental Journal, vol. xv., 1894, p. 690. 2 Methods of Filling Teeth. 424 THE TREATMENT AND FILLING OF ROOT CANALS. The use of salol in this connection was first described and advocated by Dr. A. E. Mascort of Paris. 1 Salol, the salicylate of phenol, is mildly antiseptic. When brought into contact with alkalies it is decomposed into carbolic and salicylic acids, two powerful antiseptics. It melts at 40°C. (104°F.), and if fused at or but little above this heat it crys- tallizes in a few minutes ; if the heat be raised to a higher point crystal- lization is delayed for some time after the mass has cooled far below its normal melting-point. The melted salol may be readily carried into any canal which will admit the finest broach. Portions of the material which may be carried beyond the apical foramen appear to be unirritating. Reports as to the permanence and value of this material vary from enthusiastic endorsement to unqualified condemnation. Many of those who have used salol have found, upon reopening canals which have been filled with it, an absence of the salol ; however, where the practice has been to employ a central canal filling of gutta-percha, a cone of which material is thrust into the melted salol, in such cases its absence has not been observed. Salol has been found to suffer rapid decomposi- tion in canals which have been treated with one of the fixed alkalies just before the salol was inserted. Paraffin has been employed for a canal filling, made fluid by heat and carried into the canals ; it is bland, unirritating, unchangeable, and easily removable. 2 It may be used in combination with salol or thymol, both of which freely dissolve in melted paraffin, conferring upon the mass an antiseptic value, or it may be mixed with aristol, and used as a filling in sterilized canals. 3 Before discussing the cleansing of pulp canals, certain means and methods suggested for avoiding the necessity for the toil and care necessary to mechanically cleanse the more inaccessible canals require consideration. These agents are preservative pastes. Mummification of the Pulp. — As early as the introduction of arsenous ox id as a devitalizing agent it was noted that a certain per- centage — or rather, an uncertain percentage — of cases gave evidence of little or no disease after the application of arsenic and its sealing in a cavity by a filling. Later, it was found that applications of powerful antiseptics to exposed pulps not infrequently were followed by a long- continued quiet of that organ ; still later, when more definite knowledge was possessed of the pathological results which might follow the leaving of portions of pulp substance in the canals of teeth after devitalization by arsenic, it was observed that after saturating the canals with creosote or zinc chlorid solutions, many cases gave little or no evidence of peri- cemental disturbance thereafter. 1 Dental Cosmo*, 1894, p. 352. 2 Ibid. 3 Ibid., June 1897. MUMMIFICATION OF THE PULP. 425 While it is unquestionably preferable to always thoroughly remove the last vestige of devitalized pulps, certain cases involving inaccessible or tortuous canals may present in which the time, care, skill, and expense involved in perfect cleansing are detriments to its universal practice. The only other possible solution of the difficulty is to so alter the tissue not removed that it shall remain permanently aseptic, and, if possible to make it so, antiseptic. Observations derived from clinical experience, although undoubtedly of great and permanent value, are indeterminate, and our truly scientific knowledge of this matter dates from Dr. W. D. Miller's experiments. 1 He credits Dr. Witzel with the first systematic observations in this direction. Dr. Witzel in 1874, "devitalized the crown portion of pulps by means of arsenic, extirpated that portion leaving the pulp in the canals undisturbed, their exposed ends being treated as freshly exposed pulps." This is the method followed by Herbst, who employs cobalt (which is native arsenic sulfid or metallic arsenic) instead of arsenic trioxid. Dr. Miller's experiments have shown that none but the most power- ful and penetrating antiseptics have value as permanent sterilizers. These are : The cyanid, bichlorid, and salicylate of mercury, sulfate of copper, and oil of cinnamon. Orthocresol, carbolic acid, trichlor- phenol ; and zinc chlorid penetrate the pulp tissue rapidly, but are too diffusible, disappearing in a few weeks. He classifies salicylic acid, eugenol, campho-phenique, hydronaphthol, a- and /3-naphthol, acetico-tartrate of aluminum, and some essential oils, resorcin, thallin, sulpho-carbolate of zinc, etc., as being of doubtful value. Those nearly or quite worthless are iodoform, basic anilin coloring matters, borax, boric acid, dermatol, europhen, calcium chlorid, hydro- gen dioxid, sozoiodol salts, tincture of iodin, spirit of camphor, and naphthalin. The preparation giving the best results consisted of — Mercuric chlo- rid, 0.0075 gram ; thymol, 0.0075 gram, in tablet form. The pulp is devitalized ; the crown portion and all the root portion readily accessible is removed ; one of the tablets is placed in the pulp chamber, crushed by means of an amalgam plugger, and covered with gold foil. The mercury salt tends to discolor the crown of the tooth, so that its employment should be restricted to the posterior teeth ; indeed, the necessity for its use would be, as a rule, found with these teeth, being those from which it is most difficult to extract pulp rem- nants. Dr. Miller expresses faith in the power of oil of cinnamon to 1 Proc. Columbian Dental Congress, 1893. 426 THE TREATMENT AND FILLING OF ROOT CANALS. permanently sterilize pulp fragments. He suggests the experimental application of the sterilizing tablets to such teeth as are readily sal- yable yet which are for various reasons " consigned to the forceps." Dr. Theodore Soderberg of Sydney, N. S. W., reports excellent results from a continuous practice of this variety of pulp sterilization. He employs a paste composed of — 1^. Alum exsic, Thymol, Glycerol, . da. 3j ; Zinc oxid, q. s. to make stiff paste. — M. It will be noted that he substitutes dried alum for the tannin, originally used by him as the hardening agent : his experiments showed the tannin to be productive of discoloration. Mercuric chlorid is set aside for the same reason. Oil of cassia employed in the paste also caused discoloration. At present Dr. Soderberg adds a small quantity of cocain to the paste to prevent the pain arising from the action of the dried alum. He states (Nov. 1895) that he has in a year applied the paste in 97 cases and has had no untoward results. The method of placing the material is shown in Figs. 387, 388. Fig. 387. Fig. 388. a, Caries exposing a horn of the pulp. a, Root portion of pulp ; b, mummifying paste ; c, zinc phosphate ; d, gold or amalgam. C. A. Firth of Queenleyan, N. S. W., 1 advises the omission of zinc oxid from the paste, to avoid the formation of the brown tannate of zinc. He suggests the use of a mixture of tannic acid and thymol equal parts, made into a paste with glycerol and applied with ivory instruments, to avoid discolorations. He expresses himself as gratified at the results obtained. Another formula suggested by the same gentle- man is — 1 Dental Cosmos, May, 1896. MUMMIFICATION OF THE PULP. 427 DESCRIPTION OF FIGS. 389, 390, AND 391. Fig. 389.— Fig. 3 gives in contrast a sectional view of deciduous and permanent upper teeth divided through their lateral diameters. Fig. 4, a sectional view of the corresponding lower teeth divided through their antero-posterior diameters, a, b, c represent, respectively, the deciduous and permanent front incisors in con- trast : d, e,f, the lateral incisors; g, h, i, the canines; k, deciduous molars, upper and lower; and I, m, the successors to the deciduous molars, the bicuspids ; n, o represent permanent molars. c, /, i, m, o have dotted lines indicating the thickness of enamel removed by wear, atrophy of the cementum, and reduction in the size of the pulp due to progressive calcification, these changes being incident to old age. Fig. 390 represents in Fig. 1, letters a to h and a_to^, the longitudinal or vertical sections of the sixteen upper teeth, showing the labio-palatal diameter of the pulp chamber and canal in crown and roots, the section of the molars being through the anterior buccal and palatal roots, while«the bicuspids d e and d e illustrate the result of such a compression of the root as to divide the pulp chamber into two canals— a condition which so frequently exists in these flattened roots. The double-lettered series, d d to h h and d d to hh, represent in the molars a section through the posterior buccal and the palatal roots, from which is quite readily recognized the slightly greater lateral diameter of the pulp chamber in the crown and the larger canal in the poste- rior buccal root over that in the anterior buccal root, while the bicuspids lettered eedd and ddee illustrate a modified pulp chamber and canal, with bifurcation of the root in one, these being cut through a different axis or plane from the single-lettered series. Fig. 2, letters a to h and ato A, represent the sixteen lower teeth with the section through their long diameters, as in the upper series. These incisors illustrate the compressed or flat- tened condition of their roots in contrast with the cylindrical character of the roots of the upper incisors, while the bicuspids d e and d_e illustrate the singleness of their pulp chamber and the cylindrical condition of their roots as in contrast with the flattened or compressed condition of the roots of the upper bicuspids. The molars /, g, h and f, g. h represent sections through the anterior root, illustrating its compressed condition and divided pulp chamber in the first and second molar, and a somewhat flattened one in the anterior root of the third molar ; //, g g , h h and //, g g, h h represent the single and cylindrical pulp chamber in the posterior root of the lower molars, while bb, cc and aa.bb represent the incisors and canines of the same series, with modified pulp chambers arising from modified development. Fig. 391.— Fig. 1, from a to h and .a to hj represents the upper teeth, with transverse or horizon- tal section through the base of the pulp chamber in the crown, viewing the entrance to the canals of the several roots, while the same letters in Fig. 2 represent the lower series in the same manner. Fig. 3 represents the upper teeth, with the transverse or horizontal section made below the largest diameter of the pulp chamber and through the canals after they have diverged from the central chamber, but before the roots into which they run have in the molars bifurcated. Fig. 4 in like manner represents the lower series, well illustrating the flattened or compressed condition of the canal in anterior roots of the molars and the division of the chamber, as is fre- quently found in the roots of the lower incisors. The letters aa,bb,cc,d d,ff, d_d and_e_£ (Fig. 3) represent the relative shapes, whether circu- lar, oval, or flattened, of the pulp canal in the roots of the upper central and lateral incisors, the canines, the first and second bicuspids, and the first, second, and third molars, while the same letters in Fig. 4 represent the relative shapes of the pulp canal in similar teeth in the lower series. 1 These figures are taken from v. Carabelli's Anatomie des Micrides. Fig. 389. (For description, see page 427.) 428 Fig. 390. (For description, see page 427. ) Fig. 391. (For description, see page 427.) a& L 'V'Hr- ,Q ^ - »> CO 7 h & u / * /• h 9 i &6 jr bfj / 430 FORMS OF PULP CHAMBERS AND CANALS. 431 1^. Mercuric chlorid, Thymol, Acid, carbolic, Acid, tannic, Morph. inur., Ol. menth., 01. cassise, da. 2.0 grams ; da. 1.5 gram ; da. q. s. to make stiff paste. — M. " A tannate of mercury is formed ; it is insoluble, and but little pain is caused by its absorption." It is to be understood that these preparations and this method of pulp preservation are only to be utilized when conditions exist which would preclude the perfect cleansing and filling of canals. These may be economic or the impracticability of thoroughly extirpating all pulp remnants. Failing in perfect extirpation, the paste is to be packed into parts where the irremovable pulp remnants exist. Formalin and its isomeric modification, paraform, have been used as mummifying agents, with reported satisfactory results, but the use of these substances as mummifying agents is still in the stage of experi- mental study. The irritating nature of formalin suggests caution in its permanent application to pulps or pulp canals, as several cases of chemical necrosis of tissues about the teeth have been reported from the injudicious use of the drug in question. Topographical Anatomy of the Pulp Chambers and Canals. A familiarity with the topographical anatomy of pulp chambers and canals is an essential preliminary to their proper opening and cleansing. Figs. 389, 390, and 391 (see pp. 428-430) illustrate the average pulp- chamber forms. The following outline figures (Figs. 392-427) are exact reproductions Fig. 392. Fig. 393. s & Upper central incisor. Upper lateral incisor. of sections made of typical teeth which have been shown by comparison with numerous other sections to be about the average anatomical forms. The Upper Central Incisor. — The pulp chamber (Fig. 392) approxi- 432 THE TREATMENT AND FILLING OF ROOT CANALS. mates in form that of the tooth itself. The opening of the canal is seen to be almost circular, and in the central axis of the tooth. Upper Lateral Incisor. — The chamber of the lateral incisor (Fig. 393) has a similar form ; the canal exhibits a tendency to diverge from the Fig. 394. Fig. 395. Ftg. 396. Upper lateral incisors (Ottolengui). straight line toward the apical end (see Figs. 394-396). The entrance to the canal is nearly oval. Upper Canine. — The chamber of the upper canine is large and open and has an elliptical canal entrance (Fig. 397). The root of this tooth Fig. 397. Fig. 398. Fig. 399. Upper canines. may also deflect from the line of the general axis. In rare cases a bifurcation of the root is seen (Figs. 398, 399). Fig. 400. Fig. 401. Fig. 402. Upper first bicuspids. The upper first bicuspid very commonly exhibits a bifurcation of the roots which may extend to any distance toward the crown (Fig. 400). At its entrance the pulp canal has a dumb-bell form, the handle of the dumb-bell being much attenuated. The distinct canals may begin almost at the base of the chamber, or be evident only near the apices FORMS OF PULP CHAMBERS AND CANALS. 433 of the roots. Two distinct canals maybe present even in the absence of bifurcation of the root. The roots of this tooth may be much curved. Fig. 401 presents a condition occasionally seen : a trifurcation of the root of a bicuspid. Fig. 402 represents a section through the buccal roots ; Fig. 402 also shows the neck section of the tooth. In the same mouth were found three bicuspids exhibiting the same condition. The bifurcated cuspid, Fig. 399, was from the same denture. Upper Second Bicuspid. — Sections of two typical forms of upper second bicuspid are shown in Fig. 403, a and b. In such a case as b — far from uncommon — it will readily be seen what dangers exist as to the difficulty of perfectly filling the flat general canal beyond the ellip- tical obstruction. The neck section in both types is almost alike. Upper First Molar. — The neck section of the upper first molar Fig. 403. Fig. 404. Upper second bicuspid. b a Upper first molar. (Fig. 404, a) shows a free entrance to the palatal root; the anterior buccal root has a triangular entrance, near the mesio-buccal angle of the tooth. The entrance to the disto-buccal root is very small; b, Fig. 404, shows a section through the buccal roots of the tooth. Cases are occasionally seen where a short crown is associated with very long and divergent roots (Fig. 405). Fig. 405. Fig. 406. Fig. 407. Upper molar. a b Upper second molars. Upper Second Molar. — The arrangement of canals in the second upper molar (Fig. 406, a) is much like that in the first; except that the tooth has a compressed form which brings the canal entrances closer together. A section through the buccal roots is seen in Fig. 406, b. This tooth occasionally presents marked aberrations in the location and 28 434 THE TREATMENT AND FILLING OF ROOT CANALS. distribution of pulp canals. Fig. 407 illustrates a case in which there was a trifurcation of the palatal reot. Other abnormalities of the canals of upper molars are shown in Figs. 408-413 (Ottolengui 1 ). Fig. 408. Fig. 409. Fig. 410. Fig. 411. Fig. 412. Fig. 413. Upper molars (Ottolengui). Upper Third Molar. — The three roots of the upper third molar are frequently compressed together, giving the external appearance of a Fig. 414. S Upper third molars. single round conical root. In many instances there will be found but a single large canal, as in Fig. 414, a. The rule is three canals, as Fig. 416. Fig. 417. ® Lower incisors and canine. shown in Fig. 414, 6, which shows also a section through the buccal roots. The root is generally curved backward more or less. 1 Methods of Filling Teeth. FORMS OF PULP CHAMBERS AND CANALS. 435 Loicer Anterior Teeth. — The forms of the canals and canal entrances to the lower anterior teeth are shown in Figs. 415-417. The form of partial canal bifurcation shown in Figs. 416 and 417 is noted frequently in longitudinal sections of typical teeth. Lower Bicuspids. — The forms of the canals in the lower bicuspids are much alike ; the canal of the first, however, exhibits a tendency to the dumb-bell form of entrance (Figs. 418, 419). Tortuosities of the Fig. 418. Fig. 419. Lower first bicuspid. Lower second bicuspid. canal are far from uncommon, many of them of such nature as to ren- der full and complete entrance to their ends next to impossible ; in Fig. 420. Fig. 421. Fig. 422. Lower bicuspids. Fig. 420 the root was of corkscrew form, in Fig. 421 bent at right angles, and in Fig. 422 a short crown is associated with an extremely long and bent root. Lower first molars. Lower First Molar. — The lower first molar usually presents two canals : a large open canal for the posterior root, as seen in Fig. 423, a and b, while the anterior root presents a flat ribbon-like canal very 436 THE TREATMENT AND EILLING OF ROOT CANALS, difficult of entrance. A transverse longitudinal section of the ante- rior root is shown in Fig. 423, c. In order to effect an entrance to the majority of these canals, it is absolutely essential that the rubber dam be applied and the tooth well dried. ' A section through both roots is shown in Fig. 423, b. Not uncommonly two distinct anterior canals are found, and in rare instances two distal roots may be present, as shown in Fig. 423, d. The roots of this tooth, as those of the other lower molars, as a rule, bend backward. Fig. 424 (from Ottolengui) shows an exaggeration of this bending. This tooth not infrequently requires canal treatment before the roots are fully formed. A section through the anterior half of an immature Fig. 424. Fig. 425. Lower first molar. a b Lower first molar, immature. tooth is shown in Fig. 425, a; through the posterior half, Fig. 425, b. Lower Second Molar. — A section of the lower second molar resem- bles that of the first, but distinct double canals in the anterior root are more frequently seen, as shown in the section of the anterior half in Fig. 426, a) Lower Third Molar. — In the lower third molar the roots are fre- quently compressed together, exhibiting bifurcation toward their apices (Fig. 427). Fig. 426. Fig. 427. Lower second molar. Lower third molar. The canals of any tooth may exhibit constrictions or flexions at any points of their lengths. Although there is no absolute indication as to the presence of flexions or abnormal lengths, an examination of the overlying gum should always be made, when lengths and irregularities may possibly be determined if the gum tissue and alveolar wall be very INSTRUMENTS FOR CANAL TREATMENT. 437 thin. If any of these irregularities be present it is important that they be discovered and additional care be taken to effect a complete entrance to the canals. Instruments for Canal Treatment. The description thus far has included the territory to be operated upon and its condition as regards sepsis, the agents commonly employed to produce asepsis and antisepsis, and those applied to maintain these conditions. The first, the condition of the root canals and dentin ; the second, the various antiseptics employed therein ; the third, the several materials used as canal fillings. The next study includes the instru- ments employed and their specific applications. The first are enamel chisels. These are employed to cut down weak unsupported enamel walls and those portions of enamel removable by such instruments, which interfere with direct access to the pulp canals. The next, burs, of several forms ; the first, that variety known as the " den- tate fissure bur," for cutting enamel ; next rose, inverted cone, and oval forms for enlarging cavities and removing infected dentin. Next, several forms of broaches, canal cleansers, and probes, Gates-Glidden reamers for enlarging canals ; syringes, pluggers, and finally rubber dam and the appropriate selection of clamps. In relation with this latter device, it is to be recalled that demon- strations have shown the saliva to be a highly infective fluid, for the reason that it contains a variety of pathogenic organisms which must be excluded from pulp canals if asepsis of these passages is hoped for. No other single means serves so effectively as isolation by the rubber dam. A variety of syringes will be required, a large instrument for .irriga- tion (Fig. 428), to wash away loose debris which may be present in the cavities ; smaller syringes will be required to accurately place definite quantities of medicaments in canals (Figs. 429, 430, and 431). Dentate fissure burs are invaluable instruments for removing por- tions of sound enamel walls which interfere with direct access to the root canals. Cutting from within outward, giving the bur a sawing motion, a groove may in a few minutes be extended across the occlusal face of a molar from a distal cavity to a point directly over the ante- rior root. Large rose, inverted cone, and oval burs are employed to remove the dentin which may obstruct direct entrance to the canals ; these are as a rule to be used with a draw-cut, placed first in the deepest portion of the cavity, and while revolving drawn toward the operator. Care is to be exercised that no more than necessary of the walls, particularly the floor of the pulp chamber, is to be burred away, to avoid mechan- ically weakening the tooth. 438 THE TREATMENT AND FILLING OF ROOT CANALS. The broaches employed are of several forms. A broach is, accurately speaking, an instrument designed to enlarge openings; so that the Fig. 428. Fig. 429. Fig. 430. Dental syringe. o Minim syringe. J. N. Farrar's alveolar abscess syringe. barbed nerve broach is not employed as a broach but as a pulp-extrac- tor (Fig. 432). They and other forms of extractors (Fig. 433) are used to loosen and remove debris from canals. INSTRUMENTS FOR CANAL TREATMENT Fig. 431. 439 Bulb syringe. The toughness of these instruments is remarkable. They are so tem- pered that they can be bent in any desired direction and when properly manipulated will readily follow a small and crooked canal to the apex without danger of breaking off. Two forms : with sharp hooks, for Fig. 432. Barbed pulp-extractors and holder. removing the pulp ; and straight, with the ends slightly roughened, for carrying a shred of cotton in cleansing out the canal or treat- ing alveolar abscess. The next instruments employed in this connection are what are known as Donaldson's pulp-canal cleansers (Fig. 434). The points of these palp-canal cleansers are reduced so as to enter the canal readily, and the barbs, which are cut of just sufficient depth to accomplish their work, are arranged spirally around the shaft, in effect forming a screw, so that no two cuts are exactly opposite each other (see enlarged view, a, Fig. 434). With ordinarily careful usage these cleansers will remove the pulp substance perfectly, without liability to be broken or to become fastened in the canal. If at any time the instrument does not withdraw readily from the root, a turn or two to the left (unscrew- ing) will at once release it. They are made of tough steel piano-wire, with polished vulcanite handles ; also without handles, to be used in broach-holder. The enlarged view of the Gates-Glidden nerve-canal drill (Fig. 435) shows the peculiarity of the safety Glidden-point, which will not 440 THE TREATMENT AND FILLING OF ROOT CANALS. Fig. 433. Fig. 434. Dr. Donaldson's pulp-canal cleansers. m Dr. Donaldson's spring- tempered nerve-bristles. s enlarge the canal, but will merely guide the drill into a canal no wider than itself, until it reaches the root-apex, through which only the sharp point will pass, and produce a sensation of pain that gives notice of its protrusion ; yet, unless the foramen is wider than the base of the guide, the Gates drill will not cut through the end of the root — a danger that the improved drill is specially designed to avoid. The reamers are made with their thinnest part near the junction of shaft and stem, so that should fracture of the tool occur, a long piece will be left protruding from the tooth and may be readily withdrawn. Using the series, one after the other, with care and judgment, even a tortuous canal may be suitably enlarged ; but it should be kept in mind that many roots are thin at their apical portions, and their canals, if much enlarged, may be cut through laterally; hence the advisability of employing usu- ally the smaller sizes of drills, and always the smallest first when the canal is narrow. There is a diversity of opinion as to the wisdom and propriety of using reamers of any kind in pulp canals. They are con- demned in toto by some operators ; others advise their employment in all cases. Fig. 435. Improved Gates-Glidden nerve- canal drill for engine work. THE CLEANSING OF CANALS. 441 The Cleansing of Canals. The student has been made familiar with the pathological conditions he is called upon to treat, and with his armamentarium, including the medicinal agents employed in their correction, and is now prepared to apply the one to the other. It is most apropos at this juncture that the arguments for and against the reaming of root canals should be reviewed. The valid objections urged against reaming as a routine practice are, first, the danger of encroachment upon the cementum by the reamer ; second, the breaking of the delicate reamers in the canal and the difficulty and often impos- sibility of removing the fragment when such accident occurs ; third, the liability of forming false canals by inability to confine the drill to the anatomical canal. The argument advanced in support of the practice is the direct and ready access attained by it to the length of the canal. Owing to the fineness and tortuosity of many canals it is impossible for the operator to assure himself that he has thoroughly cleansed and filled them ; by accurately and properly reaming the canals directly accessible to fine reamers they are given such form that a filling may be placed with a reasonable assurance that the apex is hermetically sealed. It is urged that as many roots — notably the anterior roots of lower molars, the anterior buccal roots of upper molars, the roots of upper bicuspids and of lower incisors — have a flattened form, their pulp canals have a ribbon form. In reaming such canals there is danger of the reamer impinging upon the cementum at the thin portion of the root. The advocate of root reaming, therefore, advises in such cases the employ- ment of Donaldson's canal cleansers to scrape away the canal walls, enlarging them uniformly. The danger of breaking reamers is always an imminent one, al- though such accidents are commonly due either to poorly made or imperfectly tempered instruments, or to carelessness upon the part of the operator. Even the most skilful must be ever on the alert to detect any unusual resistance offered to the advance of the reamer. This danger increases if the direction of the canal diverges from a straight line. It is obvious that with any instrument which is being rotated, its point must be kept in line with its shaft to minimize the strain on the part immediately above the cutting portion. The employment of reamers is therefore advised only in nearly straight and rounded roots ; the central idea to keep in mind is that reamers are employed merely to uniformly enlarge canals which already exist, never to form new ones. Root canals which have a flattened form are en- larged by means of the cleansers, using progressively increasing sizes, and supplementing their action where and when necessary with sulfuric 442 THE TREATMENT AND FILLING OF ROOT CANALS. Fig. 436. acid, as advised by Dr. J. R. Callahan. 1 This method is of great value ; it furnishes a means for entering and thoroughly cleansing and enlarg- ing canals which before its introduction were regarded as impossible of entry. It has no doubt been observed by every operator, how seldom roots which have been well prepared for artificial crowns of the post variety become the seat of pericementitis. This fact sug- gests that the mechanical removal of the existing boundary walls of the root canals, by removing those portions of dentin invaded by septic organ- isms may lessen the opportunity of sepsis. Miller has shown 2 that this infection of dentin about canals is, as a rule, superficial (Fig. 437). The observations made in the essay of Dr. Miller show also that any danger to the lateral peri- cementum by invasion of the dentinal tubules leading from the root canal is remote in the extreme. Infection to some depth does occur, however (Fig. 436). It is undisputed that the source of septic infection of the pericementum is from the canals by way of the apical foramen, Fig. 437. Fig. 4S6— Sector of a cross section from a diseased root : a, cement ; &, stratum granulosum ; c, very narrow and finely branched tubules ; d, infected district. (X 150.) Fig. 437.— Dentin from the root of an abscessed tooth, showing the penetration of cocci to a depth of about r \y mm. (rf ff in.). The side a-b bordered upon the canal. (X 1000.) 1 Proc. Ohio State Dental Society, 1894. Dental Cosmos, 1890, p. 353. THE CLEANSING OF CANALS. 443 and if the tract there represented be made aseptic no trouble need be feared. As the object in all succeeding operations is to remove and not to institute a septic condition, care must be exercised that no septic organ- isms be introduced by the operator into the field of operation. The first step is therefore the rendering aseptic of this field. The teeth should be cleansed first with a brush and soap, then the mouth be rinsed with an antiseptic, as 3 per cent, pyrozone, 10 per cent, solution of meditrina, or a lilac-colored solution of potassium permanganate. The instruments are to be sterilized, and to effect this object an excellent means is by dipping the mechanically cleansed instruments in strong ammonia water. 1 If any food or pulp debris occupy the pulp chamber it is to be washed away with the antiseptic employed to sterilize the mouth. The rubber dam is adjusted, and direct sterilization of the canals, and, when indicated, of the tissues at the apex of the root, is to be attained. Method of Entrance to Canals. — The first step or stage of the operation is the gaining of direct and free access to every canal of the tooth. This may at times appear to involve the removal of an undue amount of the crown of the tooth. Unfortunately this is true, but efforts at the conservation of too much of the crown structures and form are frequently followed by incomplete cleansing and filling of the canals. This latter is the greater evil of the two, so the cutting away of the crown is always to be done when necessary to accomplish the end in view. In the vast majority of cases in which it is necessary to remove a putrescent or septic pulp the carious process has invaded the crown of the tooth extensively ; the cavity of decay is therefore excavated until perfectly free from carious dentin ; weak enamel walls are dressed away by means of enamel chisels, and usually direct access to .the pulp chamber is gained. This is still insufficient ; the cavity must be opened so that the finest size of canal bristle can be carried directly to the apex of the root without danger of fracturing the instrument. In central incisors, as the carious cavities usually open upon the approximal surfaces, entrance is gained to the pulp chamber by extend- ing at the palatal aspect of the cavity a groove from the cavity to over the entrance of the pulp chamber (a, Fig. 438). The same rule is observed with the lateral incisors and canines. Should the pulp have died subsequently to the insertion of fillings which are mechanically faultless, entrance to the pulp canal is made in the basilar pit (b, Fig. 439). For canines the opening is made at a higher point, about one-third the way toward the cutting edge. These openings, while they should be large enough to afford free access to the 1 See also Chapter IV. 444 THE TREATMENT AND FILLING OF ROOT CANALS. canals, should not be made so large as to weaken the crown, or there is danger of fracturing it when in physiological use. Cavities in bicuspids invading the pulp are usually upon the ap- proximal surfaces ; they are to be extended over the occlusal face of the tooth until access to the canals may be had (see Fig. 440). Fig. 438. Fig. 439. Fig. 440. Fig. 441. a c Cavity in bicuspid. The same procedures are to be followed in molar teeth. In lower molars if the carious cavity be upon the distal wall, it is to be artificially lengthened across the occlusal face until the probe may be carried directly into each canal (Fig. 441, a); the same method is pursued, if for a mesial cavity. In upper molars, especial care is required to gain primary access to the anterior buccal root, and tooth structure must be cut away until this access is secured (Fig. 441, 6). Should the carious cavities open upon the buccal faces of the posterior or lingual faces of the anterior teeth, the upper cavity edge, that farthest from the gum, must be extended toward the cutting edge of the tooth until a bent probe may be readily passed to the apex of each root (Fig. 441 , c). In operating upon many, or most, of the canals of the posterior teeth it is necessary to bend the pulp extractor or canal cleanser until it is almost or quite at a right angle with the instrument carrier. In the six anterior lower teeth where openings are to be made in them in the absence of large cavities of decay, entrance is effected through the lingual wall. The advice of Dr. J. Foster Flagg is appended, as to the position of tap openings to be made in the several teeth, when the teeth if carious have not the carious cavity in such position as to afford access to the pulp chamber : " By means of a diamond drill or an inverted cone bur, a rough spot is made in the centre of the face to be perforated ; this prevents slipping of the spear-pointed drill which is then employed to enter the pulp chamber. The outlines of the chamber are to be obliterated with burs." The dentate bur is a most effective means of enlarging such openings. " The opening is to be enlarged until a fine probe may be TREATMENT OF CANALS. 445 passed into each canal ; the teeth are tapped in the following sit- uations : Upper Teeth. — Centrals and laterals : On the lingual face. Canines : On the tuberosity, or disto-labially. First or second bicuspids : On occlusal or buccal face. First molars : On occlusal, or, as a second choice, on buccal face. Second molars : On occlusal, mesio-occlusal, or buccal face. Third molars : On mesio-occlusal face. Lower Teeth. — Centrals and laterals : On lingual face just posterior to cutting edge. Canines : On disto-labial portion near the gum. Bicuspids : On mesio-buccal face. First, second, and third molars : On mesial, buccal, or mesio-occlu- sal face." Treatment of Canals. The tooth and adjacent teeth being isolated by the rubber dam, direct access to each canal having been gained, the tooth having its walls sterilized by flooding the enlarged pulp chamber with a reli- able germicide, and each instrument which has been or is to be used being sterilized, the subsequent procedures depend entirely upon the condition of the pulp chamber, canals, and dentin (and perhaps the peri- cementum), as regards sepsis. One of the several conditions described in the opening of the chapter is present ; which of these it is, governs the therapeusis. First : A case in which the pulp has been intentionally devitalized and extirpated. The pulp having been removed en masse it has carried with it, provided of course no organisms have been introduced during or subse- quent to its extirpation, all of the sources of infection. The remote danger is now the existence of small fragments of pulp tissue which if unremoved may form a soil for the development of organisms obtain- ing entrance to them ; or blood may have escaped into the canals where the dead pulp was torn from its connection at the apex. The hemorrhage may be reduced to a minimum and the operation of pulp extirpation in most cases be rendered quite bloodless by the use of one of the various preparations of suprarenal extract in combination with the local anes- thetic as an application to the pulp tissue previous to its removal. 1 Where, however, any exudation of blood or plasma takes place, it must be removed along with any remaining organic debris. Hydrogen dioxid, being the agent which will most quickly and effectively disorganize the blood corpuscles, is carried into the canals and permitted to act for a few minutes, when it is absorbed by means of 1 See Chapter , p. 446 THE TREATMENT AND FILLING OF ROOT CANALS. cotton, or taper twists of bibulous paper ; then canal cleansers, beginning with the smaller sizes, are employed to scrape the walls of the canals free of any adherent pulp shreds or odontoblasts which may have been torn off when the pulp was removed. Larger sizes are to succeed these until the caliber of the canal is made larger and smooth. If it be a round root and there be any interference with the passage of these instruments to the apex of the root, it is evident that the same difficulty would be found in carrying filling material to its apex. A judicious reaming of the root removes this difficulty and is therefore done. That size of the Gates-Glidden reamer which will enter the canal readily is revolved by hand, or, if in the engine, is revolved very slowly, stopping the moment any resistance is felt. The reamer is frequently withdrawn to remove the debris which collects behind it. As soon as resistance is felt, a fine canal cleanser is passed beyond the point and the walls scraped, when the reamer is reapplied ; this alternation of instruments is continued until sensitivity shows that the point of the reamer has reached the pericementum. The next size of reamer is then employed to enlarge the canal uniformly. As soon as a canal is reamed a tem- porary dressing of alcohol on cotton is placed in it to prevent the ingress of debris from other canals — that is, if it be a tooth having two or more roots. In upper molars, the palatal, and in lower molars the distal, root is to be first cleansed and dressed. If the subject of operation be a single-rooted tooth, preparation is now made for hermetically sealing the apex and filling the canal ; if a multi-rooted tooth, the canal next in size is entered if the root be round as evidenced by the general shape of the canal. For example, the anterior roots of lower molars, the buccal roots of upper molars or of bicuspids, which exhibit a round opening, have usually but not always a rounded body ; those showing a ribbon-like out- line are likely to have a corresponding outward form. Any efforts at reaming such canals should be confined to that portion showing a rounded opening ; thus, if a lower molar, the finest reamer, rotated by hand, the device of Dr. W. W. Walker (Fig. 442), is employed to enter and enlarge the buccal and lingual extremities of the ribbon-like canals. Any further enlarging should be done with the canal cleansers. The same rule applies to the buccal roots of upper molars and to bicuspids. When any doubt exists, the enlarging should always be done with the cleansers instead of the reamers. Not infrequently cases are found in which the root canals, or one Fig. 442. Walker pulp-canal reamers. TREATMENT OF CANALS. 447 of them, may have such contracted caliber as to refuse entrance to the finest canal cleansers. As a rule, such canals will be found in the buc- cal roots of upper molars and the anterior root or roots of lower molars ; occasionally the bicuspids, particularly the upper first bicuspids, will exhibit this condition. It is in such cases that the method of cleansing and enlarging introduced by Dr. Callahan will be found effective. A rose bur is employed to form a small pit of which the entrance of the pulp canal is the centre. In this pit a drop of sulfuric acid, 50 per cent, solution, is placed ; immediately upon the contact of the acid the finest size of Donaldson canal cleanser is passed as far as it will go into the canal, the cleanser is inserted and partially withdrawn, scraping away the calcium sulfate formed by the action of the acid upon the cal- cium salts of the tooth. The acid is quickly neutralized and fresh applications are made drop by drop, the scraping and pumping with the cleanser being continued until the point of the instrument is felt to reach or pass the apical foramen. Any organic matter, such as filaments or minute fragments of pulp tissue, which may have been present in the canal is destroyed. This applies also to organic matter undergoing de- composition or to organisms which may be present. As there is no marked degree of force required in the operation it may be pursued even in cases of pericementitis or acute abscess, to gain direct and free entrance to the seat of morbid action, the focus of germ development. In the event of the operator being unable to detect through instru- mental means the openings of minute canals, Dr. Callahan advises that a pellet of cotton containing a minute portion of acid be placed over the probable situation of each canal and sealed in over night. The follow- ing day, when the rubber dam is applied and the cavity dried, the spot of application of acid will be represented by a small white area, in which, if a canal entrance exist, it will be represented by a black dot. A pit is made at this point and acid is applied, when entrance by cleansers is attempted ; should failure to gain entrance result, it is most probable that the canal is almost or quite obliterated with secondary deposits formed by a receding pulp, hence no future sepsis is probable. As soon as the cleanser is felt to touch or pass the apical foramen the canals are syringed out with a saturated solution of sodium bicarbonate. Carbon dioxid is disengaged, which drives the debris left in the canals into the pulp chamber, and the acid is neutralized. Thus far has been described the entrance to and thorough cleansing and uniform enlarging of canals of a tooth from which the intentionally devitalized pulp has been extracted ; the immediate question is, What treatment shall now be pursued ? Owing to the method of pulp with- drawal, the contents of the dentinal tubules are as yet chemically un- changed ; and it scarcely requires argument to demonstrate that, can 448 THE TREATMENT AND FILLING OF ROOT CANALS. they be kept in a stable condition, they constitute the best material for occupancy of the tubules. Examining the list of medicaments applica- ble as preservatives zinc chlorid is the agent fixed upon as the one which will best procure an unchangeable condition of the contents of the tubules. The experiments of Prof. Jas. Truman l have shown that this agent quickly diffuses through a capillary tube containing albumin, converting it into a whitish coagulum, an albuminate of zinc, which every anatomist knows to be one of the most efficient of all preserva- tives. Anatomical specimens of parts injected with a zinc chlorid solution, and which have been subjected to all the conditions known to favor the development of putrefaction, remained unchanged after the lapse of years. It is advised, therefore — advice endorsed by a majority percentage of operators — that a solution of zinc chlorid be now placed in each canal. A twist of absorbent cotton is dipped in a solution of the salt. Should the apical foramen be large, a weak solution, about 10 per cent., is employed ; if fine, the strength of the solution may be 40 per cent. Unless carelessly manipulated or too great an excess of the coagulant be employed there is but little danger of forcing the solu- tion beyond the apex of the root. After about ten or fifteen minutes the application is withdrawn and cotton or paper cones passed in the canal to absorb any excess of the chlorid which may be present, and the canals are now ready for filling. The use of formalin as an ingredient of pulp-mummifying pastes has already been referred to. (See p. 431.) Caution in its use for that pur- pose was suggested because of the marked destructive effect which it has been observed to produce upon living tissue when applied in sufficient concentration or in considerable quantity for an extended period of time. As a topical application to root canals, its activities can be controlled with more certainty than when it is permanently sealed into a canal as an ingredient of mummifying paste. Formalin is the proprietary name for a 40 per cent, aqueous solution of the gas formic aldehyd or formaldehyd, CH 2 0. It is a powerful diffusible antiseptic and possesses the property of tanning or hardening proteid substances, forming with them insoluble compounds which appear to possess persistent antiseptic properties. For rendering the contents of the dentinal tubuli sterile, fixed, and unchangeable, formalin may be classed as fully equal in value to zinc chlorid, while for the treatment of infected dentin and of cases where infective invasion has reached beyond the apical foramen to the periapical tissues, the diffusibility of formaldehyd gives it a decided advantage over all other sterilizing agents. 1 Proc. Academy of Stomatology, Philadelphia, 1894. THE ROOT-CANAL FILLING. 449 In cases of non-infected canals where the vital pulp has been surgi- cally extirpated, the previously cleansed canal may be wiped out with a broach armed with cotton which has been moistened with a 10 per cent, solution of formalin and then be followed by immediate root filling with safety. Where, however, the medicament is to be left in situ as a canal dressing, as in the case of an infected canal following the removal of a putrescent pulp, a much more dilute solution should be employed. One to 2 per cent, formalin solution in quantity no more than sufficient to dampen the cotton dressing may be loosely sealed in a septic canal with- out danger of producing undue irritation, and one such application is in many cases all that will be required to effect thorough disinfection of the root canal if uncomplicated by chronic apical disturbance. The per- centage solutions here advised are to be understood as centesimal parts of the 40 per cent, aqueous solution of formaldehyd known as formalin, and not as percentages of the gas itself. The Root-canal Filling. When oxychlorid of zinc has been determined upon as the perma- nent canal filling, the preliminary treatment of the canal w T ith zinc chlorid solution is superfluous, as the coagulating and antiseptic action of the zinc chlorid used in making the oxychlorid cement fully answers the purpose in the short period of time elapsing before chemical com- bination of the fluid and powder results in a hardened body. Examining the available statistics regarding the several materials which have been employed for canal filling in such cases, there is found a greater percentage of success — that is, a fewer number of cases pres- ent subsequent evidences of sepsis — when zinc oxychlorid has been used. This is quite in accord with rational therapeusis ; the material is capable of hermetically sealing the apex and is unchangeable in the conditions surrounding it. Its antiseptic action probably plays little or no con- tinued part, disappearing shortly after the material sets ; it is, however, indisputable that when this material has been employed as a pulp cap- ping it has not infrequently converted the entire pulp into a hyaline coagulum which has remained permanently aseptic. This material is mentioned first on account of the ease, readiness, and certainty with which it may be placed. Gutta-percha ranks second in point of favor as a canal filling ; this not on account of any deficiency of specific properties contraindicating its use, but there is not the same certainty of accurate placement and hermetic sealing as with the oxychlorid. Gold and tin, the remain- ing materials which have found any extensive employment in such cases, are open to the same common objection, viz. difficulty of manipu- lation. 29 450 THE TREATMENT AND FILLING OF ROOT CANALS. These are the practically irremovable materials. The removable materials which have been recommended are, first — Cotton. — It is due to Prof. J. Foster Flagg that this substance has been extensively employed, not as a filling material per se, but as a medium holding an antiseptic. The variety of cotton employed is the crude uncarded cotton wool. Dr. Flagg cites as a proof of the imper- meability of this material when properly packed, that bales of cotton which have floated in sea-water for long periods, when opened show no evidences of moisture in their interior. Evidence regarding the value and danger of this material is con- flicting. It is asserted by the advocates of cotton canal fillings that, properly inserted, they remain unchanged for long periods, are readily packed into position, and if necessity demand may be readily removed. Those who oppose the use of cotton assert that it soon becomes filled with products of decomposition, and that after some years the texture of the material is destroyed, rendering its removal very difficult. In consequence of these conflicting opinions, the weight of evidence being with those who oppose its use, cotton has found but limited endorsement. The other removable materials, salol and paraffin, are innovations too recent to determine their value and position as canal fillings. The reports regarding salol are sufficiently conflicting to warrant advising its use only in conjunction with a central mass of gutta-percha or tin points ; the salol filling the space between the gutta-percha or metal point and the walls of the canal. These are the arguments for and against the several materials ; the Aveight of evidence being largely in favor of, first, the oxychlorid of zinc ; and second, gutta-percha. The question is, now, When shall the canals be filled ? Shall it be done immediately, or shall a period be permitted to elapse for assurance that no inflammatory action shall arise and the filling be a bar to its prompt reduction ? There are two causes which might be productive of inflammatory action : First, the dental manipulations of removing the pulp and cleansing the canals might be productive of sufficient irritation to give rise to inflammatory reaction ; in that event the open canal would afford an escape for inflammatory effusions. The second danger would depend upon whether septic organisms had been intro- duced or had not been thoroughly destroyed ; their sealing in the canals might be productive of septic inflammation. If the foregoing meas- ures of cleansing have been followed it is scarcely possible that any organisms could survive. General experience demonstrates that in but a small percentage of cases does the pericementum suffer markedly from traumatism during the cleansing and sterilizing of canals, so that the THE ROOT-CANAL FILLING. 451 weight of evidence clearly teaches that such canals may be filled at once, and little or no reaction occur. Rational surgical principles clearly indicate the propriety and advan- tage of immediate root filling in all cases where a sterile condition of the canal exists and where there is absence of congestion due to traumatic or chemical irritation of the periapical tissues. The increasing disuse of arsenical preparations for devitalizing the pulp and the substitution of surgical extirpation of the pulp under local anesthesia are eliminating one fruitful cause of irritation to the retentive tissues of the tooth root. Improved methods of canal treatment and the introduction of reliable germicides for the purpose have brought the problem of canal steriliza- tion almost within the limits of certainty. When dealing with a non-infected pulp canal from which the central organ has been surgically removed under proper antiseptic precautions, it is no more rational to delay the operation of root filling and subject the case to the chances of infection by repeated placing and removal of dressings than it would be to leave an opening for drainage in an abdom- inal section where pus was not a factor in the case previous to operation. It has been said by eminent surgical authority that while " we are not responsible for the germs we find in a part, we are responsible for those we introduce in a part." The repeated dressing of a root canal is a fruitful means for infecting a part which in the case of a freshly ex- tracted healthy pulp was originally sterile, which should have been kept so by the means already pointed out and subsequent infection prevented by a root filling which hermetically seals the canal and obliterates it as a means of carrying infection to the peridental membrane. In using oxychlorid as a canal filling, it should be remembered that freshly mixed zinc oxychlorid is markedly irritating to vital tissues, and it is w^ell to place between the paste and the tissues of the apical region a barrier to the former. This may be of gutta-percha. A very fine cone of gutta-percha about one-quarter inch long is dipped in oil of euca- lyptus or oil of cajuput to soften its surface : it is then carried to the apex of the root upon a fine probe and pressed into position. Or, a small pellet of cotton is dipped in a strong solution of thymol or aristol. It is extremely probable that when the freshly mixed oxychlorid is placed over it, the cotton becomes converted into amyloid which her- metically and permanently seals the apical foramen ; the same change occurs in the cotton upon which the oxychlorid is carried into position. Slender wisps of cotton are rolled thin enough to pass readily into the canals. A thin paste of oxychlorid is mixed, the cotton w r isps are rolled, in it until the meshes are full, Avhen the extremity of a wisp is caught upon the end of a long, smooth, and slender canal plugger and carried up the canal to contact with the guard at the apex ; the plugger 452 THE TREATMENT AND FILLING OF ROOT CANALS. is withdrawn about one-eighth of an. inch, and that length of the cotton is crimped upon itself; the remainder of the canal is plugged in the same manner until it is full, when the surplus length of the cotton is cut off and bibulous paper is pressed against the canal filling to absorb the surplus zinc chlorid. The floor of the pulp chamber may be covered with the stiffening paste from the mixing slab. A method by which cotton fiber loaded with the oxychlorid may be carried to the root apex with great accuracy and precision is as follows : The smallest size Donaldson bristle with smooth sides has its hooked end cut off with the scissors and the cut end made flat by rubbing lightly upon a fine Arkansas stone. This may be readily done by grasping the bristle very near to its point between the thumb and index finger and lightly rubbing it back and forth upon the surface of the stone. The bristle is then laid flat upon a glass slab and burnished from heel to point until the surface is perfectly smooth and any burr turned upon the point by the action of the stone is fully removed. A few fibers of cotton wool are then held between the thumb and index finger of the left hand, the direction of the fibers being in the line of the long axis of the index finger. The point of the prepared broach is then laid upon the cotton fibers, and both broach and cotton are rolled together between the finger and thumb. The rolling action of the finger and thumb serves to felt the cotton fiber on to the broach, and should be continued until the cotton is evenly felted over the squared end of the broach. The Avhole operation is done by the left hand. The broach is not twirled into the cotton with the right hand as is ordinarily done where a roughened cotton -carrying probe is used. With a smooth broach and the cotton fiber felted on as described, the broach may be pushed forward with considerable force into a canal without puncturing the cotton, which is securely carried as far as the broach will go. On account of the smoothness of the sides of the broach it may be easily withdrawn for a slight distance, and then engaging in the surrounding cotton it is used as a plugger to pack the cotton ahead of it, and the plugging action continues until the material is all packed in place. The adjustment of the cotton to the broach as described really forms a tube-like arrangement of the cotton with the instrument in its central lumen — an arrangement greatly favoring the operation of carry- ing the cotton into place and enabling the operator to use the cotton or any suitable fiber as a vehicle for canal dressings or for permanent filling in connection with the oxychlorid of zinc cement. If gutta-percha be the material selected for filling the canal, a careful examination is made to determine whether the apical foramen be com- paratively large or very small ; in the latter case chloro-percha may be first pumped into the canals ; in the former it is wiser to omit the fluid, THE BOOT-CANAL FILLING. 453 Fig. 443. owing to the possibility of passing it through the apical foramen. In all cases where a canal filling is to be made of gutta-percha cones it is advisable to first lubricate the walls of the canal with one of the anti- septic oils, cinnamon, eucalyptus, or cajupnt; these will facilitate the passage of the point to the apex, and as sol- vents of gutta-percha will soften its surface and permit a closer adaptation to the canal walls. Should the apical foramen be found large enough to admit the pointed extremity of one of the gutta-percha cones, the end of the latter is cut off. The canal is lubricated with the essential oil, the cone itself dipped in the same medium, its base caught upon the end of a canal plugger, and it is passed carefully into the canal as far as it will go, when the plug- ger is withdrawn ; blasts of hot air from a hot-air syringe are directed against the exposed end of the cone until it is softened, and it is then pressed firmly into position by means of fine pluggers. A sufficient number of cones are added, softened and packed in position, filling the canal flush with the pulp chamber. In fine tortuous canals it is the usual practice to first pump them full of thin chloro-percha. A portion of the solution is caught between the points of a pair of Flagg's dressing pliers (Fig. 443) and carried to the opening of the canal, when, if the points are opened, the drop of fluid is deposited there ; it is then pumped into the canal by means of a fine smooth broach. To minimize the leakage due to the shrinkage of the chloro-percha in hardening, it is ad- vised to thrust into the fluid material in the canal as large a gutta-percha cone as the canal will admit. Dr. Otto- lengui advises that the pieces of silk described in the beginning of the chapter be used and an end left project- ing into the pulp chamber, w T hen, should removal of the filling ever become necessary, this end may be caught and the entire filling withdrawn. Should it be designed to fill the canal with gold, its exact length is measured by placing a small disk of rubber dam over a canal plugger, inserting the plugger in the canal and carrying the plugger point to the apex. The floor of the pulp chamber engages the rubber dam, and when the plugger point has reached the end of the canal the little gauge piece of rubber dam marks its exact length. Minute pieces of soft gold foil are cut, and one by one are carried to the end of the canal, the rubber upon the plugger being the guide to completeness of access to Flagg's dress- ing pliers. 454 THE TREATMENT AND FILLING OF ROOT CANALS. the root apex. This method is to-day rarely followed. Dr. W. S. How advises the use of shredded tin for sealing the apices of canals. By a series of fine probes the canal length is measured (as shown in Figs. 444-448), Fig. 444. Fig. 445. Fig. 44C. and particles of shredded tin foil are carried to the apex and impacted by means of measured pluggers. Salol and paraffin are both manipulated after one manner. A very fine probe is passed into the canal to its apex ; a portion of the ma- terial is caught between the beaks of a pair of dressing pliers (Fig. 443) and held above an alcohol flame until it is melted, when the closed beaks are placed in the canal beside the probe, and opened, and the fluid material runs into the canal. Slowly withdrawing the probe, the fluid runs into the space occupied by the probe, filling the canal to the apex ; it is advisable, however, to warm a broach, and by a pumping motion Fig. 447. Fig. 448. TREATMENT OF ROOT CANALS WITH MUMMIFIED PULP. 455 insure the carrying of the filling to all parts of the canal. If salol be employed a cone of gutta-percha of such size as may be readily carried to the apex should be thrust into the fluid material, virtually filling the greater portion of the canal with gutta-percha. Several trustworthy observers have noted a disappearance of salol from canals in which it has been placed ; the gutta-percha minimizes the risk attendant upon such disappearance. The gutta-percha subserves another purpose.: should it ever be necessary to remove the canal filling, blasts of warm air directed against the end of the gutta-percha may be made to melt the salol about it, when the cone may be readily withdrawn. This melting and withdrawal are more quickly accomplished if the central mass be of metal. The use of salol as a root-canal filling is better adapted to the deciduous than to the permanent teeth, owing to its lack of permanency in some instances, as already stated. In combination with paraffin its stability is greatly increased and is an effective antiseptic non-irritant canal filling. Treatment of Root Canals with Mummified Pulps. The remaining member of the aseptic cases is that of mummified pulp. So long as these cases remain perfectly aseptic they give rise to no symptoms and are, as a rule, uncovered by accident, rarely by design. Their usual history is as follows : At some time (perhaps years) before, an exposed or almost exposed pulp has been covered with a cap or cavity lining of the oxychlorid of zinc. They have remained com- fortable thereafter. At some subsequent time it may be necessary to open the tooth, usually on account of recurring caries : the total absence of dentinal sensitivity is noted, the tooth has changed color but little, if at all, and the operator burs carefully toward the pulp to determine its condition. (It should be remarked here that absence of dentinal sensitivity in a tooth having normal color and which con- tains a very large filling is an indication of aseptic death of the pulp, and the operator should renew all of his antiseptic precautions as to isolation of the tooth by the rubber dam and complete sterilization of all instruments and of the territory of operation.) The burring is con- tinued without any evidence of sensitivity, and the instrument is finally felt to pass into the pulp chamber. There is no odor, no escape of fluid, the pulp being found dry and shrivelled. If sterilized pulp extractors are passed into the canals, the remnants of the pulp may be withdrawn, exhibiting none of the usual signs of decomposition such as odor and confluent softening. This is usually the case when pulps have died under an oxychlorid of zinc capping, the zinc chlorid acting as a preservative antiseptic. 456 THE TREATMENT AND FILLING OF BOOT CANALS. Even where the pulp has not been subjected to the action of zinc chlorid and where its death has occurred from causes which did not include access of germs from the oral cavity, as in cases of traumatic death of the pulp, it is highly improbable that any organisms are present, unless they should have been introduced by the operator from the ex- terior. The possibility of this occurring should prompt caution, for it is the experience of many that although organisms have not been present in the canals, when introduced from without they find a fruitful soil for development. Where the operation of opening into these sterile dead pulps has not been done with the strictest antiseptic precautions, re- action indicating infection may occur within a few hours or may be delayed for perhaps two days. This condition may arise even in connection with teeth whose pulps have died under a capping of zinc oxychlorid, from the fact that the quantity of zinc chlorid used in the capping material was insufficient to completely saturate the pulp tissue and render it permanently antiseptic. It is advisable, therefore, to cleanse the canals with some powerful and penetrating antiseptic to destroy any chance organisms and to insert a probationary though per- fect root filling until the time of danger has passed. The antiseptic which meets the indications is a 3 to 5 per cent, formalin solution or the ethereal 25 per cent, solution of hydrogen dioxid known as pyrozone, permitted to remain in the canals for several minutes. The canals are then dried, and for the temporary filling salol is the rational indication. At the expiration of three days if no evidences of pericementitis are present the operator may remove the salol, reapply the antiseptic, and fill the canals with oxychlorid or with gutta-percha. It should be made an invariable rule of practice never to open a sterile pulp chamber in which the pulp has become devitalized without applying the rubber dam and flooding the surface of the tooth or cavity with a powerful germicide, through which fluid the drill should be made to pass, thus absolutely sterilizing its point and at the same time exclud- ing infective organisms from the canal. Septic Oases. The second great class of cases, the septic, comprises those in which the pulp has undergone some extent of decomposition. As a rule, the first organisms which invade pulp tissue are the staphylo^ cocci and streptococci, which find a suitable habitat in the live pulp. Advancing first along the lines of the veins, their toxic waste prod- ucts causing inflammation, the organisms invade, peptonize, and liquefy the inflammatory effusions. As these cocci advance toward the apex of the root, the necrotic and altered tissues which are left behind become the breeding-ground of other organisms, particularly the bacteria SEPTIC CASES. 457 of putrefaction. The altered portions of pulp tissue are decomposed into products of progressively simpler chemical composition, until all of the albuminous substances have been transformed : first peptones are formed, further decomposition produces ptomains, next such bases as leucin, tyrosin, and the amines, together with fatty acids ; l finally the end products are hydrogen sulfid, ammonia, carbon dioxid, and water (see Fig. 398). "Fermentation and putrefaction can only occur where the fungi concerned live, and the extent of decomposition is conditioned by the number of fungi" (Ziegler). As there are several distinct types of decomposition, so is there a cor- responding number of varieties of organisms. The septic cases may be divided into two classes : First : Those in which septic invasion has not passed beyond the apical foramen and given evidence of pericemental irritation or inflammation, these tissues being threatened though not invaded. Second : Those in which the pericementum has become the seat of septic invasion. This latter class is subdivided according to the nature and extent of the septic processes : the first subdivision comprises cases of acute pericementitis non-purulent ; the second, of chronic peri- cementitis without evident pus formation ; the third, of purulent peri- cementitis, which may be either acute or chronic. 1. In the first of the first class of these cases — those in which the suppurative process has invaded the pulp to near its end — the necrotic portions of the pulp are undergoing putrefactive decomposition. To- ward the end of the process, when the apical portion of the pulp is invaded, it is not uncommon to find evidences of pericemental irritation ; this frequently ceases spontaneously, as though the irritation had caused the formation of a barrier between the tissues of the apical region and the suppurating pulp. An increasing discoloration of the dentin shows the contents of the dentinal tubules to be also undergoing de- composition. It is necessary to remove this mass, destroying the products, the causes, and the soil of decomposition : this without carry- ing infection to the vital tissues beyond the apex. When the odor of hydrogen sulfid may be detected, it is evidence that the ultimate de- composition of albuminous matter is in progress. As it is quite prob- able and an imminent danger that organisms might, upon a broach injudiciously employed, be carried from the body of the putrescent mass to the apex of the root, it is the part of wisdom and prudence to destroy the organisms as a primary measure. There is no quicker or effective means of destroying H 2 S, and probably the causes leading to its production, than applications of iodin. The reaction involved in the decomposition of H 2 S by iodin was pointed out by Dr. W. F. 1 Ziegler, General Pathology, 1895, p. 437. 458 THE TREATMENT AND FILLING OF ROOT CANALS. Litch: 1 "Id passing a stream" of hydrogen sulficl through tincture of iodin, the latter element seizes upon the hydrogen, forming hydriodic acid, which remains in solution, the sulfur falls as a precipitate ; the solution is decolorized." Any excess of iodin which remains may be readily removed by an application of ammonia water, a solution of ammonium iodid being formed which may be readily washed away. A penetrating antiseptic is now indicated, to sterilize to as great a depth as practicable. A 5 per cent, solution of formalin fulfils this indication. It is permitted to act for some time. The contents of the canal are scraped away, never pushing the broach by which the scraping is done, for fear of carrying organisms deeper into the canal. As stated, septic canals contain certain fatty bodies and derivatives of albumin, together with more or less partially disorganized pulp tissue and a mixed bacterial infection. Examining the list of therapeutic agents it is seen that one of them, sodium dioxid, possesses properties capable of neutralizing each of the offending elements. This material may be employed either in the solid form or in solution. Solutions of sodium dioxid must be made with great care to prevent escape of the oxygen. A tumbler of distilled water is set in a vessel containing ice- water ; into the distilled water the sodium dioxid is dusted very slowly in small amounts. Each addition is attended by the evolution of heat. 2 The sodium dioxid is added to the point of saturation, and reduced to the desired percentage strength by additions of distilled water. 3 A drop of the saturated solution is placed upon a wisp of asbestos fiber (as it destroys cotton fiber) and is carried into the canal ; in a few moments the cavity may be syringed, and a deeper application of the dioxid solution made — this time of 50 per cent, solution. Each time the asbestos is removed it is seen that the discolored dentin surrounding the canal becomes whiter; the discoloring matter in the tubules has been destroyed. When a broach may be passed freely to the apex of the root, and the solution comes away clear from the root, sterilization is presumably complete. A 10 per cent, solution of sulfuric acid is pumped into the canals by means of iridium broaches ; this neutralizes any free alkali which may be present. The canal or canals are next washed out with hot distilled water, dried with cotton, filled with alcohol, and well dried by blasts of warm air. Many operators immediately and permanently fill such canals ; 1 Dental Cosmos, 1882. 2 Dr. Wm, Trueman advises that the soldered lid of the can containing the oxid be perforated as a pepper caster, and the sodium dioxid shaken into the distilled water through the perforations. 3 E. C. Kirk, Denial Cosmos, vol. xxxv. p. 195; F. T. Van Woert, ibid., vol. xxxvi. p. 499. CASES IN WHICH PERICEMENTITIS IS PRESENT. 459 however, as there is the possibility that sterilization may not be abso- lute, it is the usual practice to fill the canals tentatively yet perfectly. Salol and a metallic point make an excellent canal filling in such cases. When the canals and dentinal walls are dried by means of the alcohol and warm blast they are filled with salol made very fluid, and the metallic point thrust into the canal containing it. Some slight pericemental disturbance may follow, but quickly subsides under the influence of a counter-irritant applied to the gum over the root (tr. iodin., tr. aconit. et chloroform, da. pars azq. The crown cavity is sealed with sticky temporary stopping for a few days, when if the condition of the pericementum is found normal, the salol filling is removed (if the operator desires) by heating a pair of tweezers and grasping the protruding end of the metal cone. It is the general practice to then fill the canal with oxychlorid or gutta-percha. Should the case present evidences of profound change in the contents of the tubules, i. e. much discoloration, the 50 per cent, solution of sodium dioxid may be sealed in the canal for a day ; the next day the canals are syringed freely with an acid solution of hydrogen dioxid. Dr. Kirk advises that the dentin be saturated with the sodium dioxid solution, then upon the addition of hydrochloric acid, hydrogen dioxid is formed wherever the sodium has penetrated, and drives out the soapy matters formed by the action of sodium hydroxid upon the products of decomposition. Preliminary to filling the canals it is the usual practice to fill them for a few minutes with an antiseptic, which will exercise an influence over a considerable period of time. Of all antiseptics, oil of cinnamon gives evidence of the most prolonged presence when so placed. The use of ciunamon oil in the pulp chambers of front teeth is, however, objec- tionable, owing to the tendency of the oil to discolor the dentin structure. It is therefore preferable in these cases to use a dressing of dilute for- malin (2 per cent, solution), which by its diffusibility thoroughly penetrates the tubuli, sterilizing their contents. Oases in which Pericementitis is Present. The next class for consideration includes the cases in which the tissues of the apical region are invaded. The first evidence of such invasion is tenderness of the tooth upon pressure. The cause of this is, no doubt, the inflammatory reaction of these tissues consequent upon con- tact and absorption of the waste products of organisms which are developing in the pulp canal. In the milder cases the tooth is sore to the touch, is slightly loose and extruded, and the gum over the affected root is redder than normal. Here, as in all grades of this disturbance, the aim is to get rid, first, of the causes of the inflammation ; second, when 460 THE TREATMENT AND FILLING OF ROOT CANALS. necessary to treat the inflammation itself. In effecting an entrance into the canals of such teeth — and of course they should be opened and cleansed as quickly and as thoroughly as possible — " the tooth should receive lateral support against the pressure of the burs used in excavating ; if the cavity be approximal the tip of a finger is placed against the face of the tooth on the opposite side to the bur. Should the direction of entrance be in a perpendicular line a ligature of linen twine having long ends may be tied tightly about the neck of the tooth, and traction exerted as a counter-pressure." l If the conditions permit, the cleansing and sterilizing are to be well done at once. Should the tooth be too tender to permit the usual manipulations, the gross mass is removed by treatment with sodium dioxid solution or by syringing with meclitrina and stirring with broaches ; then a pellet of cotton saturated with lysol, a strongly alka- line and penetrating cresol, is placed against the putrescent mass ; the gum is painted with iodin at a little distance from the site of the inflam- mation. When quiet is secured, the cleansing and sterilization of the canals should be thoroughly done ; and a dressing of a sedative anti- septic introduced. Campho-phenique or cinnamon oil answers well in this particular. In more pronounced cases the tenderness, extrusion, and looseness of the tooth are more marked ; in case the tooth should contain a filling beneath which a pulp has died — and this is a common history of such cases — the release of the imprisoned mephitic gases is imperative. Ex- ercising counter-pressure, a very sharp and small spear-pointed drill is passed through the wall into the pulp chamber ; it may be necessary in cases of extreme soreness to effect this entrance at the neck of the tooth as the shortest path. After a few minutes the opening is syringed out with meditrina, and a blister is applied over the gum at a distance from the tooth, about two teeth posterior to it. Several coats of saturated alcoholic solution of iodin applied in succession as rapidly as the preceding application has dried and until the surface is coated with a bronze-like layer of iodin will produce satisfactory counter-irrita- tion. An area of about 1J to 2 centimeters diameter may be thus covered. The patient is directed to immediately take a hot mus- tard foot-bath, and to use frequently a 3 per cent, solution of pyro- zone or other strong antiseptic solution as a mouth-wash. When the tooth is much extruded and is kept irritated by striking upon the occluding tooth, it is advisable to place a cap over the tooth posterior to the one affected. A cap may be readily made in a few minutes, by taking an impression in moldine or in plaster of the tooth to be capped, pouring a small die of fusible metal ; drive this into a block of soft 1 J. Foster Flagg's Lectures. CASES IN WHICH PERICEMENTITIS IS PRESENT 461 lead, and then swage a piece of silver or German silver, No. 26, to fit the die. This cap, covering the occlusal face and about half the walls of the tooth, is attached by means of zinc phosphate, thus securing surgical rest for the affected tooth. It was at one time a general prac- tice to permit the vent hole drilled at the neck of a tooth to remain open for the escape of the gases of decomposition, consequently the cases were in a constant state of sepsis. The practice is obsolete and is to be unqualifiedly condemned. In cases where the inflammatory action runs high, the tooth is ex- tremely tender, much extruded, and loose, the gum over the tooth be- comes livid, the pulse increases, there is some, and there may be marked, febrile action, the tongue is coated and the breath offensive. Energetic measures are necessary to avert necrotic action in the apical tissues. In this, as indeed in all cases without exception, the promptness and thoroughness of relief depends primarily upon the thoroughness with which the exciting cause of the inflammation is removed, i. e. the septic contents of the pulp chamber. In any case where direct access may be had to the canals, and this is very frequently the case, every effort short of that producing great suffering to the patient should be employed to wash away and broach away the putrescent material, using, where ne- cessary, sulfuric acid to enter the canals, powerful antiseptics always preceding the broach. Lysol is an excellent medicament in this con- nection, and campho-phenique another. The canal is syringed freely and repeatedly with 3 per cent, pyrozone, which should also be used as an antiseptic mouth-wash. Local bloodletting, as advised by Dr. G. V. Black, 1 is frequently an effective means for securing relief. Make a deep cut in the gum, clear to the process, the incision to be about one- quarter inch from the margin of the gum and encircling the neck of the tooth ; this will tend toward unloading the engorged vessels of the apical region. Dry cups over the face and to the neck, and always hot mus- tard foot-baths, are valuable adjuncts. Should the inflammatory disturbance run high, and a full, bounding pulse, coated tongue, marked fever, constipation, headache, and other febrile symptoms appear, attempts should still be made to abort the inflammatory action. After as thorough a cleansing of canals and anti- septic washing as possible under the circumstances, local bloodletting as described and advised by Dr. Litch 2 is efficient, by means of Swedish leeches, washing the gum, touching it with sugar, then applying the leech, which should be first placed in a test-tube, the mouth of the tube then being placed over the gum ; when the leech is gorged, it drops back into the tube. The mouth is then rinsed with warm water, to continue 1 American System 6f Dentistry, vol. i. p. 927. 2 Ibid., vol. i. p. 928. 462 THE TREATMENT AND FILLING OF ROOT CANALS. the bleeding. Quinin in doses never less than gr. vj is given in the hope of limiting the exudation into the inflamed area. As one of the best and most effective means of derivation is the induction of watery alvine dis- charges, the patient may be directed to take a saline cathartic or a rectal injection of half an ounce of pure glycerin. If the pulse remain full and bounding, and headache persist, tr. aconiti or tr. veratri viridis is to be used as an arterial sedative, gtt. j of the tr. aconiti rad., or gtt. ij of the tr. veratri viridis, repeated every hour, until the pulse slows and lessens in volume and tension. At bedtime, if the inflammation be not markedly lessened, a sedative diaphoretic is administered, Dover's pow- der in full dose, gr. x, given in hot lemonade ; while the patient is drink- ing the latter he or she is to be well wrapped in hot blankets and the feet and legs immersed in a hot mustard foot-bath. The following morning a saline cathartic — magnesia? sulph. 3ss — is given in a goblet of water. These directions (substantially those given by Dr. Litch, ibid.), may be followed with gratifying results in many cases ; even when the inflammation is not aborted, its violence is almost invariably lessened. Should the inflammation remain at its height for more than twenty- four hours, it is almost certain that pus has formed, and the indication is to give it exit. A spear-pointed bistoury is thrust through the gum over the apex of the affected root with such decided force as to pene- trate the process if possible. In the event of not accomplishing this end, the point of a spear-head drill revolving very rapidly is passed through the process to the apical region. Although this operation may be performed very quickly it may be necessary to administer nitrous oxid to quiet the patient and render the drilling painless. Anesthesia may be secured by means of the injection of 5 minims of a 1 per cent, solu- tion of cocain, to which has been added 1 to 2 minims of a 1 per mille solu- tion of suprarenal extract. Dr. Black has described a painless method of effecting an entrance to the apical region. 1 A napkin is placed about the parts, the gum dried and touched at the point of election with a drop of 95 per cent, solution of carbolic acid (trichloracetic acid full strength may be used). The necrosed membrane is scraped away by means of a coarsely serrated plugger until sensation is felt, when another drop of acid is applied, and the scratching is resumed until the bone is laid bare ; a sharp chisel is then used to open the apical region. No blood should be drawn during the operation except at the last step. The case in its present stage belongs to and is described in the suc- ceeding chapter, upon Alveolar Abscess. In any case presenting in which there is reason to believe the patient is the victim of syphilis — and alveolar periostitis is an occasional accompaniment of tertiary syphi- 1 American System of Dentistry, vol. i. p. 298. TREATMENT OF CHRONIC PERICEMENTITIS. 463 lis 2 — the use of large doses of potassium iodic! is imperatively indicated. Unless decided measures are taken to abort such cases — and the usual antiphlogistic measures are of little avail — dangerous involvement of the general periosteum may occur, leading to necrosis. Not less than gr. vj doses of potassium iodid are to be administered every three hours. Should there be evidence of detachment of the periosteum, indicated by boggy swelling, a bistoury is to be passed boldly to the bone, making a large and free incision. Treatment of Chronic Pericementitis. The most usual form of chronic apical pericementitis is that associ- ated with pus formation. It will be discussed in the succeeding chapter under the head of Chronic Apical Abscess. A not inconsiderable number of cases may be seen in which pus formation is not evident and yet a chronic inflammation is present in the tissues of the apical region. If the pulp chamber be open the cause is evident, and its treatment has been described. A not inconsid- erable number of cases are due to mal-occlusion. This point is to be carefully observed, for it frequently affects teeth containing vital pulps and free from caries. The tooth is slightly loose and sore to pressure. Examination reveals abnormal occlusion, either too severe or in the wrong direction. Should the tooth contain a filling, it usually gives a normal response to applications of heat and cold ; examining the filling a spot is seen marking excessive occlusion ; in both cases grinding off the redundant tooth structure or filling and applying a counter-irritant over the apex subdues the inflammation. Its exciting cause being removed, it subsides. A class of cases is occasionally met with in which there is evidence of sluggish and persistent inflammation about the apices of pulpless teeth which have been filled ; acute inflammatory disturbance of a severe grade occurs but seldom. The most common cause of this con- tinued inflammation is probably the decomposition of a minute filament of pulp tissue which has not been removed from a canal ; or, again, well-cleansed canals which have not been filled to the apex. Such cases are those of mild sepsis : perfect restoration to health is only pos- sible by re-cleansing, sterilizing and perfectly filling the canals. These teeth are always more or less hypersensitive even though it be unnoticed, and therefore are not of a full measure of service until cured. Other cases in which there is reasonable assurance of perfect steril- ization and complete filling exhibit vascular sluggishness over the apex of the root. Continued and repeated massage is beneficial, 2 the disorder 1 See case — Heath, Injuries and Diseases of the Jaws, 3d edition. 2 Dr. W. F. Rehfuss, International Dental Journal, vol. xi. p. 581. 464 THE TREATMENT AND FILLING OF ROOT CANALS. being apparently due to paralysis of vessel walls and not to septic causes. The tonus of the vessels may be improved by application of the galvanic current. This principle has wide application in general medicine and surgery. It is to be remembered that Avhen the tissues about the apex of a root have been irritated, it may be for months, by the products of a decomposing pulp, a series of degenerative changes may have occurred in them which require some time to remedy. Sterilization should be prolonged, and too hasty a stopping of the canal be avoided. In such cases, after each periodical treatment the canal should be dressed with some stimulant antiseptic : campho-phenique ; oil of cinnamon, or the admirable 1, 2, 3 mixture of Dr. Black : Oil of cinnamon, 1 part; Carbolic acid, 2 parts ; Oil of wintergreen, 3 " Repeated applications of tr. aconit. et iodin. are to be made to the gums. A source of chronic apical pericementitis — frequently not detected until abscess has formed and discharged, it may be, at a distant point — is found in the death of a pulp from thrombus or jugulation. At some period the tooth has received a blow, or, it may be, has been moved too rapidly by a regulating appliance, or idiopathic pulpitis has occurred. Years afterward, a chance examination may reveal a deeper color of the gum overlying the tooth than over the others ; by reflected light it shows an opacity or discoloration of the body of the tooth. It may be slightly sore to percussion, which elicits a dull sound. " Dead pulp " is diagnosticated ; the tooth is opened under extraordinary antiseptic pre- cautions and cleansed freely with sodium dioxid — the ideal material in this instance — dried, and filled at least tentatively with salol. Another class of cases in which a similar condition of the pulp is found consists of those in which a pulp has died from repeated thermal shock received through a metallic filling placed in too close proximity to it. Although constructive action resulting in secondary deposits is the usual consequence of such irritation, profound degenerative changes in the tissue of the pulp frequently occur at later periods. The treat- ment is the same as in the preceding case. Unless the degree of antisepsis stated be employed in cleansing the canals of such cases, an annoying and it may be an obstinate perice- mentitis is lighted up which is difficult to conquer. A word of caution should be spoken in regard to the importance of the removal of inflammatory troubles, particularly the subacute forms, which affect the apical pericementum. It is supposed and with good TREATMENT OF CHRONIC PERICEMENTITIS. 465 reason that not only may tumor formations have their beginning in chronic inflammations ; various reflex disturbances of sensation and of special sense may be traced to such sources ; but any inflammation having such an anatomical situation is a smouldering fire which may under certain systemic conditions become a pathological conflagration. Finally, the injudicious use of arsenical preparations in pulp devitali- zation may result in chronic irritation to a part of or the entire peridental membrane, the irritative action being prolonged indefinitely after extirpa- tion of the pulp and successful filling of its canal. This condition is due to the diffusion of the arsenic through the dentinal structure and cemen- tum, and is a result which is more easily avoided than cured. Where the arsenical application has been unduly prolonged by circumstances beyond the control of the operator, and the possibility of undue penetra- tion of the poison is suspected, the application of silver nitrate to the canal walls'will render the arsenic inert by combining with it to form the insoluble silver arsenite. The possibility of disturbance to the peridental membrane which may be induced by arsenical pulp applications should limit its use only to such cases where surgical extirpation of the pulp under local anesthesia is deemed to be practically impossible. 30 CHAPTER XVIII. DENTO- ALVEOLAR ABSCESS. By Henry H. Burchard, M. D., D. D. S. Definition.— In describing the septic inflammation affecting the tissues of the apical region in the previous chapter, it was stated that a common result of the inflammatory action was cellular necrosis and pus formation ; this condition is known as alveolar abscess or dento-alveolar abscess. Although alveolar abscess affecting some other portion of the peri- cementum may and does occur without death of the pulp/ septic infec- tion and bacterial invasion of the tissues of the periapical region from infected pulp canals is the most common source and cause of the affec- tion. The term as technically applied refers to septic apical pericemen- titis. Causes of Dento-alveolar Abscess. The exciting- causes of the disease process will be found in the pyo- genic cocci and probably other pyogenic organisms which inhabit and develop in the deepest portions of the putrescent pulp, finding entrance to the periapical tissues through the apical foramen of the tooth. Dr. Schreier of Vienna found diplococcus pneumoniae to be the excitant of inflammation in seventeen out of twenty cases of dental periostitis examined by him. 2 The ptomains and other waste products formed as the result of the life processes of these organisms cause poisoning and debility of the cellular elements of the part. Even granting that the organisms are present as the exciting cause, there is another factor involved which determines to a great extent the occurrence, time of occurrence, and severity of the disease, i. e. the predisposing causes — including under this head the condition of the tissues which favors or deters the development of the organisms. Predisposing- Causes. — It is unquestionably true that different in- dividuals will exhibit in their tissues marked differences in the degree 1 Cases reported in Proc. Academy of Stomatology of Philadelphia, 1895. * Oesterr.-ungarische Viertelj. fiir Zahnheilk., April 1893. 467 468 DENTO-ALVEOLAR ABSCESS. of resistance to the invasion of disease causes. It is a well-recognized axiom of pathology that one of the most potent antiseptics, if not the most potent, is the inherent resistance of healthy protoplasm ; that is, healthy tissues offer a barrier to the development of the exciting causes of disease, while tissues which are debilitated through any of the many causes that affect them exhibit a diminished resistance to the invasion of the causes of acute disease. Prominent among the causes which favor the development and ex- tension of pyogenic processes are the inherited conditions indefinitely classified as strumous. The tissues of children having a family history of, for example, syphilis or tuberculosis, frequently exhibit evidences of lack of vital resistance. They are attacked and readily succumb to agencies which affect children of healthy parentage but slightly if at all. Inflammations about the teeth or of the soft tissues of the mouth run a severe course ; septic affections of the pericementum are attended by involvement of neighboring lymphatics and by evidences of septic intoxication. These predispositions may persist throughout the life of the individual ; as a rule, however, they grow less pronounced or less evident with age. Acquired cachectic conditions of the adult also form a strong pre- disposition to invasion of the tissues by pathogenic organisms. It is a matter of frequent observation that tuberculosis and, in a more pro- nounced degree, syphilis are constitutional conditions which markedly diminish the resistance of the tissues. Inflammatory disturbances which in an individual free from cachexia would probably be circum- scribed, when they occur in the cachectic are diffuse and virulent. Local predisposing causes consist of faulty hygiene, producing debility of the tissues, for it is noted that abscess is more likely to run a virulent course in unclean mouths than in those kept free from fermenting and putrefying masses ; this is a general, though not a universal truth. Pathology and Morbid Anatomy. The pathology of septic pericementitis has been described in Chapter XVII. That of alveolar abscess begins as soon as there is death of cellular elements in the exudation. The exudation is liquefied in the focus of the inflammation by the action of ferments ; the leucocytes are invaded by and strive to devour the pyogenic cocci which are present — the species of warfare described by Metchnikoff; the leucocytes succumb, die, and form pus corpuscles, which are found to contain the pyogenic cocci. The cellular exudate is then broken down into a granular detritus, which, with the dead corpuscles and peptonized effu- sion, constitutes pus. The diplococcus of pneumonia is said to be a constant attendant PATHOLOGY AND MORBID ANATOMY. 469 on alveolar abscess, and this particular organism is believed by Schreier to be the usual excitant of the inflammatory action in these cases. The primary seat of the abscess is usually in the pericementum, between its attachment to the cementum and its attachment to the alveolus. From the central cavity of softening the necrotic process spreads peripherally ; cell by cell the inflammatory wall forming the outlines of the abscess and the exudates are liquefied and the cavity grows larger. The cancellated bone about the apex of the root is in- volved and becomes the seat of osteomyelitis and molecular necrosis. Larger and larger grows the volume of the abscess until the periosteum covering the alveolar process is involved, softened, and raised from the bone. The inflammatory action precedes the advance of the pus along the line of least resistance ; and if it run high the periosteum may be softened over quite an extensive area and raised from the bone by the exudation beneath it. The pus penetrating the periosteum, the soft tis- sues are involved and softened, when the pus breaks through the mu- cous membrane, discharging usually by the shortest route from the abscess to the exterior. The progress of septic destruction is along the line of least resistance, and although as a rule this points upon the ex- ternal surface of the gum immediately above the apex of the affected root, it may follow other directions. In some cases the pus finds exit through the pulp canal of the affected tooth, forming what is commonly though incorrectly known as blind abscess. This form of abscess dif- fers from that with external fistula as a result of its mode of formation rather than because of any essential difference in its pathology. . The history of an acute inflammatory stage is usually absent or it has caused but slight disturbance. Invasion of the apical pericementum by bac- teria has been slow and superficial and the inflammatory reaction restricted to the tissue immediately surrounding the apical foramen; the necrotic process has been ulcerative in character, molecular death of the membrane taking place slowly until the tissue about the foramen is lost and the denuded apex projects into a necrotic cavity which allows of drainage of its contents through the foramen and root canal. In these cases the abscess cavity is usually comparatively small, and the inflammatory action is less severe than when the pus has a longer path of exit (see Fig. 449). The pus may exhibit evidences of semi-encystment. Collections may apparently remain in the tissues of the gum for long periods with- out fistula. A case in practice presented conditions similar to that exhibited in the illustration (Fig. 450) ; it had existed for several years about a replanted tooth, and responded promptly to treatment. In other cases the line of tissue destruction and pus escape is along 470 DENTO-ALVEOLAR ABSCESS. Fig. 450. the pericementum, the pus discharging at the neck of the affected tooth. Many of these cases occur in connection with pulpless teeth which have elongated, or those in which there has already been loss of peri- cementum. Abscesses upon the upper central or lateral incisors may Fig. 449. Blind abscess at the root of an upper incisor (Black) : a, abscess cavity in bone; b, drill hole exposing the pulp chamber for treatment. Acute alveolar abscess of a lower incisor with pus cav- ity between the bone and the periosteum (Black) : a, pus cavity in the bone ; b, pus between the peri- osteum and bone ; c, lip : d, tooth ; e, tongue. perforate the nasal floor (see Fig. 451). After a period of marked perice- Fig. 452. Alveolar abscess at the root of a superior incisor discharging into the nose (Black) ; a, large abscess cavity in the bone; 6, mouth of fistula on the floor of nostril ; c, lip ; d, tooth. Alveolar abscess at the root of an upper molar discharging into the antrum of Highmore (Black) : a, abscess cavity in the bone; b, mouth of fistula on the floor of the antrum ; c, pus in the antral cavity. mental disturbance, the inflammatory action running high, causing pain and swelling of the nostril of the same side, the symptoms may suddenly PATHOLOGY AND MORBID ANATOMY. 471 abate without any evident signs of pus having been discharged. Soon after a purulent discharge may be noted from the nostril, leading to the belief that purulent nasal catarrh (ozena) is present ; many of these cases are diagnosed and treated as ozena. In injection of the pulpless incisor, particularly with pyrozone, the pus and fluid are seen to emerge from the nostril, exhibiting the true source of the pus. Abscesses upon upper second bicuspids and molars may perforate the floor of the antrum (Fig. 452). In the lower jaw the pus may pass out of the alveolar process and Fig. 453. Fig. 454. Chronic alveolar abscess at the root of a lower incisor with a fistula discharging on the face under the chin (Black) : a, abscess cavity in the bone ; b, b, b, fistula following in the periosteum down to the lower margin of the body of the bone and dis- charging on the skin. Chronic alveolar abscess of the root of a lower incisor with abscess cavity passing through the body of the bone and discharging on the skin beneath the chin (Black) : a, very large ab- scess cavity ; b, mouth of the fistula. fail to perforate the overlying soft tissues, pursuing a path which may lead to its exit upon the face beneath the jaw or chin (Fig. 453). In others the pus may burrow through the body of the bone and open upon the face. (See Figs. 454, 455.) In a case of persistent fistula opening upon the side of the face over the body of the lower maxilla, there was no evidence of inflammatory disturbance in the edentulous gum. An exploratory incision, made at a point indicated by a probe passed into the sinus, revealed the presence of a small root-fragment. Healing of the fistula was spontaneous upon its removal. Prof. M. H. Oyer 1 records a case of abscess opening 1 Proc. Academy of Stomatology, 1896. 472 DENTO-ALVEOLAR ABSCESS. over the body of the lower maxilla immediately anterior to the groove for the facial artery (Fig. 456). A flexible probe passed into the fistula Fig. 455. Fig. 456. Fistula passing down through the body of the lower maxilla (Black). Abscess with tortuous sinus opening upon the face : A, tissue of cheek ; B, floor of mouth ; C, abscess tract. appeared to enter the submaxillary triangle ; in the absence of evident dental cause, the case had been diagnosticated and treated as abscess of the submaxillary gland. The direction taken by the probe gave no indication of a tooth being involved. The usual therapeutic measures applied to a submaxillary abscess proving unavailing, a serial examina- tion, one of many, of the teeth of that side was made. In one tooth, the second molar, was a large amalgam filling. The pulp responded, though feebly, to the usual tests for vitality ; upon entrance to the tooth the anterior portion of the pulp was found partially vital, the posterior portion dead and decomposing. The pulp was removed ; antiseptics were pumped through the posterior root, found exit at the fistula, and the causal relation of the putrescent pulp and the abscess was shown by a prompt disappearance of the disease. In one case of abscess upon a lower third molar, the pus made en- trance into the tissues about the insertion of the internal pterygoid muscle. Cases have been recorded in which the pus from abscess about a lower molar has burrowed through the bone and, caught beneath the platysma myoides muscle, it has passed down the muscle, discharging from an opening upon the neck or upon the shoulder. Abscess upon an upper molar may find exit upon the face beneath the malar bone. Occasionally the duct of Steno may be involved in the abscess tract and salivary fistula result. Dr. Black states 1 that the cases of abscess opening beneath the malar bone are usually of the acute variety. As a rule, however, cases which exhibit the pus exit at a dis- tance from the seat of abscess are of the chronic variety. The acute and chronic cases differ as to their clinical histories. 1 American System of Dentistry, vol. i. p. 940. CLINICAL HISTORY OF ACUTE ALVEOLAR ABSCESS. 473 Clinical History of Acute Alveolar Abscess. Cases of apical pericementitis in which suppuration occurs usually present pronounced evidences of severe inflammatory action. The throbbing and tenderness, swelling and vascular engorgement are marked ; there may be, and usually is, more or less febrile disturb- ance with its attendant symptoms ; a full, bounding pulse, more or less oedema of the surrounding parts, the eye of the aifected side may be injected, etc., as described in Chapter XVII. under the head of Acute Pericementitis. In from twenty-four to forty-eight hours a spot of fluctuation makes its appearance at the summit of the swelling, the spot becomes yellow and soon opens, aifording escape to the abscess contents. As soon as the pus has discharged the inflammatory symptoms subside promptly and a persistent fistula remains, communicating with the abscess cavity. This comparatively benign course and termination is not universal. It is not at all uncommon to find cases which at the height of the inflammatory disturbance exhibit evidences of septic intoxication. The septic substances formed by the micro-organisms, and in other cases the organisms themselves, gain entrance to the lymph channels and are conveyed to the nearest lymphatic glands, producing evidences of inflammation in them ; swelling and pain of these glands are very common. Cases are recorded in which streptococci appear to have invaded the subcutaneous tissue, giving rise to marked phleg- monous inflammation. Dental literature contains the records of many cases indicating the occurrence of a pyemic condition consequent upon alveolar abscess ; organisms, by gaining entrance to the blood channels, forming septic emboli. The mild and less severe cases run the average course described. Many of them by finding early exit of the pus through the pulp canal of the aifected root have comparatively light inflammatory disturbance ; in those cases in which the evacuation of the pus is delayed, or in which the opening occurs at points distant- from the disease focus, the inflammatory action may be severe and prolonged. If the pus point toward the face, the skin, the subcutaneous tissues, and it may be the in- ternal periosteum also exhibit evidences of marked inflammation ; there is much swelling, the skin may become cedematous, there is redness, heat, and throbbing pain. The external application of poultices by the patient, not at all an uncommon mode of domestic treatment, may aggravate the symptoms, soften the tissues, and induce the progress of the pus to the exterior. If in any of the cases which point in the mouth an undue swelling is formed at the height of prolonged inflammatory action, pus beneath the periosteum is to be feared, the pus stripping the softened membrane 474 DENTO- ALVEOLAR ABSCESS. from the bone over a certain area. Should these cases not obtain quick relief by evacuation of the pus, necrosis of the denuded bone may occur (Fig. 457). Reattachment of the periosteum may take place even after extensive separation, provided the pus be evacuated early. Fig. 457. Necrosis of the buccal plate of the alveolar process from alveolar abscess (Black). Cachectic conditions exert a strong modifying influence upon the course and termination of alveolar abscess. In strumous or debilitated persons the disease tends to invade neighboring structures, whose resist- ance is lessened. This is well illustrated by a case of obstinate maxil- lary caries which destroyed the entire process of one side, the begin- ning of the disease being apical pericementitis of a lower bicuspid. The carious process became chronic soon after the extraction of the offending tooth, and persisted until the death of the patient from tuberculosis. Alveolar abscess occurring in syphilitic patients is prone to involve the deep structures, and more or less necrosis is not an uncommon sequel. Clinical History of Chronic Alveolar Abscess. After the subsidence of the symptoms attendant upon the formation and discharge of acute abscess, there is rarely a spontaneous healing or filling of the abscess cavity and tract with healthy granulation tissue ; the development of organisms in the abscess cavity and pulp canal con- tinues and produces a continuance of the suppurative process, forming a chronic abscess. In other cases abscess may have developed without marked inflam- matory symptoms, and yet a prolonged and obstinate pus formation occurs in the tissues of the apical region, the pus finding exit through the pulp canal, constituting what is known as blind abscess, one of the most common of the chronic types. Many of the cases which open upon the face are of the chronic variety ; during the development of the abscess and its discharge there DIAGNOSIS AND PROGNOSIS. 475 may be but little evidence of inflammatory action about the affected tooth. This is a common history of cases which have followed the death of a pulp through trauma, years before the discovery of the ab- scess. At some period a tooth receives a severe blow, and for some time is the seat of traumatic pericementitis, which subsides : it may be years after that a fistula is established in the mouth or upon the face, without a history of inflammatory disturbance. As pointed out by Dr. Black, the direction of pus-burrowing in chronic abscess is determined by gravity ; thus, if the abscess be upon a lower incisor the pus may burrow, opening beneath the chin, as shown in Figs. 455, 456. Sir John Tomes 1 has called attention to the tendency of pus to open at the angle of the jaw in abscesses affecting the lower third molars (see cases noted above). Diagnosis and Prognosis. Diagnosis. — If the pericementum of a pulpless and open tooth have been the seat of acute and marked apical inflammation of septic origin for a longer period than thirty-six hours pus is almost invariably formed, and alveolar abscess is present. The diagnostic symptoms are those of acute pericementitis described in Chapter XVII. In case any marked inflammatory disturbance is found about the maxillary region either within or without the mouth, examination of the teeth of the affected side should always be made, as a large percentage of such in- flammations are of dental origin. Any fistula existing in the maxillary regions, either within or without the mouth, is to be suspected as having origin in a septic pericementitis of some tooth. A soft silver probe is to be passed along the tract to determine its direction and, if possible, which tooth is affected. As a rule, such a tooth will itself exhibit objective evidences of abscess and the patient will give a history of subjective symptoms — those of inflammation of pericementum. Should the tooth indicated as the affected one be free from caries, the thermal test is to be applied to indicate the vitality or the necrosis of the pulp. Should the tooth not respond to applications of a pointed piece of ice, it is possible it may offer slight response to applications of heat. It is next examined by light reflected from the ordinary, or better, the electric mouth mirror, when, if the pulp be dead, opacity of the crown will be detected. An abscess upon an upper incisor opening upon the nasal floor may cause a discharge simulating that of ozena ; an examination of the nose will reveal a teat-like elevation upon the mucous membrane covering 1 Dental Surgery. 476 DENTO-ALVEOLAR ABSCESS. the nasal floor and an incisor beneath will be found carious and having a putrescent pulp, or, if non-carious, a history of traumatic pericemen- titis and a present opacity. It may be mentioned here in connection with death of the pulp from traumatism, that continued thread-biting, biting very hard substances such as pieces of ice, nuts, etc., may cause death of the organ, presum- ably by thrombosis. It is possible that the direction taken by the probe which is passed into the fistula will point away from the teeth present, passing into a space from which a tooth has been extracted. In that event the pres- ence of a root fragment, or piece of necrosed process, may be suspected. 1 Should the neighboring teeth be excluded as causes of an inflammation, there should be no hesitation in making an exploratory incision down to the end of the probe which has been passed into the fistula. Cases of dentigerous cysts have been detected in this manner. This condition would, however, be suspected when there was an absence of a tooth or teeth from the arch, no evidence past or present of pericementitis in any of the teeth of the arch, and a cystic tumor present in the jaw, or it may be a fistula discharging upon the face after a history of maxillary periostitis. Caries or necrosis, although in many cases the result of septic apical pericementitis, may yet exhibit fistula? opening into the mouth, without evident connection with the teeth. As a rule, cases of necrosis exhibit marked and wide evidences of chronic inflammation of the tissues over- lying the dead or dying bone ; there are usually several fistula? dis- charging from it. Caries may have but a single fistula and simulate closely ordinary alveolar abscess. Diagnosis is made by passing an excavator through the fistula. Dead bone is readily detected by touch, it has a rotten feel ; in caries the instrument may be passed through the dead bone in various directions, and a characteristic dead sound is elicited by tapping upon it. Careful examination of the teeth must be made in all of these cases, to determine the condition of the pulp and pulp canals. In passing an instrument through a fistula to the apex of an ab- scessed root, where the disease action has been of long duration, it may be found that the apex of the root is denuded of pericementum, and roughened — that is, the apical cementum is necrotic ; foreign deposits may be detected occupying portions of the necrotic area. Prognosis. — There are several factors which enter into the prognosis of a tooth and its surroundings which are affected by alveolar abscess. First, the severity and character of the inflammatory action and septic invasion. In cases in which inflammatory action is localized and pre- 1 See case — Dr. Black, American System of Dentistry, vol. i. TREATMENT. 477 senting none or but little febrile disturbance the prognosis is, as a rule, favorable ; but a slight amount of tissue necrosis occurs. Should, on the other hand, the inflammatory action proceed with volcanic violence, it is possible that not only may the pericementum suffer extensively, but a considerable portion of the periosteum over the process may be raised from the bone during the escape of the pus. Should this separation of periosteum be maintained for more than a few hours, the underlying bone may suffer to the extent of necrosis. In case of marked lymphatic involvement, the neighboring glands being swollen and tender, or even the skin over them exhibiting evidences of glandular inflammation beneath, more or less septic intoxication will probably occur, and un- less the focus of infection be promptly sterilized, septicemia is to be feared. Should evidences of diffuse cellulitis occur, indicating the invasion of streptococci into the adjacent soft tissues, it is a danger signal of threatening pyemia. 1 Heath 2 records a case of oedema of the glottis due to the involvement of the connective tissues about the glottis in the oedema accompanying a developing abscess upon a lower molar. The prognosis is good in a vast majority percentage of cases, when the offending tooth is extracted early in the attack, or at its height ; this applies even with apparently very grave cases ; still the prognosis as to the retention of the affected tooth is also very good, unless the abscess run a phagedenic course. In many of the cases of chronic abscess having a distant discharge the abscess may be cured and the tooth retained. Other cases obstinately refuse to heal so long as the offending tooth is present. Treatment. Treatment of Acute Abscess. — The general principles of treat- ment of alveolar abscess are those for the treatment of abscess in any part ; the details are of course modified in accordance with the anatom- 'ical peculiarities of the part to be acted upon. These principles are the removal of all dead matter, together with the active causes of the inflammation and suppuration, i. e. micro-organisms and their products, and the induction of a tissue regeneration which shall serve to restore parts lost through the formation of the abscess. The therapeutic means applied are instrumental and medicinal. The instrumental are the instruments employed to gain access to the focus of disease action, and those applied in the mechanical removal of dead parts. The medicinal measures include the agents employed to wash out the abscess tract ; second, those applied to destroy the active causes of the suppuration ; 1 See case — Dr. E. C. Kirk, Proe. Odontolngical Society of Pennsylvania, ]892. 2 Injuries and Diseases of the Jaws, 3d ed. 478 DENTO-ALVEOLAR ABSCESS. third, the remedies applied to induce new tissue growth ; and next, those employed to maintain asepsis until the healing process is complete. The great primary objects in the management of acute alveolar abscess are four : First, if the case be seen early, to use every endeavor to abort the inflammation, as described in Chapter XVII. Second, to limit as far as possible the extent of pus formation, hence tissue destruction • third, the earliest possible evacuation of the pus which has formed ; fourth, the thorough sterilization of the abscess cavity and its walls. Cases when seen may be at any stage of the disease process from an incipient pericementitis to the establishment of a fistula. The treatment of the early cases is that of pericementitis. In all of these cases one fact is never to be forgotten : that the pulp canals are the centres of infec- tion, and the more quickly and thoroughly they are drenched with powerful antiseptics the more limited will be the inflammatory action both in degree and extent, and the more limited will be the pus forma- tion. Attempts are therefore made to enter and sterilize cavities pari passu with the antiphlogistic measures applied to abort or limit inflam- matory action. Treatment of Abscess without Fistula. — Abscess has been de- scribed by the older surgical pathologists as the process through which Nature rids herself of an irritant. This is in a measure true, but it is essentially a destructive and not a conservative process. Nature does rid herself of the irritant through suppuration ; but it is done at the expense of tissue loss, and the wise surgeon endeavors to remove the irritant and limit the destruction. After the inflammatory action has persisted at its height for twenty-four hours, pus is probably present in the tissues of the apical region ; if immediate exit be given to the pus the inflammatory symptoms will subside. If the tooth be not so sensi- tive as to preclude touch upon it, an endeavor is made, after washing the pulp chamber with powerful antiseptics, to pass a very fine Donald- son's bristle through the apical foramen. In many cases this may be done ; the pus escaping through the canal, the inflammatory symptoms begin to subside. This is a case of acute blind abscess ; its treatment will be first discussed. The conditions existing are more or less remnants of pulp tissue undergoing putrefactive decomposition ; the contents of the dentinal tubules are also in process of dissolution. Beyond the apical foramen is a fibrous tissue containing bloodvessels and nerves, in the meshes of which tissue pus is forming. Beyond the spots of suppuration, the tissues, which are in small part fibrous but are mainly osseous, are the seat of inflammation. The pus evacuated, the parts tend to spontaneous recovery provided TREATMENT. 479 the sources of irritation be removed. The first step in sterilization is the destruction of putrescent matter in the pulp canals. If the tooth be sore after evacuation of the pus through the apical foramen, the patient is directed to use repeatedly an antiseptic mouth-wash, 3 per cent, pyrozone or any of the solutions of hydrogen dioxid, and report in a few hours, when the broach is again passed through the apex of the root, the canal syringed out with hydrogen dioxid and dismissed for twenty-four hours, when the inflammatory symptoms Avill have so far subsided as to permit working upon the tooth. At this sitting, a slight flow of pus Avill still be found ; the canals are syringed, rubber dam applied, but never with a clamp on the affected tooth. Sodium di- oxid either dry or in 50 per cent, solution is placed in the canals, and frequent re-applications made. At the expiration of about a half-hour the canals and abscess cavity are syringed out with an acid solution of hydrogen dioxid, and dried. The canals will now be sterilized and also the general abscess cavity. It is possible, however, and probable, that organisms may still occupy the deeper recesses of the tissue bounding the abscess cavity. The parts forming the abscess wall are of com- paratively low vitality and may not dispose of organisms present as would be done in more vascular tissues. It is the usual practice, there- fore, to apply to them a powerful antiseptic : campho-phenique, Dr. Black's 1, 2, 3 mixture, and lysol are all admirable agents in this par- ticular ; they are pumped into the abscess sac as well as possible, and the excess in the canals wiped away with wisps of cotton. There will be, immediately following this operation, a greater or less amount of exudation from the abscess walls, which diminishes as granulation proceeds about the apex of the root. The condition is one of granulating ulcer. An escape is provided for this exudation by leaving the dried canals unfilled for twenty-four hours, when a loose cotton dressing may be applied, hermetically sealing the cavity com- municating with the saliva after each dressing. In two days the dress- ing is removed, always sterilizing the tooth walls and isolating it when the cavity is to be opened. On the third day a larger dressing of cotton, dipped in campho-phenique and wrung out, may be applied. After two days, should the cotton exhibit little or no evidence of exuda- tion, a firmer dressing is applied, to remain about four days ; the next dressing remains a week, when the abscess cavity should be filled with tender granulations. Pending the organization of the granulation tissue there is probably no better canal filling than salol having a core of gutta-percha. It is unirritating and may be applied without causing irritation. Dilute solutions of formaldehyd have been found to be extremely useful in this class of cases as well as in all cases involving sterilization of the pulp canal. The high antiseptic value of formalde- 480 DENTO- ALVEOLAR ABSCESS. hyd and its great penetrating power place it among the most satisfactory agents in the dental pharmacopoeia. For the treatment of root canals with apical pericementitis a wisp of cotton moistened with a 5 per cent, solution of formalin (the 40 per cent, solution of the gas in water) and sealed in the canal will in a few hours completely sterilize it, so that usually the canal may be permanently closed within twenty-four hours. Rarely, a second dressing is required. Stronger solutions of formalin are irritating and should be avoided, as they may cause necrosis if used beyond the strength stated, or even in that strength if used in too large quantity or too frequently. Should the effort to enter the apical region through the canal fail, and pus be present, an entrance should be effected through the gum. At a point on the gum immediately overlying the apex of the affected root, a pointed bistoury is quickly thrust down to the bone, the bleeding is encouraged by the use of hot water for several minutes, when a pellet of cotton which has been dipped into 95 per cent, carbolic acid is laid against the periosteum at the bottom of the cut. In a few seconds a spear drill driven by the engine is passed through the bone into the tissues of the apical region. Any bleeding which may occur is encour- aged as above mentioned. For washing the incisions and the abscess in such cases there is no agent more acceptable than a 20 per cent, solu- tion of phenol sodique, it being both sedative and antiseptic. A thread of floss silk dipped in carbolic acid is passed into the fistula to the seat of abscess, its projecting edge lying upon the gum ; this will prevent too rapid a healing of the fistula. The case now resembles an abscess with a fistulous opening, the next variety of acute alveolar abscess ; the treat- ment for both is the same. Treatment of Abscess with Fistula. — Cases of acute alveolar abscess discharging through a fistulous opening are either seen when the pus has perforated the bone and is making its exit through the soft tissues, or in cases where the inflammatory symptoms run high, the usual methods of aborting the inflammation having failed, pus forms and the abscess discharges rapidly, it may be within thirty-six hours, The use of pepper plasters and like devices to induce pointing of an abscess are irrational ; they render no service which cannot be per- formed better and more expeditiously by an incision made down to the bone by means of a sharp bistoury. In all cases of acute apical pericementitis where the swelling of the gum is marked, an early and deep incision is useful and advisable. If pus be already formed and the abscess pointing, escape is afforded it ; if the pus have not yet per- forated the periosteum that structure receives early relief from a condi- tion w T hich might threaten it. The greater the swelling the more imperative is the necessity for this incision, which must be freely made. TREATMENT. 481 Fig. 458. A sharp curved bistoury is held as a pen, its point directed always toward the bone, and is passed boldly down to the bone immediately over the apex of the root. Inflammatory symptoms, as a rule, subside promptly as soon as exit is afforded the pus. As soon as the tooth may be operated upon, its canals are to be treated as virulently and deeply infected centres, opened freely and sterilized w T ith the utmost thoroughness. The usual and satisfactory method of accomplishing this is by means of a 50 per cent, solution of sodium dioxid ; after which a stout syringe filled with 3 per cent, pyrozone is to have its contents driven forcibly through the abscess tract, the application to be repeated until the peroxid comes away clear. A few drops of campho-phSnique or Dr. .Black's 1, 2, 3 mixture are placed in the pulp canal by means of Flagg's dressing pliers. This may be drawn into the abscess sac along its tract, emerging at the fistulous opening, by a little device of Dr. T. M. Hunter. 1 One of the rubber cups used for finishing fillings and cleaning teeth is to have its tool opening filled with gutta-percha, the concavity of the cup moistened and pressed flat against the gum, covering the fistula ; removing the pressure from the centre of the cup but keeping its edges closely in con- tact with the gum, a suction is created drawing the medicament through the abscess tract. The w r riter has used these cups, but mounted on a No. 300 mandrel (Fig. 458), for this purpose for several years ; indeed the discovery that Dr. Hunter had employed and ad- vised it as a means of emptying abscess cavities was a gratifying surprise, as he states that they serve this purpose admirably. The sterilized canals are now to be thoroughly filled with cotton twists or gilling twine which has been moistened with the last-named antisep- tic, or 5 per cent, formalin, the crown cavity sealed, and the case dis- missed. In twenty-four hours, only a slight serous exudate should be pressed from the fistula. In a week the abscess cavity should be healed. In that time a permanent canal filling may be inserted, but it is wiser to defer the filling of the crown cavity for some time — that is, if it is to be filled with cohesive gold. In case of acute abscess w r here marked inflammatory symptoms with involvement of neighboring parts persists after the evacuation of the pus, the gum overlying the tooth being purplish and tumid, the tooth very loose, and no diminution of the attendant fever, neighboring structures in addition to the tooth are in danger, and the latter should 1 Dental Cosmos, vol. xxxiv. p. 82. 31 482 DENTO-ALVEOLAR ABSCESS. be extracted. An early and free incision will frequently avert this con- dition and necessity for extraction. Should the case when first seen exhibit marked evidences of involve- ment of the tissues of the face, a threatening of the abscess toward pointing on the face, prompt and active measures are necessary. As a rule in these cases the pernicious domestic practice of applying poultices to the face has been followed, and in consequence the tissues of the cheek are distended and softened, lessening the suffering but inducing the flow of pus along the line of softening. Compresses wet with lead- water and laudanum — 1^. Plumbi subacet., 3J ; Tr. opii, 3j ; Aqua?, Oj.— M. should be laid upon the face, and an incision made at the line of junc- tion of the cheek with the gum, down to the bone over the apex of the root. As a rule, in these cases the pus has found its way into the tissues of the cheek, but drains through the incision ; a cut must always be made away from, not toward the cheek, to avoid cutting the facial artery or any of its branches. Opening upon the face may be averted by this means, even when the pus is beneath the skin. The danger of inclusion of the duct of Steno should be borne in mind should the case be one of abscess upon an upper molar, and energetic measures pursued to prevent the establishment of that annoying trouble, salivary fistula. When fluctuation of the inflammatory tumor upon the face becomes evident, indicating that an external opening must be made, it is prefer- able that it be made, with a sharp knife and not by suppuration. Scars left by abscesses discharging spontaneously are irregular and disfiguring, those following clean incision are but a line. A curved bistoury is used to transfix the summit of the swelling, the knife is then carried outward, making an incision about an inch long. In this as in all cases of abscess where pus is detected the indication is to give it immediate exit. It occasionally occurs that abscess may be found upon the lateral aspect of a tooth containing a vital pulp. The tooth is free from caries, and is perfectly translucent. The most usual situations of these abscesses are upon the labial faces of the anterior teeth and the buccal faces of the molars, between the gingival margin, which may be intact, and the apex of the root. As a rule the evacuation of the pus and dressing with antiseptics causes a speedy disappearance of the abscess. Left to themselves they discharge as a rule at the gum margin. They are a frequent associate of the condition graphically described by Dr. G. V. Black as phagedenic pericementitis. Believers in the gouty origin of this disorder note their occurrence in gouty patients. 1 In 1 Typical cases are recorded in Proc. Academy of Stomatology of Philadelphia, 1895. TREATMENT. 483 these cases the abscess is attended by more or less destruction of the pericementum. Cases may be seen in which the abscess involves the tissues near the apex of the root, the pulp being vital ; its death, how- ever, will doubtless result from the invasion. Acute apical abscess may discharge at the margin of the gum, follow- ing the pericementum. These cases are to be treated as abscess with fistula. In some cases subsequent to the treatment of the abscess there appears to be a restoration of the pericementum lost in the formation of the fistula. In others a permanent loss of tissue results. This mode of discharge is common about dead roots which have been in the jaw crown less for a long period ; a resorption of alveolar process has occurred and the root is retained by fibrous tissue. The treatment in these cases is that accorded any and all roots which may not be made serviceable — extraction . Treatment of Chronic Abscess. — For purposes of treatment, chronic abscesses are divided into two classes : those discharging through the pulp canal, what are known as blind abscesses ; second, those dis- charging upon the gum, at the neck of the tooth or in fact at any point, through a fistula. The usual condition existent with the blind abscess, is a cavity which may have any volume, its diameters, however, rarely exceeding three-eighths of an inch ; this cavity is bounded upon all sides by a fibrous capsule, analogous to the indurated surroundings of an ulcer ; the wall represented by the cementnm of the aiFected tooth may be devoid of fibrous tissue, the pericementum being necrotic. The pulp chamber is the centre of infection ; the abscess cavity is the habitat of bacteria, which cause the peptonization of the inflammatory exudate from the wall of circumvallation, and destroy the exudation corpuscles, thus producing a continued pus formation. The observation and statement of Dr. Black have been quoted above, wherein he states that gravity largely determines the direction pursued by the pus in chronic abscess. This tendency will be found to exist with the blind variety also. The tendency of long-continued pus formation about the roots of the upper teeth will be to progress along the pericementum, resulting in a molecular necrosis of that structure from the apex downward. The condition is represented in Fig. 459. The extent to which the apex of the root projects into a cavity increases with the progress of the necrotic process. In the lower teeth, the influence of gravity carries the suppurative process away from the apex of the root, the abscess cavity increasing downward (Fig. 460). If the case be seen shortly after the subsidence of the inflammatory attack which may have ushered in the suppurative process, the cavity 484 DENTO-ALVEOLAR ABSCESS. may be very limited in size, only a trifling amount of the pericementum being destroyed. It is advisable in these cases, after thorough sterilization of the canals and dentin by means of sodium dioxid or formalin, to increase the size of the natural drainage-tube, by enlarging the pulp canal ; a fine Donaldson Fig. 459. Fig. 460. Chronic blind abscess of upper incisor, showing Chronic blind abscess upon lower tooth, tendency of pus to progressively destroy peri- showing tendency of pus to sink into cementum owing to the influence of gravity. the substance of the lower maxilla owing to the influence of gravity. cleanser should pass freely through the apical foramen. The abscess cavity is now forcibly and thoroughly syringed out with 3 per cent, pyrozone. It is advisable after effervescence ceases to mechanically withdraw, or aspirate, the contents of the abscess. This may be readily done by passing the point of a syringe into the canal, filling around it with gutta-percha and withdrawing the piston, when the contents of the abscess will flow into the syringe. Any instrument (syringe) employed for this purpose should soak for hours in an antiseptic before using it in other cases (a 20 per cent, solution of phenol sodique is an excellent sterilizing agent) ; the same syringe should never be used for any other purpose. A small amount of 25 per cent, pyrozone, ethereal, may now be placed in the canals and pumped into the abscess cavity ; then canals and sac are dried by means of warm blasts, and a wisp of cotton dipped in campho-phenique and wrung out is packed in the canal. The patient reports the day following, and if no discomfort be felt the tooth remains closed until the following day. If upon opening the tooth no evidence of exudation is seen, and no effervescence occurs upon applica- tion of 3 per cent, pyrozone, the drying and dressing are renewed, to remain about three days. If any evidence of pus be detected, the canals and abscess are syringed with weak pyrozone, and a small amount TREA TMENT. 48 5 of campho-phenique, Dr. Black's 1, 2, 3 mixture, or myrtol may be pumped into the abscess, and by repeated blowing of warm blasts driven into all parts of the cavity. In twenty-four hours a slight serous flow should be observed, but if after three days any evidence of pus be de- tected, it is the signal to establish an external fistula. This is done in the manner before described. The treatment is now the same as that for the next class : chronic abscesses having fistulous opening. Chronic Abscess with Fistulous Opening*. — In these cases the canals are opened and sterilized as in all others by the powerful anti- septics named. The abscess tract is syringed out with 3 per cent, pyro- zone until bubbling at the external orifice ceases. The canals are filled with campho-phenique, or the 1, 2, 3 mixture, after the dressing-pliers method, and drawn into and through the abscess cavity and tract by means of the rubber-cup device already mentioned. In cases in which the rubber-cup device fails to cause a flow of the medicament from the pulp chamber out through the fistulous tract, the result may be attained bv filling the canals and pulp chamber with the fluid desired ; for example, campho-phenique or strong carbolic acid, and then placing over the cavity a pellet of unvulcanized caoutchouc or warmed and soft- ened gutta-percha base plate and exerting strong pressure upon it with a ball-end burnisher just enough smaller than the cavity to force the material well into the pulp chamber. This will cause the medicine to flow out at the fistulous opening, where in the case of carbolic acid its presence will be manifested by its coagulating effect upon the margins of the fistulous orifice. The canals are to be temporarily filled with cotton saturated with an antiseptic, and as a rule the case proceeds rapidly to recovery. Fresh cleansing and dressing are indicated if all evidences of inflammatory action, seen in the gum color, are not absent in three days ; in a week the external fistula should be closed. _ ,. , . Fig. 461. If after a week the fistula remain open, discharging serum, a sterilized excavator is passed through the fistula and it may detect denudation and roughness of the apical cementum. After a root has been the seat of chronic apical abscess for a long period, not only may the apical pericementum be destroyed (Fig. 461), but the cementum itself may become saturated with the products of decomposition and invaded by septic chronic absC ess : show- organisms. It is not uncommon to find deposits of ing denudation of 7 .. ill! o i_ apex of root (a to b), calculi upon the denuded cementum. feucn an apex with dep0 sits of cai- is the source of constant irritation ; it is a foreign cuius upon cemen- turn. body, and is to be removed. The operation of removal is technically known as amputation of the 486 DENTO-ALVEOLAR ABSCESS. apex. The canal thoroughly sterilized is to be solidly filled with gutta- percha. A vertical incision is made which includes the fistula and exposes the process ; the opening through the process is enlarged, by sweeping around its borders a large dentate bur. The incision, open- ing and abscess cavity are now packed with cotton saturated with phenol sodique, until all bleeding ceases. The necrosed cementum is now exposed ; a small and extremely sharp fissure bur, driven rapidly, is laid against the distal wall of the root and a constant pressure upon the bur maintained until the dead part is ampu- tated. A sharp scaler may now be employed to round the edges of the root and make the cut surface smooth. The cavity is syringed with phenol sodique, to thoroughly remove all blood-clots — favorable breeding-grounds for organisms ; as a final measure the walls are touched with campho-phenique, and the edges of the incision brought together, using if necessary a stitch to unite the upper edges. In the abscess cavity iodoform or nosophen gauze is to be packed, and renewed in a couple of days. For a week the patient is directed to employ repeatedly a mouth-wash of 3 per cent, pyrozone. No attempt should be made to fill such a tooth with cohesive foil for several months. In some of the cases of anomalous root form, such as a sharp bend upon the upper end of the root, and which renders it impossible to gain access to the apex of the root even through the aid of sulfuric acid, it may be necessary to treat the abscess through the fistulous opening. The roots are sterilized and cleansed to as great a depth as possible by the aid of sulfuric acid and fine cleansers, and the endeavor made to force hydrogen dioxid through the apical foramen and out of the fistula by means of a syringe. The cavity of the crown is filled with pink gutta-percha, and through it the nozzle of a syringe filled with 3 per cent, pyrozone is thrust, well up the canal. The piston of the syringe is forced down ; it may be the solution will appear at the opening of the fistula, or it may be the solution will fail to penetrate the fora- men and its backward pressure will force the gutta-percha from posi- tion. In that event myrtol is placed in the canal, which is filled with thread holding the same material. Three per cent, pyrozone is injected into the abscess cavity through the fistula, until effervescence ceases. The nozzle of a minim syringe (Fig. 429). charged with campho- phenique or the 1, 2, 3 mixture is passed into the abscess sac, and a couple of drops deposited. In very many cases the abscess will then proceed to recovery. The treatment should be repeated if necessary. If several dressings applied at intervals of a week do not cause a disappearance of pus formation, amputation of the offending portion of the root will be necessary. An heroic method of treating chronic TREATMENT. 487 abscesses which obstinately refuse to heal is by extraction and replanta- tion. The method applies alone to single-rooted teeth, although it has been successfully performed upon molars. The patient's mouth is to be sterilized, and the tooth extracted. It is immediately placed in a solution of 1 : 1000 mercuric chlorid at a temperature of 120° F. It has been repeatedly asserted, however, with- out satisfactory demonstration, that the cells of the deeper layer of the pericementum and the cementoblasts, and also the cement corpuscles retain their vitality for some period after extraction, and immediate replantation results in a re-establishment of the physiological union between the tooth and alveolus. It is certain that means and measures which are necessary to thoroughly sterilize the tooth before its reinser- tion would be fatal to any cellular vitality which might exist in the cementum and its covering. The pulp canal is opened from its apex and cleaned out with canal cleansers, and pyrozone 25 per cent, placed in the canal, where it is al- lowed to remain for some time. In the meantime the socket from which the tooth has been removed is syringed out with pyrozone, and should the pericementum not be adherent to the tooth, the depth of the socket is scraped by means of large spoon excavators to remove the tissues implicated in the abscess. The cavity is washed out with pyrozone, and a pledget of cotton which has been dipped in campho-phenique is placed in the socket at its bottom. The tooth is dried by means of warm air ; the soft tissues, if any be present, at the apex are cut away for about one-eighth of an inch. The canal is filled with gutta-percha or solidly filled with gold, the end of the root cut off as far as it has been denuded of pericementum, smoothed, and returned to the antiseptic solution. The cotton is removed from the tooth socket, which is syringed out with 3 per cent, pyrozone, and the tooth returned to posi- tion. It is tied to the adjoining teeth by means of silk ligatures or held in place by an appropriate retaining appliance. Occasionally the seat of an alveolar abscess may be at the bifurca- tion of the roots of a molar. This may occur upon vital teeth owing to a foreign body being driven beneath the margin of the gums and into the point of bifurcation. In these cases it is noted that the inflamma- tion affects the gum about the neck of the tooth ; over the apices of the roots there may be no evidences of inflammation ; pus forms and dis- charges quickly. Syringing out the tract with 3 per cent, pyrozone usually frees it from pus and the offending substance — it may be a bristle of a toothbrush — and the case heals rapidly. Cases are seen in which the gum attachment about the neck of the tooth is unbroken ; and free access may be had to the apex of each root of a tooth manifestly suffering from acute pericementitis, pre- 488 BENTO-ALVEOLAR ABSCESS. sumably due to a putrescent pulp. In a day or two a discharge of pus may be noted about the neck of the tooth. Such teeth when extracted exhibit an unmistakable abscess sac in the pericementum at the bifurcation of the roots. Whether the pyogenic organisms have traversed the dentin in the bottom of the pulp chamber and the cementum beneath, and thus inaugurated the suppurative process, is undetermined ; it may be, however, that waste products from this source following the channel named may have saturated the cementum with noxious material and caused the inflammation, or the organisms may have found entrance at the gum margin. The diagnosis of such a con- dition is most uncertain before pus finds exit at the gum margin. Such a case is to be treated by sodium dioxid, full strength, placed in the floor of the cavity, frequently washed away and renewed until the base of the pulp chamber is bleached white. The abscess cavity is syringed out with pyrozone. Another variety of abscess should receive mention : that occurring about lower third molars, affecting the gum tissues partially enclosing the emerging crown. The gum overlying and surrounding the erupting tooth becomes reddened, tumid, and exquisitely sensitive ; if the inflam- mation be not aborted by timely incision and antiseptic washes, pus may form, and the gum acquire an ulcerous appearance. The treatment is free incision, dividing the swollen gum, and syringing with 3 per cent, pyrozone. If there be ulcerous surfaces they are to be touched with 50 per cent, solution of trichloracetic acid. Occasionally the muscles of mastication may become affected by the inflammatory process, and inability to open the jaws result. Such cases are not uncommon when the eruption of the tooth is delayed by lack of room between the ramus of the jaw and the second molar. The extrac- tion of this latter tooth may be required before relief is secured. Complications of Alveolar Abscess. The complications of alveolar abscess are due in acute cases to the involvement of other tissues than those commonly affected in the course of abscess formation and discharge. They depend in great part upon peculiarities of the anatomical relations existing between teeth and their surroundings, and, as anatomical variations are not uncommon in these parts, aberrations of disease process may be found with unwelcome fre- quency. An examination of some of Dr. Cryer's sections x will exhibit in one case the root of a lower second bicuspid penetrating the passage- way for the inferior dental vessels and nerves. It is quite possible that an abscess upon such a tooth discharging about the fibrous sheaths of 1 Proc. of American Dental Association, 1895. COMPLICATIONS OF ALVEOLAR ABSCESS. 489 these vessels might travel to distant parts — backward through the in- ferior dental foramen, or forward through the mental foramen. The roots of molar teeth instead of having their thinnest bony cov- ering overlying their buccal aspects, may have their apices almost per- forating the lingual wall of the bone ; in others the apex of the root of a lower molar is found beneath the line of insertion of the mylo-hyoicl muscle. Abscess from such a case as this would probably discharge not into the cavity of the mouth, but in the submaxillary triangle. (See the case of Dr. Cryer's noted early in the chapter.) Dr. Harrison Allen ' records one of these cases. The septic roots of a lower third molar were the exciting cause of pericementitis, followed by osteitis and maxillary periostitis. Pus found exit beneath the mylo-hyoid muscle and gravitated, forming a collection about the hyoid bone, and from that point passed upward upon the face in the line of the facial artery. The abscess in addition pressed directly upward against the floor of the mouth and caused unilateral glossitis, from the mechanical effects of which upon the organs of respiration the patient died. The duration of the extra-maxillary complication was but four days. In the progressive resorption of the inner substance of the superior maxillary bone which results in the formation of the maxillary sinus, a process which certainly continues longer in some persons than in others, the bony structures may be removed to such an extent that but a thin layer of bone, periosteum and mucous membrane covers the apices of the roots of molars. Dr. Oyer's sections exhibit two cases in which the excavation of the sinus has proceeded down between the roots of an upper molar, creating such a condition that abscess upon either palatal or buccal roots must almost inevitably discharge into the sinus. Xo doubt many cases of incipient empyema of the antrum are aborted by the early extraction of abscessed molars, the antral complication being unrecognized. It is presumable that most of the cases of empyema of the antrum afford subjective evidence comparatively early, owing to the lighting up of inflammation and purulent catarrh. The student is advised, in studying the relations of the teeth with the maxillary sinus, to a careful and repeated reference to the sections of Dr. Oyer. He calls attention to a fact frequently overlooked and un- taught, that the orifice or opening connecting the maxillary sinus with the nasal passage is near the roof of the former, so that while the patient is in the erect position collections of fluid must nearly fill the sinus before there is a discharge. In the recumbent position, however, the fluid escapes and may be found in the nostril of one side. This is symptomatic of antral empyema. In acute cases of the antral disease there is much swelling, cedema about the eyelid, etc. ; sharp lancinating 1 Garretson's Oral Surgery, 6th edition. 490 DENTO-ALVEOLAR ABSCESS. pains dart about the jaw. In the chronic cases, large accumulations of pus may occur and not be detected until the bone is thin and bulged, emitting a crackling sound upon pressure. Extraction of the offending tooth furnishes an outlet for the pus. It is usual to attempt the passage of an instrument through the pulp canals into the antrum and endeavor to preserve the tooth. Such a drainage is insufficient ; the wall of the antrum should be perforated. This little operation is readily done : At a point about one-eighth of an inch or more above the apices of the roots of the molars an incision is made through the mucous membrane of the buccal alveolar wall, clear to the bone ; a spear-pointed drill, a large one driven rapidly by the engine, is passed instantly through the outer antral wall. The drill is directed upward and inward. The opening is made sufficiently large to permit free irrigation. Into the opening thus made the point of a syringe, perforated to sprinkle, is placed, and the cavity washed out with 3 per cent, pyrozone which has been diluted one-half and made faintly alkaline by the addition of sodium dioxid. As pointed out by Dr. W. H. Atkinson many years ago, unless the irrigating fluid be made faintly alkaline it is irritating. As a stimulant injection to fol- low, Lugol's solution (liquor iodi compositus, gtt. xx to the ounce) is excellent. The canal of the tooth is to be thoroughly sterilized and filled. In the treatment of other complications, if the case be acute, the im- mediate extraction of the offending tooth and the free use of antiseptic mouth-washes will usually effect a cure. In the treatment of chronic cases, if the focus of infection, the pulp canals, be made antiseptic and the medicinal agents can be introduced into the abscess tract through- out, surprising cures may result, as the literature of dentistry testifies. Abscess upon Temporary Teeth. — Among the most trying classes of cases with which the dental operator is confronted are those of peri- cemental disturbance affecting the temporary teeth. The operator is torn by conflicting emotions : the desire to afford quick relief to the little sufferers and the hesitancy or dread of inflicting the amount of suffering necessary to relieve the acute pain. Fortunately the pain is relatively less than in adults ; the tissues being softer the child escapes the agoniz- ing pain attending the rapid formation of pus in the apical tissues of the adult. The swelling, redness, and febrile disturbance are usually greater in the child than in the adult ; pus forms more quickly and makes its appearance in the gum sooner. The principle of treatment is the same as with the adult — evacuation of the pus. The necessary incision may be made almost painlessly by employing a sharp-pointed bistoury hav- ing a razor-like edge. The child, reassured by a gentle examination and firm kindness, is directed to open the mouth and close the eyes, COMPLICATIONS OF ALVEOLAR ABSCESS. 491 when the bistoury, held as a pen, is passed quickly into the swell- ing. The canals of temporary teeth are to be sterilized first with pyrozone, next with oil of cassia, and should be filled with " balsamo del deserto." Dr. W. H. White, to whom we are indebted for the introduction of this material, states that in roots of temporary teeth in which it has been placed the resorptive process is not interfered with. Abscess occurring upon temporary teeth should receive prompt at- tention and treatment to avoid possible injury to the permanent tooth beneath ; this, however, does not appear to be as frequent as might be supposed. There is a tendency in strumous children toward marked lymphatic involvement attending alveolar abscess ; and secondary abscess of the lymphatic glands is not uncommon. Chronic abscess in the cachectic individual which may not respond to the usual local measures of treatment may be materially benefited by constitutional treatment. This comprises regulation of the functions of the alimentary canal ; the use of such foods as beef peptonoids, mal- tose, etc. Iron and arsenic are administered when the patient is, as is usually the case, anemic. More important than any medicinal thera- peutics is systematic exercise in the open air. Raising the bodily tone raises the recuperative power of the tissues, and hitherto resisting dis- ease may be conquered. Perforated Roots. — Perforation of the walls of a root canal expos- ing the pericementum occurs, as a rule, in consequence of two causes : first, the invasion of dental caries ; second, the injudicious or unskilful use of the reamer employed in enlarging canals, or, it may be, burring through the walls in the forming of a socket for the reception of the post of an artificial crown. The direct consequence of the perforation is inflammation of the pericementum, and the usual result is ulceration of that structure. The symptoms and their severity are, as a rule, governed by the situation of the perforation. If this be at the lower half (toward the crown) of the root, there is usually a proliferation of tissue which intrudes upon the pulp chamber. This hypertrophied tissue may increase in amount, a resorption of the edge portion of the process occur, and a fungous mass bearing a close resemblance to fungous pulp bulge into the pulp cham- ber. In fact, in many cases it is impossible to distinguish between the naked-eye appearance of fungous pulp and the condition under discussion. The growth fills the pulp chamber and obscures the per- foration ; it is in addition, in many cases, exquisitely tender. In either event, whether pulp or hypertrophied gum, it is necessary to remove the growth. A spray of ethyl chlorid directed against the mass is perhaps the 492 DENTO-ALVEOLAR ABSCESS. most effective anesthetic ; in a few minutes a sharp fine-pointed lancet is passed around the growth as far as it can be, and the excised portion removed. An application of tannin will check the bleeding; pledgets of cotton dipped in tr. iodin. are packed against the remainder of the growth and covered in with cotton and sandarac varnish for twenty- four hours. This dressing is renewed from day to day until, if it be a fungous gum, the margins of the perforation are plainly seen. The canal is cleansed, sterilized, dried, and filled with salol and gutta-percha, or with paraffin and gutta-percha, to about half its depth. The re- mainder of the canal and crown cavity are washed out with 25 per cent, pyrozone, and a dressing of temporary stopping applied, filling the per- foration and yet not exercising much pressure upon the soft tissues. In two days the temporary stopping is removed and the cavity is washed out with 3 per cent, pyrozone and dried. A piece of No. 60 gold is cut, larger than the aperture ; this is dipped in chloro-percha and laid over the perforation. A disk of gutta-percha larger than the piece of foil is warmed, laid upon the foil, and pressed against it, sealing it to the cavity walls. The remainder of the cavity is then filled with zinc phos- phate. In case the perforation should be nearer the apex of the root the dif- ficulty is greatly increased. Attempts at passing cleansers to the apical foramen usually result in pricking the pericementum at the perforation and a flow of blood follows, filling the canal. The cleansers are bent so that in passing them to the apex they press against the wall opposite the perforation ; the apical portion of the canal may be detected and cleansed after this manner in some cases. The temporary dressings in these canals should be one of the antiseptic oils, cassia or myrtol. A dressing of oil on cotton should remain a week, and no attempt at canal filling be made until all evidences of pericemental disturbance vanish. A fine cone of gutta-percha is passed, when practicable, into the canal beyond the perforation ; the remainder of the canal is filled with chloro- percha, and the silk points covered with gutta-percha. The canal at the proximal side of the perforation is filled with the solution, by means of the long dressing pliers, the gutta-percha-covered silk being carried gently in position while the general mass is fluid. Balsamo del deserto should apply well in these cases. The canal is filled, or partially filled, with the material, and a large gutta-percha point introduced. CHAPTER XIX. PYORRHEA ALVEOLARIS. By C. N. Peikce, D. D. S. Definition. — " Pyorrhea alveolaris " is a generic term which, strictly defined, means a flowing of pus from an alveolus. It describes merely a symptom which may be and usually is attendant upon a variety of disorders. The term is applied in clinical dentistry to a complexus of pathological conditions which more or less clearly indicate a specific disease. As the term is now understood, pyorrhea alveolaris includes all of those cases of morbid action characterized by the following features : A molecular necrosis of the retentive structures of the teeth (their liga- ment, the pericementum), an atrophy of the alveolar walls, together with a chronic hyperemia of the gum tissue which leads to limited hypertro- phy. After a variable period the teeth drop out, and the morbid action ceases with their loss. An examination of the roots of the teeth before or after their exfoliation usually exhibits deposits of calculi upon their surfaces. The disease is generally, though not always, attended by a flow of pus from the alveoli. History. — That pyorrhea alveolaris is not a recent disease, or one due to modern constitutional states alone, is rendered evident from the examination of the skulls of ancient as well as modern races. The alveolar processes of many crania widely separated both in time and in locality exhibit marked impairment of structure which bears the closest resemblance to that presented by processes which were known to have been the result of pyorrhea during life. Recorded observations of this disorder date at least as far back as 1746, when M. A. Fauchard described its essential clinical features, but failed to designate it by any specific term. Following this, communica- tions describing the disease were published by Jourdain in 1778, by Toirac in 1823, and by M. Marechal de Calvi in 1860, in which it was described as a " conjoint suppuration of the gums and alveoli," pyorrhea inter-alveolo-dentaire, and gingivitis expidsiva respectively. The most important contribution to the knowledge of the nature of 493 494 PYORRHEA ALVEOLA RIS. the disease which had up to that date been made was by Dr. E. Magitot in 1867. In his paper he states that the disease is characterized by a slow but progressive inflammation destructive of the periosteal mem- brane and cementum, proceeding from the neck to the apex of the root and involving the loss of the teeth. From the exact seat of the lesion he designated the disease osteo-periostiti alveolo-dentaire. Soon after the appearance of the periosteal inflammation, it became complicated with diseases of the gums and the osseous walls of the alveolus, though these are never primarily the seat of inflammation. Magitot regarded the causes of the inflammation as very complex, and to be sought for not in the teeth and gums, but in certain conditions of the general nutri- tion. The gouty and rheumatic presented the disease most frequently, though its presence in those suffering from diabetes and albuminuria was extremely common. The deposition of tartar on the roots of the teeth, which might at first glance be regarded as playing an important part in the causation of the disease, Magitot considered as accidental and not to be looked upon as a causative agent. With reference to the efficacy of any treatment, however, he advised the removal of the tartar as an indispensable preliminary. The points of diagnosis differentiating between this condition and the former, that of gingivitis, however severe, were also clearly recognized and noted. Following Magitot 7 s able paper was one by Serran in 1880, in which the author took exception to certain of Magitot' s views, as well as to the term by which the latter proposed to designate the disease. He recog- nized, however, that the disease was most common in middle life and occurred principally among the gouty, the diabetic, and the albuminuric. He believed that the primary manifestation was a local congestion of the gums, followed by an exudation into the peridental membrane which destroyed its vitality and led to the formation of pus and all the other symptoms and pathological conditions characteristic of the disease. A commission composed of MM. Depres, Delens, and Magitot was ap- pointed by the Societe de Chirurgie to consider the statements of Dr. Serran. In this report 1 they denied the gingival origin of the dis- ease, and stated their belief that the periosteal membrane and the cementum were the primary anatomical seat of the lesion ; that the succession of morbid phenomena completely precluded the idea of an initial gingivitis ; that the disease begins without any trace of conges- tion of the gums ; that after its formation the pus burrows toward the gingival border, which it detaches — without, however, for a time de- stroying its normal aspect ; that only after considerable augmentation of the flow of pus and the loosening of the teeth do the gums become 1 Bulletins et Memoirs de la Societe de Chirurgie, tome vi. p. 411. HISTORY. 495 implicated ; that the disease has nothing in common with the hypothesis of a gingival malady, and that it is most frequently a manifestation of a general state, or a diathesis. These were the views entertained and published by French surgeons on the nature of " pyorrhea alveolaris " about the period when the disease began to receive consideration from American dentists. Though pyorrhea alveolaris had long been recognized in the United States and various observations regarding its pathology and treatment had been published, it was not until Dr. John W. Riggs, in October, 1875, read a paper before the American Academy of Dental Surgery, entitled " Suppurative Inflammation of the Gums and Absorption of the Gums and Alveolar Processes," that the disease began to attract the attention its gravity merited. Notwithstanding the views entertained by Magitot and others regarding the constitutional character of the disease, Dr. Riggs in his communication 1 emphatically denied that the disease is an affection of the bone or of the gums, or that it is hereditary or constitu- tional, but, on the contrary, that it is the roughened teeth themselves, in consequence of the accretions from whatever source derived, which are the exciting cause of the inflammation ; that it is purely local in origin, the result of concretions near and under the free margins of the gums, the removal of which even in the third stage is followed by cure. In 1877 Dr. F. H. Rehwinkel 2 entered his protest against the theory of the local origin of the disease, and endeavored to prove that it not only may but does exist independently of foreign deposit and must depend on other than merely local causes, and that it is an hereditary and constitutional disease. Dr. L. C. Ingersoll, in 1881, published a paper entitled " San- guinary Calculus," 3 in which it was stated that the persistent flow and discharge of pus along the side of the tooth was caused by an inflamma- tion and ulceration at or near the apex of the root ; as a result of which molecular death the liquor sanguinis escaped from the bloodvessels into the surrounding tissues and became disorganized, the lime salts crystal- lized on the surface of the roots, and formed the deposit which from its origin he designated " sanguinary calculus." This deposition he re- garded as entirely distinct from salivary calculus, and as derived from the blood — the result of inflammatory action and not its cause. In other words, he held that pyorrhea is a local disease but beginning centrally ; that is, at or near the apex of the root. 1 Pennsylvania Journal of Dental Science, vol. iii. p. 99. 2 Keport of the Committee on Pathology and Surgery, Trans. American Dental Asso- ciation, 1877, p. 96. 3 Ohio State Journal of Dental Science, vol. i. p. 189. 496 PYORRHEA ALVEOLARIS. In 1882, Dr. A. Witzell read a paper before the German Society of Dentists/ in which it was asserted that the primary pathological change was an inflammation and caries of the alveolar border followed by a deposit just beneath the free margins of the gums, which became re- tracted and reverted. The entrance of micro-organisms into this carious region developed pus which became more or less infectious. In conse- quence he termed the disease " infectious alveolitis." He regarded the disease as a primary local alveolitis, having no constitutional relations whatever, a molecular necrosis of the alveoli or caries of the dental sockets produced by septic irritation of the medulla of the bone. In 1886, Dr. G. V. Black prepared for publication probably the most exhaustive paper in print in the United States, wherein pyorrhea alveolaris is treated as a local disturbance. 2 Calcic inflammation and phagedenic pericementitis are the terms he employs to indicate its cha- racter. Though he believes it to be wholly local, he thinks a serumal or sanguinary deposit may be closely allied with its origin. He de- scribes it as a destructive inflammation of the pericemental membrane, distinct from other inflammations of this tissue though having many features in common with them. The disease, he estimates, is essentially one of the peridental membrane rather than of the alveolus, though the destruction of these two structures is so nearly synchronous that it is difficult to say which has gone first. In 1886, Dr. W. J. Reese read a paper before the Louisiana State Dental Association on " Uremia and Its Effect on the Teeth," 3 in which the chemical, physiological, and pathological relations of uric acid to the general nutrition were discussed. In this communication Dr. Reese ex- pressed the opinion that the inflammation of the pericemental membrane followed by suppuration and disorganization when in contact with the secretions of the mouth, is caused by the deposition of uric acid derived from the blood ; that the disease should be termed " phagedena peri- cementi ; " that " pyorrhea alveolaris " is a misnomer. He also stated that while the tophus on the roots of the teeth is the usual con- comitant of uric acid, it is not necessarily so, but that absorption of the pericemental membrane may take place without any deposit. Though a local treatment was advocated, he stated that without sys- temic or constitutional treatment the return of the trouble may be expected. Dr. John S. Marshall, in 1891, expressed his conviction that pyor- 1 Vierteljahresschrift far Zahnheilkunde, 1882 ; British Journal of Denial Science, vol. nv. p. 153. 2 " Diseases of the Peridental Membrane having their Beginning at the Margin of the Gum," American System of Dentistry, vol. v. p. 953. 3 Dental Cosmos, vol. xxv. p. 550. TERMINOLOGY. 497 rhea has a constitutional origin and is closely allied to the rheumatic or gouty diathesis ; " that the deposition of the concretions upon the roots of the teeth in those localities not easily reached by the saliva, or in which the presence of the saliva would be an impossibility, is due to the causes which produce the chalky formations found in the joints and fibrous tissues of gouty and rheumatic individuals." 1 The writer, in a series of papers published during 1892-94-95, 2 pre- sented a number of clinical and pathological facts which in their totality it was believed established a kinship between pyorrhea alveolaris or hematogenic calcic pericementitis and the constitutional state familiarly known as the gouty or uric acid diathesis. Recent literature by American writers has dealt largely with the problem of the etiology of the disease in question and has been princi- pally concerned in determining whether it is of constitutional origin or of local origin, or of both. Of the more important recent writings on the subject may be mentioned those of Drs. E. T. Darby, H. H. Bur- chard, G. V. Black, M. L. Rhein, E. C. Kirk, James Truman, Junius E. Cravens, Louis Jack, R. R. Andrews, and R. Ottolengui. Terminology. — No disease in the whole domain of surgery has received so many and such diverse names as the one under consideration. Each succeeding title was an attempt at the production of a comprehen- sive descriptive designation of the disease, but when it is recognized that the essential nature of the pathological processes involved is, even now, not fully made out, it is evident that the many names simply represent as many diverse views and can therefore have no permanency, nor do they, indeed, deserve any. The following is a fairly complete list of the synonyms of the dis- order : Suppuration conjointe ; Pyorrhea inter-alveolo-dentaire ; Gingi- vitis expulsiva ; Osteo-periostiti-alveolo-dentaire ; Pyorrhea alveolo ; Cemento-periostitis ; Infectioso-alveolitis ; Pyorrhea alveolaris ; Calcic inflammation ; Phagedenic pericementitis ; Riggs' disease ; Hemato- genic calcic pericementitis ; Blennorrhea alveolaris ; Gouty pericemen- titis. Clinically the cases in which these phenomena are observed may be divided into two classes : Eirst, those in which the disease process begins at the gum margin. The second class begins at some portion of the alveolus between the unbroken and apparently healthy gum margin and the apex of the root, the pulp of the tooth being alive. These two conditions are so clearly differentiated from one another that each re- quires a separate description. Between these two classes, but intimately 1 " The Kheumatic and Gouty Diathesis, with its Manifestations in the Peridental Membrane," Trans. American Medical Association, 1891. 2 International Dental Journal, vols, xiii., xv. and xvi. 32 498 PYORRHEA ALVEOLARIS. associated with the latter, are to be included the cases described by Dr. G. V. Black ' as " phagedenic pericementitis." Class I. Pyorrhea Alveolaris beginning at the Gum Margin (Ptyalogenic Calcic Pericementitis). The first class — those cases beginning not at, but immediately be- neath the gum margin — are perhaps the most common, are by some erroneously supposed to be the only type of cases, and will require description first, as their causes, progress, prognosis, and treatment differ radically from those of the second class. Causes of Class I. — As in any disease, the causes of pyorrhea alveolaris grouped as Class I. may be divided into predisposing and exciting. The predisposing causes may all be included under the head of disorders causing a subacute inflammation of the gingivae. General catarrhal conditions; small but irritating deposits upon the necks of the teeth, as the accumulations upon the teeth of smokers ; fermenting deposits of food ; spirit-drinkers 7 stomatitis, mouth-breathers' gingivitis ; overcrowding of the teeth, mal-occlusion, and non-occlusion. The pre- disposing causes may also frequently be the exciting causes. The excit- ing causes proper are, however, subgingival scaly deposits of calculi. Clinical History. — In the mouth of a patient of one of the above- mentioned classes there will be noted at some period a gingivitis — a swelling of the gum which does not extend far from their margins. It is noteworthy that in these cases, as in the succeeding class, it is usual to find the disease attack teeth which are comparatively or quite exempt from the inroads of caries. Soon after the incipiency of the disease there may be squeezed from beneath the gum margins a detritus of food debris and inspissated mucus. At a later stage a sharp scaler passed beneath the gum margin may detach a flat greenish or black de- posit of calculus. Later, the gingivae are seen to become swollen and are gradually detached from the neck of the tooth, the flattened calculus in- creases in volume, and the irritation and injection of the gum deepens. " It is probable that these deposits have their origin in a reaction be- tween the altered mucous secretion of the gingival glands and the pro- ducts of lactic fermentation, their calcic salts being derived from the saliva." 2 The detachment of the gum does not become marked until these dark scaly deposits have encroached upon the margins of the alveolus. Soon thereafter, or indeed before, evidences of infection are observed, from the fact that pus may be pressed from the pockets. The disease progresses, the teeth loosen, and ultimately drop out or are re- 1 American System of Dentistry, vol. i. 2 H. H. Burchard, Dental Cosmos, October, 1895. PATHOLOGY AND MORBID ANATOMY. 499 Fig. 462. moved with the fingers, the injected gum remaining as a flabby mass and all evidences of dental disease ceasing with the loss of the teeth. The process may involve one, two, or more teeth and in some cases an entire denture. The origin of these deposits as well as those of ordi- nary calculi are so clearly traceable to the saliva that the writer has suggested for the conditions caused by them the name of ptyalogenic calcic pericementitis. Pathology and Morbid Anatomy. — The appended figure, semi- diagrammatic, will illustrate clearly the nature of the disease process (Fig. 462). It represents a longitudinal section through a tooth and its alveolus, with the vascular supply to the tissues. The peri- cementum and alveolar walls for some distance from the apex of the root are in a healthy condition. At the neck of the tooth are seen two deposits of calculi (a, a). The overlying gum (6, b) is seen to be swollen and tumid at its edges. Immediately below the calculus, where it encroaches upon the pericementum, the latter tissue and also a portion of the alveolar periosteum is seen to have under- gone necrotic changes (d). The portion of alveolar Avail uncovered by periosteum is in process of dissolution. In the pocket beneath the calculus a collection of pus is seen (c, c), so that the tissues beyond the calculus are involved in suppura- tive degeneration, which may be slow or rapid in its progress. The diagnosis is by sight and touch and not infrequently by odor, as par- ticularly in unhygienic mouths an offen- sive odor attends the progress of the disease. The gums are tumid ; from about the necks of the teeth pus may be pressed, and touch demonstrates the presence of flat, dark, and firmly ad- herent scaly calculi. The prognosis is favorable at even advanced stages, provided certain con- ditions may be obtained, viz. a removal or correction of the predisposing causes and a perfect removal of the exciting causes. Treatment. — The treatment is based purely upon the existing conditions, with two main objects in view. The first is to remove every source of irritation ; the second, to procure surgical rest until there is a return of the surrounding tissues to a normal condition. Ptyalogenic calcic pericementitis (Burchard). 500 PYORRHEA ALVEOLARIS. 463. Cushing's scalers. As a general rule the first step of the operation consists in a careful and thorough scaling of the teeth. It is essential that the use of bulky scalers be avoided — first, for the reason that they rarely reach the deepest portions of the deposits ; second, that if they do, they cause more or less laceration of the gum, which should be kept as free from injury as possible. The instru- ments employed for this purpose by a majority of operators are the set known as Cushing's scalers (Fig. 463). Their mode of appli- cation and their position relative to the root are shown in Figs. 464, 465. No instrument with a draw cut can remove these deposits with the same thoroughness as one operated with a push cut. With proper guarding it is improbable that these instruments should do harm to the vital parts beyond the calculus. Great care should be exer- cised in the use of pushing instruments to avoid forcing the dislodged particles into the deeper tissues. The scaling is a tedious operation, but one which should be persisted in until the root of the affected tooth is absolutely smooth. The scal- ing is alternated with a washing out of the pockets with 3 per cent, pyrozone or hydrogen dioxid, which washes out the detached particles of calculus and disinfects the parts. " When the gums are tumid and interfere notably with the scaling pro- cess, applications are made of a solution of trichloracetic acid 1 : 10 upon cotton tents ; this checks oozing, shrinks the gum, giving a better view of the parts, and tends to soften the de- posits." l " It not infrequently happens that the teeth have suffered such extensive loss of their retaining structures that the operation of scaling tends to still further loosen them. In these cases the correction of mal-occlusion and splinting the teeth should be attended to before proceeding farther with the operation. The teeth should be ligatured to their fellows, and the excessive occlusion corrected by grinding away the points of contact with corundum wheels sufficiently to relieve the teeth of strain and to permit the fixing of a metallic splint by means of which the teeth may be held firmly, during and subsequent to the scaling operation." 2 Splints for these cases are usually swaged metallic caps made of 1 E. C. Kirk. 2 H. H. Burchard, International Dental Journal, August 1895. PATHOLOGY AND MORBID ANATOMY. 501 No. 31 metal, gold or silver, which are cemented to the teeth (Fig. 466). When the teeth have suitable forms, a succession of rings sol- dered together may be employed ; in other cases the teeth are lashed together by means of fine gold wire. For temporary use No. 31 or 32 annealed brass wire may be used, and when left in situ for weeks or months it exerts no deleterious effect. In fact, it appears to possess Fig. 464. Showing the manner of holding an instrument for detaching calcareous deposits when using the pushing motion. The third finger rests on the edges of the teeth, allowing freedom of the hand to make rapid and effectual movements in dislodging the calculi. antiseptic properties similar to those attributed to copper amalgam when used as a filling material. Or, if frequently renewed, floss silk may be used. Devices for this purpose are as numerous as designs for bridge work. Each root is to be perfectly scaled before proceeding to a second tooth. At the completion of the scaling the pockets are freely syringed out with pyrozone 3 per cent., and an application of an astringent made: a 10 per cent, solution of zinc chlorid, 20 per cent, solution of zinc 502 PYORRHEA ALVEOLARTS. iodic!, or tr. iodin. II. S. P. diluted one-half with alcohol. Prepara- tions of aristol and the officinal tincture of iodin are also used, all of which subserve the desired end, to FlG - 465, sterilize the parts and to constringe the dilated vessels of the gum. An antiseptic and astringent mouth-wash Fig. 466. is prescribed which the patient is to use several times daily. The follow- ing preparation applied on a small roll or tuft of cotton wool or by means of a soft toothbrush admirably meets the conditions : Showing the application of a thin flat instrument to the labial and approxi- mal surfaces of an upper bicuspid (pushing motion). 1^. Zinci chlorid., cryst., Aqua? menthse pip., S. Apply locally to the gums. 3js; fsiv.— M. As early in the treatment as possible a thorough examination should be made with a delicate exploring instrument, so that any calculi which may be detected may be removed. A method of treatment which has given much satisfaction to the writer is as follows : First thoroughly cleanse the mouth and each particular pocket with hydrogen peroxid, electrozone, or some other equally efficient antiseptic. Then with a blunt but flexible broach, gold or steel, let each pocket from which pus has been issuing be very carefully saturated with trichloracetic acid ; this is repeated each visit if pus continues to flow. Following this, the pockets and gingival borders or margins are thoroughly treated with tincture of iodin, fol- lowed with solution of hydronaphthol and alcohol. If the gingivae, however, should be tumefied, an application of carbolic acid will prove advantageous : ^. Hydronaphthol, gij ; Alcohol, giv. This must be used with caution, for it is of sufficient strength to give the patient much discomfort if brought in contact with lips and tongue. The frequency of the visits and applications must depend upon the viru- GOUTY PERICEMENTITIS. 503 lenoe of the disease. A wash for the patient's daily use made from the following formula will be of great service : 3^. Hydronaphthol, g r - x J Glycerol, gj ; Alcohol, ,?ij ; Aquae dest., ^ij. The use of hydronaphthol in pyorrhea alveolaris was suggested by Prof. James Truman. The loss of alveolar walls is permanent ; the utmost the operator can hope in extreme cases is a reorganization of the tissues which have been softened as a consequence of the inflammatory action. Class II. Pyorrhea Alveolaris of Constitutional Origin — Gouty Pericementitis. The second class of pyorrhea cases — those in which local therapeusis has not been attended with permanent good results — are usually chronic, extending over a variable period of time, owing to the fact that they are but the local expression of constitutional states. Of these many forms of pyorrhea, one is particularly persistent, terminating only, unless prop- erly treated, with the exfoliation of the affected teeth. This particular form, which has been the subject of much discussion during the past twenty-five years, the writer believes to have been shown to be but a local expression of the gouty diathesis and directly dependent on the deposition of imperfectly oxidized waste products of the nutritional process such as uric acid and urates, together with calcium salts in the perice- mental membrane ; it is probable that allied and closely related compounds, such as the xanthin or alloxuric bases (xanthin, guanin, and adenin), may also be present in small quantities. Indeed, as the gouty diathesis is largely dependent on a faulty metabolism of proteid compounds and an imperfect elimination of nitrogen-holding derivatives, it is quite possible, though not proved, that any or all of the above-mentioned derivatives may be present in any pathological deposition. Inasmuch, however, as the amounts of these compounds are small, uric acid and uratic salts must be regarded as the chief of the specific irritants. As the origin of the salts is from the blood, the writer suggested the term hematogenic calcic pericementitis. Subsequently Dr. E. T. Darby suggested the happily applicable term gouty pericementitis. Clinical History. — It is noted that many patients who have mag- nificent dentures almost exempt from caries, at a period about middle life begin to have a loosening of the teeth which if unchecked leads to the loss of the entire denture. The disease may be observed at any stage from a slight loosening to impending exfoliation. An exam- ination of many cases will show that although they present apparently 504 PYORRHEA ALVEOLARIS. diverse conditions, yet beneath these differences there is a striking uni- formity, particularly as to the family history of such patients. A complete and accurate study of the succession of symptoms which a typical case of gouty pericementitis presents from its inception to its termination is rendered difficult, owing to the lack of extended observa- tion of the disease throughout the entire period of its evolution and dis- solution. This is especially true of this disease in its earlier stages. Nevertheless from an attentive study of a large number of individual cases in various stages of development it is believed that a fairly cor- rect picture can be deduced. First as to the teeth themselves ; as stated, they are almost exempt from recent caries. The teeth frequently exhibit a tendency to me- chanical abrasion upon their cutting edges or labial surfaces. If the patient be of a sanguine temperament, or this temperament combined with the bilious, the tendency to erosion is much more pronounced. It must be appreciated that this destruction of tooth tissue has nothing in common with ordinary dental decay or with the results of friction in mastication. In nearly all cases, should excavation of cavities in the teeth become necessary, or sections of lost teeth be examined, it will be found that the pulp has receded, i. e. has suffered a continued stimulation of its func- tional activity to the extent almost of obliteration. The patient may consult the operator as to the causes of repeated attacks of dental neuralgia, or the reason of consultation may be the alteration of position of one or more teeth. An examination of the organs, however, reveals no evident cause for either the neuralgia or the displacement. If the malposed tooth be kept under observation it will usually be seen to become elevated, loosen, and finally drop out. Other teeth become affected in a similar manner. Dr. Burchard has classified the course of pyorrhea as in three stages, as follows : " First, tooth indura- tion ; second, erosion or chemical solution of the crowns of the teeth ; third, a loss of the retaining structures of the teeth. Pathologically stated, there is first a stimulative stage ; second, an irritative, charac- terized by altered secretion (erosion) ; third, the necrotic." The altered secretion pertains to the labial glands largely, and the necrosis to the pericemental membrane and the apical end of the root or that portion which has been denuded of the membrane ; while the alveolar process never, in the writer's judgment, undergoes any change except that of absorption and atrophy. By far the greater number of cases present themselves when the disease has made marked advance about one or several teeth and their immediate loss is threatened. GOUTY PERICEMENTITIS. 505 Assuming that the gouty diathesis however well or poorly developed may be a predisposing cause, and the deposition of some characteristic specific gouty material from the blood into the pericemental tissues the immediate or exciting cause, we have an explanation for the irritation and necrosis of the alveolo-cemental membrane, which even in its early stages is easily recognizable. Coexistent with the pericemental hyper- emia there is more or less redness and turgescence of the gums, accom- panied by a sense of tenderness, soreness, and in many cases neuralgic pain, which latter symptom frequently precedes all other symptoms. In individuals already suffering from pyorrhea, the early irritative stage of the disorder may be frequently observed in teeth previously free from all signs of the disease. In nearly all such instances the focus of the diseased action is confined almost exclusively to the region toward the apical extremity of the root without there being the slightest evi- dence of peripheral local gingivitis. Too much stress cannot be placed on this fact, as it unquestionably marks the incipiency of the disease and is one of the early diagnostic symptoms. Somewhere near the apex of the root a distinct swelling occurs simu- lating an acute apical abscess. The tooth is sensitive upon percussion, but less so than when affected by purulent apical pericementitis ; more- over by isolating the tooth it is found to respond to applications of cold, proving that its pulp is alive. A bistoury passed into the swell- ing is followed by an escape of blood, and usually by a glairy purulent discharge also, although not always. In some cases a probe passed into the opening may show an absence of alveolar process at that point, and by a roughness reveal the presence of a deposit upon the root of the tooth. The teeth so affected usually present an appreciable elevation or protrusion from their alveoli in consequence of the enlarged or thick- ened and congested pericemental membrane. Should this congestion be permitted to continue, the inflammatory stage in consequence of the continued presence of the irritating deposit will supervene, with its con- comitant symptoms, heat, pain, swelling, and marked impairment and in some instances total arrest of the functions of the tissues involved. Inflammation once established will eventuate in localized suppura- tion with the abatement of the acute symptoms. The location of the suppurative process, if the case be seen and recognized early, will bf- found in the large majority of cases to be near the apical extremity of the root. As a rule, the pus takes the line of least resistance and bur- rows directly along the side of the root and opens externally at the gingival border. Occasionally the line of least resistance is toward the labial surface, with the discharge of pus on the gum opposite the end of the root, thereby establishing a fictitious opening simulating 506 PYORRHEA ALVEOLARIS. the condition observed in an acute alveolar abscess ; these cases, how- ever, are very limited in number. Once established, these conditions of increased vascularity, tumefac- tion of the gums, and persistent discharge of pus may continue for months or years ; the rapidity with which the disease progresses and the extent to which the lesions develop will be directly dependent upon the state of the general nutrition and habits of the individual. As a result of the continued irritation induced by the deposit, the inflammation extends, the disturbed relation between blood and sur- rounding tissues increases, and the gums become flaccid, spongy, altered in color, and liable to hemorrhagic discharges. Associated with the congested and thickened condition of the pericemental membrane there is a gradual softening and absorption of the alveolar process, which may advance to such an extent as to almost or in some cases quite expose the root throughout its entire extent. The tooth thus freed from its retentive structures becomes loose, is freely movable in its enlarged and partially destroyed socket, is extremely liable to dislodgment by slight mechanical means, or if by care these are avoided it will within a limited time be exfoliated in consequence of the final and complete destruction of all its retaining structures. With this final result the progress of the disease is arrested. The alveolar socket being freely opened, the partially dead and decomposing tissues are removed and the remaining structures gradually restored to a normally healthy con- dition by the usual processes of repair. When once established, pyorrhea alveolaris does not confine itself to any one tooth, but may extend to adjoining teeth or make its appear- ance in rapid succession in widely separated regions of the mouth in the lower as well as the upper jaws until the whole denture becomes involved, with an eventual exfoliation of all the teeth and a complete resorption of the alveolar process. When these exfoliated teeth are examined there will be found at some point of the root surface, almost always near the apex, an incrustation of a dark, rough cal- culus, or it may be several of them, all minute. The origin of the deposits being clearly not from the saliva, which is the source of the calculi in the disease described under the head of Class I., it has been called serumal or sanguinary calculus (Ingersoll, Black) ; the writer has suggested as the name of the disease caused by such deposits, hemato- genic calcic pericementitis. These assumed gouty deposits led the writer into an investigation as to the family history of patients affected by this disease. Almost without exception these individuals have been shown to be either the victims of some phase or form of gout, of alleged rheumatism or of rheumatoid arthritis (rheumatic gout), or to have a clear family his- GOUTY PERICEMENTITIS. 507 tory of one of these disorders. Careful investigation by several other observers has brought to light similar testimony, particularly within the past three years (Kirk, Darby, Burchard, Jack, and others). It had been noted by succeeding generations of practitioners that the therapeutic resources (local) of dentistry were insufficient to either check or cure the disease condition. All local means of treatment having been exhausted and shown to be of little or no avail, there was a natural inquiry into the exact nature of the predisposing and exciting causes of the malady, so that the therapeusis might be placed upon a rational basis. Xo purely local causes having been found sufficient to account for the dental condition, all constitutional states which were known to affect the teeth or their alveoli were examined and compared with the phenomena of the dental disorder. While it was and is found that several constitutional conditions do predispose to pyorrhea alveolaris, a flow of pus from a tooth socket, and most of these conditions may be included under the heading of diseases of sub-oxidation, none of them was found to cause a disease having the precise clinical phenomena noted in connection with the one under discussion. By a process of exclusion, and finally by direct clinical and experimental evidence, the field of inquiry was narrowed down to the conditions which clinical medicine has included under the heading of the disorders of the gouty diathesis. In order to clearly comprehend the connection of the general condi- tion with the local disease it is necessary to examine the essential, the intimate, nature of gout and its manifold manifestations. Much con- fusion has arisen in the discussion of this subject due to the lack of agreement of observers as to what constitutes gout, many apparently as- suming that gout is necessarily and inseparably connected with an acute attack affecting the metatarso-phalangeal articulation (the great toe). Pathology of the Constitutional Morbid Condition. — Pyorrhea alveolaris regarded as a local manifestation of the gouty diathesis is the result of a deposition of uratic salts in the pericemental mem- brane : these, acting as a local irritant, excite a specific inflammation ; while, as in other manifestations, the deposition of the gouty material is determined by an abnormal condition of the membrane, a condition of impaired vitality, the result of some mechanical or other irritation, which predisposes it to the iufiltration. As no special manifestation of the gouty diathesis can be intelligently understood without reference to its constitutional relations, it will not be out of place to briefly consider the phenomena presented by — (1) The gouty diathesis as a constitutional malady ; (2) The special manifesta- tion here under consideration as a molecular necrosis of the perice- mental membrane, or pyorrhea alveolaris. 508 PYORRHEA ALVEOLARIS. The gouty diathesis, in the general acceptation of the term, is a con- stitutional malady which manifests itself under a great variety of forms in different individuals. It is characterized by an excess of uric acid and its congeners in the blood, due either to increased production, through impaired or imperfect assimilation of nitrogenous food, or to imperfect elimination of the normal amount of urates by the kidneys. In cither event there is a disturbance of the normal relations between uric acid production and the general nutritional process. The protean forms under which the diathesis manifests itself will vary in accord- ance with the type of constitution and with the peculiarities of organi- zation and the degree of vitality of individual organs and tissues. The lesions or pathological states observed are believed to be caused by the deposition into the tissues, from the blood, of urate of sodium. This diathesis is undeniably hereditary, as its presence is detectable in one form or another in fully 75 per cent, of all cases in two and even three generations. The diathesis can also be acquired by individuals who are subjected to the causes which rendered the diathesis hereditary. The age at which the local expressions manifest themselves lies between the thirty-fifth and fiftieth years, at a time when growth has ceased and the food supply is required only for tissue repair and heat production. It is most common among those who lead sedentary lives, who indulge in an excess of nitrogenous food beyond the capacity of the individual to perfectly oxidize, and those who consume excessive amounts of fer- mented and malted beverages and the heavier wines. The immediate cause of all gouty expressions appears to be the pres- ence of urates in the blood. The amount normally present is so slight that it is almost non-detectable by ordinary chemical methods. It was shown by Dr. Garrod that in gouty conditions the amount was increased to as much as 0.175 per 1000 parts, and that this apparently small quantity was quite sufficient to act as the irritating cause of gout — a fact corroborated by other observers. The various theories which have been advocated from time to time in explanation of this uric acid increase in the blood plasma are unsatis- factory and contradictory ; whether it is the result of imperfect elimina- tion or of increased production through excess of nitrogenous foods it is difficult to state positively in the present state of pathology. It is quite probable that the diathesis is a neurosis which affects simultane- ously the assimilative as well as the excretory functions of the body. Whatever the explanation may be as to the accumulation of urates, their presence in the blood is generally admitted to be the immediate cause of any gouty manifestation. Dr. Dyce Duckworth states that " No conception of this malady is possible which should exclude from its purview the part played in it by uric acid ; " " The most unequivocal GOUTY PERICEMENTITIS. 509 evidence of true gouty disease is that derived from the presence of uratic salts in the tissues." The immediate cause for the deposition of urates in individual tissues is to be sought for in a special vulnerability of the tissues, a loss of vitality, the result of mechanical, chemical, or vital influences. The views of Ebstein concerning the deposition of uratic salts have found general acceptance. He has apparently demon- strated that, in all connective tissues, previous to the deposition there is a primary necrosis of tissue elements without which the crystallization could not take place ; that this disturbance of tissue vitality is the predisposing factor and the crystallization the exciting factor of gouty changes. The blood plasma transuding through the walls of the capil- lary vessels carries with it urate of sodium in solution ; in the partially devitalized tissue inspissation occurs and in consequence crystallization. The urate of sodium as it accumulates acts as a specific irritant to the tissue, giving rise to a variety of phenomena in accordance with the character of the tissue involved. The gouty manifestations may be either acute or chronic. In the acute forms the signs and symptoms are those of an acute specific inflammation of a joint, usually that of the great toe. Clinical study of pyorrhea cases strongly indicates that the disease frequently attacks the den to-alveolar articulation before other articulations in point of time. The local symptoms, pain, heat, tume- faction are associated with marked constitutional reactions, disordered digestion, and numerous evidences of general disturbance of nutrition. The duration of the attack may be from a few days to several weeks. Repeated attacks lead to an impairment of the functions of the joint and a permanent alteration of its structure. In the chronic forms the symptoms are more widely distributed and their intensity is less pronounced according to the tissues involved. The various manifestations may be classified as follows : Articular gout, in which the deposit occurs in joints. Tegumentary gout, in which the deposit takes place in the skin and mucous membranes. Disease of the skin, such as eczema and psoriasis, and catarrhal affections of the mucous membranes, such as pharyngitis, chronic bronchitis, gastric and intestinal catarrhs, have long been recognized as expressions of gout. Visceral gout, in which the deposit occurs in the viscera, such as the lungs, heart, bloodvessels, spleen, liver, kidneys, i. e. giving rise to various diseased conditions or giving a peculiar cast to disease already established. Nervous gout, in which the nervous tissue is invaded, manifesting itself in a loss of mental energy, despondency, irritability of temper, headaches, neuralgia, etc. The limits of this chapter do not permit, nor is it desirable, to enter 510 PYORRHEA ALVEOLARJS. upon a detailed statement of the symptoms or diagnostic features of these various phases of the gouty diathesis; suffice it to say that, under one form or another, they are frequently present and associated with pyorrhea alveolaris. The pathology of pericemental inflammation from uratic deposition unfolds itself logically after a consideration of the diathesis in its constitutional aspects. Bearing in mind the fact that the alveolo-cemental membrane is a member of the connective-tissue group, it is not at all surprising that it also should become the seat of uratic deposits. Pathology of the Dental Disease. — Unfortunately the anatomical relations of the parts and other factors prevent the dental observer from collecting a complete and connected series of observations as to the exact pathology of the disease, so that our deductions in this direction are necessarily confined to a basis of clinical records. It is a natural inference that the pericementum is the part attacked because it is a point of minor resistance. The decreasing volume of pericementum which attends the progress of the disease in these cases is necessarily followed by a contraction of the caliber of the blood- vessels. It is not at all improbable that, as a consequence of the general physical condition, atheromatous changes occur in the pericemental bloodvessels leading to their occlusion. If it be necessary, as some pathologists maintain, that a death of cells precede the deposits in gout, this vascular change will account for the necrosis. The acid re- action of the necrotic area causes the deposition of urates, which are insoluble in acids. The deposit is the source of an irritation which in most cases is followed by inflammation, leading to inflammatory degeneration and probably coagulation necrosis of the cellular elements. The alveolar walls melt down particle by particle, the pericementum disappears, the diseased area usually becomes infected by pyogenic organisms, and the process of suppuration is an additional factor leading to the exfoliation of the teeth. As in necrotic areas of other parts, calcareous deposits occur, which cover and almost entirely obscure the primary deposit of urates. The condition following upon a deposit at the lateral aspect of a root, in its pericementum, is shown diagrammatically in Fig. 467. At a is seen the calculus embraced by a territory of inflammatory corpuscles, b. The pericementum which has so far escaped destruction is seen at c and d, that at d nourished by the anastomosing vessels from the alve- olar periosteum. At a later period this portion of pericementum be- comes involved in the degenerative process, and pus escapes at the neck of the tooth. In other cases the inflammatory degeneration extends from the deposit to the overlying gum, which is perforated. It is conceivable that such tissue changes should exist in consequence GOUTY PERICEMENTITIS. 511 of injuries sustained during ordinary dental manipulations, the careless use of the teeth in biting unyielding substances, or even in the unwise use of toothpicks, brushes, etc. This supposition granted — and of its truth there appears to be much evidence, for the disease not unfrequently Fig. 467. Hematogenic calcic pericementitis (Burchard). develops after the operation of wedging, malleting, etc. — it is reasonable to believe that during the transudation of lymph through the lymph channels of the membrane, cementum, and dentin freighted with uratic salts, deposition and crystallization would readily take place in the dento-alveolar articulation as in other localities of the body. Kot unfrequently has the writer recognized pus-exuding pockets resulting solely from wedging or long-continued malleting, and these in teeth that previously to the operation were as free from any appearance of either of these conditions as a normal tooth could be, yet an idiosyncrasy or predisposition existed — the exciting cause only being needed to develop it. With this deposit and accumulations between two unyielding bony surfaces and the pressure on the tissue elements in consequence, these salts will act as specific irritants and engender the well-known phe- nomena — pain, congestion, swelling, exudation, impaired nutrition, tissue disorganization, the formation of pus, an osteomyelitis resulting in the absorption of the alveolar process, and finally the exfoliation of the teeth characteristic of pyorrhea alveolaris. The most general seat for the deposition of these salts is toward the apex of the root, where the texture of the alveolo-cemental membrane is less firm and compact, and more bulky. 512 PYORRHEA ALVEOLARIS. The supposition that pyorrhea alveolaris is a local expression of the general diathesis has been converted into an actuality by the demonstra- tion of the presence of uric acid and its allied salts in the incrustation found on the roots of the exfoliated teeth. The chemical analyses made by Prof. Ernest Congdon of the Drexel Institute have demonstrated the presence of these salts beyond question. 1 All of the established tests for uric acid were employed and in all instances crystals of uric acid, sodium urate, and calcium phosphate were detected. In several instances sodium urates were most abundant. The constant presence of these salts on the surfaces of the roots— the presence of which is ascertained by proper analyses and aided vision — taken in connection with the fact of the coexistence of gouty disorders in other tissues justi- fies the belief that the form of pyorrhea alveolaris here described is a gouty inflammation. The derivation of the salts from the blood, the abundance of the calcium salts present, and the primary location of the inflammatory pro- cess suggested to the Avriter the term hematogenic calcic pericementitis, though it is admitted that the single epithet gouty pericementitis would be sufficiently explanatory and descriptive. The succession of patho- logical states is readily explained and justified by the uratic deposit. The formation of pus is preceded by a lowering of the vitality and solu- tion of the pericemental tissues. This having been accomplished, the disintegrating peridental membrane affords a favorable nidus for the entrance and development of micro-organisms, which can be effected either by the route of the circulation or by lesions around the gum margins which give opportunity for direct infection from the oral fluids. When organisms once gain access to the devitalized tissue they mul- tiply with great rapidity, and in so doing increase the disintegration and solution of the pericemental membrane with the formation of pus. The specific bacteria which have been demonstrated to be present in the pus are the usual forms — the staphylococcus pyogenes aureus, citreus, and albus — which though capable of producing pus are not pathogenic in the sense that they are the causative agents of the pericementitis with the formation of an abscess. The purulent fluid burrows in the line of least resistance, which in the majority of cases is toward the gum mar- gin, whence it is discharged into the mouth, the fistulous tract thus established constituting the well-knoAvn pyorrheal pocket. By the continued irritation of the uratic deposition and the co-opera- tion of micro-organisms, the inflammatory process extends until the membrane is destroyed to such an extent that it is no longer capable of nourishing and supporting the teeth. The absorption of the alveolar process is in accordance with the laws 1 See International Dental Journal, 1894, vol. xv. p. 1. GOUTY PERICEMENTITIS. 513 governing bone softening and absorption in general. Any constant pressure, whether from inflammatory exudation, from tumors, or from mechanical or infective agencies which interfere with its nutrition, will lead to softening and absorption. In pericementitis the effusion exerts a pressure in both directions, toward the cementum and toward the alveolar walls ; as the latter are spongy in character, they readily yield to the absorptive process. Should the pressure continue indefinitely, or until the alveolar walls become denuded, caries or necrosis would inevitably result. Fortunately this termination is seldom if ever seen : the most careful examination of the alveolar process of a large number of patients has failed to show any alveolar denudation ; never, in the writer's experience, has there been either caries, necrosis, exfoliation, or sequestration of bone. Xor could there be, for the reason that the teeth are removed either naturally or artificially before complete de- struction of the pericemental membrane has been accomplished. With the removal of the teeth and its associated irritants the process of re- pair at once begins. The dead and dying tissues are removed, and fibrous tissues make their appearance, organization is established, and in a short time all traces of abnormal action have disappeared. Diagnosis. — The diagnosis of pyorrhea alveolaris becomes compara- tively easy when its constitutional relations, its mode of origin, its prin- cipal symptoms and pathology are borne in mind. The only diseases with which it might be (indeed, has been) confounded are, first, that form of pericementitis which has been designated a ptyalogenic calcic peri- cementitis ; or, second, a general gingivitis due to some systemic dis- turbance such as results from mercurial ptyalism or syphilis ; or, third, a severe inflammation of continuity due to some local disturbance such as an ill-fitting partial denture or an impacted tooth, possibly a third molar, greatly aggravated by some morbid systemic condition. These forms of pericementitis, however, present many points of contrast, dif- fering in their clinical history, their pathology, symptomatology and susceptibility to treatment. In the hematogenic forms the patient, in the great majority of cases, presents some other manifestations more or less pronounced, of the gouty or rheumatic diathesis. The age at which it makes its appearance is usually from thirty-five to fifty years. The extreme pain frequently present around the roots of one or more teeth in" the early stages, and before there is any evidence of a gingivitis ; the deviation in the position, and the apparent or actual elevation of the tooth, with response to pressure ; the swelling or thick- ening of the pericemental membrane ; slight tumefaction of the gum with deep red or purplish color opposite the apical end of the root of the tooth or teeth affected — and all of this before the appearance of pus ; the isolated character of the inflammation, being usually confined to one 33 51 1 PYORRHEA ALVEOLARIS. tooth or two or more tooth in widely separated regions of the month; the exudation and discharge of pus along but one side of the. root, detaching the gum at the neck, thus establishing a sinus or pus pocket; the increase of the flow of pus from the interior of the alveolus under pressure ; the usually limited amount of calcic deposition as contrasted with the ptvalogenic form ; the destruction of the pericemental mem- brane and the denudation of the cementum ; the absorption of the alveolar process; the loosening and exfoliation of the teeth indurated in structure and changed in physical appearance are the main charac- teristics of the disorder; all these features taken in their totality so individualize this disease that there should be no difficulty in identi- fying it. In the ptyalogenic form almost the opposite conditions prevail. As a general rule there is no evidence that there is any constitutional diath- esis of which it might be an expression. The age at which it presents itself extends from the eighteenth year, sometimes earlier, to any period in later years, varying in its virulence with the varying systemic condi- tions and food habits of the individual. The presence of a calcic depo- sition around the neck of the tooth is often most abundant ; the primary gingivitis occasioned by the presence of this mechanical irritant is not confined to one tooth nor to isolated regions of the mouth ; the subse- quent extension (where neglected) and infiltration of this deposit into and beneath the pericemental membrane ; the localization of the sup- puration in the early stages around the margin of the gums ; the de- layed loosening of the teeth, the infrequent loss of the teeth and the susceptibility to successful treatment upon the removal of the salivary deposit : these features taken together fully characterize this disease and render its identification easy. Contrasting these different inflammatory states of the pericemental membrane from their inception to their termination, it becomes evident that distinct yet closely allied diseases are here very frequently confused and associated. Causation. — If we take as our point of departure the postulate that hematogenic calcic pyorrhea alveolaris is but a special manifestation of the gouty diathesis, we should expect to find in its causation the same predisposing and exciting agencies operative as in the production of all other manifestations of the general diathesis. Predisposing Causes. — 1. Heredity. — Among the predisposing causes may be mentioned heredity, which may be regarded as one of the most important factors concerned in its development. The writer feels justified in asserting, after a careful investigation into the family history of a large number of pyorrhea patients that fully 90 per cent, manifest an hereditary tendency to this disorder, parents and grand-par- GOUTY PERICEMENTITIS. 515 ents having been victims of the same disease. Magitot was impressed with the significance of this fact years ago, and stated that pyorrhea extended through two and three generations and made its appearance at corresponding periods of life and in similar types of constitution. 2. Sex. — As far as the writer's observations extend, sex does not appear to have much influence in the production of pyorrhea, women seeming to be equally affected with men ; eliminate the masculine dietary habit and there would certainly be little difference in the pre- disposition to the disease. 3. Age. — The age at which pyorrhea most frequently presents itself is the period of middle life — that is, between the ages of thirty and fifty. It may be, though it is very rarely seen before the age of thirty, and still less frequently does it make its appearance after the age of sixty. These observations are corroborated by the writings of Magitot and others. It is very evident that pyorrhea is a disease belonging largely to a period of life when growth has ceased and food is required only for tissue repair and the production of heat. 4. Diet. — A careful investigation into the dietary of pyorrhea patients will disclose the fact that there is usually a consumption of excessive quantity of both albuminous and starchy foods, much more than is necessary for the maintenance of the nutrition, and more than can be completely oxidized under the customary or existing modes of the individual's daily life. Coincidently there is also a diminished consumption of water, leading to an imperfect elimination and a reten- tion of the products of this incomplete oxidation. In connection with excessive consumption of food must be also mentioned as co-operative factors the use of fermented malt liquors, the richer claret wines, cham- pagnes, etc. While perhaps no one class of foods can be said to be especially active in the causation of pyorrhea it is evident that exces- sive quantity and variety, by impairing the activity of the digestive appa- ratus and giving rise to a large quantity of nitrogenized waste products through imperfect oxidation, would materially impair and lower the func- tional activity of the system generally and individual tissues in particular. 5. Sedentary Occupations. — Occupation is also an important factor in the production of pyorrhea. In the majority of instances the disease makes its appearance in those who are obliged to lead lives of enforced inactivity — school teachers, accountants, etc. All sedentary occupations which necessitate insufficient personal exercise will favor the imperfect oxidation of food and at the same time retard the elimination of waste products. Exciting Causes. — The immediate agency in the development of pyorrhea is undoubtedly the deposition in the pericemental mem- brane of waste products of nitrogenous metabolism in combination 516 PYORRHEA ALVEOLA RIS. with calcium salts derived from the blood. This morbific material, play- ing the part of foreign bodies, irritates and excites the membrane to inflammatory activity and all its attendant symptoms. But even ad- mitting this deposition, there must be some predisposition on the part of the membrane which makes it specially liable to such deposition. This, it is believed, is in harmony with gouty deposition in all other tissues of the body ; it is to be found in impaired nutrition and lowered vitality in consequence of mechanical strain from an overcrowding of the dental arch, contusions or injuries consequent upon the usual and apparently unavoidable dental manipulations, such as wedging and malleting, and similar procedures. It may be from the unskilful em- ployment of toothpicks, toothbrushes, etc. — though these latter are rare as compared with other acts and conditions which may impair the nor- mal nutritional condition of the pericemental membrane. On numer- ous occasions where the predisposition existed, pyorrhea has devel- oped immediately following operations upon one or more teeth. Prof. Armand Depres 1 attributes considerable importance to the overcrowded condition of the dental arch as a predisposing cause in the develop- ment of pyorrhea. Treatment. — The treatment of gouty pericementitis resolves itself into both local and constitutional. The local treatment is to be directed toward removal of the deposit and the control and the suppression of the inflammation and its con- comitants, and has been already described at p. 511 in connection with the study of ptyalogenic calcic pericementitis. Constitutional Treatment. — Whatever the predisposing cause may be, the immediate or exciting cause must ever be borne in mind. This, it is believed, to a certain extent at least is found in all of those mechani- cal agencies, so well known to the dentist, which impair or lower the nutritional level of the pericementum, thus rendering it liable, under certain systemic conditions, to a deposition of uratic salts. The ques- tion has been raised as to why the membrane of one or more teeth widely separated or occupying positions on opposite sides of the mouth, either simultaneously or successively becomes the seat of inflammation when there is no continuity of structure. The answer to this must be found in the fact that impaired nutrition and lowered vitality in such structures are due in the majority of instances to mechanical injury of these. Malocclusion may be noted as a fruitful cause. It is certainly within the experience of many observant dentists that pyorrhea has not infrequently developed around a tooth after it has been subjected to the necessary mechanical manipulations incident to tooth protection and tooth preservation. 1 Legons de Clinique chirurgicale, p. 9-656. GOUTY PERICEMENTITIS 517 This apparent interference with the nutrition of the pericemental membrane before the deposit of uric acid salts takes place is in accord- ance with what is believed to hold true for other manifestations of the gouty diathesis. As a prophylactic measure, therefore, it is suggested that whenever there is the slightest tendency to pyorrhea, or any other evidence of the gouty diathesis, great care should be exercised in all dental operations, so as not to impair the nutrition of the pericementum and thus establish the necessary condition for the uric acid deposit ; also correction of all cases of malocclusion — surgical rest as far as possible. The constitutional treatment which has been indicated as efficient in the elimination of already established uric acid conditions and the restoration of a faulty nutrition to its normal state may with great propriety be subdivided into hygienic and medicinal. The hygienic treatment embraces systematic outdoor exercise, stimu- lation of the functional activity of the excretory organs, the skin, bowels, and kidneys, and regulation of the diet, which must be insisted upon in all well-marked cases, and especially with those who, for various reasons, lead sedentary and inactive lives. Increased muscular activity quickens circulation, induces deeper and fuller respiratory movements, leads to greater vigor in the general nutritive processes ; waste products are removed more rapidly and the combustion of the food increased by the absorption of a large amount of oxygen. The promotion of the func- tional activity of the eliminating organs is well recognized as an import- ant hygienic measure. The perspiratory and sebaceous glands and the surface capillary circu- lation should all be stimulated by sponging of the skin with cold water, vigorous friction, and an occasional Turkish bath, where such treatment is not contraindicated by pulmonary or cardiac affections. AVhere the liver and intestinal glands are deficient in secretion with prevailing constipation, they should be stimulated into activity by the use of saline waters ; most excellent for this purpose being the Hunyadi Janos and Friedrich>halle. These are especially to be commended because they contain a large percentage of sodium and magnesiiun sulfates, both of which are useful as eliminating agents. The kidneys should be assisted in the excretion of waste products by the free use of negative waters, or waters in which the saline con- stituents are present in minimum quantity. Hot or distilled water in sufficient quantity will flush the alimentary canal, increase the volume of blood, and stimulate the kidneys to increased activity. It is not only a common observation, but rather a remarkable fact, that gouty patients are inclined to drink but a com- paratively small quantity of water. One quart of hot water taken daily, in four doses, before breakfast, between meals, and at bedtime, is 518 PYORRHEA ALVEOLARIS. considered most beneficial in its effects in dissolving and removing irri- tating products. The most important of the hygienic measures in the treatment of all gouty manifestations is that pertaining to the diet. As uric acid is a nitrogenized compound and therefore presumably one of the imper- fectly oxidized products of albuminous or nitrogenized food, it is desir- able that such foods be excluded as far as possible from the daily diet. The value of this measure is admitted and insisted upon by all clinicians. In the milder manifestations of the gouty diathesis such as we assume exists in pyorrhea, it is not so imperative that all albuminous food be prohibited ; nevertheless, as many patients are consumers of large quantities of meat, it would be well to insist, if the effort to cure is to be made, upon the total exclusion of beef, veal, mutton, and pork, restricting the patient in albuminous diet to white meat of fowl, oysters, fish, and lobsters. Cheese, beans, and the white of eggs are considered objectionable, and in many cases of acute gout are strictly prohibited by the attending physician. Experience has shown that various alcoholic drinks, such as cham- pagnes, port, madeira, and sherry, are particularly liable to give rise to the accumulation of uric acid. The lighter wines, as claret and hock, are not considered so injurious. The malt liquors, beer, ale, and porter, are also by many clinicians considered in their influence to be great offenders. The medical and constitutional treatment, it is obvious, should be directed toward the elimination of uric acid and its compounds. For this purpose remedies which promote the formation of soluble and easily diffusible products which are readily eliminated by the kidneys are indicated. From time immemorial the alkalies and alkaline com- binations have been used with marked success in the management of all phases of the gouty diathesis. The treatment of acute gout necessitates, of course, different or more vigorous remedies than those required for the subacute or chronic forms with which the dental practitioner will be called upon to deal. Of the various alkalies, lithium compounds — the citrate and car- bonate — have been found well adapted to the milder phases of the disease. The writer has had much satisfaction in using, on the sugges- tion of Dr. E. C. Kirk, the tartarlithine lithium bitartrate, also alka- lithia prepared in the same form as the above-named compounds — com- pressed tablets containing five grains each ; one tablet three or four times daily will be found sufficient. Should the use of these lithia tablets not agree with the patient, the potassium carbonate in ten-grain doses, in some simple bitter — gentian or quassia water — three or four GOUTY PERICEMENTITIS. 519 times daily, may be substituted. A valuable adjunct to the medicinal treatment is the free use of alkaline waters, which assist in the elimi- nation of waste products, though it is probable that the good effects attributed to these are largely due to the quantity of liquid consumed. The Saratoga, Vichy, alkaline waters of Wisconsin, the Marienbad, Carlsbad, Apollinaris, etc. have all been found efficacious. Should the patient be very dyspeptic, as is frequently the case, remedies directed to the digestive viscera are of course indicated. If anemia be a concomitant, iron and quinin will be necessary. A combination which has been found of great value in improving the quality of the blood is one of iron and a salt of potassium. Blaud's pill, consisting of these two ingredients, is a desirable form for administration ; one three times a day will be sufficient. There is in addition one factor which may be regarded as therapeutic or at least prophylactic, and which is deserving of more than a passing notice, viz. the exercise of great care in the avoidance of injuries to the pericemental membrane, wherever there is a possibility of the presence of the unfortunate diathesis. However ingenious our interpretation of pathological conditions may be, and however plausible our deductions may appear, the ultimate test of their value will be the readiness with which they yield to and disappear under appropriate treatment. If pyorrhea alveolaris be a manifestation of the gouty diathesis, and the symptoms and pathological conditions which characterize it be ex- cited and maintained by the deposit and pressure of uric acid and its salts, it should be in general terms amenable to the therapeutic measures which have been efficacious in the treatment of all other forms of gout in other portions of the body. It must be borne in mind, however, that though a case be cured for a period of six months, or even a year, this does not preclude a relapse should the patient return to an improper diet or irregular mode of life. It is hardly necessary to say that this is true of all diathetic diseases. In individuals predisposed to uric acid accumulations, a new mode of life is to be instituted and followed with extreme care for a long period of time. The conclusions entertained may be represented in a condensed form in the following postulates : (1) Pyorrhea alveolaris of constitutional origin — which is its most destructive and unyielding form — primarily begins as a local inflam- matory disorder in tissues on the side of the root near the apical ex- tremity, and secondarily advances in the very large majority of cases toward the gingival borders. (2) The cause of this inflammation, or gingivitis and pericementitis, is the plasma exudation from the bloodvessels, freighted with salts 520 PYORRHEA ALVE0LARI8. which in their deposition and crystallization upon the cementum of the root and infiltration of the more vascular tissues, exert the influence of foreign bodies and react as irritants. (3) The salts in question, as disclosed by chemical analysis, are cal- cium and sodium urates, free uric acid, and calcium phosphate. - (4) The chemical nature of these salts indicates a condition of the blood in which there is an excess of uratic salts and uric acid due to either increased formation or imperfect elimination. (5) The excess of these salts, as is well known, is regarded by gen- eral pathologists as indicative of a faulty metabolism, and is the imme- diate cause of a series of local disturbances to which the term gouty has been applied, the nutritional disturbance giving rise to what is known as the " uric acid diathesis." (6) An attentive study and accurate observation of the various organs and tissues of patients suffering with pyorrhea alveolaris have disclosed the coexistence, in a very large proportion of them, of one or more local expressions of this constitutional diathesis. (7) Eecognition of the fact that a constitutional malady presents itself, one phase of which only has claimed the attention of the dental practitioner, indicates that a treatment designed to be curative must have reference not only to the local expression, but especially to this important systemic condition as well. (8) Results from "constitutional treatment in connection with the usual local applications in a number of well-authenticated cases of pyorrhea alveolaris have been so markedly satisfactory that the writer feels fully justified in his assumptions regarding the origin of the disease. While the foregoing pages embody views quite consistent with an extended experience, yet the writer fully appreciates the fact that many abnormal conditions closely allied in superficial characteristics to those above recognized and described may exist without any other local expressions indicating a uric acid dyscrasia. The association of the class of dental diseases included under the generic title of pyorrhea alveolaris with conditions of general mal- nutrition has been recognized by many writers during the past hun- dred years, but until within very recent times no systematic attempt had been made at their classification. Dr. M. L. Rhein, who has closely studied the relations existing between general disorders and the dental diseases, finding that many general diseases are accompanied by the symptom pyorrhea alveolaris, and that the dental disorder persists so long as the general disease is in activity, suggests that the diseases known under the latter title be divided into two classes — pyorrhea simplex and pyorrhea complex. GOUTY PERICEMENTITIS. 521 Under the head pyorrhea simplex are included all of those varie- ties and cases in which local therapeutic measures suffice to effect a cure. 1 Pyorrhea complex covers those cases and varieties in which local therapeusis fails to subdue the dental disease, and which are associated with some perversion of general nutrition. This class is subdivided into four groups : (a) Those due to nutritional disorders such as gout, diabetes, chronic rheumatism, nephritis, scurvy, chlorosis, anemia, leukemia, pregnancy ; (6) Those occurring during attacks of acute infec- tive diseases, as typhoid fever, tuberculosis, malaria, acute rheumatism, pleurisy, pericarditis, syphilis; (c) Those due to nervous disorders, cerebral diseases, spinal diseases, neurasthenia, hysteria ; (d) Con- ditions resulting from the action of toxic drugs — mercury, lead, iodids. Dr. Rhein believes from his studies that each member of the group of pyorrhea complex has a distinctive clinical expression, which might be utilized as diagnostic signs of the constitutional conditions. One who is familiar with oral abnormalities and able to differentiate them must be very liberal in the interpretation of causes in order to embrace the wide range of pathological conditions which, in some stages of development, present appearances that would or could very properly be termed pyorrhea alveolaris, yet whose very ready response to topical remedies would naturally suggest that they were not associated with a uric acid habit. While fully recognizing the fact that this uric acid dyscrasia can be associated with almost any disease which is a concomi- tant of malnutrition, we must remember and fully appreciate the fact that imperfect assimilation of food and faulty metabolism are often responsible for local abnormalities, and at the same time they may be factors in the establishment of a uric acid dyscrasia. In one's judgment of the soundness or unsoundness of theories or hypotheses, the fact must not be overlooked that affections of the kid- neys, the liver, the lungs, the heart, the mucous membrane, the stomach, etc. may exist without any other recognized expression, or we may have irritation of the pericemental membrane alone associated with any one of them, the disturbance of the normality of this tissue being severe or slight as the functional or organic abnormality of the organ is exalted or inconspicuous. While in the previous pages the treatment advocated had reference mainly to that form of pyorrhea the concomitant of the gouty diathesis, it must nevertheless be borne in mind that a similar condition of the pericemental membrane is at times associated with other perversions of the general nutrition, as pointed out by Dr. M. L. Rhein, and which 1 Denial Cosmos, 1894, p. 780. 522 PYORRHEA ALVEOLARIS. therefore must receive treatment especially adapted to the general con- stitutional state. Inasmuch as these constitutional conditions are complex in their manifestations and their medicinal and hygienic management almost exclusively in the hands of the physician, the duty of the dental prac- titioner is confined largely to the question of diagnosis ; the local treat- ment, however, must be varied in accordance with the peculiarities of the local pathological condition. CHAPTER XX. DISCOLORED TEETH AND THEIR TREATMENT. By Edward C. Kirk, D. D. S. Discoloration of a tooth is consequent upon death of its pulp. While death of the pulp does not always or necessarily involve dis- coloration of the tooth structures, yet when the condition does exist the general cause is as stated. Reference is here made to a progressive interstitial staining of the entire dentin structure, and is exclusive of certain metallic stains, and also localized stains resulting from the imbibition of pigmentary matters which occasionally are observed where small areas of dentin have become denuded of enamel covering, or where the latter has been so imperfectly formed as to afford an in- sufficient barrier to the ingress of pigmentary matters from the food or oral secretions. Three classes of conditions are presented for consideration and treat- ment : First, cases where discoloration has resulted from death of the pulp due to causes other than its exposure ; second, discoloration from pulp death consequent upon exposure ; and third, special discolorations due to adventitious causes superadded to the conditions affecting the cases included in the foregoing second division. Any of the numerous traumatic causes which bring about death of the fltflp, e. g. blows, sudden contact with hard substances, biting threaas, violent thermal shocks, the injudicious application of continuous force in regulating, or the application of arsenous oxid to the dentin (see p. 425), where no exposure or only minute exposure of the pulp exists, may produce hyperemia and congestion of the pulp, or strangu- lation of its circulatory system, the formation of emboli, thrombus, hemorrhagic infarct, etc., leading to a breaking down of the corpus- cular elements of the blood, the escape of hemoglobin from the stroma of the red corpuscles, its solution in the blood plasma, and resulting infiltration of the tubular structure of the dentin by the hemoglobin solution, giving the tooth a distinctly pinkish hue when examined by direct or transillumination. Teeth so affected rapidly change in color through various gradations in tint from the original pinkish hue, w T hich becomes yellow ; this, grow- ing darker, passes into brown, and after the lapse of considerable time the tooth may become a permanent slaty gray or black. 523 524 DISCOLORED TEETH AND THEIR TREATMENT. The violence of the pulpitis preceding the death and disintegration of the pulp, in a considerable degree determines the rapidity of the process of subsequent tooth discoloration. Where congestion of the pulp has been relatively slight and the necrotic process has proceeded slowly, the sudden infiltration of the dentin with hemoglobin does not occur, consequently the initial change in color following complete death of the pulp may be so slight as to escape detection except upon most searching examination with special means of illumination, and even then may be manifested only by a slight diminution in the normal translucency of the tooth as compared with adjoining teeth. Such teeth, however, if permitted to remain untreated, eventually grow darker, and while they may not acquire a degree of discoloration equal to those which have suffered sudden and violent death of the pulp, still they become so unsightly as to demand treatment for the restoration of their normal color. The Rationale of the Process of Discoloration. — In teeth dis- colored as a consequence of the death of the pulp without its exposure — viz. those of the first class — it is evident that the sources of pigmenta- tion are internal to the tooth and are to be sought for solely in the products of decomposition of the elements of the pulp tissue and of its vascular supply. The proteid elements of the pulp tissue are complex combinations of carbon, oxygen, hydrogen, nitrogen, sulfur, and phosphorus, which in their gradual breaking down by the process of putrefactive decom- position are split up finally into carbon dioxid, water, ammonia, and hydrogen sulfid, with possibly the formation of traces of phosphatic salts. The group of substances entering into the composition of the histological elements of pulp tissue contains no constituents wnph in the progressive changes resulting from putrefactive decomposition should form compounds likely to cause permanent discoloration of the tooth structures. When, however, the vascular supply is considered as a factor, the explanation of the ^ cause of discoloration in the cases in question becomes reasonably clear. The red blood corpuscles contain as their characteristic component hemoglobin or oxyhemoglobin according as the blood is venous or arterial, and this substance is its essential coloring ingredient. When undergoing gradual decomposition, hemoglobin passes through a variety of alterations in its chemical constitution, accompanied by a corresponding series of color changes. A familiar illustration of these color changes is furnished by the cycle of color alterations witnessed in a bruise. Immediately following an injury to the flesh, of the character alluded to, an extravasation of blood in the bruised territory occurs, causing undue reddening of the RATIONALE OF THE PROCESS OF DISCOLORATION. 525 skin ; this is soon followed by an increasing darkening of the tissue, until there results what is popularly termed a " black-and-blue spot." Further decomposition of the coloring matter of the extra vasated blood induces a variety of color changes ranging through the scale of yellows and browns, until the pigmentary matter is finally removed by absorp- tion through the capillary bloodvessel system of the part. In passing through its cycle of color changes, hemoglobin undergoes several alterations in composition during which a number of definite compounds are formed, each having marked chromogenic features. Of these decomposition products, methemoglobin (brownish red), hemin (bluish black), hematin (dark brown or bluish black), and hematoidin (orange), are the most important and best known. While the gradual decomposition of the coloring matter of the blood here noted may and doubtless does account for certain phases of tooth discoloration, other factors which exert a profoundly modifying influence upon the process are yet to be considered. The putrefactive decomposition of the proteid elements of the pulp results, as before stated, in the production of hydrogen sulfid in con- siderable quantity. The albumins contain from 0.8 to 2.2 per cent, of sulfur (Hammarsten) which in the splitting up of the compound during putrefaction yields a large amount of hydrogen sulfid. In pulp decom- position this hydrogen sulfid is generated in contact with the hemoglobin and necessarily exerts a marked modifying action upon the decomposi- tion process of that substance. Miller says, " If a current of sulfuretted hydrogen is conducted through fresh blood or a solution of oxyhemo- globin in the presence of air or oxygen, sulfomethemoglobin is formed, which is greenish red in concentrated solutions and green in dilute solu- tions. If we lay a freshly extracted tooth in a mixture of meat and saliva so that a part of the enamel surface remains free, and moisten the surface with blood, it will take on a dirty-green color if kept at blood temperature in an absolutely moist condition for from twenty-four to forty-eight hours. It is quite possible that the dirty-green deposits which form in putrid conditions of the mouth, in stomatitis mercurialis, scorbutica, gangrenosa, etc., or even in inflammatory conditions of less importance, as well as in cases of absolute neglect of the care of the mouth, may owe their green color to the presence of sulfomethemo- globin." As in pulp decomposition hydrogen sulfid is being formed in the presence of hemoglobin, this fact warrants the belief that a combina- tion takes place resulting in the formation of this same compound, which Miller regards as productive of certain stains upon the external surface of the teeth. The slaty gray or bluish pigmentation always noticeable upon the 526 DISCOLORED TEETH AND THEIR TREATMENT. visceral walls and frequently beneath the skin of animal bodies under- going putrefactive degeneration is a familiar example of the action of hydrogen sulfid upon decomposing hemoglobin in hemorrhagic extrava- sations, and is a process and form of pigmentation exactly analogous to that which is here described as taking place in the dentinal structure from putrefactive decomposition of the pulp. " When red corpuscles are jnst beginning to disintegrate, the coloring matter formed is hemo- globin j but the yellow and brown granular masses found in cells and lying free in tissues are, as a rule, derivatives of hemoglobin, not hemo- globin itself. These derivatives are divided into two groups according as they contain iron or not, the former being called hemosiderin, the latter hematoidin." l " When acted upon by ammonium sulfid (a deriv- ative of putrefactive decomposition of albumin) hemosiderin becomes black, iron sulfid being formed." 2 Grohe 3 believes that as a result of putrefaction iron is liberated from its compound with hemoglobin, so that when thus freed it readily combines with the hydrogen sulfid. Iron is the most important element to be considered in the list of factors causing the discoloration of this group of cases. It is the iron constituent of the red corpuscles which is the essential chromogenic factor from first to last in their cycle of color changes. The process of putrefactive decomposition consists of a series of chemical changes wrought out through the agency of micro-organisms, involving the breaking down by successive stages of highly complex organic compounds and their resolution into compounds of much sim- pler constitution. It is not known to what extent this splitting up of the components of the pulp and its vascular elements is ultimately car- ried in the series of changes resulting in the permanent discoloration of the tooth. From what is known of the ultimate composition of the compounds involved it may, however, be safely inferred that, reduced to its lowest terms, the result would be the formation of iron sulfid, the elements of which, with the exception of some unimportant alkaline and earthy salts, are the only ones entering into the original compounds which are fixed and therefore capable of forming a stable residuum in the tubular structure of the dentin. While iron sulfid as such cannot be held wholly accountable for the final bluish-black color of a tooth which has reached the stage of permanent discoloration, the pigmentation is almost certainly due either to it or to some allied compound in which iron and sulfur, with some organic constituents, largely enter, and which by a further slight decomposition would yield true iron sulfid. The significance and importance of a recognition of the possible presence of the iron compound as a factor in tooth discoloration is further brought out in the study of bleaching methods (pp. 542 and 558). 1 Ziegler, General Pathology, 1895. 2 Ibid. 3 Virchow's Archiv., Bd. xx. DISCOLORATION FOLLOWING DEATH OF THE PULP. 527 Discoloration of Teeth folio-wing- Death of the Pulp consequent upon its Exposure. — When death and decomposition of the pulp is consequent upon exposure of that organ, through caries or otherwise, to the irritative influences of infective agents present in the oral secretions and food, or to thermal shock, etc., the putrefactive process involving the pulp tissues is modified in character and rapidity to a degree which may aifect the character of the resulting discoloration. Thus the yel- lowish or brownish discoloration so often seen in teeth Avhose pulps have been devitalized through systemic or traumatic causes, and which in many cases appears to be more or less permanent in character, is rarely observed in those teeth whose pulps have been devitalized through exposure by caries. In these latter cases the progress of the putrefactive process is com- paratively rapid, the conditions being more favorable so that the color- ing matter of the blood is sooner reduced to its lowest terms in the scale of decomposition products, i. e. to the slaty blue or black pigmentation before noted. In addition to the increased rapidity of putrefactive de- composition incident to cases of discoloration following pulp exposure, another and important modifying factor in the process of discoloration is the ingress afforded to the oral fluids, food materials, and other ad- ventitious substances which find their way into the mouth and ulti- mately, through the open cavity of the tooth, to its pulp canal and thence to the tubular structure of the dentin. These extraneous sub- stances, in the course of time, may infiltrate the tooth structure, and while no especially noticeable or characteristic effect may be observed so far as color is concerned, yet they frequently exert an influence upon the coloration of the tooth which so alters its character as to render successful bleaching treatment extremely difficult and a resort to special methods or a variety of methods necessary. The introduction of fatty or oily substances or of astringent and coagulant matters, for example, may act upon the coloring matter in such a way as to permanently " set " it in the same manner that mor- dants form insoluble compounds or lakes with the dye-stuffs used in the dyeing of textile fabrics. Another and important class of substances which frequently are the cause of staining of the tooth structure are metallic salts which are used in dental therapeutic treatment or are accidentally formed during the application of corrosive medicaments to the teeth, through the action of such remedies upon fillings in situ or upon the instruments by which the applications are made. For example, the use of iodin or sulfuric acid in connection with steel instruments and the subsequent use of medicaments containing tannin as an ingredient. The treatment of these conditions will be separately considered. 528 DISCOLORED TEETH AND THEIR TREATMENT. Tooth-Bleaching. — Use of Ohlorin. Nature of the Problem Involved in Tooth-Bleaching". — The bleaching process is dependent upon a chemical reaction between a com- pound having color and some substance capable of so affecting its com- position that the color is discharged, or, in other words, of so affecting the integrity of the color molecule as to destroy its identity, which results in a loss of its distinguishing characteristic, viz. its color. The substances concerned in discoloration of tooth structure, as has been previously shown, are derived from the pulp and its vascular elements and the organic contents of the tubular structure of the dentin, through the gradual putrefactive processes which become operative subsequent to the death of the pulp. These pigmentary products of pulp decomposition we know to be organic in character ; and further, that they exhibit the property of color by virtue of definite conditions of molecular composition — that is to say, a certain arrangement of a definite kind and number of atoms has resulted in the formation of a molecule having its individual group of chemical and physical prop- erties, among which latter is a characteristic color. Whatever brings about an alteration in the composition of the mole- cule at once destroys the identity of the matter so treated. Hence if we can act upon the coloring matter which gives rise to the staining of a tooth by means of an agent capable of effecting an alteration in the atomic arrangement or composition of the color molecule, we may expect to remove or discharge its color feature. Two general classes of substances have been successfully used as bleaching agents : First, those which act by virtue of their power to evolve oxygen in the active or nascent condition, and known as oxidiz- ing agents ; second, those which act in an opposite manner by virtue of their strong affinity for oxygen and which are called reducing agents. The oxidizing bleachers destroy the identity of the color molecule by seizing upon its hydrogen element to form water. The reducing agents act by removing the oxygen atom from the color molecule to form by- products depending upon the character of the reducing agent used. Chlorin and its associates iodin and bromin act as indirect oxidizing bleachers ; the dioxid of hydrogen and of sodium are direct oxidizers. Potassium permanganate may also be classed with this group, though its successful use as a bleaching agent depends upon a subsequent treat- ment of the substance to be bleached with some solvent capable of re- moving the manganese dioxid formed as a by-product of the action of the permanganate. It has somewhat extensive and satisfactory use as an agent for bleaching sponges, and has been used for bleaching teeth, but is of greatly inferior value to other agents for the latter use. TOOTH-BLEACHING— USE OF CHLOBIN. 529 The only agent belonging to the group of reducing bleachers which has thus far been found available for bleaching teeth is sulfurous oxid, either in the gaseous condition or in aqueous solution. Chlorin as a Bleacher. — The general use of chlorin as a bleaching agent in the arts no doubt suggested its use in the treatment of tooth discoloration. Its introduction as a tooth-bleaching agent, as well as the assembling of the general principles of tooth bleaching into a co-ordi- nate system, are due to Dr. James Truman, whose method depends upon the liberation of chlorin from calcium hypochlorite, commonly called bleaching powder or " chlorinated lime," in the pulp chamber and cav- ity of decay in the tooth. Chlorin is liberated from the bleaching pow- der by the action of dilute acetic acid ; this taking place in contact with the discolored structure, it is rapidly bleached as a result of the action of the chlorin upon the coloring matter contained in the dentinal tubules. Numerous modifications of this original method of bleaching tooth struc- ture have been suggested, but, as the ultimate result in each is accom- plished through the activity of chlorin, a rational understanding of the mode of action of chlorin in this relation is of importance as an aid to the intelligent use of those methods for tooth-bleaching which are dependent upon or owe their efficacy to that agent. Chlorin is an elementary gaseous body, greenish in color, soluble in water, having a disagreeable odor, intensely irritating to the air-passages when inhaled, and poisonous when breathed in sufficient quantity. It has a strong affinity for all metallic bodies, entering into direct combi- nation with a number of them, under favorable circumstances, with great energy — forming, as a rule, compounds that are soluble in water. One of its distinguishing features and one which is directly concerned in its use as a bleaching agent is its strong affinity for hydrogen. So strong is this affinity, that when a molecule of chlorin is brought into contact with a molecule of water under favorable conditions, the hydro- gen of the water molecule is seized upon by the chlorin to form chlor- hydric acid and the oxygen is set free in the nascent state, a condition under which its oxidizing powers are exhibited in their greatest intensity. This powerful affinity of chlorin for hydrogen enables it to decompose many other hydrogen-containing molecules in a similar manner, form- ing chlorhydric acid and destroying the identity of the matter acted upon. It has been shown that all organic compounds which are the products of the vital processes of the animal body contain hydrogen as an im- portant constituent. This applies also to the decomposition products whose presence in the tubular structure of the dentin is the cause of tooth discoloration. These organic stains exhibit the property of color by virtue of 34 530 DISCOLORED TEETH AND THEIR TREATMENT. certain definite conditions of molecular composition ; hence, if chlorin is caused to act upon the coloring matter which causes the staining of a tooth, by seizing upon and combining with the hydrogen of the organic pigment, the identity of the compound as such is destroyed, and its characteristic feature, that of color, is lost. The principle here outlined is involved in what is termed the direct action of chlorin in bleaching. There is, however, another method by which chlorin is believed to act as a bleacher in which its function is indirect. In some cases it has been observed that chlorin fails to act except in the presence of moisture, and the rationale of this is that the bleaching under such conditions is effected by nascent oxygen liberated from the water molecule when the chlorin combines with its hydrogen to form chlorhydric acid ; thus : Cl 2 + H 3 «= 2HC1 + O. That such is the nature of the process in many cases is a reasonable deduction from the behavior of chlorin under analogous conditions where it acts indirectly as an oxidizing agent. Whatever may be the exact nature of its ultimate action, it is to be borne in mind that its bleaching effect is due solely to the alteration which it makes in the composition of the color molecule, and that it has no solvent power whatever on the organic matter upon which it acts. It changes its characteristics, but does not remove it by solution. It should be also noted in this connection that the chlorin compounds of most of the metallic elements, especially when in dilute solution, are almost colorless as compared with many of the other metallic com- pounds — the oxids and sulfids for example. Hence it is that where stains owe their color to the presence of certain organic compounds with some of the metals, or even where the coloration is due to decom- position products of hemoglobin, the color may readily be discharged by chlorin, but if the iron chlorid thus produced remains in the tooth structure it is gradually decomposed and new combinations of it are liable to occur, which results in a return of the discoloration. All tooth-bleaching methods should aim not only to discharge the color by suitable chemical means, but should go farther than this and, as far as it may be possible to do so, remove all organic debris from the tubules, for as long as any remains the tendency to a return of the dis- coloration is always a possible and indeed probable menace to the com- plete and permanent success of the operation. Where the tubular contents cannot be successfully removed, the tendency to a return of discoloration may be combated by hermetically sealing the tubular orifices with an impermeable resinous varnish or permanently coagulating them. This feature is described more fully in relation to the details of the bleaching procedure. Teeth Suitable for the Bleaching Operation. — In deciding upon TOOTH-BLEACHING— USE OF CHLORIN. 531 the advisability of attempting the bleaching operation in any given case, the general conditions which determine the judgment of the operator with respect to all dental operations should govern his course. As all therapeutic and restorative measures in dentistry are a series of compromises with disease conditions or their sequelae, it is the duty of the operator under all circumstances to capitulate upon the basis of greatest advantage to the patient. Therefore if discoloration of a tooth is practically the only factor in the problem presented by a given case, the effort should be made to restore the organ to its normal condition of color. The same rule should be applied to all cases of discolored teeth in which structural loss bv caries or fracture has not been so great as to preclude a satisfactory restoration by proper filling or replace- ment of the lost structure by a porcelain inlay. The cases in which it is not advisable to attempt a bleaching operation are only those in which loss of structure is so extensive as to require a crowning operation. In the judgment of many operators it is considered useless to at- tempt the bleaching of any teeth excepting the incisors, because of the difficulty and length of time frequently required for the successful bleaching of canines, bicuspids, and molars, owing to the thickness of their walls and the consequent depth of structure requiring treatment. It is also held to be useless to attempt the bleaching of teeth which have been discolored by metallic stains throughout their structure. The fallacy of such a view is self-evident when it is considered that if any portion of the dentinal structure of a discolored tooth is amenable to the bleaching treatment, its complete restoration is simply a question of continuance or repetition of the operation until the desired end is attained. With regard to discoloration by metallic stains, while teeth so af- fected present problems of great complexity, and require not only special study but the application of special methods of treatment based upon proper recognition of the chemical relationships involved between the nature of the stain and that of the agent used for its removal, the attempt should be made in justice to the patient, even though ultimate failure result, in order that the necessity for destruction of the natural crown for the purpose of its replacement by an artificial substitute may, if possible, be postponed for as long a period as may be attainable. Preparation of the Tooth for the Operation of Bleaching".— Cer- tain general details are necessary to be observed in the preparation of teeth for the bleaching operation, whatever may be the method of treat- ment employed. Appropriate treatment for the removal of all septic matter from the pulp chamber and canal, and for the relief of any existing condition of irritation of the pericemental membrane and tissues of the apical region, should have been carried out and the tooth brought to the condition in 532 DISCOLORED TEETH AND THEIR TREATMENT. which permanent closure of the apical foramen of the root may be safely performed. The rubber dam should be adjusted with especial care and only include the tooth to be bleached. If two adjoining teeth are to be bleached they may both be isolated by the dam, but in no case should one or more adjacent normal teeth be included with the tooth to be bleached. While the inclusion of teeth adjacent to the one which is the subject of any ordinary dental operation is in nearly all cases desirable, there are good reasons why such a plan should not be pursued in the bleaching procedure. The chemicals used for the purpose may possibly have some disintegrating or solvent action upon the enamel structure, and such action, should it occur, should be confined strictly to the tooth undergoing treatment and held within the limits of safety by close observation and appropriate treatment, which conditions cannot be as thoroughly controlled and the process as satisfactorily managed when several teeth are included within the territory of operation. Furthermore, as nearly all of the bleaching agents used or those which are employed as adjuvants in the process have a more or less irritative or escharotic effect upon the soft tissues of the mouth, extra precautions must be taken, in adjusting the dam, against leakage at its attachment to the cervix of the tooth. As the chances of leakage are greatly multiplied when several holes are punched in the dam for ad- justment to as many teeth, it is for this reason also that no other than the tooth to be treated should have the dam adjusted to it. Supposing the tooth to be an upper incisor, the dam should be slipped over it and the margin of rubber encircling the cervix should be gently carried under the free margin of the gum either by means of a small flat burnisher of suitable angle and curvature, or by means of a waxed floss-silk thread. One or two turns of a ligature should then be thrown around the cervix below the dam to hold it securely in place. The dam may be fixed with greater security, especially as against any accidental traction made upon it during the operation, by fastening it with a ligature made as follows and thrown around its cervix : A piece of waxed ligature silk about eighteen inches in length has a large knot tied at about its middle portion by making six or eight turns of the thread loosely around the end of the index finger of the left hand. Upon withdrawing the finger a series of loops are had through which one of the free ends of the thread is now passed, as in making the first half of a flat knot, as illustrated in Fig. 468. By drawing upon the free ends of the thread until all of the loops are closed upon themselves, a hard knot of more or less spheroidal shape is formed about midway between the ends of the ligature. The ligature so prepared is placed around the tooth in such a manner that TOOTH-BLEACHING— USE OF CHLORIN. 533 the knot as described shall be located upon and at the middle portion of the palatal cervical margin. A half knot is then made by tying the ligature in front so that it shall rest directly opposite the palatal knot, viz. at the middle portion of the labial cervical margin. The ligature is drawn into fairly close contact with the tooth, and, with both ends held firmly in the left hand and drawn somewhat tense, the portion encircling the tooth is firmly but gently forced up against the rubber Fig. 468. dam and gingival margin, the ligature at the same time being drawn tightly until the anatomical constriction of the tooth at its cervix will serve to hold it from slipping downward, especially upon the palatal aspect of the tooth. When the ligature is found to be securely placed as described, the knot upon the labial aspect is completed and further enlarged in bulk by re-tying the thread four or five times. The free ends of the ligature should then be cut off close to the knot. As an additional safeguard against leakage of irritating bleaching agents through the cervical attachment of the dam, and out upon the soft tissues, it is well after making the tooth perfectly dry to paint the ligature and a narrow band of its adjacent territory with chloro-percha, which will effectually prevent any accident from leakage. The placing of a large knot upon the palatal aspect at the cervical margin has another decided advantage in that it not only holds the dam more securely against slipping downward, but holds it away from the palatal surface, which is ordinarily the point of entrance to the pulp chamber and canals in these cases. The point of canal entrance may, however, be through an approximal cavity, if such an one affords sufficient access. The canal filling in all cases of bleaching without exception should be gutta-percha. No other material used for canal filling possesses the generally desirable qualities needed for that purpose in this class of cases. The extent of the canal filling should include one-third, or at least not over one-half, of the distance from the apex. A considerable portion of the canal beyond the level of the gingival margin is thus left unfilled in order that the coronal end of the root may be bleached as well as the tooth crown. This is especially necessary where more or less recession of the gum from its normal attachment has occurred, 534 DISCOLORED TEETH AND THEIR TREATMENT. leaving the cervical cementum exposed to the action of the oral fluids, food, etc., which have a tendency to cause discoloration of the exposed root tissue. The root being filled as directed, all fillings wherever existent in the tooth should be removed. This is a preliminary procedure which should not be omitted in any case, but where any bleaching method is used which involves the employment of chlorin as the active agent it becomes imperatively necessary for reasons which are explained in con- nection with the description of the chlorin methods (page 529). Aside from other considerations, the removal of all fillings preparatory to the bleaching operation has a decided value in facilitating the process by ex- posing an increased area of the dentinal structure and thereby permit- ting the action of the bleaching agent over a larger territory of ingress. When all fillings or softened tooth structure have been removed, as well as all septic and extraneous matter of whatever character, by mechanical process, the tooth should be washed thoroughly with dilute ammonia water, or better with a hot solution of borax in distilled water in the proportion of 3J to f gj. The object of this treatment is to re- move by saponification and solution all fatty matters which may obstruct the ingress of the bleaching agent into the dentinal structure. In nearly all cases where discoloration has occurred from a decom- posed pulp and where the canals and pulp chamber have been left untreated, there will be observed, on opening into such a pulp chamber for the first time, a dark layer of oily or greasy material lining its walls. The thorough removal of this dark layer should be effected prior to any attempt at bleaching, as it appears to prevent the ingress of the bleaching agent into the dentinal structure. The most satisfactory method for removing the dark greasy layer is by the use of suitable instruments — either properly shaped spoon or hoe ex- cavators or round burs in the engine. The thorough removal of this layer necessitates free access to the pulp chamber, which should be as a general rule obtained by means of an ample opening upon the lingual aspect of the tooth in the case of incisors, and through the morsal surface in bicuspids, etc. Having by mechanical means and through the agency of borax or ammonia and hot distilled water effected a thorough cleansing of the interior portion of the tooth, it should next be dried to the extent of having all superfluous moisture removed, and it will then be in condi- tion for the application of whatever method of bleaching may be chosen for the particular case in hand. Dr. James Truman's Method. — This, as before stated, was the first method successfully employed for bleaching teeth. It consists in liberat- ing chlorin from ordinary chlorinated lime by means of a weak acid TOOTH-BLEACHING— USE OF CHLORIN. 535 in the pulp chamber of the tooth. Any acid will effect the liberation of chlorin from the bleaching powder, but acetic, tartaric, or oxalic are generally used. Care must be observed in selecting a good quality of bleaching powder, as that substance rapidly undergoes decomposition spontaneously, especially in a moist atmosphere. Good chlorinated lime is a dry powder having a strong odor of chlorin. If it is moist or pasty and has but a feeble odor it should be rejected as worthless. Brands of bleaching powder dispensed in metallic packages should not be used, as they are invariably contaminated with metallic chlorids due to the slow action of the contents upon the containing package. This is par- ticularly the case where sheet-iron boxes are used. The return of dis- coloration in many cases after bleaching by the Truman method is undoubtedly due to the use of bleaching powder so contaminated. The powder dispensed in glass bottles or in paraffined paper cartons is more reliable. Its application to the tooth may be effected in several ways : (a) By packing the dry powder in the pulp chamber and then moist- ening the latter with the acid ; (6) By mixing the powder with sufficient distilled water to make a coherent mass which is more easily manipulated, then packing it in the pulp chamber and applying the acid ; (c) By first moistening the interior of the tooth with the acid, next dipping the instrument into the powder and then into the acid, each time carrying the mixed materials into the tooth until the desired change of color is produced. Probably the most satisfactory method is to pack the dry powder into the tooth and apply the acid to it, after which immediately seal the cavity with a single pellet of gutta-percha. By using a 50 per cent, solution of acetic acid the evolution of chlorin will take place with a satisfactory degree of uniformity, and not so rapidly as to interfere with its penetration throughout the discolored tubular structure of the dentin. The bleaching mass may be sealed in place by means of oxyphosphate of zinc if desired, but it is usually unnecessary to use anything other than gutta-percha or one of the soft temporary stopping materials for this purpose. The case may be dismissed for one or two days and the treatment as outlined repeated at similar intervals until the tooth is restored to normal color. The instruments used in connection with this process should be of vulcanite, bone, ivory or wood. Upon no consideration should steel, gold, or platinum instruments be used, as chlorin acts directly upon each of these metals, forming soluble chlorids which if carried into the tooth structure will give rise to a permanent staining of most intract- 536 DTSCOLOBED TEETH AND THEIR TREATMENT. able character. The only metals which may be safely used in connec- tion with any chlorin process of bleaching are zinc and aluminum, the chlorids of which are colorless. Aluminum instruments for the purpose may be quickly improvised out of wire or heavy plate. Gold instruments have been recommended, but they are open to the very grave objection of forming a chlorid by direct combination with chlorin, which salt is one of the most important staining media known to the histologist ; as a matter of fact the writer has seen several cases where a permanent purple staining of the tooth has resulted from neglect to remove gold fillings before applying the chlorin method of bleaching, and there is certainly no reason why the same result should not follow the using of gold instruments in the same connection. When the tooth has been restored to its proper color it should be thoroughly washed with very hot distilled water, dried out with bibu- lous paper and thoroughly desiccated with a current of dry hot air, after which the canals, pulp chamber, and cavities should be filled with oxychlorid of zinc. The final filling or the cavities of entrance and of decay should be postponed until by a lapse of considerable time the permanence of the operation has been established. This probationary period may with advantage be prolonged to four or six months. The final washing of the tooth with hot distilled water previous to the insertion of the zinc oxychlorid filling is a feature of the opera- tion which requires special care and attention. As left after the appli- cation of the bleaching agent, the pulp chamber and canals and denti- nal structure are filled with free chlorin in solution, calcium acetate, or other salt of calcium depending upon the nature of the acid used in the process, and some undecomposed bleaching powder. These sub- stances should be thoroughly removed by the hot-water douche. At least a pint of water should be strongly injected into the interior of the tooth by means of a large bulb syringe, before the dam is removed. A towel held in close proximity to the tooth will catch the water as it re- turns from the tooth and protect the clothing of the patient. Distilled water should in all cases be used for this irrigating douche, as river water and many other specimens of water from natural sources contain iron in solution, which could readily become a contaminating factor leading to subsequent return of discoloration. Zinc oxychlorid is selected as the permanent filling for the pulp chamber for the reason that it is necessary to so act upon the bleached organic residuum in the tubular structure as to prevent any alteration of its character which may result in the production of a subsequent coloration. Zinc chlorid possesses the property of converting many organic substances into unalterable compounds by its coagulant action, TOOTH-BLEACHING—USE OF CHLOPJX. 537 thus tanning or mummifying animal tissue and preserving it indefi- nitely. A mass of zinc oxychlorid, before it sets — I. c, before chemical combination takes place between the zinc oxid powder and the zinc chlorid liquid, is functionally free zinc chlorid — and as a matter of fact the properties of zinc chlorid are manifested by such a mass for a con- siderable period of time after the mass has apparently set. "When introduced into the pulp chamber and canal, its action upon the organic debris in the tubuli is as stated, and the material, if the operation has been successfully performed, is effectually prevented from further alter- ation, upon which condition the permanence of the operation depends. Another method for preventing subsequent alteration of the bleached organic debris in the tubular structure is to thoroughly desiccate the tooth by means of the hot-air blast and saturate the dentin with some insoluble resinous varnish, such as copal ether varnish, or what is still better the solution of trinitrocellulose in methyl alcohol, known in com- merce as " kristaline " or at the dental depots as " cavitine." The pulp chamber and canals may then be filled with any suitable filling. As between the oxychlorid of zinc filling and the varnish lining the choice in general should be of the former. The varnish lining is adapt- able more especially to cases of long standing where complete liquefac- tion of the tubular contents has left them practically empty, and where as a consequence there is nothing upon which zinc chlorid can exert its coagulating effect. Other Chlorin Methods. — The solution of chlorinated soda known as Labarraque's solution, or Liquor sodae chloratse U. S. P., may be applied to the previously desiccated tooth structure until the dentin is saturated with the solution, after which an application of a dilute acid is made which liberates chlorin. The chemical principles in- volved are exactly analogous to those upon which the method with bleaching powder depends, the only difference being that the source of the active agent, chlorin, is in one case its calcium compound, which is a dry powder, and in the second case the analogous soluble sodium compound of chlorin is the material from which the active agent is evolved. The precautions necessary to be observed are exactly the same as those required in Truman's method already described. The results obtained by this process are not as thorough or as satisfactory as by the Truman method. Chlorin per se has been used for tooth-bleaching, and was the basis of a method devised by Dr. E. P. Wright of Richmond, Ya. Wright's method involved the use of a complicated apparatus by which a glass vessel of about a half-liter capacity, and filled with chlorin previously prepared in the laboratory, was connected by means of a 538 DISCOLORED TEETH AND THEIR TREATMENT. doubly perforated rubber stopper and two pieces of rubber tubing with a glass adapter, around the open end of which was tied the rubber dam encircling the tooth to be operated upon. About midway of the length of one of the rubber tubes connecting the chlorin reservoir with the rubber dam was interposed an ordinary syringe bulb, so arranged with hard-rubber valves that by repeatedly compressing and relaxing it the chlorin would be drawn from the reservoir and injected through a glass delivery jet into the pulp chamber. Return of the gas to the reservoir was provided for by the second piece of rubber tubing first alluded to. In this way a continuous jet of chlorin was thrown into and about the tooth, which, by means of the rubber dam, was placed in a close cham- ber forming a part of the apparatus ; none of the gas could escape into the surrounding atmosphere. The complexity of the apparatus was a formidable obstacle to the general use of the method and it was abandoned, though the results were in many cases very satisfactory. The Dioxid Bleaching Methods. Bleaching" by Means of the Dioxid of Hydrogen and the Dioxid of Sodium. — The commercial introduction of solutions of hydrogen dioxid marked a new era in the operation of bleaching discolored teeth. The bleaching property of hydrogen dioxid had been known to chemists for many years, but the application of this property to tooth-bleaching dates from the medicinal use of hydrogen dioxid solutions for the treat- ment of purulent conditions of the pulp canal and about the roots of teeth. When applied in the canals of discolored and infected teeth it was observed that a noticeable bleaching of the discolored structure resulted. The hint thus given was further studied until it was found that under proper conditions the whole structure of a discolored tooth might be successfully restored to normal color. The earlier preparations were found to be lacking in strength ; aqueous solutions containing more than 3 or 4 per cent, of absolute hydrogen dioxid were found to be too unstable to keep for any length of time, and hence w T ere unreliable. The problem of securing a stable high-percentage solution of the dioxid was solved by using ether as a menstruum, and the 25 per cent, solution of hydrogen dioxid made by McKesson & Robbins of New York and sold as " caustic pyrozone " is now generally used where hydrogen dioxid is employed as a bleaching agent in connection with discolored tooth structure. Hydrogen dioxid, H 2 2 , belongs to the class of " oxidizing bleach- ers," and owes its activity in this respect to the weak state of chemical combination in which one of its atoms of oxygen is bound to the water molecule. Many substances serve to disrupt the compound and liber- ate one of its oxygen atoms. In contact with pus, blood, inspissated BLEACHING BY HYDROGEN DIOXID. 539 mucus, albumin, and in fact almost every kind of dead organic matter, its decomposition takes place, evolving oxygen and decomposing the organic matter either wholly or in part. Hydrogen dioxid does not bleach all of the decomposition-products of hemoglobin with equal facility. It quickly removes the pink discoloration following the initial extravasation of hemoglobin into the dentin, but when the brown stage has been reached indicative of the formation of hematin its action is but dight. Later, however, it bleaches more readily. The refractory nature of hematin with respect to hydrogen dioxid has been experimen- tally tested upon the substance out of the mouth. In bleaching discolored teeth with hydrogen dioxid the ethereal 25 per cent, solution known as pyrozone is directly applied to the internal portions of the tooth upon small pledgets of cotton or cotton wisps rolled upon a fine flexible canal instrument. After each application the ethereal menstruum is evaporated by blasts of warmed air from a hot-air syringe, and the applications similarly made are repeated until the desired effect is produced. It has been found in practice that more rapid and permanent effects are produced when the pyrozone solution is rendered alkaline. This may be readily done by the addition of a few drops of liquor ammonia? fortior or by a solution of one of the caustic alkalies, e. g. sodium or potassium hydroxid or sodium dioxid. A very satisfactory method of securing the alkaline effect in this pro- cess is that suggested by Dr. D. N. McQuillen. His method is to first treat the pulp chamber and canals with applications of Schreier's Kalium-natrium preparation and after the debris from its action has been mechanically removed with instruments and cotton twists, with- out washing the canal, an application of pyrozone is made. The bleaching action follows with great rapidity, and has apparently greater permanence than where the pyrozone is used alone. In cases where the action proceeds very slowly, for example when at the end of a thirty minutes' continuous treatment the bleaching is not complete, it is well to seal an application of pyrozone upon cotton in the canal and allow it to remain for twenty-four hours, when a second treatment will usually complete the operation. In this as in all bleaching operations it is advisable to fill the tooth temporarily with some easily removable filling in order to test the per- manence of the operation, and after the lapse of a reasonable time if there is no tendency to a return of the discoloration the canals and cavity may be permanently filled. Dr. Harlan's method consists in acting upon hydrogen dioxid by aluminum chlorid. The aluminum salt is packed in the cavity and moistened with the dioxid. The technique of the procedure is the same as for the methods already described. This process was origin- 540 DISCOLORED TEETH AND THEIR TREATMENT. ally classified with the chlorin methods, as the decomposition was sup- posed to take place according to the following equation : A1 2 C1 6 + 3H 2 2 = Al 2 O s + 3H 2 + 6C1. Experimental study of the reaction between aluminum chlorid and hydrogen dioxid by the writer developed the fact that oxygen and not chlorin was given off, and that the aluminum chlorid was unaltered during the process. Hence it was discovered that the reaction was simply clue to a catalytic action of the aluminum salt (a property which in this relation it shares in common with many other metallic salts), whereby nascent oxygen is liberated from the hydrogen dioxid. The process, therefore, has no greater value than those in which hydro- gen dioxid is directly applied. The aluminum chlorid being an active coagulant is contraindicated as a factor in the bleaching process until a point has been reached where a coagulant is needed as a fixative after the bleaching has been effected. The Sodium Dioxid Method. — Sodium dioxid, Na 2 2 , is the chem- ical analogue of hydrogen dioxid, and like the latter is characterized by the readiness with which it parts with its atom of loosely com- bined oxygen under similar circumstances. The essential difference in its properties is the character of its by-product after its decomposition has taken place. Itself a strong caustic alkali, it still retains its alka- line and caustic properties after the loss of one of its atoms of oxygen, becoming Na 2 0, which in combination with water is ordinary sodium hydroxid or caustic soda. This substance as well as the sodium dioxid has not only a saponifying property for all of the vegetable and animal oils and fats, but also a solvent action upon animal tissue. This property is of great value in removing from the dentin structure all of the con- tained organic matter, whether normal or in a state of decomposition. Having the oxidizing and consequently the bleaching quality in addi- tion to its solvent and saponifying properties it is, therefore, one of the most valuable bleaching and detergent agents at our command. The substance is dispensed as a yellowish white powder in tin cans or glass bottles hermetically sealed, as it is very hygroscopic and after twenty-four hours' exposure to moist air absorbs nearly its own weight of water ; it also loses much of its activity. For use as a bleaching agent it is applied to the dentin in saturated solution. In making the solution especial care is necessary in order to avoid elevation of temperature, by reason of the energy with which it enters into combination with the water. If the solution is allowed to become heated in the making, decomposition of the compound with loss of oxygen occurs and its bleaching power is destroyed. The . BLEACHING BY SODIUM DIOXID. 541 solution is best made by pouring into a small beaker of about one ounce capacity about two drachms of distilled water, and immersing the beaker in a larger vessel or dish containing ice-water or pounded ice. The can containing the dioxid powder should then have its lid per- forated with a number of small holes similar to the lid of a pepper caster, and the powder be slowly dusted into the distilled water in the small beaker ; or the powder may be gradually dropped into the water by tapping it from the point of a knife or spatula. The powder is added to the water until the solution assumes a semi-opaque appearance, indicating the point of saturation. On removing the beaker from the cooling mixture, the dioxid solution will in a few minutes assume a transparent, straw-colored appearance and is ready for use. The applications are to be made similarly to the hydrogen dioxid applications, but upon asbestos fiber instead of cotton, as the latter is acted upon by the sodium dioxid and converted into a glue-like mate- rial, amyloid, which is difficult to remove and interferes with the suc- cess of the operation. After the dentin, which should have been previously desiccated, is thoroughly saturated with the dioxid solution an application of 10 per cent, sulfuric acid should be made, which neutralizes the strong alkali, forming sodium sulfate and hydrogen dioxid, thus : Na 2 2 + H 2 SO, = Na 2 S0 4 + H 2 2 . The reaction is usually attended with some effervescence, which taking place in the tubular structure of the dentin, mechanically forces out its contents and thus exerts a detergent action upon it. The tooth should now be washed with hot distilled water in copious quantity and the dioxid application repeated, omitting the subsequent treatment with acid but washing again thoroughly with the hot water. Sodium dioxid solution, as prepared for bleaching, may be applied to the pulp chamber and root canal without the preliminary treatment required where other bleaching agents are employed. It is without harmful irritative action upon the apical tissues unless used in excess or forced through the foramen by careless manipulation. It is a power- ful germicide and disinfectant, and therefore peculiarly suited to the treatment of putrescent cases, which by its action are rendered sterile and aseptic as well as bleached at one operation. Its saponifying and solvent properties completely remove the greasy dark layer of decom- posed material which is found lining the pulp chamber and canals alluded to on page 546, so that the use of the sodium dioxid method makes unnecessary the application of borax or ammonia for its removal as a preliminary. When used for its sterilizing property the foramen 542 DISCOLORED TEETH AND THEIR TREATMENT. should be allowed to remain unsealed until after the bleaching operation has been completed. It sometimes happens that the improvement in color following the application of the dioxid methods is only partial and the result falls short of restoration to normal ; or, in other words, the bleaching reaches a certain point beyond which the color resists the further action of the bleaching agent. In such cases the decomposition of the color molecule has probably resulted in the formation of iron oxid as an end-product. In practice this residual discoloration can generally be removed by treatment with oxalic acid. A small crystal is to be sealed in the moist pulp chamber for twenty-four hours, and afterward washed out with a copious irrigation of hot distilled water. The sodium dioxid method removes more completely than any other the tubular contents, and the result is unique from the fact that not only is the tooth restored to normal color but to normal translucency ; the opaque white effect resulting from other methods of bleaching is due to the bleached organic debris remaining in the tubuli, but by the solvent action of the strong caustic alkali this is removed. The final treatment of the tooth is the same in this as in other methods, though the dentin should be desiccated and saturated as thoroughly as possible with an unalterable varnish before the final filling is inserted. The Sulfurous Acid Method. — Reference has already been made to sulfurous acid as the single example of the reducing type of bleach- ing agent. Its activity is due to its affinity for oxygen, and it bleaches by seizing upon and combining with that element of the color molecule, thus destroying its identity and consequently its color. Attempts have been made to utilize the bleaching property of sulfurous acid in the treatment of discolored teeth by direct applications of the solution of the gas in water and by igniting small quantities of sulfur in the root canal by means of the electro-cautery wire. These methods have, however, proved inefficient. The gas may be successfully used in bleaching teeth by evolving it from its compounds placed in the cavity and root canal in a manner analogous to that employed in the Truman chlorin process already described. For this purpose the writer's method may be con- veniently employed : 100 grains of sodium sulfite and 70 grains of boric acid are separately desiccated and afterward ground together in a warm dry mortar. The powder is then to be transferred to a tightly stoppered bottle. For bleaching purposes the powder is packed into the root canal and cavity of the tooth, and then moistened with a drop of water and the cavity immediately closed as tightly as possible with a stopping of gutta-percha previously prepared and warmed. A reaction CATAPHORIC BLEACHING OF TEETH. 543 ensues between the boric acid and sodium sulfite whereby sulfurous acid is liberated, thus : 2H3BO3 -f 3JS T a 2 S0 3 = 2JSa 3 B0 3 + 3H 2 +3S0 2 . The process is effective in many cases where the chlorin methods have failed, but is slow in its action and is largely superseded by the dioxid- of-hydrogen and dioxid-of-sodium methods. Cataphoric Bleaching of Teeth. Since the revival of interest in cataphoresis and its application to dental operations its possibilities as an adjuvant in the tooth-bleaching process are being investigated with much promise of valuable results. It has been found that aqueous solutions of hydrogen dioxid may be car- ried into the dentinal structure with great ease by the cataphoric action of the continuous current. The appliances necessary for tooth-bleaching operations by this means are practically the same as those required in the treatment of hypersensitive dentin, and are detailed at length in the chapter dealing with that subject (page 189). The resistance offered by the hard structures of the tooth is much greater after loss of the tooth pulp, requiring a much higher voltage pressure to drive the bleaching agent into the tissue. While in some cases 25 to 30 volts will be all that is necessary, some cases will require as high as 60 volts to carry 1.5 milliamperes of current through the dentin. The ethereal solution of hydrogen dioxid has been found to oppose too great resistance to the current, but the aqueous solution containing a slight addition of some salt to increase its conductivity is entirely manageable. A 25 per cent, aqueous solution of hydrogen dioxid may be quickly made by shaking together in a test tube one volume of water and two volumes of 25 per cent, pyrozone. The H 2 2 dissolves in the water, and the ether of the pyrozone may be removed by pouring the mixture into a small evaporating dish of porcelain or glass and gently heating it over a water bath until all of the ether has evaporated. The addition of a small quantity of sodium acetate or sulfate will greatly diminish the resistance of the solution to the passage of the current. With the tooth isolated by the rubber dam and having received the treatment preliminary to bleaching, as already described in detail, the aqueous solution of H 2 2 is dropped upon cotton within the tooth cavity and a platinum needle anode is applied in contact with it. The cathode may be a sponge electrode moistened with salt solution and held in the hand or applied to the cheek or neck. The hand, however, is preferable because of the amount of voltage required in the operation. Great care must be exercised that the external surfaces of the tooth are 5-44 DISCOLORED TEETH AND THEIR TREATMENT. kept dry so that short-circuiting of the current may not take place. In some cases a more rapid effect is obtained by making contact of the cathode pole through a needle electrode upon the external surface of the tooth, and with the anode applied to the pyrozone solution on cotton within the tooth. The cotton must at all times be kept wet with the solution. The arrangement of the electrical terminals with respect to the bleaching operation is both theoretically and practically correct as de- scribed, viz. the flow of current should be from the anode point through the bleaching solution and tooth and the body of the patient to the cathode. In practice it has been found in some cases which have failed to bleach with the elements arranged in the series as stated, that upon reversing the poles and direction of current flow the bleaching has rapidly followed. The explanation of this apparent paradox is that by the application in normal order H 2 2 was first carried into the tubular structure, and the reversal of the current has acted upon the tubular contents now saturated with the dioxid, and by its propulsive as well as electrolytic effect removed the pigmentary matter pulpward from the tubuli. Bleaching with reversed poles would be impossible without previous saturation of the dentin by the dioxid solution. Dr. M. W. Hollingsworth has devised an ingenious anode for feed- ing the bleaching solution or other medicament into the cavity as de- sired. The instrument (Fig. 109) is described in Chapter VI. Another device by Dr. Hollingsworth is of especial value, as it makes possible the enveloping of the entire tooth with the bleaching fluid in which it is immersed as in a bath. The appliance is shown in Fig. 469. Dr. Hollingsworth's device for applying the bleaching agent to the tooth. situ in Fig. 469, and consists of a thin vulcanized caoutchouc bulb shaped like the bulb of a medicine dropper. Through a perforation at its rounded end made with the ordinary rubber dam punch, the tooth is slipped by mounting the bulb on the applicator (Fig. 470), and CATAPHORIC BLEACHING OF TEETH. 545 forcing it over the tooth as though it were a rubber dam. A glass tube Fig. 470. Applicator. is then attached to the open end of the bulb, and to the glass tube is connected a spiral platinum wire electrode (Fig. 471). Before the elec- Fig. 471. Tube electrode. trode is attached the bulb and glass tube are completely filled with the aqueous pyrozone solution by means of a duplex syringe (Fig. 472), the Fig. 472. Duplex syringe. lower and larger bulb of which exhausts the contained air in the appa- ratus and the smaller thumb bulb injects the bleaching solution into the exhausted apparatus. Connection is now made with the source of cur- 35 546 DISCOLORED TEETH AND THEIR TREATMENT. rent as usual, and the bleaching is very rapidly effected. Dr. Hol- lingsworth recommends the addition of about 1 per cent, of zinc sulfate to the aqueous pyrozone solution, which not only diminishes the resist- ance to the passage of the current, but has a coagulating effect upon the bleached organic matter which gives it translucency and greatly enhances the permanency of the operation. The results obtained by this method are extremely satisfactory. Bleaching Methods for Special Stains. Pulpless teeth are especially liable to discoloration from external and accidental causes. If decayed and the cavity has remained unfilled for a length of time many substances which find their way into the oral cavity either as food or as medicine may produce discoloration when absorbed by the tooth through the open cavity walls. Metallic salts are particularly apt to cause such staining by reaction with the sulfids with which the dentin structure is usually saturated during decomposition of its organic contents. Many of the medica- ments used in pulp-canal treatment or even for hypersensitive dentin may stain the tooth structure, and finally the action of sulfids in the structure of a pulpless tooth may react with amalgam fillings, forming salts of mercury, silver, tin, copper, etc., which are absorbed by the tooth, resulting in its discoloration. The treatment of these stains, which were grouped as Class III. at the beginning of this chapter, is extremely difficult and often unsatisfactory. However, there may arise individual cases of discolorations of this class where it is of the utmost importance to remove them, and much may often be accom- plished when the causes of the discoloration are known and the proper bleaching method is applied. Gold stains may arise, as has been already indicated, from the inju- dicious use of gold instruments or failure to remove all gold fillings when applying some one of the chlorin methods of bleaching. In the course of time where this has happened the tooth assumes a pinkish hue Avhich merges into a characteristic violet or purple, finally becom- ing black. Iron stains may arise from the use of steel instruments in connection with the chlorin methods of bleaching or in contact with iodin or any of the mineral acids in connection with canal treatment. The iron stain is yellowish at first, gradually becoming brown and finally black. Copper and nickel stains may arise from contact with these metals or their alloys, as copper amalgam or nickel or German silver dowels for artificial crowns or anchorages for fillings. The stains from these metals are — for copper, bluish to black, and for nickel a characteristic chlorophyll green which eventually becomes black. BLEACHING METHODS FOR SPECIAL STAINS. 547 The best general treatment for all of the foregoing stains is to re-bleach the tooth by the chlorin method, with especial care as to the several precautions already recommended, and when the color of the metallic stain has been discharged by conversion of the dark-colored salt into a soluble chlorid, wash the tooth thoroughly first with dilute chlorin water 50 per cent., and afterward with hot distilled water to remove all of the metallic chlorid which has been formed. The process may require repetition to secure permanent results. Silver stains are comparatively easy to remove, either by an applica- tion of the chlorin method or by saturating the tooth with tincture of iodin, thus converting the silver salt into a chlorid or iodid as the case may be, after which it may be dissolved out with a saturated solution of sodium hyposulfite applied as a bath to the tooth. For this pur- pose the Hollingsworth bulb dam (see Fig. 471) answers admirablv, and although the experiment has not as yet been tried, there is good reason to believe that the cataphoric method with electrodes applied in reverse order would under these circumstances greatly facilitate the solution and removal of the metallic salts. Mercurial stains are always black from the formation of mercuric sulfid, and are removable by the same method as are silver stains, with the exception that where the stain has been converted into a chlorid by the chlorin method, the mercuric chlorid is best removed by an aqueous ammoniacal solution of hydrogen dioxid, or when the stain has been converted into mercuric iodid by the use of a saturated solu- tion of potassium iodid. In both cases a final washing with hot dis- tilled water is a sine qua non. Manganese stains frequently occur from the use of potassium per- manganate, in solution or in substance, in the treatment of putrescent canal conditions. The manganese stain is a characteristic mahogany brown. It is very readily removed by a 25 per cent, aqueous solution of hydrogen dioxid in which oxalic acid crystals have been dissolved to saturation. A few applications of this mixture will quickly de- colorize the stain, after which a liberal treatment of hot distilled water is required as in the foregoing cases. In all cases a careful diagnosis of the chemical nature of the dis- coloration should be made when possible. Much information upon this point may be gained by a detailed study of the present condition of the tooth and its environment, but in addition to this the patient should be questioned as to the history of the case, and especially as to its previous treatment. The data thus obtained should be carefully noted and treat- ment instituted in accordance with the conditions to be met. Success in the bleaching of teeth demands a recognition of the fact that each case presents individual peculiarities, that the problem is 548 DISCOLORED TEETH AND THEIR TREATMENT. essentially a chemical one always, and that the bleaching method in any given case must be selected with especial reference to the character of the discoloration and applied with due care as to its details in order that the chemical requirements of the operation may be intelligently met ; without which care success is impossible. CHAPTER XXI. EXTRACTION OF TEETH. By M. H. Cryer, M. D., D. D. S. Indications for the Operation. It is impossible to formulate a set of exact rules by which the prac- titioner may be governed, in deciding upon the extraction of teeth. So many circumstances both local and general must be taken into consid- eration that little more can be done than to suggest the most important causes which demand the operation. Deciduous Teeth. — The indications for extracting deciduous teeth are — First : When the teeth are a source of irritation aifecting the gen- eral health or comfort of the child and do not respond to treatment. Second : When the deciduous teeth are preventing the eruption of the permanent teeth into their normal positions. Occasionally a de- ciduous tooth will assist in the proper placing of a permanent one, in which case it should not be removed as long as it is of such use. Third : When a lower permanent incisor shows signs of erupting on the labial side of the deciduous tooth, the latter should be removed at once, but if the erupting tooth appears on the lingual side the removal of the deciduous tooth may in that case be delayed somewhat longer. Fourth : When upper permanent incisors show a tendency to erupt on the palatal side of the temporary teeth, the latter should be extracted, but when they are erupting on the labial side the deciduous teeth may be allowed to remain for a time, as they are often useful in forcing the permanent teeth outwardly. This, however, must be closely watched to prevent the permanent incisors from moving too far. Permanent Teeth. — The indications for extraction of the permanent teeth are — First : Diseased roots which cannot be cured and so made useful for crowning, or assisting in retaining a bridge, plate, or other pros- thetic device. 549 550 EXTRACTION OF TEETH. Second : Teeth of mastication that have lost their occluding teeth and in consequence thereof are being pushed from their alveoli and are a source of trouble. As a rule, this refers only to the second or third molars, and more particularly to the third molar. When it occurs with other teeth the opposite vacant space should be filled by an artificial tooth to prevent the extrusion of the natural tooth. Third : When incurable abscesses originating from teeth in the upper jaw tend to open into the nasal chamber, maxillary sinus, or zygomatic fossa, the teeth associated with such abscesses should be ex- tracted. When diseased teeth are the exciting cause of an incurable ab- scess in the lower jaw which opens or threatens to open externally on the chin, jaw, or below the bone into or upon the neck, they should be removed. Fourth : Teeth which occupy irregular positions in the arch, that cannot be corrected so as to become useful or contribute to the gen- eral symmetry of the mouth, should be removed. Fifth : Erupting teeth that are retarded because of lack of room in the jaw, if giving pain, should be extracted or else the tooth that is preventing the eruption should be removed. A marked example of this is often found in the eruption of the third molar when all the other teeth are of good size and are in place. These molars when retarded often cause the greatest distress, sometimes producing serious results, and must then be extracted ; if they cannot be safely removed the second molar may be extracted, in consequence of which the third molar will usually be erupted near its place. When an upper third molar is erupting under the same circumstances there is usually less difficulty, as having but slight resistance distally it can erupt outwardly or slightly back- ward, though, should it impinge upon the soft tissues covering the ramus of the lower jaw, it should be extracted. Sixth : Teeth so badly diseased that they will not respond to treat- ment and are a source of discomfort to the patient should be removed, as they impair the general health. Seventh : First molars. There has been much discussion regarding the early extraction of these teeth, many claiming that if the pulp of one becomes devitalized at an early period of life and it is deemed best to extract it, the other three should also be removed. No fixed general rule, however, can be given ; each case must be considered separately. There are cases where the extraction of all is necessary, and others where it would be a most unwise thing to do. When the anterior teeth are fully in position, the bicuspids occluding correctly and the second molars are about to erupt, the case may then be one for extracting the four first molars, provided it be necessary to extract one of them, or if it be likely that one or more of them will be lost in a few years. INDICATIONS FOR THE OPERATION. 551 If, however, the bicuspids are not in good position, it is better not to extract the first molars, as they assist in keeping the jaws the proper distance apart, and in preventing the lower anterior teeth from biting against the upper gum. Removal of Sound Teeth Preparatory to Inserting- Artificial Dentures. — When preparing the mouth for an artificial denture the removal of sound teeth may be indicated as a measure of expedi- ency in relation to mechanical and hygienic considerations. For ex- ample : (1) Roots which a plate or bridge would cover, excepting when they assist in holding the device. (2) Teeth from which the gums have receded to such an extent as to become useless or unsightly. (3) Teeth that are being extruded from their alveoli from the ab- sence of occluding teeth. The extraction of these depends, however, on the extent of " elevation " and the possibility of placing occluding artificial teeth in position. (4) Where there is but one tooth remaining, or two teeth standing together, or in certain cases when several isolated teeth remain which cannot be made to contribute to the mechanical adaptation of an arti- ficial denture, extract when in the upper jaw. They interfere with the fitting of an upper plate, but in the lower jaw they may be useful in retaining the plate. (5) When there are two teeth, one on each side of the upper jaw, in good position and desirable shape for clasping, do not extract unless they are the third molars or the oral teeth. (6) In preparing the upper jaw when two canine teeth alone remain, or when there is also a molar or bicuspid, or both, and it is decided to extract the molars and bicuspids, then extract the two canine teeth also. It has been claimed by some of the very best dental practitioners, whose opinions must be respected, that by keeping these teeth the expression of the face is less likely to be marred. For the following combined reasons, however, extraction is advised : a. It is very difficult to obtain a correct impression of the mouth while these teeth only are in position. b. It is nearly impossible to perfectly match, grind, and arrange the lateral incisors beside single canines. c. The adhesion of the plate to the mouth is interfered with, as air and food work in between the plate and these natural teeth. d. The plate is very much weakened by being cut out for the accom- modation of these teeth at what might be termed the abutments of the arch. In the lower jaw single teeth which are sound are usually of great 552 EXTRACTION OF TEETH. importance. They should not be removed, as they assist in retaining a denture by means of clasps or other devices. Especially is this true in persons advanced in years, as then the alveolar process is generally much absorbed. If the lower process is much absorbed even an imper- fect tooth will do good service of this character for a time, and if it is the first plate the patient has worn it will serve a good purpose by assisting in the retention of the plate until the patient has become ac- customed to it, after which the tooth, if giving trouble or if it is un- sightly, may be removed and an artificial one placed on the plate. Instruments and Accessories for Extracting. The instruments used in extracting teeth are forceps and elevators of various shapes and sizes. Forceps. — The forceps should be made of steel of the best quality for the purpose obtainable, in order to give great strength and stiffness, and at the same time toughness, so that they will not break. Forceps that will spring or bend destroy the sensitivity of the hand using them in such a way as to prevent the operator from discerning in what di- rection the resistance to extraction is being made. The beaks of the forceps as a general principle should be shaped so as to fit and adjust themselves to as great a surface of the various teeth or roots as pos- sible so that they may take a firm hold. They should be at such an angle in relation to the handles as will permit them to be easily and readily placed in the proper position without obscuring the view of the tooth to be extracted. The inner surface of each beak should be concave in a transverse section and without serrations, as these are of no assist- ance, but tend to weaken the beaks and are difficult to clean. The edges of the concave portion should be sharp enough to cut through the alveolar process if necessary. The points of the beaks should be sharp and tapering so they can be forced into position. The handles should be of a shape to allow a firm grasp, and as the hands of different operators vary in shape and size it will be evident that the same size of forceps handles will not be perfectly satisfactory to all. The curvature of the handles should vary according to the general or special use of the for- ceps. The curved ends, as seen in Fig. 473, are of little use, and should be done away with in all forceps excepting perhaps those made especially for the upper and lower molars. The joints of extracting instruments should be so made that the handles can be separated by some simple mechanism to permit of thorough and easy cleansing. Figs. 473 and 474 represent an instru- ment of this character. There are others of the same nature, but INSTRUMENTS AND ACCESSORIES FOR EXTRACTING. 553 Fig. 473. this being the most simple and the strongest should be gen- erally adopted unless a similar device can be adapted to the " knuckle-jointed " instrument. (Fig. 475.) There should be no sharp angles or crevices, and if the ordinary forceps be used, that portion around the joint in a transverse section should be oval. Forceps are often made with octagonal joints, but these should be condemned, as they may not only hurt the lips of the patient, but in case of a slip, which may happen with the best operators, they are more liable to cause injury by striking the other teeth ; moreover they are very clumsy and require more room. Fig. 474. Antiseptic universal lower molar forceps. Joint of an antiseptic lower molar forceps 554 EXTRACTION OF TEETH. Unless the antiseptic joint (Figs. 473 and 474) is used the union of the joints is usually made upon one of two principles : first, by one half passing into a mortise in the other and held in the center by a pinion Fig. 476). The second is known as a knuckle-joint (Fig. 475) made by each portion being let half way into the other and held to- gether by a screAV. This is a neater joint and does away with many of the objectionable fea- tures noted in other forms of forceps joint. All handles should be ser- rated as shown in the illustra- tion s, and the instruments if properly cared for need not be nickel-plated. The number of forceps in a practical set will vary with the requirements of every individual who extracts teeth, therefore only the general principles which should govern the selection of a set of instru- ments will be here given ; at the same time the uselessness of a very large selection is here em- phasized. As an illustration of the range of tooth extractions which may be performed with a limited number of instruments the forceps represented by Figs. 476 and 477, showing the exact size, will serve as examples. They are smaller than the ones generally used, especially in America. The instrument shown in Fig. 476 may be used almost universally for the upper teeth. Fig. 477 is a forceps of the same general character as that in Fig. Knuckle-joint root forceps. INSTRUMENTS AND ACCESSORIES FOR EXTRACTING. 555 476, only the beaks are at a different angle with the handles. This pair Fig. 476. Fig. 477. ®§^ r ££P- I'M Universal upper incisor and root forceps. Universal lower incisor and root forceps. may be used similarly for the lower teeth. These forceps are useful in all cases, except in the full arch, when either a first or second molar is 556 EXTRACTION OF TEETH. Fig. 478. Fig. 479. For the ten upper anterior teeth. Root, upper front. Straight. INSTRUMENTS AND ACCESSORIES FOR EXTRACTING. 00, to be extracted. If the teeth are large, the jaw strong, and the line of grinding surfaces concave, it is ? f - ., Fig. 480. better to use the special lower molar forceps as shown in Figs. 473 and 486. Fig. 478 and Fig. 479 rep- resent very useful forceps for extracting the ten upper an- terior teeth. Fig. 479 has longer beaks and its points are finer. In skillful hands where too great a force will not be brought to bear on the points they are the better forceps. Under nitrous oxid and where many teeth are to be extracted, thus requiring rapid work, the instrument shown in Fig. 478 is preferable. Figs. 480 and 481, right and left, represent forceps specially used for extracting the first and second upper molars on either side. The outer beak is made pointed for the purpose of pass- ing in between the buccal roots, the inner beak is concave in order to grasp the palatal root. Figs. 48*3 and 484 show bayonet- shaped forceps, that illustrated by Fig. 483 being especially made for extracting the upper third molars, Fig. 484 being used for upper roots. The ends of the handles of all forceps which are forced in by the palm of the hand should have a broad surface as shown in Fig. 484. These forceps are popular with many operators. The writer considers' them clumsy, as they obscure the proper view of the tooth and its associated parts. Right upper molar. 558 EXTRACTION OF TEETH. Fig. 481. Fig. 482. Left upper molar Hawk-beaked forceps. INSTRUMENTS AND ACCESSORIES FOR EXTRACTING. 559 Fig. 483. Fig. 484. Universal upper third molar. Dorr's upper root forceps. 560 EXTRACTION OF TEETH. Fig. 485. Fig. 486. Universal lower canines and bicuspids. Universal lower molars, designed by Dr. Chapin A. Harris. INSTRUMENTS AND ACCESSORIES FOR EXTRACTING. 561 Fig. 487. Fig. 489. Root, lower. Half curved. 36 Elevator. Right and left scalers used for extracting roots. 562 EXTRACTION OF TEETH. Forceps for Extracting Lower Teeth. — Instead of the beaks of the forceps being nearly on a line with the handles as in those for the upper jaw, they are bent at nearly a right angle. For the incisors of the lower jaw there are no better forceps than those shown in Fig. 477. This instrument is very useful in extracting the lower third molar when fix- ation of the jaw from diffuse cellulitis in the region of the temporo- maxillary articulation renders it difficult to open the mouth sufficiently for inserting a larger instrument. In such cases the forceps should be carried backward in the vestibule of the mouth with the inner beak passing between the upper and lower teeth ; when the beaks reach the third molar the inner beak can usually be forced over the inner surface of the tooth and into position, after which the tooth can be grasped and extracted. The forceps represented in Fig. 476 can also be used to advantage for these teeth, the operator standing behind and working over the head of the patient, as shown in Fig. 539. Fig. 482 exhibits a hawk-beaked forceps for extracting the anterior lower teeth. It is very popular with some operators, especially those in Europe. The writer does not recommend it. Fig. 485 also exhibits a special instrument. It is made for extract- ing the lower canine and bicuspid teeth of either side. Fig. 486 is a special instrument used for the lower molars of either side. The beaks are pointed, with a concavity on each side of the point to allow it to pass in between the roots. The two concave portions fit against each root. Fig. 487 represents a universal lower root forceps. Elevators or Eoot Extractors. — There are many kinds of ele- vators used in extracting roots. Some are also occasionally used in the extraction of teeth (usually the third molar). Fig. 488 shows one of the most useful forms of this instrument. It is especially useful in extracting third molars w r hen the teeth in front of them are in position. Also for the removal of impacted teeth by passing in between the impacted tooth and an adjoining tooth, or between the tooth and the bone, the concave portion being placed against the tooth to be removed. It is also useful as a gouge at times in removing bone that is overlying an impacted tooth. Fig. 489 represents two elevators ; they are similar to right and left scalers, being made somewhat heavier ; they are extremely useful in extract- ing roots. They are so unlike an extracting instrument that patients do not dread the appearance of them as they do that of forceps. By care- fully inserting the blade with the point toward the root to be removed, between it and the adjoining root or tooth, and giving a slight rotary motion, the point will force the root from its socket with but little pain. Figs. 530 and 531 illustrate two other forms of elevator, w T ith their mode of application in the removal of roots. Lancets. — Figs. 490 and 491 represent various forms of lancets. IXSTRUMEXTS AXD ACCESSORIES FOR EXTRACTING. 563 the more useful of which are Nos. 1 and 5, which are all that are required for lancing in extracting or for relief of retarded eruption of deciduous or other teeth. They are also useful in general surgery of the mouth. The handles should be made of metal instead 490. f W ood, in order that they may be thoroughly sterilized. Fig. 491. Lancets with ebony handles and with solid steel handles. Scissors. — A good pair of curved scissors, as shown in Fig. 492, should be at hand in case a portion of gum tissue is found to be attached to the root. If the scissors were slightly more curved they would be even better adapted for this purpose. In connection with the instruments already men- tioned, there should be a mouth mirror (Fig. 493) and a few excavators and probes for general exami- nation of the teeth, especially for examining the position and character of a root or impacted tooth which it is purposed to extract. Mouth Props. — When an anesthetic is to be given it is advisable to use some kind of a mouth prop, in order to keep the mouth well open. Corks 1J inches in length, \\ inches at the base, and f of an inch at the small end are very useful for this purpose when placed between the jaws, with the small end in the mouth. Some operators do not use them, as they may interfere with the giving of the anesthetic by impeding respiration upon beginning the administration. The majority of patients, if asked to hold the mouth open while taking the anesthetic, especially nitrous oxid and oxygen, will keep it open during the anesthetic stage. 564 EXTRACTION OF TEETH. Fig. 492. Fig. 494 illustrates excellent props devised by Dr. Frederic Hewitt, of London, England. The Mechanical Mouth-opener (Fig. 495). — This instrument is made in various shapes and sizes. It is inserted between the jaws when the props are to be removed or in cases of trismus, and may also be used to separate the jaws and retain them so in cases of emergency or during certain operations within the oral cavity. All dentists, and especially those who extract teeth, should have at least one pair of pharyngeal for- ceps (Fig. 496). It is possible that they may never be used, but on the other hand an accident may occur such as a fragment or tooth slip- ping into the pharynx, where if the finger cannot reach it this instru- ment will be absolutely necessary. Surgical Anatomy. — To extract teeth successfully it is first neces- sary to be perfectly familiar with the general shapes of the different Fig. 493. Curved scissors. Mouth mirror. teeth and their position in relation to the jaw and to their associates, in order that the operator may intelligently apply the force in the line of the least resistance required for their removal. This knowledge cannot be obtained from books ; they are but the guides to it. The jaws of the dead subject must be dissected — both the cleaned bones and those with the soft tissues left upon them. "Dissection" means that not only shall the superficial relations be studied, but that the bones shall be cut INSTRUMENTS AND ACCESSORIES FOR EXTRACTING. 565 in various directions, both with the saw and other instruments, until the relations of the teeth of the upper jaw with the floor of the nasal chamber and the maxillary sinus are fully understood. In the lower jaw the relations of the teeth with the inferior dental canal and the position of the roots, especially those of the third molar, must also be thoroughly known. Fig. 494. Hewitt's mouth props (half size). The alveolar process of both jaws is made up of two plates, external and internal, consisting of dense compact bone without a true line of de- Fig. 495. Mechanical mouth-opener (half size). marcation between the process and maxilla proper. The sockets for the roots of the teeth are situated in the interspaces between these plates and Fig. 496. Pharyngeal forceps (half size). are surrounded by a very thin porous plate of cortical bone. The remaining space is filled with cancellated tissue, small bony channels, con- 566 EXTRACTION OF TEETH. nective tissue, nerves, vessels, etc. As this process belongs to the teeth, is developed with them, and is for the purpose of holding them in posi- tion, it disappears to a greater or less extent when the teeth are lost. The resorption of this process does not take place alike in each jaw. In the upper jaw the external plate disappears more rapidly and to a greater de- gree than the inner plate ; in the lower jaw the resorption of the two plates is about equal in extent and rate. The inner plate of the upper jaw is partially supported by the external plate of the palatal process, in fact one merges into the other. The outer alveolar plate of the upper jaw being resorbed to a greater extent than the inner one is of advantage to the dentist in fitting teeth to the gums ; consequently, in extrac- tion that fact should be remembered and injury to the internal plate avoided. At the same time it does no harm to remove a small por- tion of the outer plate, though loss of the gum tissue should be avoided if possible. In the lower jaw it is not so important to avoid Fig. 497. Alveoli of permanent teeth— upper jaw. removing slight portions of the inner plate, as resorption takes place about equally in the two plates. These plates may be resorbed in such a manner that a slight ridge is left between the places which they occupied. This resorption of both plates of the alveolar process of the lower jaw makes it more diffi- cult to fit single plain teeth in the lower than in the upper jaw SURGICAL ANATOMY Fig. 498. 567 Alveoli of permanent teeth— lower jaw. Fig. 499. Typical upper and lower jaw. 568 EXTRACTION OF TEETH. Fig. 497 shows the alveoli of the upper denture, Fig. 498 that of the lower. Fig. 499 illustrates a typical upper and lower jaw, the external sur- Fig. 500. Showing the occlusal surfaces of the upper teeth. (From same skull as Fig. 499.) faces of the crowns of the teeth, also a normal occlusion. Figs. 500 and 501 illustrate the occluding surfaces of the teeth and their relations with each other. They are made from the same skull as Fig. 499. r Fig. 501. Showing occlusal surfaces of the lower teeth. (From same skull as Fig. 499.) Fig. 502 is from a photograph taken from the right side of a skull. It gives a good representation of a fairly normal occlusion of the SURGICAL ANATOMY. Fig. 502. 569 Showing the buccal surfaces of the crowns and roots in position. Fig. 503 Hi ■From the same jaw as Fig. 50^ 570 EXTRACTION OF TEETH. teeth, their shape, roots, and their relation with the cancellated tissue and the inferior dental canal or cribriform tube of the lower maxilla. Hiatus semiluminari. Fig. 504. Middle ethmoidal cells. I — Crystalline lenses. Uncinate process. Middle turbinated bone. Middle meatus. Maxillary sinus, nferior meatus. Inferior turbinated bone Vestibule of mouth. First molar. Distal root first molar. Inferior dental nerve. An anterior view of a vertical transverse section of the head, showing the relations of the jaws and the U-shaped bone of the mandible. In the upper jaw the bone is thin over the position of the molar teeth, and their roots are comparatively straight ; none of these should be difficult to extract. The buccal roots of the first molar are somewhat divergent from each other. The same roots of the second molar spread only slightly as they leave the crown and close in at the points. The roots of the third molar are together and slightly curved backward. In the lower jaw the roots are comparatively straight. Those of the first molar are spread only a little apart, this being the usual condition. The roots of the second molar are almost straight and are nearly parallel with each other. The anterior root of the third molar curves slightly backward until it joins the posterior root. SURGICAL ANATOMY. 571 Fig. 503 is taken from the left side of the same jaw as Fig. 502. In Fig. 502 the roots have been exposed down to their apices ; in Fig. 503 only the external or cortical plate has been removed. These two illus- Oms Oms 1st M 1st M Posterior view of vertical transverse section of the head from the same skull as Fig. 504, showing the ostium maxillare, which is indicated on each side by a cord passing through it : Om, Ostium maxillare ; 1st M, first molar. (rations give a correct idea of the relations of the teeth to the internal structures of the jaw. Figs. 504 and 505 are good illustrations of the relations of the roots with the floor of the maxillary sinus usually found in the white race. Fig. 506. .4r 1st M JR 2d Bi Idn Ar 1st M, Anterior root of first molar : i? 2d Bi, root of second bicuspid ; Idn, inferior dental nerve : Up, U-shaped or cortical section of lower jaw. In the negro there is usually a considerable thickness between the teeth and the floor of the sinus. It will be noticed that the roots of the molars pass up on both sides of the sinus, and because of this fact 572 EXTRACTION OF TEETH. it is necessary in extracting teeth from a jaw of this character to use the greatest caution, otherwise a portion of the floor of that cavitv might also be removed. Or if a tooth be broken and much upward force used Fig. 507. Central Lateral incisor, incisor. Canine. /);/ ' ^. First bicuspid. Second bicuspid. Second bicuspid. First bicuspid. Canine. Horizontal section of the upper and lower jaws cut a little beyond the free margin of the alveolar process, showing the forms and position of the roots of the various teeth. in endeavoring to take hold of the root, the latter could easily be forced into the sinus. The lower portion of Fig. 504 gives a general idea of a transverse section of the lower jaw made posterior to the mental foramen. Especial attention is drawn to the U-shaped formation of the cortical portion of the lower jaw which terminates in the two plates of the alveolar process,, and between which the roots are imbedded in SURGICAL ANATOMY. 573 the cancellated tissue. It also shows how the roots extend toward the inferior dental nerve. There is no line of demarcation between the alveolar process and the body of the bone. Fig. 506 shows the relation, length, and position of the second bicus- pid, showing that its root is sometimes placed to the inner side of the anterior root of the first molar. The roots of these bicuspids are flat, as will be seen by looking at Fig. 526. On taking into consideration their length, position, and thinness it will be readily seen why it is so often difficult to extract them without breaking. Fig. 507 is taken from horizontal sections of the lower and upper jaws, showing the transverse sections of the roots of the teeth. The section is made a little above the margin of the alveolar process of the upper jaw and a little below in the lower. The illustration shows the shape and position of the various roots, with their relations to the pro- cess and to each other. Particular attention should be given to the fact Fig. 508. £ Re Rli Horizontal section of the lower jaw cut in the region of the points of the roots of the teeth : Dn, Dental nerve ; R 3d M, roots of third molar ; R 2d M, roots of second molar ; R 1st M, distal root of first molar; R 2d Bi, root of second bicuspid; R 1st Bi, root of first bicuspid; Re, root of canine ; Rli, root of right lateral incisor. that the roots and process are in such close relation as to make it im- possible to force the beak of a forceps between them without breaking one or both plates of the process. The lines leading from the roots 574 EXTRACTION OF TEETH. show the proper direction for applying what is known in extracting as the "out-and-in motion." Fig. 508 represents a horizontal section made through the lower jaw near the ends of the roots, and from the same bone as that shown in the lower half of Fig. 507. The cancellated portion with the soft tissue filling the spaces can be plainly seen. The nerve passing into its tube, the ends of the roots of the second and third molars, the tip of one of the roots of the first molar, and the roots of the first and second bicus- pids are all plainly shown. A little of the lateral incisor can be noticed, but the centrals do not reach so far down. Figs. 509 and 510 are taken from a sagittal section of the upper jaw, external to the infraorbital foramen, and through the roots of the Fig. 509. Fig. 510. Om Anteroposterior division of the maxilla, showing opening of a dental abscess within the antrum and an infraorbital sinus : Ifs, Infraorbital sinus ; If, infraorbital foramen ; Pic, piece of paper passing through infraorbital canal; Ms, maxillary sinus ; Ac, apical abscess. Om, Opening into malar bone ; Ifs, infraorbital sinus. molar teeth. This illustration shows how the roots often extend above the lower portions of the floor of the sinus, an abscess from the palatal root of the first molar having discharged into the floor of the sinus at the point Aa. It has been demonstrated both anatomically and clinically that in- fectious matter from a suppurating tooth may eventually give rise to an inflammation of the meninges of the brain. Should pus from a dento- alveolar abscess discharge into the maxillary sinus it may pass out into the hiatus semilunaris and ascend into the frontal sinus or in the vicin- ity of the cribriform plate of the ethmoid through the infundibulum when SURGICAL ANATOMY. 575 Fig. 511. Longitudinal division of a mandible, exposing the cancellated tissue in the body of the jaw and between the sockets of the teeth. Fig. 512. i? *5 E F G H I J Sections made at different points from a mandible which was not quite normal in its density. 576 EXTRACTION OF TEETH. the passage through the hiatus into the middle meatus is small or con- stricted, as it usually is when inflamed, or the pus may pass directly through the infundibulum. Recent research has shown that the frontal sinus, the cribriform plate of the ethmoid, and the meninges of the brain are in close relation at the anterior portion of the cribriform plate, a dis- eased condition at which point is liable to involve all three structures. Fig. 513. Fig. 511 is from a longitudinal section of the lower jaw, and gives a good idea of the cancellated tissue, the relations of the sockets of the teeth to one another^ and the position of the inferior dental canal. Fig. 514. f\ j - f _ , An uncommon impacted lower third molar. Fig. 512 is taken from several transverse sections of a lower jaw. The bone is not quite normal, as several teeth were extracted before death, the loss having caused changes in the character of the bone. Some of the sections show but one canal, while in others there are many, SURGICAL ANATOMY. 577 requiring close observation to determine in which the inferior dental nerve and vessel has passed. Fig. 515. A view of an impacted lower third molar. Fig. 513 is taken from the inner side of the right half of a lower jaw. The second molar has been broken off, the roots still remaining in position. The points of the roots of the third molar pass out through Fig. 516. A second view of an impacted lower third molar, as shown in Fig. 515. Part of the distal root of the second molar has been resorbed, exposing the root canal, more than likely causing the devitalization of the tooth, and thus producing neuralgia. the inner wall a considerable distance below the mylo-hyoid ridge. A portion of the ridge has been cut away, exposing the remainder of the internal surface of the roots. This will be further alluded to when ex- traction of the lower third molar is considered. 37 578 EXTRACTION OF TEETH. Figs. 515 and 516 are from the outer side of the right half of a lower jaw, Fig. 515 showing an impacted third molar lying horizontally in Fig. 517 Inner side of left half of lower jaw, showing an impacted third molar. the jaw. Fig. 516 is of the same jaw with the tooth removed from its bed, showing the inner surface. The second molar is a pulpless tooth Fig. 518. (Same as Fig. 517, with the impacted molar removed from its bed.) the distal root of which shows where the impacted tooth has pressed against it, causing the absorption of a portion of the root and exposing the pulp canal within, producing death of that organ. This must hav.e SURGICAL ANATOMY. 579 caused neuralgia. The cancellated tissue of this bone, it will be noticed, is not like that shown in Fig. 503, the change in the character of this tissue being the result of irritation. It will be seen that the roots of the Fig. 519. Right half of lower jaw, showing a lower third molar with thickened and curved roots. other teeth in this jaw are longer than usual, the canine tooth passing below the nerve and to the outer side. Figs. 517 and 518 represent the inner side of the left half of a lower jaw. It shows an impacted third molar pointing slightly downward. Fig. 520. Left half of lower jaw, showing a third molar lying horizontally and the hone much more dense than normal. The distal root of the second molar is slightly absorbed. On uncover- ing the tooth and taking it from its bed, it was found to be incased in a thin shell of bone as though the dental sac had ossified separately around this tooth ; this thin incasement of bone may, however, have been an 580 EXTRACTION OF TEETH. inflammatory product. The inner portion of this shell can be seen in position. The nerve and its accompanying tissue passes into the infe- Fig. 521. Showing two ordinary impacted lower third molars. rior dental foramen immediately against the shell, and has the appear- ance of being flattened out. It divides and sends a branch around the internal half of the shell. Fig. 522. X-ray picture made from the left side of Fig. 521. Figs. 519 and 520 are taken from the right and left halves of the lower jaw. Fig. 519 shows the internal surface of the right half; SURGICAL ANATOMY. Fig. 523. 581 Jf\ /■ W k Side view of two ordinary impacted lower third molars, the hone having heen removed in order to expose the roots. Fig. 524. Showing an inverted lower third molar erupting into the submaxillary fossa (Dr. Whitney). 582 EXTRACTION OF TEETH. Fig. 520, the external surface of the same. In Fig. 519 the roots of the third molar curve backward, are joined together, and are so enlarged by an abnormal deposit of cementum caused by continued hyperemia due to the prolonged irritation that the form of each root Fig. 525. Deciduous teeth— left side (Burchard). is lost ; the bone also is much thickened. Fig. 520 shows an impacted tooth pressing directly against the one in front of it, the roots of which have become much enlarged by the deposit of cementum. The sur- rounding bone is also thickened and much more compact than the nor- Fig. 526. Permanent teeth— right side (Burchard). mal bone. The character of the cancellated tissue of the lower jaw is lost by the deposit of bone caused by continued irritation of that tissue. Figs. 525 and 526 show the normal forms of the teeth, and Fig. 527 is taken from a group of abnormal teeth. If only normal conditions of the teeth had to be considered, as shown in Figs. 525 and 526, SURGICAL ANATOMY. 583 extraction would be a very simple operation, but unfortunately this is seldom the case. It often happens that even when the teeth them- selves are normal they are situated in abnormal positions, and for this Abnormalities in teeth. reason alone their extraction becomes necessary. In fact, so varied and complicated are the different abnormalities presented, that it would be impossible to describe them all. The diagnosis of unerupted teeth occu- pying abnormal positions has been greatly facilitated by special applica- 584 EXTRACTION OF TEETH. tions of the skiagraphic method. Its further use in this connection is but a question of time and development. A careful study of the com- plications most frequently occurring will, however, give good preparation for meeting the emergencies. Figs. 513 to 524 and 528 show abnormal positions of various teeth. It will be readily seen that no set of rules could be made to govern the extraction of these teeth ; therefore only the general principles govern- ing extraction can be here set forth. General Principles in Extracting Teeth. These principles may be classified under the following heads : (1) Management and Position of Patients. (2) Selection of Instruments. (3) Technique of the Operation. Management of Patients. — The first important step toward a suc- cessful operation in dentistry is to gain the confidence of the patient, who must be brought to rely entirely on the judgment and skill of the Fig. 528. Abnormal jaw showing impacted canines. operator. If the operator feels entire confidence in his own ability to successfully carry out an operation he can, by his manner of approaching the patient, impart a feeling of almost absolute trust in his skill. This feeling of confidence in himself should be cultivated, as it is evident that a slight nervousness on his part, even though he be most skillful, will tend to alarm the patient to such an extent as may cause great interference with the operation. Position of the Patient. — The principal object to secure in placing the patient is to obtain a good view of the affected tooth and GENERAL PRINCIPLES. 585 contiguous parts ; after which the position should be made as comfort- able as possible both for the patient and operator, taking care that the territory of operation can be reached with but little strain or effort. The position both of patient and operator varies slightly for the extraction of each tooth. The main points to be observed are to have the particular tooth to be operated upon in view, and the head of the pa- tient in such a position that it can be controlled by the left arm and hand. The chair should be steady, strong, and comfortable, with arms and a good head-rest of rather a concave shape. It should also have a suit- able foot-rest. . When the regular dental chair is not obtainable, an ordinary strong wooden chair can be used. If two of these chairs are placed back to back the extra one gives a good place for the left foot of the operator, and a head-rest may thus be made of his thigh. The patient should be directed to grasp the seat at both sides with his hands. At times it may be necessary to extract while the patient is in bed or on an operating table ; in such cases the operator must obtain the best position available. Where an operating table or couch is used it is well, if possible, to stand at the head of the couch or table and a little to one side of the patient. By reaching over the head, the for- ceps shown in Fig. 476 may be used to advantage in work on the lower jaw; the same forceps may be used for the upper jaw by standing to one side of the patient. If the operator is ambidextrous, so much the better, as it is very advantageous to be able to use the instrument in the left hand, especially in extracting the teeth of the right side of the lower jaw. The operator in this case standing on the left side. If, however, only the right hand can be used, the operator should, as a rule, stand at the right of the chair, the left arm and hand being used in various ways to control the head of the patient. The mouth is opened as far as necessary, and the left hand is then used to hold the lips away and keep the jaw as steady as possible. (See Figs. 536 and 537.) In using the elevator, as shown in Figs. 488 and 529, for the removal of teeth from the left side of the mouth, especially for the lower third molar, the oper- ator should stand on the left side of the patient. The index finger of the right hand should be placed in the mouth by the lingual side of the tooth, and the thumb placed on the buccal side of the first and second molars. This gives steadiness to the jaw and lessens the risk of slipping. Selection and Use of Instruments. — The selection of instruments depends on the nature of the operation to be performed. The means used in extraction should be of the most simple character. Many deciduous teeth and permanent teeth from about which most of the process has been resorbed can often be easily extracted with the thumb and finger. Children feel less apprehension with this method than when an instrument is used. The thumb and finders should be covered with 586 EXTRACTION OF TEETH. a napkin, and the thumb placed on the inner surface of the tooth with the fingers against the outside of the jaw. The tooth is then forced out- wardly toward the cheek or lips. The roots of the deciduous teeth often break, but this is of little importance, for when extraction is demanded the roots are weakened by the natural process of resorption and will soon disappear. Elevators of the various patterns shown in Figs. 488, 489, Fig. 529. Manner of holding elevator Fig. 500. 529, 530, and 531 should be used whenever practicable for removing roots, and in some cases teeth also. Fig. 488 is especially useful in re- moving the third molars, especially if they be impacted. When the internal anatomy of the jaws is well understood, this will be appreciated. Fig. 530. Elevator in use labially. Fig. 507 shows how firmly the roots are embraced at their necks between the two hard plates of compact tissue. It is usually impossible to force an instrument between the roots of teeth and these plates with- GENERAL PRINCIPLES. 587 out breaking the internal or external walls of the latter. The cancel- lated tissue between these plates is, however, soft and yielding, and into Fig. 531. Elevator in use lingnally. this a properly shaped elevator can be passed between the roots. After pushing the instrument with the point toward the root to be extracted and the back toward the contiguous tooth or root, using the latter as a fulcrum, revolve the elevator slightly, prying at the same time, and the root will leave its socket with little or no injury to the surrounding tis- sue. Elevators should be firmly grasped and held in such a manner that if a breakage or slip should occur the instrument will be prevented from wounding the soft tissue. If root forceps were used in cases of this kind it would be almost impossible to avoid injuring one or the other of the plates when removing the root. It is often advisable to use the forceps by passing the beaks between the plates and grasping the root on its approximal surfaces, instead of the external and internal surfaces. Even whole teeth may be extracted in this way when there are no adjoining teeth or roots. A similar plan is sometimes used in rapid extracting under nitrous oxid, where roots or teeth have been extracted on each side of a tooth, the beaks passing into the sockets of the extracted teeth, thus grasping the tooth to be removed on its approximal sides. This mode of operating must be followed with care, especially in teeth situated below the maxillary sinus, as the floor of that cavity may be easily injured. (See Figs. 504 and 505.) Lancing. — Lancing for extraction is not usually required, though there are cases where it is quite necessary. If the teeth have been 588 EXTRACTION OF TEETH. standing alone for a long time, especially those in the back part of the mouth, the gums are apt to become firmly attached to them ; when this is the case it is well to sever the connecting tissue by the use of the lancet before extracting. In extracting roots where it is necessary to remove a portion of the external plate of the alveolar process, it is well to make an incision in a line over the root, through the gum to the bone ; it is even advisable to slightly dissect the gum and periosteum from the bone on each side of the cut. This is done in order that the external beak of the forceps may be passed along the bone as far as de- sired. By thus lancing, the parts will afterward come together and quickly heal, whereas if the gum is cut by the forceps it will not heal so well. In extracting roots in the lower jaw, if the lancing would cause the blood to cover the parts and obscure the operator's view it should be omitted. Use of Forceps. — As nearly all operators are right-handed, the instruction as to the use of forceps will be given with that understand- ing, most of the special instruments being made for that hand. The forceps are grasped in the right hand with the palm toward the body, the thumb on top of and partially between the handles (which will indi- cate to a great extent the amount of pressure being exerted upon the tooth), pressing against the handle nearest the palm just back of the joint. The first finger should rest a little between the handles, thus giving a firmer grip on the right handle (see Fig. 532), which might be termed the fixed, or passive, handle ; while the other one is the movable, or active, handle. Many operators do not place the first finger between Fig. 532. Use of forceps. the handles (see Fig. 533). The second and third fingers pass to the outside of the left handle and are used to close the forceps, while the little finger resting between the handles is used to open the forceps, the thumb being used to force the beaks into the required position. GENERAL PRINCIPLES. 589 After the forceps are in position for extracting, the first finger is placed along the side of the second finger to give more power to extract. After it has been decided to extract by using the forceps, the par- ticular forms indicated must be selected and arranged in a convenient place, ready for immediate use as needed. Especially should this be Fig. 533. Use of forceps. the case when the operation is done under the anesthetic influence of nitrous oxid. It is under such conditions that the fewer forceps used the better ; the writer generally uses but one forceps (Fig. 477) for the extraction of any or all teeth except the first and second molars ; for those teeth, when the other teeth are in position, he advises using the special forceps. Having the patient's head in position, the forceps are grasped as previously described and the beaks adjusted to the tooth. As a rule, the inner beak should be placed in position first, and then the outer one — this is very important, especially for the lower teeth — taking care not to include a portion of the tongue or the soft tissues of the floor of the mouth, as both are liable to get in the way. When the forceps are adjusted to the inner and outer surfaces of the tooth, they should be forced between it and the gum until they come in contact with the 590 EXTRACTION OF TEETH. edge of the alveolar process. It is a common error of students to use too much force in pressing the handles together; only sufficient force should be used to securely hold the tooth or root. The forceps should grasp as much of the roots as possible, avoiding pressure upon the crown and being careful not to force the beaks between the alveolar plates, as this would result in breaking one or both plates over the tooth or root extracted and also over the adjoining tooth. Cases have occurred in which the entire external plate of one side has been forced off in this way. At times it may be advisable to take away a portion of the outer plate, in which case the lancet shown in Fig. 490 should be used to cut through the gum a little beyond the point of process to be removed, dissecting up the gum slightly ; the inner beak is then adjusted and the outer one passed between the divided gum and the process as far as required ; the forceps should then be closed with only sufficient force to cut through the bone and grasp the tooth, taking care not to crush it. After the forceps are in position the tooth is loosened by rotating it slightly if it be a round conical-rooted tooth, such as a central incisor, but if it be a flattened one it should be removed by an outward and inward movement. By the " out-and-in motion " is meant that after the forceps are ap- plied the force used in loosening teeth is directed in such a manner that the tooth is worked outward and inward from the median line of the mouth (see Fig. 507, in which the lines show the direction of the motion for each tooth). The individual teeth do not always bear the same relation to the median line of the jaw as shown in Fig. 507. When the axis of a tooth is not regular it should be loosened by mov- ing backward and forward, and the movement should be in line with its strongest diameter, which lessens the danger of breaking the tooth. In the upper jaw the inward movement is made after the outer, but with not so much force, as the structure on the inner side is more dense. Rotation of a tooth in extracting is seldom practiced, as the single- rooted teeth are usually flattened and teeth that have more than one root cannot be rotated. Of the single-rooted teeth, the upper central incisors alone have roots nearly conical in shape which permit rota- tion as well as the out-and-in motion. A rotary motion is usually of advantage in extracting the roots of the upper first bicuspid when not double, and of the upper molars after the crowns are broken away so that the roots are disunited. These roots are usually round, conical, and somewhat curved in shape. GENERAL PRINCIPLES— DECIDUOUS TEETH. 591 If possible, the tooth should be kept in view during the operation so that the results of the movements may be seen. A beginner may let the forceps slip and extract the wrong tooth when he is not observ- ing each movement, but an experienced operator can depend on his sense of touch to a very great extent. The amount of pressure a tooth will stand while loosening it by an " out-and-in motion " depends on the size, condition, and density of the bony tissue surrounding it and the accurate fitting of the forceps to the tooth. Experience is the only reliable guide in this matter. When a tooth resists ordinary effort, if the operator is not quite sure of the cause of the resistance of the tooth, it is better to desist temporarily and allow the patient to rest, in order to investigate the condition of the tooth and its surroundings. Fig. 519 will give some idea of the causes of the resistance offered by apparently normal crowns. After the forceps are applied and the tooth slightly moved, if the operator has a cultivated sense of touch he will feel that the tooth is yielding in one particular direction ; as a general rule the tooth should be carried in that way. The force applied to safely and judiciously extract teeth should be made with arm and wrist motion ; if the whole body is used the sense of touch is blunted and accidents are liable to occur. Extracting' Deciduous Teeth. — In extracting the deciduous teeth Fig. 534. Skull of a child about six years of age, showing all the deciduous teeth in position and nearly all the developing teeth. the principles involved are nearly the same as for the permanent. A care, however, must be taken that is not necessary with the perma- 592 EXTRACTION OF TEETH. nent teeth, i. e. y to avoid injuring the developing permanent teeth that are situated immediately beneath them. Fig. 534 shows all the deciduous and the developing permanent teeth except the lower third molar and the upper molars. It gives a true idea of their relative positions. Special attention is drawn to the position of the crowns of the bicuspids as related to the deciduous molars. It will be seen that they are situated between the roots of the latter teeth, and by using undue force in adjusting the forceps these crowns could easily be misplaced, extracted, or injured. If the deciduous teeth are extracted at the proper time they can usually be removed by the thumb and fingers as described. If not, one of the forceps shown in Figs. 476 and 477 should be used. Extraction of Individual Permanent Teeth. The anatomy of the individual teeth and the majority of their often-repeated variations as well as the general principles govern- ing the extracting operation being understood, the extraction of each tooth will now be studied, those of the upper jaw being first considered. The Upper Teeth. THE CENTRAL INCISOR. This tooth has a strong, round conical root. The forceps are carried into position by placing the inner beak at the palatal surface of the neck of the tooth ; the outer one is then placed in position and the instru- ment forced upward with a slight rotary motion between the gum and the tooth until it comes in contact with the alveolar process. As the root is round and conical, it is loosened by rotation and the out-and- in motion and then removed by drawing it directly from its socket. It is, as a rule, easily extracted. the lateral incisor. This tooth is much smaller than the central. The root is flattened and somewhat curved, the apex being often bent in the direction of the canine teeth. After applying the forceps as directed for the central incisor, the motion should be outward and inward. As the tooth has a delicate root, the force used must be light. When loosening and removing it, care must be exercised, as its root is not straight. The tooth is carried in the direction of the least resistance, which is usually toward the canine tooth. UPPER TEETH. 593 THE CANINE. This tooth is usually more firmly set in the jaw than any other, and it often requires considerable force to break up its attachments. The root is long and slightly flattened. After applying the forceps its attachments are broken up by the out-and-in motion. After loosening it is usually easily removed from its socket. As this tooth is erupted after the adjoining teeth are in position, it is often malposed. If the deciduous canine has been lost before its proper time, and the first bicuspid has pushed forward, there is no room for the canine to take its true position. This irregularity varies to a great extent. The canine may also be out of position from unknown causes. A marked specimen is seen in Fig. 528, where both canines are impacted. They were entirely covered by a bony lamina. Sometimes the roots of these teeth project into the maxillary sinus, or even into the nasal chamber, while the crowns are impacted be- tween the palatal plate and the plate forming the floor of the nose. Fig. 535 represents a Fic^535. canine, lateral, and central incisor which were extracted from the sinus, the roots being imbedded in its inner wall. Teeth thus im- pacted are often a source of trouble in vari- ous ways and when discovered should be re- ^-^ ^ _ „_- , , ill Canine, lateral, and central moved. When the tooth is so covered by bone incisor extracted from that the forceps cannot be applied the bone maxillary sinus that L # L L ip were causm g neuralgia. must be cut away sufficiently to allow the forceps to grasp it. A very good instrument for removing the bone in the upper jaw is the elevator shown in Fig. 488 ; after the point has been sharpened it may be used as a chisel or gouge. THE BICUSPIDS. The first bicuspid usually has a bifurcated root and the only motion that can be used safely for loosening is the out-and-in, as these roots are sometimes considerably divergent. The removal after loosening is not always easily accomplished, a little outward pressure being frequently necessary. If the force required is used too suddenly the inner root is liable to break. The second bicuspid usually has a single flattened root, though occa- sionally it is bifurcated. The motion used to loosen this tooth is the outward and inward, using the same precaution as with the first bicus- pid on account of the possibility of a double root. 38 594 EXTRACTION OF TEETH. THE FIRST AND SECOND MOLARS. These teeth are nearly similar, having three roots, two buccal and one palatal, which vary so much in degrees of separation that no set rule can be given for their extraction. The roots of the first are usually more divergent than those of the second. Only the out-and-in motion can be used, rotation being out of the question in loosening them, as Fig. Showing position for extracting upper teeth of left side. the roots often diverge to a great extent. (See p, Fig. 527.) After the tooth has been loosened there is at times a difficulty in removing it, on account of the distance around the three roots ; owing to their divergence this distance is greater than the size of the anatomical neck of the tooth corresponding to the opening of the socket. The only general rule that can be given is to carry it in the direction of THE UPPER TEETH. 595 the least resistance. Each tooth has more or less of an individual character, and therefore the operator must be governed by circum- stances. The main precaution to be observed is not to be in too great haste, as there is danger of breaking one of the roots or re- moving a large piece of the outer plate of the alveolar process. (See Accidents, p. 612.) THE THIRD MOLAR. This tooth so varies as to the shape and number of its roots that it is seldom spoken of as an abnormal tooth, no matter in what form or position it may be found ; the greater number have roots curved back- ward and outward. Their position in the jaw also varies considerably, The forceps shown in Fig. 476 is the instrument to use in extracting. After the forceps have been firmly placed, the principal motion is the out-and-in, though more out than in. If there is much resistance the hand should be carried outward and upward, or in the direction of the least resistance. This tooth is sometimes erupted at the side of the Fig. 537. Showing position for extracting upper teeth of right side. alveolar process (Fig. 538) with its occlusal surface pointing toward the cheek. It is not well to have the mouth opened too far, as it brings the coronoid process of the lower jaw in the way. In stating the general rules of extracting, caution was given not to make the movements faster than could be seen ; this applies very partic- It is so near the ascending ramus in the ularly to the third molar. 596 EXTRACTION OF THE TEETH. lower jaw that it is possible, especially when the roots are curved and spread out, to fracture this angle, or in the upper jaw the tuberosity may be broken away, thus opening into the maxillary sinus. The gum tis- sue often adheres to the posterior portion of this tooth ; when this hap- Fig. 538. An impacted upper third molar. A similar condition found on the opposite side of the skull. pens it is best to desist from attempts at extraction and sever the tissue from it with a curved lancet or scissors before removing the tooth with the forceps, or, as before advised, dissect the gum away before applying the forceps. The Lower Teeth. As a rule, the teeth of the lower jaw are more difficult to extract than are those of the upper jaw, the lips and cheeks being in the w T ay. The tongue is also troublesome, covering the tooth, and when the inner beak of the forceps is placed in position especial care must be used to prevent part of the tongue or floor of the mouth from being caught in the instrument. THE ORAL OR ANTERIOR TEETH. (For position see Fig. 539.) These six teeth have small single, straight, compressed roots. Their extraction is only necessary when they become loosened by accident or from disease or when it is necessary to clear the mouth for inserting artificial teeth. The operator should stand a little back and to the right side of the chair, being somewhat elevated above the usual posi- tion. Pass the first finger of the left hand between the lips and the alveolar border, and place the remaining fingers beneath the chin with the thumb on the inside of the teeth. For the incisors use the lower THE LOWER TEETH. 597 root forceps shown in Fig. 487 or the universal forceps shown in Fig. 477. The canines are larger and more firmly set ; delicate root forceps, therefore, are not usually suitable ; the instrument shown in Fig. 477 or, better, the bicuspid forceps (Fig. 485) are much to be preferred. An out-and-in motion is proper for loosening all these teeth. Fig. 539. Showing position for extracting lower anterior teeth. THE BICUSPIDS. The lower bicuspids have compressed roots seldom bifurcated, and are generally extracted by the out-and-in motion. The special forceps for these teeth should be made so that they grasp a considerable por- tion of the surface of the tooth. These teeth are often difficult to extract without breaking when all the teeth are in position, the roots 598 EXTRACTION OF TEETH. being long and narrow and often situated in an awkward position. As shown in Fig. 506, the position of the roots of the second bicuspid is a little to the inner side of the anterior root of the first molar. The tooth illustrated in this particular case would be very difficult to extract without breaking. THE FIRST MOLAR. (For position see Fig. 540 for the left side, 541 for the right side.) The first molar, if in a mouth where all the teeth are in position, is generally the most difficult of all the teeth to extract. The roots are usually long and diverging. It is lower in the arch than the other teeth, and is in fact similar to an inverted keystone ; consequently, when extracted it is drawn through the arch. When the teeth are close together the second bicuspid and second molar yield a little, but great care must be taken that one or both of these teeth are not extracted Fig. 540. Showing position for extracting lower teeth of the left side. with the first molar. In placing the forceps on the lower molars the points of the beaks of the special molar forceps (Fig. 473 or 486) are placed in between the roots on each side of the tooth. Care should be exercised to avoid including a portion of the tongue or soft tissues of the floor of the mouth in the forceps. If the forceps are not well placed the wrong tooth may be extracted, as it is possible for them to slip in between two teeth. THE LOWER TEETH. 599 In loosening these teeth the out-and-in motion is used, and as they are wedged in it is often necessary to continue this motion while extracting them from their sockets. At times it is advisable to move the tooth out- Fig. 541. Showing position for extracting lower teeth of the right side. wardly after it has been slightly lifted from its socket. Occasionally the roots diverge so far that either the crown has to be broken from the roots at their bifurcation or the tooth divided in the line of bifurcation with splitting forceps ; each root being then extracted separately. THE SECOND MOLAR. The roots of this tooth are not as diverging as those of the first molar, as may be seen by examining Fig. 502, nor is the tooth wedged in as tightly as in the case of the first molar. The out-and-in motion is required for these teeth, using the same precautions that are necessary in the extraction of the first molar. THE THIRD MOLAR. In this tooth the roots may vary so much in number and shape that it can hardly be said to be a typical third molar. Fig. 502 shows what might be called a typical third molar, but these are only found in well- developed jaws, where the teeth are not so large as to cause crowding, or where there has been no inflammatory condition causing excessive deposit 600 EXTRACTION OF TEETH. of lime salts within the cancellated tissue. They vary in character from the one shown in Fig. 50^ to those shown in Figs. 513 to 524 inclusive. There are also third molars having three, four, or five roots. Fig. 527, a shows another form of the third molar ; 6, c, d, e, and / show where the third molar has united with the second molar ; g and h illustrate three molars united ; i, j, k, l y m, n, o, and p show variations of roots. The positions these teeth occupy may vary in all degrees from that shown in Fig. 502 to those shown in Figs. 513 to 524 inclusive. Where the third molar is in the position shown in Fig. 502 and there are no other complications, its extraction is easy. The tooth is removed by placing either the special lower molar forceps shown in Fig. 486 or the forceps shown in Figs. 476 and 477 in position, and using the out- and-in motion with a slight raising of handles. If Fig. 476 be used the beaks should be turned downward and the handles carried upward. But when it is of irregular form and position, as shown in the various illustrations, the difficulty increases with the degree of variance from that of the typical tooth shown in Fig. 502. These cases should be closely studied. If portions of the teeth are in view, as shown in Figs. 519 and 520, they will assist to some extent in the diagnosis of the position of the roots. In this particular case, the bone as well as the roots being much hypertrophied, it would be impossible to extract the roots without fracturing the process to a greater or less extent. It will be noticed, on examining the section Fig. 519, that to have fractured the inner portion of the jaw, the inferior dental nerve and vessels and also the mylo-hyoid nerve and vessels would be endangered. If in attempt- ing to extract this tooth it should not yield to a pressure which if in- creased would break the bone, it is better to desist and cut away the bone with a bur (shown in Fig. 582) in the surgical engine, as was done in the case of the specimen from which the illustration was made. Those rep- resented in Figs. 515, 516, 517, and 518 are uncommon cases and would be more difficult to diagnosticate, as no portion of the teeth was in view. Usually a satisfactory diagnosis of their position can be made by the use of a properly shaped excavator, especially by those who are experi- enced in the handling of such an instrument and who are thoroughly con- versant with the normal and pathological anatomy of these parts and recognize the pathological symptoms that are indicated. No one without this knowledge is properly equipped to diagnose teeth in this position, much less to extract them. An X-ray picture may be of service, especially in the absence of this knowledge of the general principles of the diseases of the jaws and face. After making the diagnosis of an impacted tooth in such a position, if it is to be removed the operation should be done in the hospital, the patient should be anesthetized by ether, and, as in all ex- tractions of teeth, the same antiseptic precautions should be taken as are used in general surgical operations. Then by the removal of the soft THE LOWER TEETH. 601 tissue by a small curved knife and the use of proper burs, driven by the surgical engine, the tooth can be liberated from its bony prison. Figs. 521 and 523 show more common forms of impacted lower third molars and are comparatively easy to diagnose. The following description will cover the general procedure of extract- ing ordinary forms of impacted lower third molars, except that in a few cases it will not be necessary to cut the crown. Fig. 542. Showing two impacted lower third molars. Fig. 542 is an illustration of two impacted lower third molars. Part of the crown of the left lower third molar was broken away in an endeavor to extract the tooth, leaving the pulp exposed. By careful ex- amination with an excavator it was found that the anterior cusps were interlocked within the concave portion of the distal surface of the second molar, and were so far down in the tissue that a carborundum disk could not be used to remove them. The patient being etherized, a mouth-gag was placed in position, and a portion of the soft tissue removed with a small knife. The revolving spiral osteotome (Fig. 543) was placed 602 EXTRACTION OF TEETH. Fig. 543. within the broken crown or into the pulp chamber, cutting almost through the balance of the crown. Then by passing the point of the osteotome under the crown and between it and the bone, a space was made in the tooth and in the bone, which allowed the point of the elevator, shown in Figs. 488 and 529, to pass between the tooth and the jaw. The writer now seldom uses the forceps to remove a tooth after loosening it with the elevator. In using the elevator on the left side, as in this case, it is operated with the right hand, the surgeon standing on the left side of the patient. The left forefinger is placed in the mouth, by the lingual side of the tooth, and the thumb is placed on the buccal side of the first and second molars. This gives steadiness to the jaw and lessens the risk of slipping. As the tooth is raised from its socket, the forefinger is placed so as to bring the tooth out of the mouth. If the tooth to be removed is on the right side, the elevator should be used with the left hand if possible (the surgeon standing on the right side). If the operator must use the elevator with his right hand he should, however, manage to guard and steady the parts with his left hand. Fig. 544 is made from three photographs of the tooth after extraction. A shows the outer or buccal side of its roots, in about the same position as w 7 hen in the jaw. The distal cusps were broken away in a former Fig. 544. Two forms of Cryer's spiral osteotome. A B C Showing three views of the tooth extracted from the left side of Fig. 342. endeavor to extract it. The greater portion of the crown was cut away with the surgical engine. On the side of the tooth there is a groove extending backward, downward, and inward, cut by the osteotome. It was along this groove that the elevator was forced under the tooth, caus- ing the slight remaining portion of the crown to fracture. In B the tooth is turned slightly outward, in order to show three roots and the line of fracture which liberated the tooth. In c the tooth is turned upon its buccal surface, showing the two anterior cusps which were locked under the distal surface of the second molar. In Fig. 513 the third molar is in such position as to be easily ex- tracted, though if proper care were not used the extraction might have serious consequences. It will be noticed that the points of the roots are just through the inner U-shaped cortical portion of the lower jaw below THE LOWER TEETH. 603 the mylo-hyoid ridge and project into the submaxillary region. Now, should this tooth or the roots be pushed downward in attempted ex- tracting, as is sometimes taught, it might be forced into the submaxillary region and consequently be lost for a time, with the possibility of having to perform a subsequent surgical operation to cut it out from the neck. An impacted third molar often causes great distress by initiating an inflammation which extends to the region surrounding the angle of the jaw, and often including the temporo-maxillary articulation and soft parts within the mouth. Under these conditions the jaws can only be partly opened, deglutition is impaired, and solid food cannot be taken. If any part of the tooth can be seen, the difficulty is not so great. Relief must be given, and, as a general rule, the offending tooth should be ex- tracted. Circumstances may arise in which the removal of the second molar may become an unavoidable preliminary to the removal of the third molar. As the mouth can only be opened slightly, it is impossible Fig. 545. Showing the direction in which the lower third molar is to be extracted. to use the large special molar forceps. An elevator is sometimes recom- mended in these cases, but it may prove to be a dangerous instrument to use under such conditions, for when the tooth is lifted out of its posi- tion in the mouth, it might slip back into the larynx. It is well in some cases to loosen a tooth with an elevator and then remove it with the forceps shown in Figs. 476 or 477, as they are small and are so shaped that the beaks can be carried back to the tooth mainly aloug the vesti- bule of the mouth, the inner blade being placed between the teeth by passing the forceps back of the second molar. Often it is impossible to see completely what is being done ; therefore, it is not well for a beginner to undertake this kind of extracting. After the forceps is in position the tooth should be worked in any direction in which it will yield ; this is generally outward, upward, and backward, in the manner of unfastening a hook. (See Fig. 545.) When the lower 604 EXTRACTION OF TEETH. third molar is impacted near the gonion or external angle of the jaw, it may be necessary to open it from the outside through the soft tissues. When such is the case the surgical engine should be used for cutting the bone. Treatment after Extraction. The operator should recognize immediately any accident that may have happened during the operation of extraction, and treat it as the circumstances indicate ; but if nothing unusual occurs, then the patient may be allowed a few moments' rest, after which the mouth should be carefully examined. If there be any loose portions of the process or pieces of gum hanging to the parts operated upon, they should be re- moved by any convenient means, such as small forceps, a curved pair of scissors, or a curved lancet (Figs. 490 and 492). When several teeth have been extracted, leaving ragged edges of the outer walls of the alveolar process, these should be removed with the excising forceps or, better still, by the use of either forceps Fig. 476 or 477, according to circumstances, as the beaks can be carried between the gum and the process better than can the blades of the excising forceps. An antiseptic mouth-wash consisting of a tablespoonful of phenol sodique to a glass of water should be used several times daily for the next few days. Any other suitable antiseptic mouth -wash which may be more agreeable to the patient may be used instead, though the phenol sodique is highly efficacious. Occasionally, in a few days after extraction, pain will be noticed in and about the alveolus, especially when the tooth has been the seat of pericemental inflammation. Relief in such a case is usually given by removing any clot that may have formed, and breaking down the de- generated tissues which should have adhered to the root. A pledget of cotton saturated with the full-strength solution of phenol sodique or campho-phenique should then be inserted as a dressing. Accidents. When accidents of any kind whatever occur, the operator should be calm and appear perfect master of the situation. He should be pre- pared to successfully deal with whatever conditions may arise. One of the most common accidents is the breaking of a whole or portion of a tooth or root. If the operator has any doubt of his ability to remove the tooth entire, he should inform the patient that there is a possibility of its breaking, in which case not to be alarmed. If the tooth is removed without breakage so much the better ; even if it does break it will not cause alarm to the patient. It is more desirable that all of a tooth should be removed, for if its surrounding membrane has ACCIDENTS. 605 been inflamed, or if a root having a portion of the pulp attached has been broken, either will be the source of obstinate pain. It is better, however, under some circumstances to let certain roots remain if they are broken than to break away a large amount of process. Koots are sometimes so situated that they can be easily forced into the maxillary sinus (see Figs. 504 and 505), or into the submaxillary region (see Fig. 513), or upon the inferior dental nerve. If there exist reasons for believing that the root will not cause undue pain, and there Fig. 546. Fig. 547. Fig. 548. Fig. 549. Fig. 552. Fig. 550. Fig. 553. Fig. 551. Fig. 554. be danger of breaking a large amount of process, it is preferable to let it remain, as in a short time the contraction of the soft parts and their expulsive efforts will force the root outward, and it can then be removed without danger. If roots are forced into the maxillary sinus they must be followed and removed. When several teeth are to be extracted under an anesthetic, if the gum should adhere unduly to one of them, the operator should desist from its removal and proceed with the other extractions, after which the adherent gum should be severed with a curved lancet or a pair of curved scissors and the tooth then removed. If the gum be much torn and the bone exposed to a great extent, it should be held in place 606 EXTRACTION OF TEETH. by a few interrupted sutures. If, however, proper care be taken in extracting, this should not occur. In extracting crowded teeth, or those having frail alveolar surround- ings, it is possible to remove a piece of the alveolar plate, especially in extracting the first and second molars, the broken piece extending back- ward, forward, or in both directions to the adjoining tooth. (See Figs. 546 to 554.) The tooth in front may even be partially lifted from its socket. As soon as the operator sees the impending accident he should either stop and see if his method of extraction could be im- proved, or, this point being negatively decided, hold the parts in posi- tion with the left hand as well as he can, and after the tooth is removed force the injured parts into position ; they will usually stay, but if not, appliances of appropriate form can be used for retention. In extracting the upper third molar, the tuberosity is sometimes broken away, opening into the maxillary sinus (see Figs. 546, 547, 548, 551, and 554, showing where teeth have been carried away with the tuberosity). If it is a simple fracture the parts can be forced into place and they will in a short time reunite. But if the parts are torn loose it will be of little use to try to replace them • the best course is to trim away the ragged edges, using the curved scissors for this purpose. After such a fracture it is possible that hemorrhage may occur from rupture of the superior dental artery. This is sometimes difficult to control. One of the best remedies, however, is to tightly pack the parts with medicated gauze. This application must be left in for a few days and then be carefully removed. It is sometimes well to take out only part of the gauze at a time, the loosened portions being cut off with a pair of curved scissors. Hemorrhage after extraction usually ceases in a short time, and then there is no occasion for treatment ; when, how- ever, the adjoining parts are much inflamed, or the patient is in an anemic condition, or the case is one of hemorrhagic diathesis, special treatment will be necessary. Hemorrhage of extraction may be divided into two classes, arterial and capillary. When arterial, it is usually located in the socket of the tooth, and may usually be stopped without much difficulty by taking a twist of absorbent cotton, shaping it into a thin tapering roll, and thoroughly packing the socket. Before inserting the cotton tampon, it should be rolled in tannic acid until the fibers will hold no more, then the cotton is to be packed tightly into the alveolus with a dental plugger. In packing the cotton it is well to begin at one end and crimp it upon itself until the socket is entirely filled. The plug in a few cases may require retention in position by compression. This is accom- plished by holding a few folds of muslin or similar material over the plug, closing the mouth and binding the jaws together with a few turns of a ACCIDENTS. 607 Barton's bandage. (See Fig. 555.) The 25 per cent, ethereal solution of hydrogen dioxid in small quantity on cotton packed into a bleeding socket is a most efficient styptic, and will effectually control severe hem- orrhage after extraction. Care must be exercised not to use the solution in excess, as it may cause injury to adjacent parts. Where hemorrhage occurs from the surrounding tissue, as in patients in an anemic condition or in cases of hemorrhagic diathesis, the case usually falls into the hands of a general practitioner for systemic treatment, but the local treatment usually employed by physicians in these cases is often unsatisfactory, many using Monsel's solution of persulfate of iron, which, although it may be a good styptic for use in Fig. 555. Barton's head bandage. other parts of the body, should not be used in the mouth. The local treatment in such cases, whether soon after extracting or not, is first to remove all clots from the wound and find the exact place or places from which the blood is exuding. A suitable styptic and compression are the principal means used for stopping it, the latter perhaps being the most important. Tannic acid applied on cotton, lint, or similar substances is a good styptic to use in the mouth. Compression can be applied as the iDgenuity of the operator may direct. AVhen a hemorrhage occurs from a socket between sound teeth, it can be readily controlled by two ligatures, making one fast to each tooth, then placing in position and tying the four ends to- gether Over the COmpreSS, as shown in Fig. 556. Showing compress and ligatures. In a few rare cases an impression of the parts should be taken in wax or modelling compound in order that a vulcanite or metallic plate can Fig. 556. 608 EXTRACTION OF TEETH. be made to hold the styptic compress in position. After the com- press is in position warmed modelling compound can be placed over it and the jaws brought together and retained in place by a head bandage. A plug of hardening plaster of Paris may be made and forced into the bleeding socket in obstinate cases, or in extremis the extracted tooth might be soaked well in phenol sodique and reinserted. The systemic treatment is often important ; if the patient is seen to be anemic or known to be of the hemorrhagic diathesis, the treat- ment should be begun before extracting. This is done by thoroughly building up the system by a course of hygienic and tonic treatment. The cause of bleeding in cases where the hemorrhagic diathesis exists is but imperfectly understood ; the blood may be so defibrinated that it has lost the power of coagulation and so will not form a clot, or the muscular coats of the vessels have lost their tonicity, either through general debility or the lack of energy in the vasomotor nervous system, which prevents their contracting so as to close the lumen. Certainly the walls of the capillaries permit free transudation of the blood. In good health the proper coagulation and the contraction of the blood- vessels will stop the hemorrhage even when an artery of consider- able size is lacerated, especially if the flow be held in abeyance by arti- ficial means for a short time. It is when the blood will not coagulate and the vessels fail to contract that a thorough systemic treatment must be given. This lack of normal function on the part of the blood and vessels may arise from various diseases, and in order to judiciously treat a patient exhibiting the hemorrhagic diathesis a thorough exam- ination must be made and such treatment given as the diagnosis indi- cates. Among the most common causes of hemorrhage are anemia, syphilis, purpura, tuberculosis, and a generally impaired vitality, rarely an over-acting heart; the passive hyperemia attendant upon a weak heart is a potent factor requiring a course of preliminary treatment. Specific and special diseases must of course receive the treatment peculiar to these conditions. On general principles the following tonics are advisable : Quassia, cinchona and its alkaloids, iron in its various forms, sulfuric and hydrochloric acids, arsenic, phosphorus, nux vomica and its alkaloid strychnin. With these general tonics various hemo- statics can be given, such as alum, tannic acid, ergot, erigeron Cana- densis, and gallic acid. Very frequently the digestive organs require special medication, when such remedies as pepsin, pancreatin, hydro- chloric acid, and bismuth subnitrate are indicated. The following prescriptions have proved to be very excellent in their special province. As general tonics : USE OF GENERAL ANESTHETICS. 609 1^. Strychnine sulphatis, Acidi arsenosi, ad. gr. j ; Quinise sulphatis, PT. XXX o Ferri sulphatis exsiccat., gr. xv. M. et ft. piluhe No. xxx. S. One immediately after each meal. Ify. Elixir ferri, quinise et strychnia?, f^iv. S. Teaspoonful four times daily. To improve digestion and assimilation : 3^. Acidi hydrochloric! diluti, f^ij ; Ext. ignatise amaris fid., f^j ; Pepsin, 3iss ; Ext. ipecacuanhse fid., Tttiv ; Infusi gentiana? comp., q.s. ut ft. fovj. — M. S. Dessertspoonful in sherry glass of water immediately after meals. In cases of undue hemorrhage after extracting, it is well to adminis- ter a hemostatic while at the same time styptics and pressure are being applied locally. The following are very good : ]^. Vin. ergotse (Squibb's), f§iij- S. Teaspoonful every two hours. 1^. Ext. ergotse solidificat., 3j ; Ext. cannabis indicse, gr. v ; Strychnia? sulphatis, gr. ss. M. et ft. pilulse No. xxx. S. One pill three times a day. Gallic acid and aromatic sulfuric acid may be administered. Digitalin given in doses of ^ to J a grain three or four times daily for a series of weeks will often effect such change in the capillaries as to overcome the hemorrhagic tendency. This has been repeatedly and suc- cessfully accomplished in epistaxis, and as the conditions are analogous it can be employed in this diathesis with expectation of similar results. Extraction under the Influence of General Anesthetics. While it is undoubtedly true that the extraction of teeth under the influence of a general anesthetic is in accordance with the general spirit of the age which seeks to spare all suffering or cause the infliction of but slight pain, yet many evils attend such general and too often indiscriminate use. a A patient under the effect of so powerful a drug that consciousness is destroyed is nearer death than an ordinary human being, since the primary depressive influence upon the high 39 610 EXTRACTION OF TEETH. nervous centres may speedily pass to the lower vital centres in the medulla oblongata." l The indiscriminate use of general anesthetics, beside their possible danger to life and health, has an accompanying evil in the demand for the extraction of teeth which are salvable and useful, but which a patient insists upon having removed in order to avoid the discom- fort attendant upon their treatment and filling. No one questions or denies the enormous benefit of general anesthetics in dentistry, particularly when painful operations are to be performed upon ner- vous women and children, but if the patient be willing to suffer a little pain it is generally better to extract without a general anesthetic, as in that case the patient can assist the operator by keeping the head in a desired position with the mouth and lips well open, and in various other ways, while under the influence of an anesthetic the muscles supporting the head, jaws, and cheeks are so relaxed that it is difficult to keep the mouth and lips well open. If the operation is to extract a difficult tooth, the operator is limited to the time when the patient is under the influence of an anesthetic, and in the case of nitrous oxid the time is very short ; but without an anes- thetic there is not this limitation as to time, and the extraction may be done with that care and deliberation essential to a proper operation. It is an important rule in any branch of surgery that the time required to do an operation must be sufficient to do it properly and without un- necessary injury to the adjoining tissues. Examination of a Patient before the Administration of a Gen- eral Anesthetic. — The physical examination should be made in such a way that it will not cause alarm to the patient. The result of this ex- amination governs the selection of the anesthetic, and to gome extent shows how far the patient should be carried under its influence. It has been said that a greater amount of care should be used if the patient has or is suspected of having organic or functional disease of either the heart or the lungs. This is quite true ; but at the same time the greatest amount of care should be observed in all cases. For the physiological action of various anesthetics the student is referred to special works on this subject. The question often arises whether anesthetics should be used at all if the patient has either organic or functional disorder of the heart. That depends to a large degree on other conditions of the patient. If the shock of extraction will be less under ether or nitrous oxid, then by all means give the anesthetic and carry the patient fairly well under its influence, so that there will be neither pain nor knowledge of the ope- ration. Occasionally patients suffering from heart disorders can bear a certain amount of pain without shock ; in such cases it is better, if the operation be a simple one, to extract while in the normal condition. 1 H. A. Hare, Park's Text-Book of Surgery, vol. li. USE OF GENERAL ANESTHETICS. 611 Fig. 557. The use of ether for extracting has certain advantages. If for any reason the operation requires longer time for its performance than the influence of the nitrous oxid will last — say from one to two minutes — it is better to use ether. Ether can be given after the patient has become anesthetized by nitrous oxid and oxygen and he may be kept un- der its influence for a considerable time ; in this way the struggling stage of ether is avoided. When the teeth are to be extracted at the patient's home or at any other place outside of the office, ether is more conve- niently carried than nitrous oxid. If properly used and the patient has perfect confidence in the operator, it can be so administered that one, two, or three teeth may be extracted during what is known as the first stage of ether anesthesia, before complete unconsciousness and long before the strug- gling stage commences. The best way to accomplish this is to administer the ether in a cone made by a napkin or towel, with the small end slightly opened so as to alloAV the patient to inhale a small quantity of air ; it also permits the patient to exhale freely and with a less suf- focating effect. It is well to place in the cone a small soft sponge that has been well washed with hot water. After the cone is ready the patient should be instructed to breathe several long and full inhalations ; this clears the lungs of much impure air and ac- customs the patient to the kind of breathing required. Then the appliance is placed in front of and some distance from and above the mouth and nose, being careful to allow none of the ether to drop from the cone upon the face, as it will demoralize the patient. The inhaler is to be advanced toward the face slowly and gradually, watch- ing the effect upon the pa- tient ; if there is a tendency to cough, the advance should Nitrous oxid gasometer. . . , .., ., . , be interrupted until this has passed. After the cone has closed tightly over the mouth and nose, it is a good plan to ask the patient to hold up the left hand as long 612 EXTRACTION OF TEETH. as possible ; this will concentrate his thoughts upon the act and away from the operation. When the hand begins to fall, the request to raise the hand should be repeated ; it will soon fall, and in a few seconds afterward one, two, or three teeth may be removed, the number de- pending entirely upon their position and the difficulty to be overcome in their extraction. As soon as the teeth are extracted the head of the patient should be raised from the head-rest and the body carried forward, and, having a hand cuspidor in front, the patient should be Fig. 558. - - Water line To gas cylinder Sectional view of gasometer. requested to eject the blood from the mouth ; this direction is usually complied with. The patient in most instances recovers in a few moments and with no disagreeable after-effects, but if the ether is carried beyond the struggling stage to the point of complete sur- USE OF GENERAL ANESTHETICS. 613 gieal narcosis the nauseating after-effects are very disagreeable unless the patient has been thoroughly prepared for the occasion. Nitrous oxid is the anesthetic most commonly administered for the extraction of teeth, and under ordinary circumstances is the best. Until lately every operator was his own maker of the gas — this was a great disadvantage — but now it can be procured in a liquefied form com- Fig. 559. Nitrous oxid inhaler. pressed in cylinders. There are many different appliances used for 614 EXTRACTION OF TEETH. the administering of this gas even when using it in a condensed form. One of the most prominent is that shown in Figs. 557 and 558, in which the gas is drawn into a reservoir and then passes through a flex- ible tube to the mouth-piece (Figs. 559 and 560). Fig. 560. Hood inhaler. The two principal mouth-pieces are Fig. 559, which should have the detachable lip-shield removed so that the tube may be placed directly into the mouth and the lips compressed around the tube by the operator, at the same time closing the nostril by the thumb USE OF GENERAL ANESTHETICS. 615 Fig. 561. Stand for compressed gas cylinder, gas bag, tube, and inhaler. 616 EXTRACTION OF TEETH. and finger, and Fig. 560, which is known as a hood inhaler; it is made to cover the nose as well as the mouth. The advantage of the first mouth-piece is that the lips may be closely watched for the change of color denoting oxygen-starvation of the blood, which the experienced operator combats by admitting a certain amount of air with the gas as required. Fig. 562 represents a portable appliance to be used at a patient's home or away from the regular office. Fig. 562. Portable nitrous oxid apparatus. Dr. Hewitt's Method.— Dr. Frederick Hewitt of London, England, has devised the apparatus shown in Figs. 563 and 564. The three cylinders contain the compressed gas, two being filled with nitrous oxid and one with oxygen. The valves of the cylinders are opened by a key which is controlled by the foot of the operator. The tube passing from the cylinders to the receiving-bag is double, a smaller tube being placed within the outer larger tube. The receiving-bag is also double, being divided by a rubber septum into two compartments which have their outlet in the double tube which leads to the inhaler. To the receiving- bag is attached a mixing-chamber, and to this the inhaling-tube or hood is fastened. This appliance is used very successfully in England and has been introduced into the United States. It has proved satisfactory to all who have tried it. The bags and tubing should be made of more durable material when intended for use in the American climate. USE OF GENERAL ANESTHETICS. 617 The manner in which the appliance is used is as follows : The valves in the mixing-chamber (Fig. 564) are closed, then oxygen is let into its compartment of the receiving-bag until the latter is nearly filled, when the nitrous oxid is admitted into its compartment. The patient being prepared, the inhaling-tube or ,hood is placed in position, and the patient is directed to breathe — long, full, and steadily. If the tube is used it is necessary to close the nose by the thumb and finger. Fig. 563. Complete apparatus of Dr. Hewitt for administering mixed nitrous oxid and oxygen. The valves are not changed for a few inhalations, during which time only air is inhaled ; then, pressing the indicator a downward to the first notch 6, the air is cut off, and the patient receives pure nitrous oxid ; this is allowed for a few more inhalations, and then the indicator is car- ried to the next notch and one part of oxygen is allowed to pass into the respiration. When the indicator is carried to the third notch two parts are received by the patient, and so on until the maximum amount of oxygen required by the patient has been reached. It has been found by careful study of many thousands of cases and by special scientific investigation that the asphyxial condition incident to most cases of nitrous oxid inhalation is quite unnecessary to the pro- 618 EXTRACTION OF TEETH. duction of nitrous oxid anesthesia. It is also justly considered to be subjecting a patient to an unwarrantable danger to permit the asphyxial effect to manifest itself to a profound degree, as in many cases it is a menace to life and health, and might have a fatal effect. The object of Dr. Hewitt's method is to control or eliminate the asphyxial element by administering a requisite amount of oxygen. Fig. 564. Showing arrangement of the mixing-chamber, with dial and valve for controlling the relative proportions of the gases. No fixed rule can be laid down for the quantity of oxygen to be added, as each case will require a different amount and this amount varies during the several stages of the anesthetic procedure. The operator is guided entirely by the symptoms of the patient during the administration, his object being to avoid on the one hand the tendency toward asphyxia indicated by cyanosis of the lips, and return of con- sciousness and sensation on the other hand, which is easily produced by an excess of oxygen. By the admixture of oxygen, as in Dr. Hewitt's method, the anesthesia is somewhat prolonged over the ordinary nitrous oxid method and is slower of induction, but there is entire absence of cyanosis, stertorous breathing, jactitation, or any of the symptoms of asphyxia. The modification of the Hewitt apparatus that has been lately introduced embodies certain features that make it an improvement on the original apparatus. The arrangement of the mixing-chamber in reference to the bags containing the gases is such as to enable the operator to more accurately control the mixture that is USE OF GENERAL ANESTHETICS. Fig. 565. 619 Apparatus for administering nitrous oxid and oxygen combined : a, key to oxygen bag ; b, key to oxygen cylinder; c, gauge showing percentage of oxyqren being administered, d, mixing- chamber ; e, e, keys to nitrous oxid cylinders ; /, key 10 nitrous oxid bag. 620 EXTRACTION OF TEETH. administered to the patient. By a turn of the levers a and /(Fig. 565) any gradation of the gases may be obtained, from pure nitrous oxid on the one hand to pure oxygen on the other. The construction of the apparatus is such as to better withstand the climatic conditions than the Hewitt apparatus. A brief description will suffice to show the working of the apparatus. There are three cylinders, two containing compressed nitrous oxid, and the other compressed oxygen. Two bags, one of black material to contain the nitrous oxid, the other of red material to contain the oxygen. The key to each cylinder (see 6 and e, e) opens the valve and allows the gas to pass into its respective bag. By opening the valve (see /) of the nitrous oxid bag the gas passes into the mixing-chamber, from which it flows through the covered rub- ber tube to the inhaler. When it is desired to combine oxygen with nitrous oxid, open gauged valve (see a, c) to the oxygen bag ; this will admit the oxygen into the mixing-chamber. Both gases will pass through the tube to the inhaler. The proportion of oxygen used will be determined by the degree to which the gauged valve is opened. By closing the valve of the nitrous oxid bag, oxygen can be given separately. Similar results are obtained when air is admitted, instead of oxygen, to the patient during the nitrous oxid administration. The details of this procedure are set forth in the following chapter. CHAPTEE XXI. (Continued). EXTRACTION OF TEETH UNDER NITROUS OXID ANESTHESIA. By J. D. Thomas, D. D. S. Where the operation would cause excessive pain, the extraction of a tooth without the aid of an anesthetic is to-day little short of bar- barous. It is cruel to the patient, and if the subject be a child, wantonly so. Very few people can submit to the operation without more or less physical resistance, and even though this be involuntary no operator can do full justice in such a case, no matter how skillful he may be. Such resistance causes more or less unnecessary strain to be applied in one direction or another against the process, which results in increased inflammation as a sequence. Besides, as a rule the liability of breaking the tooth or portions of the alveolar plate or other accidents is increased a hundredfold. Nitrous oxid is in all respects the very best anesthetic for the pur- poses of the dentist. Properly used, it is almost entirely free from danger and is rarely productive of nausea or depression as an after- effect, even temporarily. It seldom requires over sixty seconds to pro- duce anesthesia, and in less than that period of time the patient is fully recovered, with no knowledge of the operation, and is ready to depart as soon as bleeding ceases. To accomplish such a result, of course, requires experience and some degree of dexterity, but the con- ditions are such that any dentist with a fair amount of experience can operate successfully with it for the removal of from one to four or five teeth, and perhaps more — the main essential in operating by the aid of nitrous oxid being to utilize every second of time during the period of anesthesia, and not to waste it in hunting forceps or deciding how they should be used. The best success is obtained by formulating a system of working by which one can accomplish the most in the shortest space of time. The operating period seldom extends over forty-five seconds and often less, so that every second wasted in any way whatever is so much time lost, and success is diminished to just that extent. Nitrous oxid must be absolutely pure, and if be kept over water it 621 622 EXTRACTION OF TEETH UNDER NITROUS OXID. must be fresh. In former times when the dentist manufactured his own gas, to insure perfect purity it was necessary to test the ammonia nitrate before using it for making the nitrous oxid, but at the present day the pure gas is made with great accuracy by the manufacturers and is supplied chemically pure, compressed in cylinders, so that the individ- ual dentist is relieved of the responsibility of manufacturing his own gas and of the troubles necessary to secure purity. The first essential to success in its administration is a perfect inhaler. This should be sufficiently large to permit the patient to breathe without the slightest exertion. Patients are always in a more or less nervous state upon approaching the dental chair for extraction. There is usually accelerated heart-beat and consequently deranged respiration, and unless they can breathe through the inhaler with per- fect freedom they labor under a sense of suffocation which adds greatly to their apprehension and disturbs their equanimity while passing under the influence of the anesthetic. The inhaler shown in Fig. 560 is perhaps the best one upon the market, but has the disadvantage of having hard disk valves, and while the size is sufficiently large for most purposes the space between the outer circumference of the disk and the inner circle of the pipe is so small that it does not at all times permit of free ingress of the gas to the lungs, and, besides, such valves are not always airtight. The best inhaler is one made of vulcanized rubber turned to the proper dimension and fitted with valves made of rubber dam (Fig. 566). These valves have the property of fitting closely, making the Fig. 566. Thomas's inhaler. passages airtight, and being flexible they admit the gas to the lungs with little or no obstruction. This inhaler is the one employed by ADMINISTRATION OF NITROUS OXID. 623 most operators who make a specialty of extraction, and is made only upon special order. In giving nitrous oxid it is necessary that the valves of the inhaler shall be airtight, for if there is a leakage by which air is constantly being admitted, it will interfere greatly with the production of the desired results. The hood face-piece should never be used. Aside from the impossibility of fitting the face so closely as to preclude the admis- sion of some air during the administration, particularly when beard exists, it covers the lips from view, and these are an important index during the process of anesthesia ; the color of the blood as shown through the mucous membrane of the lips should never be lost to sight. There is no separation of the elements of nitrous oxid at the tem- perature of the human body, or during its inhalation, consequently it is practically an inert gas so far as its power to support life is con- cerned. It possesses strong anesthetic properties but it is also to a degree productive of asphyxia, and the color of the lips must be ob- served as a guide to indicate the extent to which asphyxia is taking place. It has been previously said that the valves of the inhaler must be airtight, for a constant leakage of air will prevent the production of complete anesthesia, and yet at the proper time during the inhala- tion the admission of air, controlled by opening the nose or raising the lips, is not only desirable but essential to the proper and successful ex- hibition of the anesthetic. By the judicious admission of air at the proper time the accompany- ing symptoms of approaching asphyxia are obviated and perfect anes- thesia is secured without any of the convulsive muscular twitching which takes place when the pure gas is given. Dr. Hewitt of London advocates the admixture of oxygen with nitrous oxid, for which he has introduced the appliances described on p. 617, but by admitting air as here suggested similar results are obtained with less manipulation. The use of props to keep the jaws open is necessary to insure success. They give free scope for operating, and there is no time lost in prying the mouth open, as nearly always happens when props are not used. Props made of hard wood and of different sizes are the most satisfactory ; they should have strings attached, more to reassure the patient than for any other reason. Unfortunately, a number of years ago a patient died as a result of getting a cork in the larynx, and this has never been forgotten. Consequently the string is an assurance to the patient that the prop cannot slip down the throat. The ordinary dental chair is not desirable for use in administering nitrous oxid, particularly those chairs having stationary footstools at- tached. Patients are sometimes restless, and every motion made by the 624 EXTRACTION OF TEETH UNDER NITROUS OXID. feet upon a fixed footstool will produce a responsive movement of the body, thereby increasing the risk of accident to the part being operated upon. A detached stool upon casters is easily pushed away, so that any disposition to move the extremities may be permitted without affecting the stability of the upper part of the body. This apparent resistance on the part of the patient is not necessarily the indication of a knowledge of what is being done ; the upper brain function may be paralyzed while the sensory peripherals and motor ganglia are not, under which circumstances the patient is not thoroughly anesthetized. Resistance may take place at the beginning or just at the termination of the anesthetic procedure, and if the operator ceases at once the patient will declare absolute unconsciousness of the operation. It is, however, sometimes permissible to operate during the stage just noted in cases where the systemic conditions are such that it would be unwise to carry the patient to the state of profound insensibility. These are, however, exceptions and not the rule. To have the exhibition per- fectly satisfactory there should be no resistance or outcry. A competent assistant is necessary, not only as a protection against charges which might be suggested by lascivious dreams — as has occurred when ether has been employed (though the period of insensibility under nitrous oxid is so short that it would seem that no one, however evilly or honestly disposed, could ever sustain such a charge) — but an assist- ant can render much aid by holding the tube, lowering or raising the head, taking care that the operator does not bruise the lips, holding the patient if restless, particularly the hands, and waiting upon the patient during recovery from the anesthetic. The assistant should be a woman, as it adds very materially to the comfort of female patients to have such a person in attendance. The operator should receive the patient in such a manner as to inspire entire confidence. If necessary, any doubts or possibilities of accident should be clearly explained to the patient, so that in the event of untoward results there will not be a humiliating sense of failure. The patient is seated, and after a careful examination has been made and the condition of the tooth or teeth is ascertained, the prop is placed where it will be least in the way. The assistant then places the tube in the mouth and the patient is directed to close the lips and breathe through the mouth instead of the nose ; in the meantime closing the nostrils with the third finger and thumb of the left hand, the first and second pressing the upper lip about the mouthpiece, while the thumb and fingers of the right hand support the lower lip. While inhaling the gas it is desirable that patients should breathe as in ordinary respiration, for two reasons : First, if instructed to take long and deep breaths they exert themselves beyond their natural THE OPERATION OF EXTRACTION. 625 rhythm, and with unconsciousness comes involuntary suspension for some seconds, and should it occur in one who becomes quickly asphyxiated the few seconds of suspension are sufficient to produce alarming symp- toms which will require some effort to counteract. Second, if the patient breathe slower or less deeply than is natural there is a sense of suffocation produced which grows in intensity until unconscious- ness supervenes, when the lungs and diaphragm will exert their func- tion, producing violent respiratory effort which will be followed by marked exhaustion upon recovery. None of these effects need be produced if the operator have complete control of the situation. No one can explain the symptoms of approaching and complete anesthesia in such a manner as will inform a novice sufficiently well to undertake the responsibility of administering the gas ; these can only be learned through observation and experience, but the first prominent indication will be a discoloring of the lips and subsequent pallor of countenance, which is not, however, an indication of cardiac depres- sion, but is due to the blood color shown through the skin. Should the patient be of the blonde and florid type this appearance will be more marked, and it is here that the admission of a small amount of air is called for, particularly if the blueness seems to approach more rapidly than the anesthesia. If the pure gas is given to complete narcosis, there will be twitching of the muscles of the neck and wrists. Stertor and irregular breathing and sometimes decided convulsive action occur, which to one inexperi- enced becomes distressing, if not alarming, to behold. All these symptoms are at once relieved by air-breathing, and if there is a judicious admission of air during the administration of the anesthetic they will be avoided entirely. The patient being anesthetized — and the instruments being always, in place so that there will be no delay in picking up the pair of forceps required, so that every second of time may be utilized by the work in hand — the next step is the extraction. The Operation of Extraction. — The proper way to perform the operation is to stand in one position, at the right side of the patient, during the whole proceeding. For extracting with the greatest facility the operator should assume such a position that in standing erect the patient's head will be about opposite his upper waistcoat pocket. To do this a pair of stools should be used, one just back of the chair and oue by the side which may be easily pushed aside when not needed. While administering, the operator can stand upon the floor, and ascend the stool just before the time for operating. This position is assumed by the most successful operating specialists, and is adopted as the result 40 626 EXTRACTION OF TEETH UNDER NITROUS OXID. of long experience and dictated by the desire to bring about a position for work which permits of its most rapid performance and at the same time enables the operator to bring to bear the greatest amount of force with the least physical exertion. When extracting, for example, a lower tooth, and it is necessary to force the beaks of the forceps well down through the process, the instrument is manipulated by the hand and wrist with the arm held closely to the body to steady it. The weight of the body is allowed to descend to the proper degree by bending the knees, and when the for- ceps are fixed, should force for pulling be required, the straightening of the knees will raise the body, the arm being held firmly as described. The hand will be used exclusively for manipulating and guiding, while the force will be supplied by straightening the knees much the same as is applied in lifting weight from the ground. Of course, to become expert one must have all of his limbs equally trained. In operating on the upper jaw the method is much the same, only reversed, bending the knees first to lower the body and forcing the instrument to position by straightening and throwing as much of the bodily weight upon the arm, by bending the knees, as is necessary for pulling. By so doing a tooth will never be allowed to leave the socket suddenly as by a jerk, for the operator has perfect control of his hand and wrist, and the danger of bruising the opposite teeth in either jaw by the forceps is avoided. The Forceps. — Seven pairs of forceps are all that are used by the writer for extraction in ordinary cases. For the upper teeth, a right and left pair for the molars, a bayonet-shaped instrument with the outer beak pointed to fit between the buccal roots, and both beaks serrated. In working upon both sides of the mouth a pair without pointed beaks may be used with advantage to avoid changing. One alveolar pair suffices for the roots of all molars and bicuspids on either side. These are made bayonet-shaped with smooth concave beaks, but having well sharpened edges. The pair for the incisors is straight, with beaks simi- lar to the alveolar pair, and when extracting, say all the upper teeth, can be used upon all ten front ones with equal facility. For teeth in the lower jaw the molar pair is made with both beaks pointed, serrated, and gracefully curved so as to bring the force as nearly direct as possible; these are equally applicable for all the molars on either side and are shaped the same as the alveolar pair. The alveolar pair are shaped the same as those for the molars, have smooth concave beaks with sharp edges, and are used for all molar roots and bicuspids (Fig. 567). The pair for front teeth is curved under the handle and may have serrated beaks, as the roots of the lower centrals and laterals THE OPERATION OF EXTRACTION. 627 Fig. 567. are so flat that a sharp beak is apt to cut them off, if too much grasp is applied. They seldom require the force necessary the extraction of other teeth. The writer prefers forceps that are not nickel-plated, as this imparts a slippery or " greasy " feeling to the handle, making the hold less secure, which induces an increase of force in the operator's grasp, with greater liability of cutting or crushing the teeth. With forceps having beaks that are not serrated, teeth having conical tapering roots will prevent the perfect fitting of the cutting edge ; these will sometimes slip through the posterior opening of the upper or lower alveolar pairs with great force. The writer has seen, in one instance, a tooth slip through the beaks of an unserrated pair of for- ceps and break a pane of glass in front of the chair, and an under single molar root which shot up with sufficient velocity to penetrate the soft palate. In extracting, particularly under nitrous oxid, no instrument should be used which will not securely retain any tooth or root until it is safely placed outside the mouth. Elevators are wholly out of place when work- ing under an anesthetic. They permit no control of the root or tooth whatever, and the liability of a tooth slipping into the throat under such circumstances is too great to warrant the risk. The art or " knack " of extract- ing does not consist of giving a rotary motion to one kind of tooth and a lateral or " in-and-out motion " to another, but rather of " working " the tooth in the socket without any pulling until it is started or loosened from its at- tachment, when the pulling force may be applied, and to do this the forceps must be placed upon a tooth so nicely that the tooth and Alveolar forceps. instrument will feel to the hand 628 EXTRACTION OF TEETH UNDER NITROUS OXID. as one continuous object, so that the slightest motion in any direction will have immediate effect in " starting " the tooth. The operation is completed by continued working while the pulling is applied in the direction which will prove the most effective in dislodgment. This " working " should be done with as little motion as is possible, for the smallest degree of straining upon the process laterally only adds so much more distention to the alveolar plates, and increases the inflammation and pain after the operation. When nitrous oxid was first introduced and extracting was transferred to those who made it a specialty, it was noticed that there was less soreness of the mouth follow- ing the operation, and it was thought by some that the oxygen of the gas produced a beneficial effect upon the blood which caused better healing, but such is not the case. The object, in extracting, of one who becomes expert by constant practice is to save the surrounding parts from all unnecessary strain, consequently less pain and soreness follows the operation. There are teeth having curved and divergent roots, and cases of exostosis, which will require great effort to remove, but even in these the position as- sumed and the process of "working" the tooth in the direction of the force applied all tend to accomplish the result with less injury than would be otherwise produced. In this way the breaking of a tooth need seldom occur unless inten- tionally. If in extracting an upper or lower molar one finds by the extra amount of force required that it will not readily yield, then it is better to break the crown off and with the sharp alveolar forceps remove the roots separately. This can be done with less injury to the alveolar plates than if much greater force were applied to remove the tooth as a whole. There will be cases of fracture of points of roots which are much curved or divergent, but many of these retained fragments may be per- mitted to remain until in the process of exfoliation they come to the surface if their retention is regarded as likely to give rise to less trouble than the injury incident to their removal would cause. But these need rarely occur if the operator has by experience acquired that sense of feeling which tells him at once the direction of the curve or the size of the exostosis. Inverted or impacted third molars are the most difficult cases which present themselves for extraction. Instead of being surrounded by pliable process they are planted in compact bone at the angle of the jaw, bound in by the second molar in front and hard bone on the buccal side, so that above it in the angle is the only direction offered for removal, working them toward the tongue where the bone is thinnest. THE OPERATION OF EXTRACTION. 629 In addition to the difficulty in removing these teeth, this severe process of pressing the inner alveolar plate toward the tongue excites a state of inflammation, easily communicated to the soft tissues of the throat, and the after-effects assume in many cases such serious condi- tions that it is better practice to remove the second molar. If the third molar is sound it may remain and will cause no further trouble, as the primary difficulty was caused by crowding and pressing upon the second molar ; and should it be necessary, from decay, to re- move it, the extraction of the second molar first, renders the operation simple and easy of accomplishment. CHAPTER XXI. (Concluded). LOCAL ANESTHETICS AND TOOTH EXTRACTION. By Henry H. Btjrchard, M. D., D. D. S. Prior to the discovery and application of cocain, the local anes- thetics employed to produce a condition of analgesia of the structures surrounding a tooth to be extracted were sprays of extremely volatile substances. Through the rapid evaporation of a spray of one of the lighter hydrocarbons, a condition of refrigeration of tissues was brought about during which a tooth could be extracted painlessly. Sprays of rhigolene and of ethylic ether have been superseded by those of ethyl and of methyl chlorid, these substances being more volatile ; directed in a fine spray over the gum of the tooth to be extracted, an intense local anemia is produced, and as a consequence analgesia results. If the refrigeration be rapidly produced and the operation be performed promptly upon the attaining of analgesia, the frozen tissues recover with but slight reaction. It is to be remembered that the tissues are frozen, and if the action be prolonged a condition akin to chilblain is present. The mode of application is as follows: All of the mucous membrane, except that over the roots of the doomed tooth, is to be pro- tected from the spray by means of napkins. The spray is directed against the exposed gum, the vial containing the ethyl chlorid being held about a foot from the mouth. When the gum becomes intensely anemic, indicated by pronounced whiteness, the tooth is to be extracted. Ethyl chlorid must be kept in a cool place, and far from any flame ; it is inflammable and explosive. Preparations containing cocain (benzoyl-methyl-ecgonin) have to a great extent superseded all other local anesthetics employed for this purpose. It was clearly shown soon after the introduction of this alkaloid that its local anesthetic action when applied to the gums did not extend beyond the depth of the mucous membrane, so that its epi- dermic application does not render the operation of tooth extraction painless. The hypodermatic application was found to render the tissues infiltrated perfectly analgesic. A recklessness was evinced in its use after this method which was promptly followed by repeated disasters ; 631 632 LOCAL ANESTHETICS AND TOOTH EXTRACTION. a formidable list of casualties grew. Reports of cases of respiratory and of cardiac paralysis following its employment were not uncommon. It apparently needed disaster to demonstrate that cocain belonged in the category of actively poisonous alkaloids, being by no means the bland and safe agent many operators seemed to think it. This lesson, learned at great cost, is one the operator is ever to heed, particularly in the hypodermatic employment of the agent. Dr. M. H. Cryer has re- ported l cases of ascending degeneration of the trunks of the maxillary nerves following upon cocain injections about the jaws. For the origin, composition, physiological effects, and toxicology of the drug the student is referred to the standard works upon materia medica. There are several points, however, which cannot be over- emphasized, the first being in regard to the drug itself. A full dose of cocain hydrochlorid by the stomach is about gr. f . The composition of the commercial specimens is not constant ; some of them appear to contain the actively poisonous alkaloid isatropylcocain. A safe dose when applied hypodermatically is not in excess of gr. \. The lethal effect of cocain is upon the respiratory centre. Its absorption is followed by a stimulation of the cardiac and respira- tory functions, which is commonly followed by a reaction, the stimu- lation giving way to depression. Idiosyncrasies as to the effects of cocain are common ; cases of susceptible women have been noted in which gr. \ produced toxic effects. It is to be noted that the depres- sion following as a secondary effect upon the primary stimulation may not occur for an hour or later. In prescribing cocain for hypodermatic injection, the analgesic is the first element to be considered in the prescription. The dose is not to exceed gr. -J-. The second factor demanding attention is a physio- logical antidote, one which will not neutralize the analgesic effect and yet will prevent the toxic action of the cocain upon the cardiac and respiratory functions. Morphin is that agent. As its full physiological effect is not required, a small dose, gr. -^ will be sufficient. The next ingredient of the prescription is an agent which shall prevent abrupt spastic contraction of the arteries and heart. Trinitrin is this agent. One drop of the 1 per cent, solution is the indicated dose. Fungi develop freely in solutions of cocain, so that if the pre- scription is to be a permanent solution, an antiseptic is required to prevent decomposition. Cinnamic alcohol answers well for this pur- pose. One drop of carbolic acid to each half-grain of cocain is an efficient antiseptic. By boiling cocain is split up into methyl, benzoic acid, and ecgonin, so that cocain solutions cannot be sterilized by boiling. 1 Proa. Academy of Stomatology, Philadelphia, 1896. COCAIN. 633 The dose commonly employed of the l'fi components of the prescription in Ify. Cocainse hydrochloride g r - i } Morphinse sulph., g r - A; or Atropine sulph., g r -TTo; Trinitrin. (1 per cent, sol.), gtt. j ; Acid, carbolic, gtt. j ; Aquse, q- s. 3ss. — M. S. The above represents a half-syringeful and is a full dose. This solution has been employed with general success, provided strict antiseptic precautions have been taken. Untoward results are occasionally found even with this seemingly safe formula. In the hypodermatic use of cocain the relatively safe maximum dose should never be exceeded and the exact amount administered in a given case always definitely known. A common error has been the dependence upon solutions of a given percentage composition. The danger of such dependence becomes evident when it is considered that the safe maxi- mum dose of cocain salt may be easily exceeded by the use of a sufficient quantity of a low-percentage solution, while on the other hand it is quite possible to keep within the limits of safety by using minute quantities of a high-percentage solution. The supposed harmlessness of a dilute cocain solution is erroneous and misleading unless the factor of the absolute quantity of the drug contained in a given amount of solution is constantly kept in mind. A method which is in all respects safer and which enables the oper- ator at all times to know the exact amount of cocain salt injected is to make the solution upon the basis of eight grains of the salt to one ounce of the menstruum, which will give one grain in each drachm and -^ of a grain in each minim. Of such a solution from five to eight minims may be injected about a tooth with a reasonable degree of assurance that the safe limits of physiological effect have not been exceeded. The menstruum in which these ingredients are combined is an inter- esting feature. It has been repeatedly shown that the injection of a quantity of water will produce anesthesia of a region. The nerve fila- ments are compressed by the fluid and do not transmit painful impres- sions. Dr. Schleich of Greifswald l follows, for the induction of local anes- thesia for operations in general surgery, an infiltration method. The injection is divided and the punctures made seriatim about the territory to be operated upon. The remarkable feature of his procedure is the minute dose employed. He uses a 1 : 4000 solution of cocain, to which 1 T. Parvin, Proc. Phila. Co. Med. Soc, Nov. 13, 1895. 634 LOCAL ANESTHETICS AND TOOTH EXTRACTION. is added }of 1 per cent, sodium chlorid and a small quantity of 4 per cent, tricresol. One syringeful, about a drachm, is sufficient to infil- trate the tissues about a tooth and render its extraction painless. A drachm of the 1 : 4000 solution contains about gr. T ^- of cocain. The strongest solution employed by Schleich is a 1 : 500. A drachm of such a solution would contain less than gr. \ of cocain. Dr. W. F. Litch (ibid.) has pointed out that low-percentage solutions will give a safer result than those of high percentage, even though the absolute amount of the drag should be the same. It is seen, therefore, that the quan- tity of menstruum in which the dose of cocain is suspended is an im- portant consideration. Tablets for making Schleich' s solutions may be had of pharmaceu- tists. Tablets for making the strong solution contain — 1^. Cocainse hydrochl., g r -i> Morphinse hydrochl., gr. -^ ; Sodii chlorid., gr. ^-. S. Dissolve in Ttl 100 of distilled water. Prof. E. Sauvez 1 records 15,000 injections of cocain for local anes- thesia in tooth extraction without accident, and quotes a record of 7000 cases of cocain anesthesia by Prof. Reclus with entire success. Sauvez recommends the use of not over 1 c.c. of a 1 per cent, solution of cocain hydrochlorid in distilled water. This amount may be injected safely with the patient in the sitting posture, and without danger of syncope. When more than 1 centigram (.154 grain) is in- jected the patient should be recumbent. Stovaine is the designation of a new local anesthetic recently discov- ered by M. Forneau, and is said to possess certain advantages over cocain. According to Sauvez, it is not more than one-half as toxic as cocain, and possesses a vaso-dilator action instead of the vaso-constrictor action of cocain. It is equal in anesthetic property to cocain and less costly. Sauvez has used it in 100 cases, in doses of 1 c.c. of a .75 : 100 solution. Almost without exception the nostrums advertised and sold under high-sounding titles, for employment in this field, contain cocain. Neither their names nor any information vouchsafed by their venders give any indication of the amount of alkaloid present, and so all of them should be tabooed. It is nothing short of criminal to employ these nostrums without a knowledge of their exact composition. Tropacocain (benzoyl pseudo-tropin) has been employed to render 1 " A Study of the Best Means of Local Anesthesia for the Extraction of Teeth," by Dr. E. Sauvez, Proceedings Fourth International Dental Congress. SCHLEICH'S SOLUTIONS. 635 the operation of tooth extraction painless. It possesses decided advan- tages over cocain. It is only one-half as toxic • has but slightly de- pressant action upon the cardiac ganglia ; has no paralyzant action upon the respiration ; anesthesia is more quickly produced, and its solutions are slightly antiseptic. Solutions of the drug are made in distilled water ; the full dose is gr. ^ to f. The reader, of course, at once draws the correct inference that Schleich/s method gives promise of safety. Applications made hypo- dermatically of the elaborated prescription presented are not without danger even in physiological dose. It is necessary that the field of operation be made aseptic before injection. The mouth should be washed repeatedly w T ith a powerful antiseptic, 3 per cent, pyrozone, 10 per cent, electr ozone, or 3 per cent, formaldehyd solution. The syringe should be aseptic ; repeated washing of syringe and points in a 25 per cent, solution of phenol sodique will serve this end without detriment to the syringe piston or the metallic parts of the syringe. A syringe having stout finger-rests and holding one drachm is employed. The needles should be reinforced for half their length, and should have sharp, fine points. The gum is to be dried and touched with a 20 per cent, solution of cocain ; in five minutes the needle may be inserted painlessly. The syringe is filled with the analgesic solution, the needle screwed on, and the piston pressed down until all air is expelled from the syringe and needle. The latter is now thrust into the gum about midway between the neck of the tooth and the apex of the root, until it comes in contact with the alveolar process, when it is slightly withdrawn and a few drops of the solution are driven into the tissues. A second injection is made over the apex of the root ; if the strong solutions be used, the amount of fluid injected must not contain more than gr. ^ of cocain ; even though several punctures be made. Care must be exercised to confine the injection to the tissues of the gum ; if the submucous tissue beneath the junction of the cheek and gum be injected into, alarming emphysema may result. For multirooted teeth an injection is made over each root. If Schleich's solution be employed, a full drachm of fluid should be in- jected, until the gum over the tooth is tense and white, when extrac- tion may be accomplished painlessly. In some instances the intense anemia present at the moment of extraction may be succeeded by local hemorrhage as soon as reaction is established. An antiseptic hemostatic should be applied to the alveolus after extraction ; phenol sodique, full strength, is an admirable agent for this purpose. 636 LOCAL ANESTHETICS AND TOOTH EXTRACTION. The imminent dangers to be feared in this connection are : first, the toxic effects of the drug. As these are usually manifested in contrac- tion of the bloodvessels the antidote is amyl nitrite. A supply of pearls each containing TH iij of amyl nitrite should be kept in the medicine cabinet. When a patient exhibits great pallor, a small pulse, and bluish- white lips, one of these pearls is crushed in a napkin and the nitrite quickly inhaled. The conjoint administration of gtt. xx. aromatic spirits of ammonia, or about half an ounce of brandy, is advised. Should these measures not prove promptly effective, artificial respiration should be immediately begun and be prosecuted vigorously. The second danger is septic infection, either through imperfectly sterilized instruments or by carrying septic organisms from the mucous membrane covering the gum into the deeper tissues during the opera- tion of injection. This is avoided by a careful sterilization of the syringe before it is used, and the repeated applications of antiseptic mouth-washes previous to injection. Prescriptions which contain a large percentage of carbolic acid are liable to cause sloughing. Injections forced between the periosteum and bone may produce serious injury. The introduction of eucain as a local anesthetic was due to the observed chemical similarity of that synthetic body with cocain ; an instance of presaging the physiological effects of a drug by its chemical composition. Its local effect upon bloodvessels is to produce hyper- emia, instead of the ischemia induced by cocain. It is less poisonous than cocain and its solutions are chemically more stable. Its primary action upon the central nervous system is one of exaltation, and this is followed by paralysis, the effect being central, not ascending. The sedative central influence causes a quickening of the heart-beats through sedation of the inhibitory (pneumogastric) nerves. Although eucain is less toxic than cocain it also produces a greater degree of analgesia ; so that the dose need not be greater than that of cocain, about \ to f of a grain being the maximum. Eucain may be kept in permanent and stable solution in distilled water. A 10 per cent, solution may be made in distilled water (48 grains of eucain hydrochlorid to the ounce of distilled water) and the solution sterilized by boiling, which does not decompose eucain. From five to eight minims of such a solution is a proper dose. The precau- tions to be observed and the mode of application are the same as for cocain. Besides the dangers arising from the hypodermatic administration of a physiological overdose of this class of analgesic drugs, and the local danger of infection from non-sterile solutions or instruments, there is to be strongly emphasized the danger of local necrosis due to the poisonous SCHLEICWS SOLUTIONS. 637 effect of the drugs themselves upon the tissue elements when directly injected. In nearly all cases in which extraction is sought the tissues about the tooth are in a condition of lowered vitality, brought about by the local toxemia resulting from the infection which has produced the inflammatory process. The injection of a protoplasmic poison, such as cocain, eucain, and their congeners, into the inflamed territory causes a still further depression of vital resistance, which, if sufficiently pro- nounced, may become total and permanent. Hence, tissue-death or necrosis, with subsequent sloughing, will necessarily result. Where the inflammatory process about a tooth is at all pronounced, it is much wiser to discard local anesthetic methods for the far safer procedure of general anesthesia induced by nitrous oxid or ether. CHAPTER XXII. PLANTATION OF TEETH. By Louis Ottofy, D. D. S. The tkansplantation of a tooth signifies the insertion of a nat- ural tooth into a natural alveolus other than the one it originally occu- pied. The tooth may be an old and dry specimen transplanted into an alveolus from which a tooth has been recently removed, or it may be a freshly extracted tooth transplanted from one part of the mouth of an individual to another part of the mouth of the same individual, or it may be a freshly extracted tooth transplanted from the mouth of one person into that of another. Replantation signifies the replacing of a tooth in the alveolus whence it had been removed by design or accident. The operation may be performed at once or at any time before the socket is filled with new tissue. Under the term implantation are included all those operations which involve the formation of an artificial alveolus for the reception of the root of a human tooth. The operation of altering the size or form of an existing alveolus to receive a tooth belongs to this class, although it is a combination of trans- and implantation. The operation of replantation probably far antedated that of trans- plantation, as the latter preceded implantation, but its definite history is unknown. It is safe to presume that it has been practiced ever since mankind conceived of the natural healing power of the body. Even when performed with crudity and without any clear comprehension of the mode of repair, favorable results have been reported. The ope- ration is at present an uncommon one : the condition for the relief of which it was at one time practiced with comparative frequency, chronic alveolar abscess, has been found amenable to less radical treatment. The operation of transplantation is first noted in the writings of Ambroise Pare in the sixteenth century, though credit has generally been given to Dr. John Hunter, who gave the subject considerable attention. Hunter's experiment of implanting a tooth in the comb of a cock is classical. The records of the operation do not exhibit any 6r9 640 PLANTATION OF TEETH. great measure of success attending it. Hunter noted cases of trans- plantation of dead teeth which remained for years. No one disputes with Dr. Younger of San Francisco the authorship of the operation of implantation. The date of his first operation was June 15, 1885, although Bourdet in 1780 was the first to mention the operation, stating that " irresponsible persons claim to make a socket, and implant into it a tooth." An attempt at partial implantation is recorded in Dental Cosmos, vol. xix. p. 258. In order that an intelligent conception may be had of the intimate nature of the biological conditions which surround the teeth after inser- tion by either of these operations, it is essential to study the general Fig. 568. Fig. 569. 15 1 A tooth and its normal attachment and vascular supply : 1, 1, Apical pericementum in which is seen the main pericemental artery, 5 .; 2, 2, anastomosing bloodvessels or channels of the alveolar walls ; 3, 3, the marginal anasto- mosis of alveolar and pericemental arteries. Conditions following replantation: 1, 1', The pericementum and inflammatory effusion between pericementum and alveolar walls ; 2, 2, source of blood-supply to the area of repair ; 3, 3, terminations of alveo- lar arteries ; 5, obliterated apical artery. processes which attend the repair of tissues, and their behavior toward foreign bodies. As all of these operations are performed under the strictest antiseptic precautions, the consideration of bacterial influence is omitted at this juncture. As it is impossible to secure specimens which would show these several parts in their true relations, the illustrations are neces- sarily diagrammatic and theoretical. 1 Figs. 568-571 are from drawings by Dr. H. H. Burchard. BIOLOGICAL CONDITIONS IN PLANTATION 641 Fig. 568 exhibits a longitudinal section of an incisor, its attachments and support, together with its vascular supply, in its normal relations, the bloodvessels from the pericementum anastomosing with those of the alveolar periosteum. The pericemental space is filled with fibrous tissue. To avoid confusion the nerves and veins have been omitted. Fig. 569 represents the conditions following replantation. The tooth has been sterilized and its pulp canal hermetically sealed. The perice- mental bloodvessels have been destroyed in extraction. Portions of the pericementum are seen clinging as fibrous remnants to the cemen- tum. The remainder of the alveolus is filled with inflammatory corpus- Fig. 570. Fig. 571. Conditions following transplantation : 1,1', Embryonic tissue which will be organ- ized into repair tissue replacing the original pericementum ; 5, obliterated apical vessels. Conditions following implantation : 1, 1, Alveo- lar arteries ; 2, 2, gingival margin ; 3, inflam- matory still unorganized tissue filling the space between the cementum and walls of the artificial alveolus ; 4, 4, phagocytes, mul- tinucleated cells attacking cementum of im- planted tooth ; 5, obliterated apical vessels. cles. The vascular supply to the regenerated pseudo-pericementum is derived first from the vessels of the alveolar periosteum via the alveolar process. Fig. 570 shows the conditions existing soon after the operation of transplantation. The mechanical violence of extraction has irregularly enlarged the natural alveolus. The tooth, its apex rounded, is shown with the blunted extremity. The vascular supply is similar to that of Fig. 569. The alveolar space is filled with inflammatory corpuscles. 41 642 PLANTATION OF TEETH. Fig. 571 exhibits the conditions probably existent soon after an im- plantation operation. The vascular supply is the same as shown in Figs. 569 and 570. Instead of having a layer of periosteal bone, the for- mation of the artificial alveolus is into the spongy medullary bone. The artificial alveolus, being necessarily different in size and outline from the tooth, is filled with inflammatory products. Some of the cells, becoming multi-nucleated, are seen to be exercising their phagocytic — or, in this connection, resorptive — function upon the cementum. Replantation and Transplantation. Replantation. — In the present state of dental practice the following conditions may be regarded as warranting replantation : (1) When a tooth has been dislodged by traumatism, a blow by a ball, club, or fall, etc. (2) When a. tooth has been accidentally removed by the slipping of the forceps during the performance of a dental extraction. (3) When some disease, otherwise incurable, affects either the root or some portion of its alveolus. The first two causes are practically the most frequent under which replantation is justifiable. In case a tooth has thus been dislodged and found, it should at once be cleansed of all foreign matter and then be carefully examined for fractures or other injury. Any cavities present should be filled, the contents of the root canal removed, and the space filled in the manner described later ; fractured or abraded portions or surfaces are to be made smooth, and the tooth placed in an antiseptic solution. A careful ex- amination of the socket should then be made. It will be noticed when the accident has befallen a young individual, that as a result of the flexibility of the bone, the alveolar process is seldom fractured — an accident more prone to happen in adult life. Some discrimination should be exercised as to the promptness with which to replant the tooth. If there is considerable inflammation as the result of injury, it is not advisable to immediately replace the tooth. In that event the socket should be made aseptic and if possible normal hemorrhage re-established. As a general rule several days should be allowed to intervene when the inflammation is excessive ; otherwise a tooth may be replaced at any time as soon as it has been prepared. The governing pathological principle is as follows : Immediately after an injury, a certain amount of inflammation takes place and there is retrograde metamorphosis — a destruction or breaking down of tissue ; and this is not the most favorable time to expect re-attachment to take place. As a rule, within a few days a building-up process, constructive REPLANTATION AND TRANSPLANTATION. 6±3 metamorphosis, has set in, and the replacement of a tooth at this time is likely to be followed by more favorable results. This period sets in at any time from three days to a week, the socket being then partially filled with active living cells. Just prior to the replacement of the tooth the socket and the gum surrounding it having been cleansed and sterilized, the tooth itself being brought forth from its antiseptic medium, it must be promptly replanted. As a rule, constant but not severe pressure will permit the tooth to assume its original position in the socket, although sometimes it is necessary to remove a part of the apex of the root or slightly deepen the socket by means of a suitably shaped bur. It hap- pens occasionally that the location of the tooth and the general surround- ings are such that a tooth like this may be retained without any further attachment, but as a rule it is not safe to trust to uncertainties regarding the attachment of the tooth. An impression of the tooth and its neigh- bors can be quickly secured with Melotte's compound or in clay, a die is easily made, from which a cap, such as will be described, is quickly made. It is needless to dwell upon the second cause mentioned. No dentist can ever be excused for accidentally removing a sound tooth, but in case the accident does happen the above procedure is indicated. The opportunities enumerated under the third section are also, for- tunately, exceedingly rare. The cases in which formerly replantation was resorted to, on the ground that the case was incurable, are now much less frequently met with, and when they are encountered they often yield to treatment, which is now more clearly understood — such as amputation of the root, removal of the necrosed portion of the alveolar process, etc. When, however, it has been decided to extract a diseased tooth and to replant it, diseased portions of the root should be removed and a sufficient time allowed to elapse before replantation for the socket and tissues to have assumed a healthy aspect, even if this should necessitate the enlargement of the socket. In cases of pyorrhea alveolaris, which sometimes has been suggested as coming under this class, treatment by replantation is out of the ques- tion, provided the case has made sufficient progress to suggest such a course. Replantation implies the presence of a socket, and when pyorrhea alveolaris has made any great degree of progress, the socket is wanting. Hence it is but in rare cases that an attempt to cure by this method is justifiable. Dr. Louis Jack 1 has recorded marked success in several cases at- tending an operation of modified replantation for the cure of some of the earlier phenomena of phagedenic pericementitis, notably the common malposition due to what has been termed voluntary tooth movement. 1 See Trans. Academy of Stomatology, 1895. 644 PLANTATION OF TEETH. Transplantation. — There is a broader range for the practice of transplantation than either of the other operations treated in this chapter. As has been seen, replantation is limited in its application, and implantation must, from the nature of the operation, be also con- fined to a comparatively circumscribed sphere. The operation may be performed at any period of an individual's life, although as a rule young, vigorous, and mature adult life offers the greatest promise of success. Any socket in any part of the mouth, when placed in a healthy condition, is a more or less favorable location for the reception of a tooth about to be transplanted. It is true that sometimes a socket needs to be enlarged or deepened for this purpose, but this is a comparatively simple matter. Before the advent of the intelligent practice of crown and bridge work, treatment of diseases of the pulp and peridental membrane, the bleaching of teeth, and the intelligent practice of orthodontia, transplantation was resorted to as a remedy for the correction of many trivial disorders. In the light of the present day, transplantation is confined to sockets whence teeth have been removed for any cause which could not be remedied by some other method of treatment : sockets which remain as the result of the loss of teeth from accident of any kind (the lost teeth not having been recovered) ; from which roots beyond salvation have been extracted ; from which diseased teeth must be removed ; from which roots have been removed having carried crowns or having served as abutments for bridges until their period of usefulness has passed. The same rule laid down for the care of a socket previous to re- plantation holds good for transplantation ; namely, that inflammation must be reduced, and the tooth transplanted into the socket at a time when progressive constructive metamorphosis is taking place. This period is stated as usually from three to seven days after the removal of the tooth. In instances where considerable disease, such as a chronic alveolar abscess of years' standing has been present, even a longer time should be allowed to intervene before transplantation. Preparation of Teeth for Plantation. With the exception of such special directions as are necessary in each class of the operations described in this chapter, the following general directions are applicable to all cases. The Scion Tooth. — For replantation a recently dislodged tooth is supposed to be at hand, hence there is a fresh tooth. For transplanta- tion it is implied that the tooth is either at hand or about to be secured, but in a case of transplantation or implantation the age of the tooth may be unknown and indefinite. Teeth have been planted whose age and origin have been absolutely unknown, and they have become firm PREPARATION OF TEETH FOR PLANTATION. 645 in their new locations. Nevertheless it seems reasonable to take the ground that whenever it is possible, teeth should be fresh and something of their previous environment should be known. There are no cases on record where disease has been transmitted through the medium of a planted tooth, although portions of the early literature of this subject do indicate such results. The principal objection to old and dry teeth is that, the water having been evaporated, these teeth are almost invaria- bly fractured or cracked from shrinkage. When these fractures extend to the crown portion, the enamel frequently chips off within a short time after the tooth has been planted ; while in some instances the entire root has been fractured. Another objection to teeth promiscu- ously gathered is that it is seldom possible to find teeth in which the crowns are sufficiently perfect to be serviceable and to be presentable in the mouth. The crown of a dry tooth permits of but slight altera- tion with the grinding stone or sandpaper disk without endangering its integrity ; while if it is affected by caries to such an extent as to require an extensive operation, the life of the filling is likely to be of shorter duration than a similar operation performed on a freshly extracted tooth or a tooth with living connections. For this reason it is preferable to use only the roots of teeth, attaching to them artificial crowns. This permits the selection of a crown suitable in size, color, and shape, and which may be ground for articulating purposes — an important matter in these cases. If therefore an old, dry tooth must be used, let it be carefully selected with regard to the absence of checks or cracks or fractures, and if it be impossible to secure a tooth with such a crown, let there be selected a good root to which a crown, as described later, can be attached. If a freshly extracted tooth can be secured, even though the crown may be slightly carious, the necessary filling operation is advisable, and such a tooth should be used, if possible. Root-filling-. — Roots may be filled either from the apex or through an opening or cavity in the crown. Gutta-percha seems to answer all the necessary purposes, but for a short distance from the apical extrem- ity it is well to fill with gold wire or foil. Pericementum. — The theory that the pericementum becomes revivi- fied does not seem to be tenable ; at least the proposition that life is maintained in the pericementum for any considerable period of time after the tooth has been removed from vital attachment is not in accord with general physiological laws, although periosteum as a tissue main- tains its vitality for a time after separation. 1 For the purpose of secur- ing an attachment there is no necessity for the presence of the perice*- 1 See Ziegler's General Pathology. 646 PLANTATION OF TEETH. mentum ; but it is reasonable to assume that the nearer to natural states the root and the socket are in, the more favorable will be the prognosis. It is therefore a safe rule to follow, to preserve as much of the perice- mentum as is possible. The preservation of the pericementum has an advantage from the fact that after the tooth has been planted, the peri- cementum under the influences of bodily heat and moisture expands and thus acts in the nature of a sponge graft, enabling the tissues to more quickly obliterate spaces which are present and to attach them- selves to the root. Subsequent Care of Planted Teeth. — Numerous methods for the retention of planted teeth have been recommended by various authors at different times. While many of them are original and ingenious, all are to be condemned except those means which look to the firm, rigid, immovable retention of the planted tooth for a definite period, that of surgical repair. Neither the rubber-dam splint, silk ligature, nor gold or other metal wire comes under this heading. Planted teeth must be retained immovably for a period of two to six weeks, occasionally from two to eight, ten, or twelve weeks. The shortest time of immobility consistent with subsequent attachment is preferable. The tooth to be transplanted or implanted should be fitted after preparation in a model, made from an impression of the gum where the tooth is to be planted and of the adjoining teeth, as shown in Fig. 572. An impression is then taken of it and of the adjoining teeth on each side. A retention cap is then swaged to cover the grinding surfaces of three or more teeth, half the length of the crown on the labial surface and nearly the full length on the lingual or palatal surface, as shown in Fig. 573. Fig. 573. Model showing prepared tooth in place : Model showing retention cap a, Gold filling at cervical joint. in situ. The cap may be made of pure gold, platinum, or German silver. The gauge, according to the metal used, should be from No. 32 to No. 38. This cap is cemented upon the crowns adjoining the planted tooth in such a manner that it may be removed without disturbing the PREPARATION OF TEETH FOR PLANTATION. 647 planted tooth. The operator can remove the cap by springing the metal away from the teeth, examine the condition of attachment of the planted tooth, and replace the cap if it should be necessary. Where the articulation interferes with the retention of the cap, the latter may be ligated to the adjoining teeth in addition to being cemented to them, and still admit of removal without disturbing the planted tooth. There is at present no method of ligaturing or banding the teeth which will permit removal of the ligature or band without more or less disturbance of the planted tooth. Aside from the necessity of immobility for a certain period, the planted tooth and surrounding tissue generally require but little atten- tion. In occasional cases the tissues may be stimulated, by painting the gum with a mixture of equal parts of tincture of aconite root, chloroform, and iodin paint (the latter is a saturated solution of iodin in alcohol), or by the use of stimulating mouth-washes, notably those containing capsicum. The patient should be cautioned to encourage the downward growth of the gum by the use of the toothbrush, to prevent the accumulation of remnants of food or saliva, and to pre- vent their subsequent putrefaction should particles become unavoidably lodged around the tooth or cap. This is best accomplished by using a cameFs-hair brush dipped in hydrogen dioxid or pyrozone, electrozone, meditrina, etc., washing out the interstices frequently. A syringe or spray from an atomizer may be used. Artificial Roots. — Experiments have been performed looking toward the use of roots other than those of natural teeth. Roots made of ivory, corrugated or perforated porcelain, lead, gold, platinum, and other metals have been used. The writer's experiments in this direc- tion have all resulted in failure. There is no recorded evidence that any have resulted successfully. Mode of Attachment. — As to the mode of attachment of planted teeth the subject is clouded in obscurity. From the nature of the con- ditions it is difficult to secure definite information. Dr. Younger holds to the belief that the pericementum becomes revivified and hence the attachment is almost physiological. Others maintain that the filling of the space around the root of the tooth with compact bone tissue is sufficient to account for the retention of the tooth. In the appear- ance of planted teeth which have failed there should be found the best illustrations of the causes of success. It is probable that a planted tooth, by reason of the absence of the cushion formed by the living pericementum, causes more or less irritation in the socket; that this irritation leads to resorption of the root; that in this resorption and the subsequent filling up of these rescrbed surfaces are found reasons for the success of the operation. Fig. 574, at a, a, shows how a par- 648 PLANTATION OF TEETH. tially resorbed root may be retained in place. The length of time during which a planted tooth is retained depends entirely upon the rapidity of the resorptive process and the activ- Fig. 574. ity of the tissues in maintaining a healthy con- dition. Replanted and transplanted teeth have been known to do good service for from twenty to forty years. The time of the observation as to implanted teeth is shorter, the oldest cases being less than twenty years old. In the writer's observations, extending over a period of nearly eighteen years, a number of teeth have been noted An implanted tooth in which have been retained successfully for ten situ: a, a, excavations of years; how much longer they will remain ser- the cementum due to re- . , -, -. , n .,, sorptive process. viceable, and what percentage of success will attend later cases, will require further time to determine. Dr. Younger has had successfully implanted teeth under observation, at last report, for eleven years. Precautions. — There is no special danger connected with any of the operations described in this chapter, provided the usual antiseptic pre- cautions are observed and dangerous anesthetics avoided. Aside from these, during the operation of replantation and transplantation no special skill is necessary ; certain precautions are, however, essential. Inasmuch as implantation is an essentially esthetic operation, it should be borne in mind that it is confined principally to the ten anterior teeth, and that it is more frequently performed in the upper jaw than in the lower. The territory involved is therefore limited. The operator who contemplates forming in this territory a socket for the reception of the root of a tooth should be intimately acquainted with the anatomical and histological relationships of the various parts. In the first place it should be remembered that where alveolar resorption has taken place, the relative depth of bone is considerably less than where a tooth is still in situ and surrounded by the normal alveolar process. The operator must therefore not penetrate deeper into the bone than the original depth of the socket may have been. Indeed, it is not as a rule necessary to penetrate so far. In the upper jaw the principal danger in making a socket for the reception of central incisors lies in the proximity, posteriorly, of the anterior palatine nerve, artery, and vein, which have their exit from the bone through its foramen, often near the roots of these teeth. With the lateral incisor the principal precaution necessary is the preservation of the labial plate of the alveolus. If the lost tooth has been absent for some time, and much resorption has taken place, it is sometimes im- possible to drill a socket so that the tooth has a proper direction and PREPARATION OF TEETH FOR PLANTATION. 649 prominence in the arch, and yet be able to secure a bone covering for its labial surface. As a rule there is sufficient process in the canine region to enable the operator to secure all the attachment desirable. The bicuspid and molar regions present the danger of perforation of the floor of the maxillary sinus. This is liable to happen anywhere from the first bicuspid to the second molar. Extreme caution should be ex- ercised to avoid it. In two instances in practice the perforation was fol- lowed by no unpleasant complications. Care was taken not to infect the sinus, the teeth were implanted in the usual manner, and the cases re- sulted successfully. Subsequently one of these teeth was lost, but dur- ing the process of root attachment or encystment the perforation into the sinus was closed. In the lower jaw the principal difficulties encountered are the follow- ing : In the incisive region there is a deficiency of alveolar process, and hence much difficulty is encountered, at times, in securing a sufficiently deep bony socket. At the location of the canine tooth the lower jaw becomes broader and there is usually sufficient room to enable the making of a good socket. In the premolar region the principal pre- caution necessary is in regard to the mental foramen. It must be borne in mind that normally the exit of the nerves and vessels at this point is directly below the second bicuspid tooth and that when resorption of the alveolar process has taken place this foramen is often near the upper border of the jaw. From this point posteriorly implantations are rarely performed, and when done the principal precaution must be in regard to the inferior dental canal, which is near the surface if much resorp- tion has taken place. Artificial Crowns. — The precautions necessary in the selection of a tooth for transplantation or implantation have been noted, and it might be proper at this time to describe the prepara- tion of a root with an artificial crown, presuming that it is only in rare instances that a suitable entire natural tooth can be obtained. Attention was called to the necessity of securing asepsis of the root, and the filling of the root-canals has been described. The most suitable form of crown has been found to be the Logan, which is ground to suit the occlusion and Natural root with , artihcial crown. cemented into the root canal without much regard as to a careful fit at the cervix of the crown to the root. After the cement has hardened, the margin between the root and crown is pre- pared with engine burs, and a filling of gold introduced, making a circle around the tooth. When this is polished down there is a perfect gold filling level with the root and crown, which is preferable to a soldered band. (See Fig. 575.) 650 PLANTATION OF TEETH. General Considerations. Asepsis. — The operations described in this chapter must always be performed under perfect aseptic conditions ; that is, the hands and person, instruments and other accessories, the tooth about to be planted, and the field of surgical operation, must be maintained in a clean, aseptic condition. Any of the usual, accepted methods can be resorted to. As a rule, however, the drugs selected for this purpose should not be of an irri- tating nature. For the hands and person, pure soap followed by a 5 per cent, solution of carbolic acid is sufficient. The instruments and other accessories can be kept free from inoculating bacteria by the use of pyrozone, formalin, euthymol, or a 5 per cent, solution of carbolic acid. The use of bichlorid of mercury in the proportion of 1 part to 2000 of water is also permissible, although it is not as advisable on account of its irritating nature. The sterilization of the tooth about to be planted differs according to circumstances. A tooth whose source is unknown, and which has been kept in a dry state for a long period, will not be benefited by being placed into an antiseptic solution until just prior to the time when it is to be used. Hence dry teeth can be kept in any clean box covered with clean cotton until they are ready for use. After the necessary preparation hereinafter described, the dry tooth should be placed in a solution of glycerol and carbolic acid (about 5 per cent, of the latter), and just before using, it can be placed in a pyrozone solu- tion or in a solution of carbolic acid and water. Freshly extracted teeth should, of course, have their pulp chambers and root canals cleansed and hermetically sealed, and then be placed at once in fluid, preferably in glycerol to which a few drops of carbolic acid have been added. Teeth and roots so treated have been preserved for eight years. The field of operation may be quickly sterilized and cleansed of adhering mucus by mopping the surface with a ball of cotton saturated with hydrogen dioxid 3 per cent, solution just previous to operating. It is, of course, of exceeding importance that the socket into which a tooth is about to be planted shall be free from disease germs or bacteria. As a general rule flowing blood is the best of antiseptics, washing away any bacteria which may become lodged from external sources, hence so long as a socket is constantly being filled with flow- ing blood during an operation, but little further care need be bestowed upon it. As a general rule the socket and the tissues surrounding it will react more quickly after operation the less the medication has been ; hence the very slightest and mildest of antiseptics are indicated. Zinc chlorid 2 to 5 grains to the ounce of lukewarm water, hydrogen dioxid 3 per cent., or the 5 per cent, solution of carbolic acid in lukewarm water, give most satisfactory results. These solutions will be found quite sufficient to maintain the field of surgical operation aseptic. GENERAL CONSIDERATIONS. 651 Anesthesia. — For the purpose of allaying pain, the use of anes- thetics is justified when imperatively demanded, but unfortunately, in the plantation of teeth the benefits derived are frequently outweighed by the disadvantages accruing from their use. Anesthetics are either general or local. An operator would scarcely be justified in assuming the risks attendant upon the use of chloroform, ethylic ether, ethyl bromid, or any of the combinations in which these anesthetics are administered. Nitrous oxid would, in the majority of instances, be contra-indicated by reason of the shortness of the period of anesthesia which it induces. There do not appear to be any records of satisfactory results with hypnosis. That field is open to the intelligent investigator whose inclinations lie in that direction. Local anesthesia, therefore, is the means generally employed. The use of cataphoresis with local anes- thetics has not as yet been satisfactory for this purpose. The method adopted has usually been confined to the injection or other introduction of cocain, the dose being variable, but usually about 5 to 15 minims of a 4 per cent, solution of the hydrochlorid. A seri- ous objection has been noted to injection through the gum, viz. that more or less sloughing or destruction of the tissues may result, and this is very unfavorable for subsequent success. In replantation or trans- plantation, sufficient anesthesia is often obtained from the wash used in cleansing the socket ; but in implantation the formation of the new socket is often an exceedingly painful operation, and in these cases good results may be had by dipping the instrument with which the socket is being made, into crystals of cocain, and thus by the friction of the instrument rubbing it into the parts that are being operated upon. The subject of anesthesia may be dismissed with the sole injunction that its use should be resorted to only in those instances where it is absolutely necessary. The majority of the cases of plantation are per- formed with no more pain than is inflicted in filling operations. The same care should be given to the retention of transplanted teeth as is given to the retention of replanted teeth. Teeth thus carefully transplanted, in individuals of good health, often remain as useful members for a number of years. In the past insufficient atten- tion has been given to asepsis, and this, coupled with the fact that the root had not always been properly filled, has not resulted in as much success as is attained with present methods, and yet transplanted teeth are known to have remained in a healthy and serviceable condition for from twenty to forty years. 652 PLANTATION OF TEETH. The Operation of Implantation. Implantation, in order to yield the best results, should be confined to mouths which are habitually clean and free from disease, and to a part of the individual's life during which the power of the developed mental processes is not impaired. Unclean personal habits, the ex- cessive use of stimulants, and occupations calling for an unusual ex- penditure of nerve force are unfavorable. A suitable case having been selected, an impression of the space and of the teeth adjoining it is taken. A plaster cast is made, the proper-sized socket drilled therein, the tooth is selected and prepared, either with or without an artificial crown in the manner previously described, the occlusion is adjusted, and a retention cap is made. These preliminaries having been satis- factorily accomplished the case is ready for the operation. Under the heading of General Considerations the question of anesthesia has been already treated. The first step in the operation is the making of an incision through the gum tissue. A number of different kinds of incisions have been recommended by different operators, nearly all of them looking toward the preservation of the largest amount of gum tissue. Some recom- mend a crucial incision X, turning back the four corners of the gum tissue. Others have recommended an incision in the shape of the letter H, turning back the two flaps thus made. The principal objection to all of the incisions recommended lies in the fact that they all look toward the preservation of the gum tissue equally for the labial and lingual surfaces ; Avhile, as a matter of fact, if proper provision is made for the protection of the cervical line on the labial surface, the lingual surface will take care of itself, for it will be noticed in cutting through the gum tissue that it is much thinner where it reflects over the alveolar border upon its labial aspect than upon its lingual. Hence, frequently, if no attention whatever has been paid to the retention of gum tissue on the lingual surface, the neck of the tooth will nevertheless be sufficiently protected. Fig. 576. Incision in gum for implantation. Another serious objection to an incision which leaves two or more points or margins to be preserved, is that the tenacity of the gum tissue THE OPERATION OF IMPLANTATION. 653 Fig. 577. makes it utterly impossible to preserve these various flaps and projec- tions intact from the cutting instruments. The writer's method consists in an incision resulting in one flap, with a view of protecting the labial surface of the tooth to p IG 573. be implanted, and of preserving this single flap from in- f-g jury during the progress of the operation. A combina- tion, or rather a modification, of the most suitable incis- ions recommended is therefore the one shown in Fig. 576. This incision is made with ordinary chisels as shown in Fig. 577, cutting with the chisel to and including the periosteum, lifting it for- ward and holding it out of the way of the operator by means of an instrument similar to the one shown in Fig. 578. The operation thus far is usually sim- ple and as a general rule not very pain- ful. The drilling of the socket varies with different individuals according to the density of the bone, the length of time that the tooth has been out, etc. In some instances the reamer or trephine or knife pro- gresses rapidly, while in others progress is very slow, or sometimes variable as the instrument enters into medul- lary spaces or passes through the more or less dense parti- tions which divide these medullary spaces from each other. The operator will determine during the operation, by the progress he is making with different instruments, which are the best to use. In some instances the entire socket can be made with an ordinary engine bur, while in others the strongest instruments especially designed for implantation are none too strong. In some instances an instrument which clears itself well during one operation clogs annoyingly during another. It is desirable to de- scribe at this point the various useful instruments which have been designed and are now upon the market. While all of them are not necessary, some one or more of each class are indispensable. The trephines of Dr. Younger, of San Francisco, Avhich have been improved by Dr. W. W. Walker of New York, have (as shown in Fig. 579), a set-screw collar, also shown detached, which slides on the shank and is first fixed by a set-screw as a gauge of the length of the tooth root. As will be noticed the trephines cut only on the edge, and hence they do not entirely clear themselves ; Instrument for holding flap during the operation. 654 PLANTATION OF TEETH. the reamers described on a succeeding page are then used to remove the core and enlarge the socket. Fig, 579. o ooOO 12 3 4 5 Younger-Walker trephines. Fig. 580. Rollins' spiral knives. The spiral knives (Fig. 580) devised by Dr. W. H. Rollins! of Boston are in many cases very useful. They are also open to the objection of clogging. As an improve- ment upon these the spiral crib knife shown in Fig. 581 has the advantage of permitting the core to pass within it. Fig. 581. Fig. 582. Ottofy spiral crib knife. j i Two forms of Cryer' spiral osteotome. 12 3 4 5 Ottolengui's reamers. Dr. R. Ottolengui, of New York, has devised a set of reamers (Fig. 583). There are nine leaves to each reamer and each leaf is divided into five teeth. Three of the leaves reach the apex of the cone point and thus allow a more rapid forward drilling into the bone. A sliding collar forms a gauge to indicate the proper depth to drill. THE OPERATION OF IMPLANTATION. 655 The reamers designed by Dr. Younger, illustrated in Fig. 584, are also very suitable for this purpose. Dr. Oyer's spiral osteotome — two forms of which are shown in Fig. 582, one with dentate edges, the other without — is an admirable instrument for forming the artificial socket. AYhen it is necessary to deepen or alter the shape of the socket, it is done very simply with either the ordinary burs of the dental engine or, what is preferable, a bur with a long shank such as shown in the accompanying illustration (Fig. 585). Fig. 585. Fig. 584. # • « 12 3 Dr. Younger's reamers. 12 3 4 Engine burs with long shank. The following are to be recommended : Nos. 1 and 3 of the Walker- Younger trephines, Nos. 1 and 3 of the Younger reamers, Nos. 1 and 2 of the Rollins spiral knives, Nos. 1 and 2 of the Ottofy spiral crib knives, and Nos. 1, 3, and 4 of the Ottolengui reamers and Cryer's osteotome. During the progress of the drilling of the socket, the tooth should be frequently inserted until a proper adjustment has been secured. Occasionally these teeth can be implanted and so perfectly fitted that it is almost impossible to remove them with the unaided fingers ; wdiile at times the bone is so cancellated and the tissues so flabby that a socket, no matter how carefully drilled, will not retain the tooth in place. Nothing is gained by a too close adjustment of the root, as pressure must un- doubtedly be exerted, and pressure causes resorption, and may be fol- lowed by inflammation. A fair, moderate fitting of the root is all that should be aimed at: Just before the final adjustment the socket, gums, tooth, and all parts contiguous thereto, should be placed in an aseptic condition and the cap adjusted in the manner before described. Though the tooth may be adjusted to its socket so that immediately afterward it exhibits much firmness, yet in a few days subsequent to the operation it invariably shows less rigidity and an apparent tendency 656 PLANTATION OF TEETH. to loosening. This result is probably due to the resorption of those areas of contact between the tooth and its artificially formed alveolus where the greatest amount of pressure is exerted. The period of loosening is generally quickly followed by a progressively increasing firmness and immobility of the tooth caused by calcification of the exudate thrown out by the walls of the alveolus in the process of repair of the surgical injury to which it has been subjected by the operation. Planted teeth, when lost, are lost as a rule as a result of resorption of their roots. The process seems analogous to the resorption of the roots of deciduous teeth. Present records seem to indicate that re- sorption of the roots is slowest in progress in replanted teeth ; it is more rapid in transplanted teeth, and most rapid in implanted teeth. Intelligent observation over replantations and transplantations extends from twenty to forty years. The observation of implanted cases extends at this writing to about nineteen years, and successful cases have been under observation which have remained in the mouth over twelve years. The writer has the records of cases which have remained and done good service for the same length of time. CHAPTER XXIII. MANAGEMENT OF THE DECIDUOUS TEETH. By Clark L. Goddard, A. M., D. D. S. Eruption. — The first operation the dentist is called upon to perform for the deciduous (temporary) teeth is lancing the gums as an aid to eruption of those organs. This is not necessary in normal but only in pathological cases. Although gum tissue in its normal condition is comparatively insensitive, Avhen it is inflamed it is exceedingly tender. The principal source of pain, however, is not in the tissue overlying, but when a tooth, bound down by the dense gum tissue above it, by its own growth presses upon the formative organ below, it causes pain which in many cases may be so excessive as to cause reflex disorders of alarming character. Dr. J. W. White * says : " The manifestation of functional inharmony from pathological dentition will depend, as in trouble arising from any other disturbing cause, upon the temperament and health of the child, its dietetic management, and its hygienic surroundings. In some cases there is a gradual development of biliary, gastric, enteric, and cerebral complications, a slow but steady loss of vital power, with no effort at recuperation and feeble resistance to the undermining influences which gradually but surely wear out the young life. " In other cases the indications of disturbance of function are mani- fested primarily in the nervous system : the symptoms are all charac- teristic of acute derangement and are dangerous from their violence and uncontrollability. High fever, vomiting, choleraic diarrhea, men- ingitis, convulsions, stupor and death are the rapidly succeeding phenomena. Between these two phases there is every conceivable grade of symptoms, every imaginable complication." By many, as an objection to lancing the gums it has been urged that, in case the tooth does not erupt immediately, cicatricial tissue is formed over it which will bind the tooth down more rigidly than before. Cica- tricial tissue is, however, of a lower degree of organization than normal tissue, and is more easily broken down. 1 Amer. System of Dentistry, vol. iii. p. 327. 42 657 658 MANAGEMENT OF THE DECIDUOUS TEETH. Fig. The indications for interference are not so much local as general — the fretfulness, inability to sleep, and other symptoms mentioned by Dr. White. The gum tissue over the erupting tooth may or may not be highly inflamed, but the absence of such inflammation does not contraindicate lancing. In fact some of the gravest systemic disturbances occur where no local mani- festations are evident. The object is to divide the gum tissue which binds down the tooth and to allow it free egress. The most suitable instrument is shaped like that shown in Fig. 591 and sometimes used for lancing around teeth before ex- traction. It should be held like a pencil in writing, so that one or more Angers can form a rest and guide. For operating on the lower jaw the child is best seated in the lap of the operator with the head against his breast. By passing the left arm around the infant's head and in- serting the left thumb in its mouth with the fingers under the chin, the lower jaw can be held rigidly while the right hand performs the operation. For operating on the upper jaw it is best to lay the child across on the nurse's lap. The operator takes the head on or between his knees, opens the mouth by inserting one or more fingers of the left hand, and holds the thumb and forefinger on each side of the alveolar ridge, thus prevent- ing injury to contiguous parts during possible struggles of the child. For incisors a simple longitudinal incision is made, a little longer than the cutting edge of the tooth. The lancet should be sharp, so as to easily penetrate to the tooth. No harm will be done except to the blade of the lancet. For the canines a single incision is good, but a crucial incision is better. Sometimes lancing is necessary for the canine after it is partially erupted, as the gum tissue, pierced by the point only of the tooth, may form a dense ring around this point and interfere with further eruption. In such a case a division of this ring in two or more opposite places will give relief. For the molars a crucial incision is best, one cut ex- tending from the posterior buccal to the anterior lingual cusp, and the next from the posterior lingual to the ante- rior buccal. Sometimes lancing is necessary for these teeth after partial eruption. After the cusps have pierced the gum. the tooth may be held back by the bands of tissue in the sulci. In Gum lancet. ERUPTION AND DURATION. 659 such cases division of these bands in the same direction as before de- scribed for an unerupted tooth will give relief. Sharp-pointed curved scissors are well adapted to this latter operation. Fig. 587 will illustrate the direction of the incisions described. The relief afforded is generally immediate. In one case a child who had been fretful for several days, and who had not slept at all during the day, was asleep in the writer's arms within five minutes after the ope- ration. The gum tissue is not very sensitive, so the operation is often * painless. The little sufferer will A often recognize the relief obtained ilfcib / and point to other portions of the gums for further relief. Duration of the Deciduous 3S^i^ c Teeth. — The importance of filling r^^ \ cavities in the children's temporary teeth is often overlooked, even by ^%e --- " ^ dentists themselves, as these teeth are Lines of incision in lancing : a, a, over the -ill i molars ; b, b, over the canines and incisors Supposed tO be lost SO early as to before eruption . w , over the molars render such Operations Unnecessary. and canines after partial eruption (J. w. r™ • • ii • i i ■ White). This is generally true with the in- cisors, is less true with the canines, while the molars often need at- tention. Fig. 534 (see Chapter XXI.) shows the relations of the deciduous to the permanent dentures in a child of about six years of age. A study of the following table will show that while the incisors are superseded early by their successors the molars are in place nearly twice as long : Time of Eruption. Loss. Duration. Central incisors 6-8 months. 6th-7th year. oh to 6J years. Lateral 7-9 " 7th-8th " " " < ; " First molars 14-16 " 9th-10th " 7* " 9 " (1 yr. 2 m.-l yr. 4 m. i Canines 17-18 " flnf. 8th-10th " (l£yrs.) lSup.llth-12th " 7 " 10 " Second molars 18-24 " 12th-13th " 10 " 11 " (1£ yrs.-2yrs.) The temporary molars should be preserved for three reasons : 1st. To prevent the child suffering pain. 2d. To allow r proper mastication of food. This latter is of extreme importance, as these years are especially important ones in the child's growth. If he is prevented by pain from properly masticating his food it will not be assimilated, and a habit of 660 MANAGEMENT OF THE DECIDUOUS TEETH. swallowing food without masticating may be continued even when the permanent teeth have erupted. 3d. To preserve the fulness of the arch for the permanent teeth. Early loss of the deciduous second molar will allow the first per- manent molar to move forward and occupy room that should be pre- served for the premolars (bicuspids). Early loss of the first temporary molar will allow the second temporary and the first permanent molar to move forward. The crowns of the temporary molars are much larger than the necks, and caries of the approximal surfaces will allow them to crowd together with the same result. Approximal fillings inserted should be so shaped as to preserve the original contour. If the first permanent molar thus moves forward of its natural position a smaller arch is left for the successional teeth. The result may be a constricted arch, a pointed arch, upper protrusion, or the labial displacement of the canines. Fig. 588. 1 Decalcification of the deciduous teeth. The numbers indicate years. Odontalgia. — The first visits by children are usually for the relief of " toothache/' and may occur at any age from two years upward. The first treatment of most children's teeth should be palliative. In many cases a fear of the dentist has been engendered, which it should be the prime object to remove. Make the acquaintance of the little patient in the reception room, talking perhaps of things altogether foreign to the case in hand, and distract its attention. If the child is very timid examine the teeth while it is seated in an ordinary chair, or in its parent's lap, and apply some dressing to relieve the pain. In the operating room the chair should be adjusted to its smallest size ; a special child's seat may be used, or a cushion half the size of the chair seat, and not too soft. The child's head should be made comfort- able in the head-rest. The operator should not let the child detect him in an endeavor to hide instruments ; the necessary ones may be shown to him if they arouse his curiosity, and their purpose explained. 1 Prof. Pierce in Amer. System of Dentistry, vol. iii. p. 639. ODONTALGIA. 661 On account of the difficulty the child has in making himself under- stood, or from his not knowing what he wishes to describe, diagnosis is difficult. A child cannot always distinguish just where pain is felt, nor always remember its exact location. In most cases the first occurrence of pain is during mastication. It is necessary to ascertain whether pain is caused by an erupting tooth, a nearly exposed pulp, a pulp inflamed and dying, a putrescent pulp, or an alveolar abscess. If the nearly exposed pulp is suspected, test it by the application of a drop of cold water. Pain during masti- cation may be caused by thermal changes, by pressure of food in the cavity, or by pressure on a tooth whose pericementum is inflamed. If the tooth is aching while the child is in the chair, syringe out the cavity with warm water, dry it with bibulous paper, and apply a pledget of cotton saturated with oil of cloves, campho-phenique, or whatever has been found effective with permanent teeth. Fletcher's carbolized resin l has been invaluable for this purpose in the writer's practice. Applied on a pellet of cotton it acts as an anodyne, and the resin hardens in the cotton, forming with it a temporary stopping which will even bear the force of mastication for a few days. It is sometimes best to renew this dressing a few times before attempting a more per- manent treatment or filling. If the child cannot be brought to the office again within a few days, let the parent provide himself with a bottle of the carbolized resin and an inexpensive pair of dressing pliers. Instruct the patient how to apply the cotton dressing. This is the best domestic remedy for odon- talgia. Other medicaments may be used by the parent, such as oil of cloves, campho-phenique, etc., but their effect is much more temporary. A more durable dressing may be made by mixing zinc oxid and car- bolized resin to the consistence of putty and applying it in the cavity previously dried. It hardens under moisture, and makes a stopping that will remain, in some cases, for several weeks. During such palliative treatment, sometimes unavoidably extended over several weeks or even months, the child is growing older, is gain- ing experience, is becoming used to manipulation, begins to recognize the benefit of treatment of the teeth — in a word, is being trained or educated for a good patient for whom more permanent operations may be attempted. Prof. L. L. Dunbar says : "As a domestic palliative always at hand, in the treatment of pulp exposure and restricting odontalgia, use ammonia on cotton : its repeated use will devitalize the pulp, at the same time effecting its removal by saponification. " 1 Carbolic acid, Resin (colophony), ad. %j ; Chloroform, ^E 88 ' 662 MANAGEMENT OF THE DECIDUOUS TEETH. Treatment with Silver Nitrate. More than forty years ago the application of silver nitrate for arresting decay was advocated, but for many years no notice was taken of it. Within the last five years it has been advocated again, especially for use in the temporary teeth. The fact that it blackens the decayed surface is not as objectionable as with permanent teeth. Dr. Stebbins l advocated the use of a solution of the crystals of silver nitrate in cari- ous cavities in temporary teeth. He applies it by means of a small stick inserted in a socket instrument as shown in Fig. 589. Many Fig. 589. cases will need no further treatment, decay being completely arrested. Some cases will need secondary treatment after a few months. In many cases he advises filling the cavity with gutta-percha after the application. Dr. C. N. Peirce 2 advises saturating pieces of blotting paper with 40 per cent, solution of silver nitrate, and keeping these on hand for use. Dr. E. C. Kirk advises the use of asbestos felt for saturation with the solution in preference to blotting paper or cotton. He says : 3 " The contact of silver nitrate with vegetable fiber of any sort involves not only a destruction of the fiber but also of the silver nitrate, so that the preparation in a short time loses its desirable qualities." He advises that the asbestos felt be heated before the blowpipe before saturation, to burn out any organic material which may be present. Dr. A. M. Holmes 4 advises its use as follows for approximal cavities : " Cut away the walls to a V shape, and with a piece of gutta-percha, softened by heat, of the proper size to fill the space, bring the surface to come in contact with the diseased part of the teeth, into contact with the powdered crystals of silver nitrate and carry it to the place in the tooth or teeth prepared for its reception, packing it firmly and leav- ing it there to be worn away by use in mastication. When that takes place, the surfaces of the teeth treated will be found black and hard, with no sensitiveness to the touch or to change of temperature, and they will remain so indefinitely. In case the child is so timid as to 1 International Dental Journal, 1891, p. 661. 2 Ibid., 1893, p. 152. 3 Dental Cosmos, 1893, p. 667. i Ibid., 1892, p. 982. FILLING MATERIALS. 663 prevent this course, dry the cavity, take out as much softened dentin as the patient will permit, carry the crystals on softened gutta-percha into the cavity and pack it, leaving it until such time as desirable to make a more thorough operation." In the writer's opinion it is better to open approximal cavities from the occlusal surface rather than make V-shaped spaces, as the full diameter of the teeth should be left to preserve the fulness of the arch. Silver nitrate in its action penetrates but a short distance. The Character op the Patient. The conditions of operating on the deciduous teeth vary so much from those pertaining to the permanent teeth that a different consid- eration must be taken of filling materials. The little patients 7 mouths are small. They are often too young to reason with or to understand the purpose of the operation. They have been too often frightened by thoughtless remarks of their elders in speaking of their dentist. Oftentimes the first sitting must be utilized merely to make the acquaintance of the child, perhaps cleaning the teeth a little, or intro- ducing some palliative dressing in an aching tooth. The greatest care should be taken not to hurt the child. After it has gained a little experience it recognizes the benefit of the treatment, and will often submit to operations that older patients even shrink from. Filling Materials. Gutta-percha. — Pink base-plate gutta-percha is a most valuable filling material. In approximal cavities where it is not exposed to wear and where the shape of the cavity is such as to retain it, it is practically indestructible. In occlusal and compound cavities in which it is exposed to wear it has wonderful durability, lasting in some cases for several years. Directions for Use. — Cut the gutta-percha in small pieces and place them on a gutta-percha warmer (see Fig. 279), where they can be kept soft but not heated enough to injure the material. The instruments also should be warmed (see Fig. 286). Occlusal Cavities. — Cut away the margins of thin enamel with suitably shaped chisels, and remove the decayed and softened dentin with scoop and hatchet excavators. Do this as thoroughly as the patient will permit, but do not sacrifice the patient to thoroughness, for the thorough removal of softened dentin is not as essential as with per- manent teeth, because the gutta-percha is, by mastication, kept in such 664 MANAGEMENT OF THE DECIDUOUS TEETH. accurate contact with all the walls of the cavity that further soften- ing will go on very slowly if at all. No special attention need be paid to the form of the cavity, except that its mouth should not be larger than the rest, nor should any parts of the cavity be inaccessible to the filling material. After excavating, dry the cavity with, bibulous paper, and apply campho-phenique, oil of cloves, or carbolic acid, to sterilize any softened dentin which may not have been removed. For drying cavities, prepare paper cylinders, of different sizes, as follows : Tear the bibulous paper in strips from half an inch to two inches in width. Roll or twist each of these strips into a rope, but not too tightly — just enough to retain the shape. Cut these ropes into cylinders from a quarter to half an inch in length. Some of these will be as large around as a lead pencil and others no larger than the lead itself. Protect the tooth from moisture as well as possible. For lower cavities fold a small napkin diagonally from the corner till it is about half an inch wide. Put the end of this between the gum of the upper canine and the lip and extend the napkin back between the upper molars and the cheek beyond the last tooth, then down behind the last lower molar, and press it between the lower teeth and tongue. Tell the patient to raise the tongue as it is applied, then to lower the tongue and hold the napkin with it. The part of the napkin between the upper teeth and the cheek will cover the mouth of the duct of Steno, and prevent or absorb the flow of saliva. It is better to cover the mouth of this duct with a piece of spunk about half an inch in diameter before applying the napkin. The folds of napkin between the lower teeth and tongue and under the tongue will absorb the saliva from the submaxillary glands. This part of the napkin can be held in place with a mouth mirror or other blunt instrument, by the operator or assistant. After applying the napkin use a large bibulous paper cylinder to absorb the moisture from the tooth to be filled and also from contiguous ones. With smaller cylinders or pellets dry the cavity. Apply once more campho-phenique or other medicament, and absorb the excess. The gutta-percha having been meanwhile warmed and softened, pick up a small piece of it with a cold round-pointed instrument and press it into the cavity. If the cavity is not large, a single piece of gutta-percha of a diameter less than that of the cavity, but longer than the cavity is deep, can be pressed in quickly and at one movement. For medium-sized cavities select a piece of gutta-percha large enough to cover the floor of the cavity and press it into place with a cold instrument, as a warm instrument might drag it from its place. Add similar pieces, pressing each one to the place in which it is to remain, till the cavity is full. If at any time the gutta-percha in the FILLING MATERIALS. 665 cavity becomes so hard as to lose its plasticity, apply a warm instrument to soften the surface, so that the next piece will adhere to the others. As the filling nears completion select a small piece for the last, just large enough to complete the filling and no more, so that none will have to be trimmed away, for in trimming the surplus away the filling may be drawn from contact with the walls of the cavity. In filling large cavities it may be necessary to hold the first piece in position with another instrument till sufficient material is added for self- retention. At the completion of the filling slight pressure with a warm instrument should be made in such a manner as to force the material against all the margins of the cavity. Approximal Cavities. — Where possible, approximal cavities should be opened from the buccal surfaces, as advised by Dr. Bon- will, as in such cases gutta-percha fillings will not be exposed to the force of mastication. This plan is not often practicable because the patient is seldom presented till the cavity has become visible by open- ing into the occlusal surface of the tooth. In such cases cut away the enamel only enough to give access to the cavity, excavate the decayed dentin, and trim the buccal, lingual, and cervical walls until a smooth, firm margin is obtained. In filling such a cavity use small pieces of softened gutta-percha, pressing each piece where it is to remain, and avoid a surplus. Press the gutta-percha against the adjoining tooth as if it were a matrix or a fourth wall of the cavity and let it remain. It is useless to trim it away from the adjoining tooth, because the force of mastication would soon spread the filling against it again. If an approximal cavity cannot be readily shaped so that it will retain the gutta-percha, it may be packed against the adjoining tooth, as if it were an occlusal cavity. It will prevent decay, especially if sil- ver nitrate is applied as described on page 668, and maybe retained till the patient is older, when a more thorough operation may be performed. The spreading of the gutta-percha by the force of mastication will tend to separate the teeth — which is sometimes an advantage ; and also to press upon the gum in the interproximal space — which is a disad- vantage. In filling children's teeth we cannot always reach the ideal, but must select the method and material which will have the greatest advantage with the least disadvantage. If the teeth separate so much that the pressure of the gutta-percha upon the gum tissue becomes a serious annoyance, some other material must be substituted. To prevent the impinging of the gutta-percha upon the gum in the interproximal space, Dr. M. W. Hollingsworth x has invented a space 1 Dental Cosmos t 1896, vol. xxxviii. p. 553. 666 MANAGEMENT OF THE DECIDUOUS TEETH. guard, consisting of a concave elliptical piece of metal coated on the convex surface with gutta-percha. This guard is to bridge over the interproximal space. It is placed in position with the instrument shown in b, Fig. 590, which is warmed slightly, so that the point can Fig. 590. Fig. 591. enter a small hole in the guard and adhere to the gutta-percha on the under side, as shown at c. The guard is placed in the cavities, after warming the gutta-percha, as shown in Fig. 596, and thus covers the cervical borders. Gutta-percha is now filled in over the guard as if the two cavities formed a single crown cavity. Advantages of Gutta-percha. — It is easily applied to the cavity ; it is insoluble ; is durable even when masticated upon ; is a non-conductor of thermal impulses ; the filling is finished as soon as the cavity is full ; it spreads under the force of mastication, and is thus kept in contact with the walls of a cavity ; it can be used even under moisture. Disadvantages. — Gutta-percha is softer than other filling materials, and hence wears away more rapidly. In approximal cavities it will spread the teeth apart, and may then press upon and irritate the gum. Dryness of the cavity, though very desirable, is not absolutely necessary. Advantages of Zinc Phosphate Cement. — It is a poor conductor of heat ; it withstands the force of mastication better than gutta-percha ; it adheres to the walls of the cavity, and hence will remain where no other material can ; it is easily applied ; its color may be selected to match the tooth. Ames' copper cement seems to be even a better preservative than zinc cements in places where the black color is not objectionable. Disadvantages. — Absolute dryness of the cavity is a prerequisite to its success ; it must be kept dry for several minutes after it is inserted in the cavity. Zinc phosphate cement disintegrates in some mouths much more rapidly than in others. If placed too near the pulp it may by chemical irritation devitalize it. FILLING MATERIALS. 667 Application of the Rubber Dam. — While many hesitate to attempt the use of the rubber dam with children, it will be found upon trial that most of them will submit to it without trouble, and many will prefer it to other means of keeping cavities dry. Although there is an advantage in applying the rubber dam before excavating — because dryness makes the teeth less sensitive, and a clearer view of the cavity is obtained — still, for the sake of not tiring the little patients by too long restraint in one position, it is better to do most of the excavating before its application. The small size of the necks of the deciduous teeth compared with that of the crowns renders the retention of the rubber dam easier than with permanent teeth. Even considering the smallness of the patients' mouths, the application of the rubber dam is not difficult in many cases. For retaining the rubber dam on the second molar a clamp will sometimes be necessary, but for the other, deciduous teeth a floss silk ligature will be sufficient. Having punched holes of suitable size through the rubber dam, apply it over the teeth affected. If the cavity is in the occlusal or buccal surface only, it will not be necessary to apply it over more than one tooth, but if the cavity is in the approximal surface it will be necessary to apply the rubber dam over two or some- times three teeth, or even more, if several cavities are to be filled at one sitting. It is not always necessary to tie a ligature around the neck of the tooth, as merely passing the waxed floss silk between the teeth will often force the rubber around the neck of the tooth enough to retain it even above an approximal cavity. The silk may then be removed by drawing the end through between the teeth. With a thin burnisher or spatula turn up the edge of the rubber around the neck of the tooth toward the gum. The tendency of the rubber then will be to slide in that direction and not off over the crown. If a ligature be necessary to hold the rubber above the edge of an approximal cavity tie it tightly around the neck of the tooth, even forcing it toward or under the edge of the gum with an instrument when necessary. The clamp on a second molar may often be dispensed with after a ligature is applied, unless it is needed to hold the rubber out of the operator's way. The only object in omitting the clamp is to pre- vent pain or discomfort to the child. If a simple ligature will not retain the rubber on a second molar before the first permanent molar has appeared, its efficiency may be greatly increased by stringing a bead, about an eighth of an inch or less in diameter, on the thread and tying a simple knot in it so that the bead will be in about the middle of the ligature. Tie the ligature around QQS MANAGEMENT OF THE DECIDUOUS TEETH. the tooth so that the bead will lie against the distal surface of the second molar on or near the gum. This bead will prevent the rubber slipping off the tooth. A short cylinder of bibulous paper can be tied in the ligature and applied with the same effect, and even a large knot in the ligature on the distal surface of the tooth will often answer the purpose. The corners of the rubber dam should be held out of the way by a suitable holder extending around the head. The lower border may be held out of the operator's way by small weights, hooked in the edge. Dry the cavity and the whole tooth or teeth, and complete the excavation. Pilling' Cavities with Cement. — As cement can be applied easily in undercuts and very irregularly shaped cavities it is not necessary to cut away the enamel more than is sufficient to enable the operator to thoroughly remove the disintegrated dentin. Even the thorough re- moval of the latter is not as essential for a cement filling as for other materials, for, if the edge of the cavity can be made smooth and the softened dentin be thoroughly sterilized, the cement will hermetically seal it and prevent further disintegration until it is worn away beyond the sound edges. The operator may take much greater risks in leaving disintegrated dentin than with permanent teeth, for the object is simply to retain the tooth till the time arrives for its successor to appear. It must be remembered in excavating cavities in deciduous teeth that the pulp is much larger in proportion to the size of the crown than in permanent teeth, and that in trying to make undercuts or retaining grooves deep enough to retain a filling, the pulp may be exposed — an accident which should be carefully guarded against, for the pulp has not even the recuperative power possessed by the pulp of a permanent tooth proper treatment. Moreover, death of the pulp prevents normal re- sorption of the root and may thus cause irregularity of the permanent teeth. For most cases the cement should be mixed as thick as can be easily and quickly manipulated, but if the pulp is nearly exposed the cement should be used so thin that it can be applied without pressure, by flowing it over the floor of the cavity. Cement mixed moderately thin will adhere better to the walls of the cavity than when it is as thick as it is possible to apply it. The thinner the cement, the longer time it will take to harden, but the thicker it is mixed the more dur- able it will be. Do not keep the little patient in a constrained posi- tion longer than necessary. The easier the first operation is for him the more readily will he return for the second. If the pulp is very nearly exposed apply Fletcher's carbolized resin over the floor of the cavity. For this purpose remove the stopper of the bottle till by evaporation the carbolized resin has thickened to the FILLING MATERIALS. 669 consistence of molasses. Dip a small probe in the thickened mass, so that a small drop will adhere to the end. This drop may be then con- veyed to and spread over the floor of the cavity. This will prevent contact of the cement with the most sensitive dentin and lessen the possibility of deleterious action on the pulp. Where it is possible to apply the rubber dam and excavate thoroughly the same excellent result with cement may be expected as when it is used in permanent teeth, but often it is not possible to operate as thoroughly. By applying melted paraffin 1 or sandarac varnish to the cement the rubber dam may be removed sooner than otherwise, and the cement will be protected from moisture by the coating of paraffin or varnish. As paraffin is insoluble in any agent that can attack it in the mouth, the more it is absorbed by the cement the longer it will protect it from everything but wear ; therefore, do not be content to merely flow the melted paraffin over the cement, but hold a heated instrument in contact with the filling and keep the paraffin melted until all that is possible is absorbed. If an approximal filling has been inserted pass a very thin heated spatula between the cement filling and the adjoining tooth to make sure that the paraffin covers it to its cervical margin. When the rubber dam cannot be applied, cement may still be used with success if the cavity can be kept dry with napkins or rolls of cotton or spunk until it is inserted and quickly covered with melted paraffin. Deep cavities may be advantageously lined with cement and protected with paraffin till the cement is hard, when the paraffin may be removed and gutta-percha or amalgam inserted. Occlusal fillings of cement can be kept dry by applying temporary stopping very soft as soon as the cement is put in. Gilbert's is excel- lent for the purpose, as it adheres to the cement. Buccal fillings, some- times approximal, may be protected in the same way. A thin tempo- rary stopping may be left to be worn away by occluding teeth. Cavities in Incisors. — Decay in deciduous incisors is much more rare than in the other teeth, and they are lost so early in child life that it is seldom necessary to fill them. Zinc phosphate cement, is the best filling material for these teeth, because they are so small that it is very difficult to shape the cavities properly for retaining other materials. If it is found that cement disintegrates rapidly in approximal cavities, an attempt should be made to shape them so as to retain gutta-percha. The first filling of cement may have removed the sensitiveness suf- ficiently to allow deeper excavating at a subsequent sitting, or there may have been a deposit of secondary dentin, thus removing the pulp from danger of exposure in properly shaping the cavity. Amalgam. — While amalgam is a valuable filling material, its use 1 Dr. Bon will's suggestion. 670 MANAGEMENT OF THE DECIDUOUS TEETH. necessitates much greater care in the preparation of cavities than is necessary with gutta-percha or cement, for it neither spreads under mastication like the former nor does it adhere to the walls of a cavity like the latter. The spreading of gutta-percha will stop a leak that would be fatal to an amalgam filling, and cement will adhere in a cav- ity from which amalgam would be easily dislodged. Amalgam should be used when the decay can be thoroughly excava- ted and the cavity prepared with strong smooth edges, and good under- cuts or retaining grooves. As amalgam is a better conductor of thermal impulses than either of the materials before mentioned it will not be tolerated so near the pulp, hence deep cavities must be lined with either gutta-percha or zinc phosphate. The large size of the pulp of deciduous teeth — greater in proportion than that of the permanent teeth — must not be forgotten in exca- vating, and often it is impossible to make suitable retaining grooves for amalgam without cutting dangerously near the pulp, especially in ap- proximal cavities. The preparation of occlusal cavities is comparatively simple, as the enamel may be easily cut away so as to make firm edges, slightly bevelled, and to allow thorough excavation of softened dentin. The burring engine can be used to greater advantage with children than many would suppose. The whirring noise often distracts their attention from a slight pain they might otherwise notice, and the assur- ance that the work can be done more quickly is a great encouragement. In preparing approximal cavities for amalgam a free opening should be made in the occlusal surface and given a dovetail shape, extending farther upon the occlusal surface in proportion to the size of the cavity than in permanent teeth, because more reliance must be placed on it for retention than upon lateral grooves, for there is not much depth of dentin in which to make them. The cervical border of the cavity must be smooth and the floor at right angles to the long axis of the tooth. The lateral walls must be cut smooth and bevelled, and may be „ kqo slightly grooved. If the cavity extends below the margin of the gum the latter should be crowded away with a temporary stopping or by packing a tightly rolled pledget of cotton between the teeth and relying on its swelling. In many cases it is possible to extend an approxi- ^repared cavity showing ma j cavity to the sulcus and make a step anchorage, bevelling of enamel . . ° edges, a,a, and square as in permanent teeth. base for filling, b. While the application of a rubber dam is not as essential as in using cement, it is a great advantage, for it renders the proper preparation of the cavity more certain, but it need not be applied EXPOSED PULPS. 671 till the cavity is nearly prepared. Its use is more often necessary with the lower teeth than with the upper. Amalgam should not be mixed too dry, but should be plastic enough to be packed easily without crumbling. In occlusal cavities introduce a piece half as large as the cavity, and with a small ball burnisher spread it over the floor of the cavity toward the walls. Introduce other smaller pieces and proceed as before until the cavity is nearly full. Excess of mercury is thus forced to the edges of the cavity, whence it can be brushed away with cotton or bibulous paper. The last pieces of amalgam should be " wafered," as recommended by Prof. J. Foster Flagg — that is, squeezed in chamois skin with large flat-nosed pliers till as much mercury as possible is pressed out (see Fig. 281). This leaves the amalgam in a thin, brittle wafer, too hard for ordinary use. Break it up in pieces half the diameter of the cavity. Press one of these in the middle of the nearly completed filling. It will readily absorb the excess of mercury that has been worked to the surface, and can be spread toward the margins with a round burnisher. Other pieces can be burnished on till the filling is quite hard. In filling approximal cavities the same plan may be followed if a matrix of thin steel or German silver be used. In lieu of the matrix a very thin spatula may be held between the teeth. Whenever possible, fillings in deciduous molars should be contoured to avoid the crowding of food between the teeth and also to prevent the first permanent molar from crowding them together and thus taking up room which will be needed by the bicuspids. The child should be cautioned against masticating too soon upon approximal fillings, though no caution is needed in case of occlusal fill- ings hardened by the " wafering " process. Tin and gold are excluded from the list of desirable filling materials for temporary teeth, not because they are not good filling materials but because the circumstances are such that they cannot be used to advan- tage. Though a small gold filling may be inserted in a few minutes in an occlusal cavity, the insertion of a large gold filling would be inflict- ing a needless cruelty on a child on account of the length of time it must be held in one position. As the insertion of a tin filling is nearly if not quite as difficult and tedious an operation, it is open to the same objection. Exposed Pulps. On account of the difficulty of properly capping an exposed pulp in a deciduous tooth, the operation should seldom be attempted. It is better to devitalize the pulp and remove it. The writer has found the following formula 1 an excellent one : 1 Used by Dr. E. N. Clarke in the "fifties." 672 MANAGEMENT OF THE DECIDUOUS TEETH. Jfy. Acidi arseniosi, Morphise acetatis, Pulv. opii, da. pars 03q. Creosoti q. s. to make paste. Why opium and acetate of morphia should both be used in the same prescription is not clear, as their properties are so nearly the same, but the paste has been satisfactory in devitalizing pulps with no pain, or with a minimum amount. Other formulas may be equally satisfactory. In occlusal cavities its application is simple. Excavate the softened dentin as thoroughly as possible without inflicting pain, using spoon- shaped excavators to prevent puncturing the pulp. If the excavation can be carried far enough to apply the paste directly to the pulp its action will be more rapid. Dry the cavity, apply a small amount, not larger than half a pinhead in size, with a small probe and cover it with a pellet of cotton, or place in the cavity a small pellet of cotton one side of which has been touched to the paste. Add enough pellets of dry cotton to fill the cavity, then apply a drop of sandarac varnish, suf- ficient to saturate at least half the depth of cotton. This is a better plan than dipping the pellets in the varnish before inserting, because an excess of the latter is apt to come in contact with the pulp and cause pain, or, penetrating between the paste and the pulp, may render the former inoperative. Temporary stoppings such as Gilbert's, White's, or Fowler's are excellent for sealing the cavity, but take a little more time than cotton and varnish. Such temporary stopping should be well softened by heat to prevent pressure on the pulp in its insertion. A good plan is to warm the end of the long stick of stopping and press it into the cavity, using the remainder of the stick as a handle, then remove the surplus and smooth with a warm instrument. In approximal cavities extending near or under the margin, the gum should be protected, before applying the paste, as follows : Make, by rolling between the fingers, a cylinder of cotton as long as the width of the tooth and about the size of the lead of a pencil. Saturate it with sandarac varnish and pack it between the teeth upon the gum, extending part of it below the edge of the cavity, thus sealing this portion of the cavity and reducing it nearly to the form of an occlusal cavity. Paste applied in an approximal cavity so protected cannot flow upon the gum unless too great a quantity has been used. The paste should be applied and sealed as in an occlusal cavity. " Devitalizing fiber " is very satisfactory and may be used with less fear of its aifecting the gum tissue. The paste may be allowed to remain in the cavity for from twelve to forty-eight hours. The possibility of the dressing being dislodged, so FILLING PULP CANALS. 673 as to allow the paste to come in contact with the gum tissue, should warn one to have the patient return much sooner than when the case is an occlusal cavity from which it is impossible for the paste to escape. Much has been said about the danger of application of arsenic in deciduous teeth when the roots are undergoing resorption, but the writer has never seen any bad effects from such use ; still it must be admitted that the ratio of danger varies with the degree of resorption of the root. An examination of Prof. Peirce's diagram (Fig. 588) will show the average amount of resorption at different ages, and enable one to discriminate. The writer believes that the sensitiveness of a deciduous pulp varies inversely with the amount of resorption of the root, and that devitalization is called for in very few cases in which there is danger of deleterious action. Prof. L. L. Dunbar advises the use of aqua ammonite for devitaliz- ing the pulp of a temporary tooth, by applying it on a pledget of cotton in the cavity, one or two applications being sufficient in most cases. This plan is not open to the objections urged against the use of arsenous oxid. When the pulp is devitalized, open the cavity freely into the pulp chamber and apply on cotton a solution of tannic acid in glycerol. Leave this about a week, by which time the pulp tissue will have be- come so hardened by the tannin that it may be removed much more readily than without such treatment. The application of mummifying paste is advised by many, after devitalization, to avoid the necessity of removing the pulp. If a real mummifying paste can be found, its application will be the ideal treatment. Filling Pulp Canals. In the pulp canals apply iodoform paste made by mixing iodoform and glycerol to such a consistence that it can be readily applied on a probe. Fill the pulp chamber with ''temporary stopping" or gutta-percha, and the cavity with cement, gutta-percha, or amalgam according to indications. If the tooth be very frail, fill the cavity with cement, because, owing to its adhesive properties, it strengthens the tooth. If the cavity be approximal and it is desirable to wedge the teeth apart, use pink gutta- percha. If the walls be strong and some time will elapse before the natural exfoliation of the tooth will occur, fill with amalgam. If absorption of the roots occurs, the iodoform in the canals will not interfere. 43 674 MANAGEMENT OF THE DECIDUOUS TEETH. Salol, which was advocated as a root filling for permanent teeth by Dr. A. E. Mascort x of Paris, France, is well adapted also for filling the canals of deciduous teeth. " It is a white crystalline powder, insoluble in water and glycerol, but soluble in alcohol, ether, chloroform, etc. ; fuses at 40° C. but crystallizes quickly again." Melted together, salol and aristol, salol and iodoform, or salol and paraffin, become liquid like salol alone. After a pulp canal is thoroughly dried the salol may be fused on a small spatula and carried to the canal, into which it will be taken by capillary attraction or a broach may be heated and inserted in the salol. A small quantity will adhere like a drop of liquid and may thus be carried to the canal. The heated broach may be again introduced in the canal to insure thorough application. Dr. Mascort uses the hypodermic syringe with a small needle for introducing into the canals. It will crystallize in a very short time, making a solid fill- ing. Though the writer has not had much experience with salol as a root filling, he is so far well pleased with the result. (See Chapter XVII.) Alveolar Abscess. The treatment should be the same as with the permanent teeth, that is, removal of the cause — which is, almost invariably, a decomposed pulp. Even with a decomposed pulp an abscess seldom occurs if there be any opening from the cavity of decay to the pulp chamber, unless such opening has become stopped by some foreign substance. Make a free opening into the pulp chamber and with a syringe wash out as much of the contents as possible. Dry the chamber and with a " minim" syringe (see Chapter XVII. , Fig. 429), or drop tube, apply hydrogen dioxid. While capillary attraction will carry this into a dry canal, the application of a nerve broach, preferably platino- iridium, will serve to mix it thoroughly with the contents of other canals, and increase its efficiency. If a fistulous opening has formed through the outer alveolar plate but not through the gum, an opening should be made through the latter with a sharp lancet about five minutes after the application of 4 per cent, cocain hydrochlorid solution on a wad of cotton. If hydrogen dioxid can be forced from the pulp chamber through the root canals and fistulous opening, the accumulated pus will be thoroughly evacuated and the cure hastened. As a rule, however, the abscess disappears after the cause is removed, that is, the putrescent or decomposed contents of the pulp chamber and canals. After drying the pulp chamber and canals, apply iodoform paste 1 Dental Cosmos, 1894, p. 352. PROPHYLACTIC TREATMENT. 675 therein and seal the cavity for a few days with temporary stopping. When the inflammation of the pericementum has disappeared the pulp chamber and canals may be filled as before directed. In many cases the inflammation of the pericementum will be so great, or in popular expression the tooth so " sore " to the touch, when the case is presented that at the first sitting nothing more can be done than to make an opening into the pulp chamber to allow the escape of pus or gases of decomposition. By this means the pain will be re- lieved and the rest of the manipulation and treatment may be left till the inflammation has subsided. Prophylactic Treatment. This lies more in the hands of the parent than of the practitioner, but should be strongly urged by the latter upon the former. The nurse or parent should begin early to clean the child's teeth by means of a cloth wrapped around the finger. If the teeth cannot be kept clean in this manner a small brush should be used, especially after eruption of the molars. Floss silk should be used daily between the teeth. One end of the silk should be held in each hand in such a manner as to pass over the end of each index finger and be made taut between them. This taut part can be pressed down between the teeth and passed up and down against the approximal surface of each tooth, then one end of the thread should be released from one hand and pulled through the interdental space with tire other. This will drag out any particles of food that may be there, and is much better than the toothpick for the purpose. If particles of meat or other food have lodged so firmly that the plain waxed silk will not dislodge them, tie a single knot in the thread and pull that through. This cleansing with the cloth, brush, and silk should be done before the child retires at night, for that is the " period of decay." The parts are at rest longer than at any other time, and the fluids of the mouth are not kept in circulation between the teeth by means of the tongue, lips, and cheeks. Theoretically the teeth should be thus thoroughly cleaned after each meal, but " satiety breeds disgust," and it is not best to insist on more than will probably be accomplished. Children will soon learn to use the brush and floss silk themselves, and finding the mouth much more comfortable when "clean" they will endeavor to keep it so. Many a child has been denied candy for years from the belief that " sweets decay the teeth," but parents may be as- sured that no harm will be done if the " sweet " is not allowed to remain between and around the teeth till it becomes acid, and that 676 MANAGEMENT OF THE DECIDUOUS TEETH. may be prevented by cleansing the teeth after the candy or sugar is eaten. A child may be taught cleanliness in this manner who would be only taught rebellion by the repeated denial of sweets, the reason of which he cannot understand. Prophylactic mouth-washes should be used — such as listerine diluted to a 10 per cent, solution. CHAPTER XXIV. ORTHODONTIA. By Edward H. Angle, M. D., D. D. S. Occlusion. The term " irregularities of the teeth," as it is usually applied to express the condition of their abnormal arrangement, does not properly express the full meaning of these deformities. The term "mal-occlu- sion " is far more expressive, for in studying the subject we must fully appreciate the importance of the dental apparatus as a whole, and the relations, not only of the two arches to each other, but of each indi- vidual tooth to all other teeth in both arches. The shapes of the cusps, crowns, roots, and even the very structural material of the teeth and their attachments are all designed for the pur- pose of making occlusion the one grand object, in order that they may best serve the purpose for which they were intended — namely, the cut- ting and grinding of the food. Examined carefully, it will be seen that perfect occlusion is incom- patible with any degree of mal-occlusion, and that the arrangement of the teeth must be even and regular, each contributing support to the others, and all in perfect harmony. Not only this, but the jaws, the muscles of mastication, the lips, and even the facial lines will then be in best harmony with the peculiar facial type of the individual. Therefore we should be constantly impressed with the importance of normal occlusion in the study and treatment of these deformities, for it is the very basis of the science. So in the following pages occlusion has been made the central thought, and on it is based the classification of mal-occlusion, as well as the nomenclature, diagnosis, and treatment, and the definition of orthodontia (from the Greek opdo^, straight ; doouc, tooth), as that science which has for its object the correction of mal- occlusion of the teeth. Mal-occlusion is the perversion of normal occlusion, and for its intel- ligent comprehension it is of tlie utmost importance that we first thor- oughly consider normal occlusion, and the principles operative in estab- lishing and maintaining it. Occlusion, as the basis of the science of orthodontia, is the student's most important lesson. Its proper comprehension presupposes a knowl- edge not only of the normal relations of the occlusal surfaces both of 677 678 ORTHODONTIA. permanent and deciduous teeth, but of their forms, structure, and at- tachments, their growth and development, as well as that of the jaws and related muscles. There can be no intelligent comprehension of the subject of orthodontia without this knowledge. Fjg. 593. Typical occlusion. (Broomell.) The perceptions of the student should also be broadened by a com- parative study of the teeth of the lower animals. By referring to Figs. 593, 594, and 595, which represent the teeth in ideal or normal occlusion, it will be seen that each dental arch describes Fig. 594. Typical occlusion. (Summa.) a graceful curve, and that the teeth in these arches are so arranged as to be in greatest harmony with their fellows in the same arch, as well as with those in the opposite arch, yet that each case differs as types of faces differ. The curves of the dental arches, the inclinations of the teeth, their sizes OCCLUSION. 679 and lengths, their structure and dimensions, all vary and must vary to be in harmony with the peculiar type and temperament of the indi- vidual, yet all are exactly the same in the main principles of occlusion — principles as old and older than the earliest records of man's teeth. The lower arch is somewhat smaller than the upper, so that in occlu- sion the labial and buccal surfaces of the teeth of the upper jaw slightly overhang those of the lower. The key to occlusion is the relative positions of the first molars. In normal occlusion the mesio-buccal cusp of the upper first molar is re- ceived in the buccal groove of the lower first molar ; the teeth posterior to the first molars engage with their antagonists in a precisely similar Fig. 595. Typical occlusion. (Cryer.) way ; those anterior interlock with one another in the interspaces until the incisors are reached ; of these the upper usually overhang the lower about one-third the length of their crowns, though the length of over- bite varies, being greater in the teeth indicating the bilious and nervous temperaments, and less in the sanguineous and lymphatic types. The upper central incisor being broader than the lower, it necessarily extends beyond it distally, overlapping in addition about one-half of the lower lateral incisor ; the upper lateral occludes with the remaining por- tion of this tooth and with the mesial incline of the lower cuspid ; the mesial incline of the upper cuspid occludes with the distal incline of the 680 ORTHODONTIA. lower cuspid, the distal incline of the upper occluding with the mesial incline of the buccal cusp of the lower first premolar. In the same order the series of buccal cusps of the premolars occlude — the mesial incline of each upper occluding with the distal incline of the correspond- ing lower tooth. The distal incline of the second upper premolar occludes with the mesial incline of the mesio-buccal cusp of the lower first molar. The mesial incline of the mesio-buccal cusp of the upper first molar occludes with the distal incline of the mesio-buccal cusp of the lower first molar ; the distal incline of the mesio-buccal cusp of the upper first molar Fig 596. ^1 *&? ^ >""/ *&*& m fit m ^^af* **#** jA •• t&sS&sSi lis ■ 1 1 #'** Of ],-• _ ■ ' x^;'';J t F 71} J HK >•' i - trt .1 (Fig. 601), however, the arches are more or less shortened and reduced in size, with a corresponding crowding of the anterior teeth. Fig. 602. Class II. — When the lower jaw is distal to its normal relation with the upper jaw, and the lower first molars lock distally to normal, it must CLASSIFICATION AND DIAGNOSIS. 689 necessarily follow that every succeeding permanent tooth to erupt must also occlude abnormally, all the lower teeth being forced into positions of distal occlusion, causing retrusion of the entire lower jaw. This condition of distal occlusion is the determining characteristic of Class II., and it produces very marked and very characteristic inharmony in the facial lines. Of this class there are two divisions, each having a subdivision : Division 1 is characterized by distal occlusion of both lateral halves of the dental arches, a narrowed upper arch, lengthened and protruding upper incisors, short and practically functionless upper lip, lengthened Fig. G03. lower incisors and thickened lower lip which rests cushion-like between the upper and lower incisors, increasing the protrusion of the former and the retrusion of the latter. This form of mal-occlusion is always accompanied and aggravated, at least in its early stages, indeed, if not caused, by mouth-breathing due to some form of nasal obstruction. The mal-occlusion typical of this class is shown in Fig. 602. Subdivision, Division 1, has the same characteristics, differing only in that the distal occlusion is unilateral, as shown in Fig. 603. Division 2 is characterized also by distal occlusion of both lateral halves of the dental arches, and retrusion instead of protrusion of the 44 690 ORTHODONTIA. upper incisors. In this division there are no complications from patho- logical conditions of the nasal passages, hence the mouth is kept closed the normal amount of time, and the lips perform their normal functions, which causes the repression of the upper incisors until they come in contact with the already retruded lower incisors, causing crowding of the upper teeth in the canine region, or at the angles of the mouth, where the force from lip pressure is not so great, as shown in Fig. 604. Subdivision, Division 2, has the same characteristics as the principal Fig. G04. division, differing chiefly in that the molar occlusion is unilaterally distal, as shown in Fig. 605. The marring effect on the facial lines of the mal-occl usion of division 2 and its subdivision is both marked and characteristic. Class III. is characterized by mesial occlusion in both lateral halves of the dental arches, the width of one cusp in the beginning or in simple cases, but more in more pronounced cases, as in Fig. 606, for these cases are always progressive. In cases belonging to this class, CLASSIFICATION AND DIAGNOSIS. 691 the arrangement of the teeth in their respective arches varies greatly from quite even and regular alignment to considerable crowding, espe- Fig. 605. ciallv in the upper arch. There is usually a decided lingual inclination of the lower incisors and canines, which becomes more and more pro- Fig. 606. nounced as the case progresses, and which is due to the pressure of the lower lip in the effort to close the mouth. In addition to the inharmony in the relations of the jaws, there is 692 ORTHODONTIA. usually inharmony also in the sizes of the two dental arches, especially in fully developed cases, due to the asymmetrical development of the maxillary bones, the angle of the lower jaw being more obtuse than normal, but it may also be the result of overdevelopment in the body of the jaw. Other characteristics met with in this class are considered in the section on Treatment, page 839. Fig. G07. "^^^^^^^^fl [L 5 20 520 A S: J ■il 520 _^W§i 520^^^W^^ i ^"^SB ft RIGHT 520 fTp 'LEFT :H In all cases belonging to this class the marring of the facial lines is most noticeable, and in direct proportion to the extent of mal-occlusion (Figs. 807 and 815). Subdivision, Class III. — This subdivision differs from the principal division only in degree, one of the lateral halves of the arch only being in mesial occlusion, the other being normal, as shown in Fig. 607, the arches crossing in the region of the incisors. CLASSIFICATION AND DIAGNOSIS. 693 That all cases of mal-occlusion met with will be found to be embraced in the above classification is more than probable. There still remains, however, one possible class — viz., where one of the lateral halves of the lower arch is in mesial occlusion while the other is in distal occlusion ; but cases having these characteristics are so very rare that no further reference to them is necessary, the writer having never seen but one or two cases. In diagnosing cases according to the above classification, it will be seen that the occlusion of each of the lateral halves of the arches is important, and must be considered separately and with equal and care- ful attention, always beginning with the first permanent molars. In developing cases of the second and third classes when the lower jaw may be in a state of transition and has not attained to distal or mesial occlusion the full width of a cusp on one or both sides, the beginner may be a little puzzled as to the proper classification, but upon careful inspection and close study a majority of the inclined planes will be found to favor one particular class, the co-relation of the first molars being, of course, the most important factor. The loss of a tooth or teeth by extraction is followed by such marked changes in the positions of the remaining teeth that diagnosis is some- times greatly complicated. Therefore great care and judgment should be exercised, making allowance for the tipping of teeth and other changes which have taken place as a result of extraction, in order to determine their original positions. This point being decided, the cor- rect diagnosis according to the above classification becomes easy. A brief recapitulation of the classification is here given for con- venience of study and for ready reference : Class I. — Arches in normal mesio-distal relations. Class II. — Lower arch distal to normal in its relation to upper arch. Division 1. — Bilaterally distal, protruding upper incisors. Usually mouth-breathers. Subdivision. — Unilaterally distal, protruding upper incisors. Usually mouth-breathers. Division 2. — Bilaterally distal, retruding upper incisors. Normal breathers. Subdivision. — Unilaterally distal, retruding upper incisors. Normal breathers. Class III. — Lower arch mesial to normal in its relation to upper arch. Division. — Bilaterally mesial. Subdivision. — Unilaterally mesial. Out of several thousand cases of mal-occlusion examined, the pro- portion per thousand belonging to each class was as follows : 694 ORTHODONTIA. Class 1 692 Class II. Division 1 90 Subdivision 34 Division 2 42 Subdivision 100 Class III. Division 34 Subdivision 8 1000 Facial Art. Art, as related to the human face, must ever have an important bearing on the study of orthodontia, for the mouth is a most potent factor in making or marring the beauty and character of the face, and the positions of the teeth are to a very large extent responsible for the proper form and beauty — or the lack of it — of the mouth. No one can be beautiful unless the mouth is in harmony with all the other features, and no one afflicted with mal-occlusion can have a mouth that is thus in harmony. The duties of the orthodontist force upon him great responsibilities, and there is nothing in which the student of orthodontia should be more- keenly interested nor better informed than in the study of the artistic proportions and relations of the features of the human face; for each of his efforts, whether he realizes it or not, makes for beauty or ugli- ness, for harmony or inharmony, for perfection or deformity. The orthodontist must ever place foremost in importance the normal occlusion of the teeth, for only in normal occlusion is their greatest usefulness and beauty possible. Many patients would never seek treat- ment were it not that the mal-occlusion of their teeth produced inhar- mony in the lines of their faces, and the improvement in the beauty of proportion and artistic effect which may often be wrought by intel- ligent effort on the part of the orthodontist is marvellous and almost incredible ; but his efforts may also be equally efficacious in producing or enhancing ugliness and deformity if unintelligently directed. But in order that our efforts may be intelligently directed toward the ideal, there must be some grand principle as a basis from which to reason, or we must be but gropers in the dark, experimenters, produc- ing results which may cause embarrassment or even bitter regret. Though human faces are all greatly alike, yet all differ. Lines and rules for their measurement have ever been sought by artists, and many have been the plans for determining some basic line or principle from which to detect variations from the normal, but no line, no measurement, admits of anything nearly like universal application. The beautiful face of the Apollo Belvedere has very largely been FACIAL ART. 695 used as a guide toward the ideal and from which to judge variations, but this is impracticable and misleading, for, notwithstanding the beautiful harmony of proportions of this face, with its straight line touching the frontal and mental eminences and the middle of the wing of the nose, its range of application has been found to be very limited in gauging the harmony or inharmony of a very large number of other faces. This is easily understood when we remember that the Apollo face represents the type or ideal of Grecian beauty, while now the Greek type is rarely seen, and in its place we have, especially in America, many types and the greatest number of variations of each type, each face being Ftg. 608. practically a law unto itself, and presenting demands as to measurements and proportions peculiar to itself. According to one of our foremost teachers of art, Mr. E. H. Wuerpel, there is a principle for our use which is equally applicable to all faces* — viz., the principle of balance, of symmetry. We must be able to detect whether the features — that is, the forehead, the nose, the chin, the lips — of each individual face balance, harmonize, or whether they are out of balance, out of harmony, and especially whether the mouth is in harmo- nious relations with the other features, and, if it is not, what is necessary to place it in balance. 696 ORTHODONTIA. The faculty of determining the proper balance of the features is a difficult one to attain. The authority above referred to says that only one in two or three hundred art students ever succeed in mastering it, Fig. 609. Fig. 610. I fl* and these only after much observation and practice in sketching and modelling faces. Fig. 611. Fig. 612. Unpromising as this seems, it is doubtless correct, yet we have a rule for determining the best balance of the features, or at least the best FACIAL ART. 697 balance of the mouth with the rest of the features, that artists probably know nothing of, and one that for the orthodontist is more unvarying and more reliable than even the judgment of the favored few — a rule so Fig. 613. invariable and with so few exceptions that we may consider it a law, and if it be not applicable in all cases, the exceptions will be so Fig. 614. very rare that they are hardly worth considering. It is, furthermore, a rule so plain and so simple that all can understand and apply it. It is 698 ORTHODONTIA. that the best balance, the best harmony, the best proportions of the month, in its relations to the other features, require that there shall be the full complement of teeth, and that each tooth shall be made to occupy its normal position — normal occlusion. Fig. 608 shows the face of Apollo. The face is a study of symmetry and harmony of proportion, and such lines are wholly incompatible with teeth in mal-occlusion or without the full number of teeth. Fig. 609 shows another face, which is also one of much beauty and fine proportions. It is also somewhat of a Greek type, and the lower half of the face shows lines which could only have been molded over teeth normal in number and position, and accompanied by normal con- ditions of development and nasal function. Fig. 610 l shows a face that is a blending of the Greek and Roman Fig. 615. types, and it also is in fine balance, though very different from that of Apollo. The features are large and prominent and the head is large, but there is a harmony of size, relation, and proportion that forms a most pleasing whole. The face, while in fine balance, is perhaps not beautiful from a physical standpoint, but it is more. It is beautiful from an intellectual standpoint, possessing strength, nobility, majesty — that, in the writer's opinion, is lamentably lacking in the Apollo face. Figs. 611 and 612, and Fig. 613 show the faces of two normally devel- oping children, though it will be observed that they are of strikingly dif- ferent types. The proportions of the faces, the balance of the features, and the harmonious lines of the mouths tell as truthfully that they are being molded over teeth developing normally in normal occlusion as the models of the teeth themselves, shown in Figs. 614 and 615. 1 William Whipple. FACIAL ART. 699 In these cases nature lias been able to work unhampered by detri- mental pathological conditions, which is apparent in the results. Of course, it must be understood that changes in the contour of these young faces must take place with greater development. The noses and chins will develop and become more prominent, and after the eruption of the permanent canines there will be more of an acute angle between the nose and the upper lip, especially in the face shown in Fig. 613. But the point we would emphasize is the normal development and con- sequent normal balance and symmetry of these faces, and if we will notice any child, or any person who has reached maturity with the teeth in normal occlusion, we will find an equal harmony of balance of the mouth with the other features. It has been well said that "probably the greatest reason why there is such uniformity of harmony in the facial lines of young children is that their teeth (the deciduous teeth) are prac- tically free from mal-occlusion " (Dr. R. Anema). Fig. 616. The writer would not be understood as implying that every face with lines and features in harmony of balance must necessarily be beautiful, nor even that placing mal-occluded teeth in normal occlusion will always put the whole face in harmony of balance. There may be defects in the face, as lack of development of the nose or chin, or unequal develop- ment of the malar bones or any of the bones of the face, or defects in the eyes or ears, or in the shape of the head, which, of course, could not be remedied by the correction of mal-occlusion, but the best harmony of such faces, or of any face, is only possible when the teeth are in normal occlusion. Mal-occlusion, or the loss of teeth by extraction or non- eruption, or a combination of these two causes, are responsible for far more faces out of balance and out of harmony than any other cause or combination of causes, and this inharmony and lack of balance of the mouth exists just in proportion to the degree of mal-occlusion. For a true understanding of what is meant by harmony of proportion and balance of faces, a careful study must be made of faces that are out of balance as well as of those that are in balance. 700 ORTHODONTIA. The effect on the facial lines of the varying forms of mal-occlusion found in the three different classes varies not only with the degree of mal-occlusion, but also with the individual type of face, yet, notwith- standing this, the type of facial deformity produced by each separate class of mal-occlusion is so constant that, after some practice, the close observer may classify with much accuracy the mal-occlusion of the peo- ple he observes without an actual examination of their teeth. This is also true in the case of extraction, or the loss or lack of teeth from any cause. Fig. 617. In Class I. the chin and nose will usually be found in relatively normal balance with the forehead and general contour of the face, and the lines of abnormality confined more or less to the mouth itself. Fig. 616 shows such a case in the profile of a boy fourteen years of age, and the lack of balance in the flat and sunken lines of the mouth clearly indicates diminished sizes of the dental arches. This lack of normal contour of the mouth will be more impressive when it is remem- bered that at this age a boy ? s mouth should be relatively more prominent than that of a man, for the reason that his face has not yet reached its full growth, while the teeth are full-sized at eruption. FACIAL ART. 701 Fig. 601 shows the reason for this lack of normal contour — namely, lack in the development of the alveolar process and pronounced crowd- ing of the teeth. The correctness of our rule is verified in the corrected occlusion, shown in Fig. 744, and in the restored facial lines in Fig. 617. Fig. 618 shows the profile of the face of another boy, aged eleven, whose facial lines were also thrown out of balance by reason of mal- occlusion of his teeth, Class I. Again, it will be noticed that the chin and nose are in good harmony with the general contour of the face, and that the lack of balance is confined to the mouth, and that this time the lips, both upper and lower, instead of being flat and sunken, as in Fig. 618. the last case, are too full and prominent. By referring to the mal-occlu- sion shown in Figs. 755 and 756, we at once see the reason. The teeth, instead of being bunched in the canine region and flattened in front, are bunched, rotated, and prominent in the incisor region. Another point will be noted in this connection — namely, that it is the unnatural position and prominence of the upper teeth that causes the lower lip to protrude. When the lips are closed naturally over teeth in normal occlusion, the lower lip rests against the tips of the upper incisors, and it is the upper teeth, not the lower, as is usually supposed, that estab- lish the curve of the lower lip. In this case, however, there is also another reason why the lips are so prominent — namely, that owing to the excessive overbite (due to crowding of the incisors) the space for the 702 ORTHODONTIA. lips is too short for their natural closure, and when brought together they are protruded unnaturally, giving an expression as of pouting to the mouth. Fig. 760 shows the occlusion after each tooth had been normally placed, which also naturally resulted in establishing the normal length of bite, and the placing of the features in fine balance, as shown in Fig. 619. Fig. 620 shows the profile of a young girl whose mal-occlusion, belongs to Division 1, Class II., and the lines of inharmony shown in this face are characteristic of all cases of this division of this class of mal-occlusion, and also of the subdivision. In cases belonging to the first class, as we have seen, the mouth is Fig. 019. , Fig. 620. the only feature greatly out of harmony ; but in these cases the nose, the mouth, and the chin must be greatly out of balance, both with each other and with the general contour of the face, due to the type (distal) of mal-occlusion of this class, as illustrated in Fig. 602. To attempt to restore balance and harmony of proportion to this face by placing all the teeth in normal occlusion is perhaps to seem to put our rule to a severe test, but its correctness is shown in the result on the facial lines in Fig. 621, and while the face may still not be beau- tiful, we believe that by no other means could it have been placed in so nearly ideal balance or harmony. It will be observed that this type of face differs greatly from the straight-line Apollo face ; yet in cases of mal-occlusion both types of face are equally susceptible of being restored FACIAL ART. 703 to the correct balance normal to each, and both by the same method — namely, the establishment of normal occlusion. Since in this case there has been established normal relations of the muscles and of the inclined planes of the teeth, and normal nasal respiration has also been established, the further development of this face will be toward the normal — toward harmony — instead of in the opposite direction, as had been the case since the day the nasal trouble first caused mouth-breathing, or since the first abnormal locking of thei inclined planes of the first permanent molars. The face oii'the left of Fig. 622 shows the profile of a young man's face which is fairly typical of the lack of balance of facial lines due to Fig. 621. w V "11/ 'T ^* >■ 7 \ mal-occlusion of the second division of Class II. The mal-occlusion is shown in Fie. 795. The head is large and well shaped, and the forehead and nose strong and in good balance, but there is a weakness about the mouth and chin that is greatly out of keeping with the general contour of the head. We have but to study the mal-occlusion to readily detect the cause — namely, distal occlusion with normal nasal and lip functions which have pushed the upper incisors back to occlude with the retruded lower incisors and caused a crowding and overlapping in the canine region. Again, the rule was applied and each tooth made to occupy its nor- mal position, with the most gratifying result on the facial lines, shown on the face in the right of Fig. 622. Those weak lines of inharmony have been changed to others of strength and harmony of balance, in 704 ORTHODONTIA. contrast to the lines that must have followed had extraction been resorted to as the plan of treatment. The restored occlusion is shown in Fig. 796. The disfiguring effect on the face caused by mal-occlusion of the Fig. 622. subdivision of this division of Class II. are similar to those just show n in the full division. Fig. 623 shows the profile of a girl, aged thirteen, whose facial lines were thrown out of balance by reason of mal-occlusion of Class III., as shown in Fig. 812. A very superficial study of the mal-occlusion Fig. 623. Fig. 624. m is sufficient to show us the reason for the flat upper lip and unnatural prominence and heaviness of the chin and lower lip. The simple application of our rule produced the result in facial lines shown in Fig. 624, and in occlusion shown in Fig. 813. FACIAL ART. 705 When the teeth are placed in conformity to the plan of nature, the lines of the mouth are of necessity molded into the most harmonious that human effort can produce. Thus far we have considered the marring effect on the facial lines resulting from mal-occlusion when the normal number of teeth are present ; but there is another phase of mal-occlusion almost if not quite as common and equally destructive to the balance and beauty of the face — namely, the lack of teeth from non-development or non-eruption, or their loss from extraction. The loss of even a lateral incisor not only produces great inharmony Fig. 625. of occlusion, but equal inharmony in the facial lines. Fig. 625 shows the profile of a young lady whose upper right lateral incisor failed to develop, as was revealed by the arrays, and the resultant inharmony in the relations of the upper and lower lips, as well as the impleading angle between the upper lip and nose, is readily seen. It can be imag- ined how great would have been the improvement in the facial lines had that tooth developed normally and the upper arch been enlarged to accommodate it. Since this is true, what must we think of the frequently advocated practice of extracting one or both lateral incisors or even canines in the supposed hope of relieving crowded conditions of the teeth ? The profile on the left of Fig. 626 shows the effect on the facial lines of an effort to prevent mal-occlusion by the extraction of the per- fectly sound four first permanent molars at the age of nine years, which is in keeping with a belief still practised by many of the old school. We 45 706 ORTHODONTIA. need possess very little artistic perception to readily detect the great inharmony of the mouth with the other features. The lack of balance is so pronounced as possibly to create the impression that all the teeth have been lost, and that the lady is wearing badly proportioned artificial dentures. The profile on the right of Fig. 626 shows the facial lines restored to normal balance, or as nearly so as was possible at that age of the patient, established by the placing of the teeth that remained in their normal relations. Fig. 772 shows this, and the case ready for the inser- tion of artificial substitutes for the missing molars. Fig. 626. Fig. 627 shows the profile of the face of a young lady where extrac- tion of both upper first premolars was resorted to by the writer several years ago in carrying out the old plan of treatment for the reduction of " labial protrusion of the upper incisors," or a case belonging to Division 1 of Class II. The effect of this treatment, instead of improving the facial lines, especially the angle of the nose with the upper lip, was to cause their greater inharmony, and has been the occasion of lasting regret. The writer wishes to indelibly impress on the mind of the student that since normal balance of the lines of the mouth with those of the other features is dependent on the normal occlusion of the teeth, they are necessarily thrown out of balance and out of harmony just in proportion ETIOLOGY OF MAL-OCCLUSION. 707 as the teeth are out of normal occlusion, and that since extraction always produces mal- occlusion just in proportion to the number of teeth ex- tracted, where mal-occlusion did not previously exist, and exaggerates and complicates it where already existing, its effect on the facial lines is inevitably as inharmonious, not to say deforming, as its practice is unpar- donable. Extraction is further discussed in the section on Treatment. Ftg. 627. Etiology of Mal-occlusion. Many of the causes which are operative in producing mal-occlusion are as yet very imperfectly understood. Only a few of those most easily recognized will be here considered. Premature Loss of Deciduous Teeth. — The deciduous teeth not only perform the important function of masticating the food required by the child up to the period of their normal loss and their replacement by the succeeding permanent teeth, but they also assist in a mechanical way in the development of the alveolar process, and probably in the develop- ment of the jaw as well. The permanent teeth being larger and more numerous than the deciduous, the greater space required for them is provided principally by 708 ORTHODONTIA. the lengthening of the lateral halves of the dental arches. This is influ- enced largely by the development and eruption of the permanent molars posterior to the deciduous molars. If the mesio-distal diameters of the deciduous teeth be not impaired by caries and the teeth remain the nor- mal period, the first permanent molar in taking its position in the arch must force its way between the second deciduous molar and the ramus of the jaw if below, or the maxillary tuberosity if above. Coincident with the development of the jaw, the deciduous teeth are carried forward, and the normal mesio-distal lengthening of the process takes place. If, however, one of the deciduous teeth be prematurely lost, as, for example, the lower first molar, the erupting permanent molar will exert its wedging influence only distally to the lost tooth ; it will occupy a portion of the space, and will not cause any forward movement of the anterior teeth. If, meanwhile, no teeth have been lost in the same side of the opposing arch, the wedging process will have pushed forward the deciduous teeth and the normal development will have occurred. There will thus be an inequality between the jaws on the affected side, with the establishment of mal-occlusion. And this is not the only evil, for, the space occupied by the lost tooth having been closed or greatly diminished, the eruption of the succeeding permanent tooth (the first premolar) will be prevented entirely, or it will be forced into buccal, or, possibly, lingual occlusion, as in Fig. 702. The shortened lateral half will not develop, and the lower arch will consequently be smaller than normal, which must result in protrusion of the upper incisors by the lower lip being forced beneath them, or, as we have already noted, in an irregular arrangement of the teeth in the upper arch through the effort of nature to restore harmony in the sizes of the two arches by lip pressure, with a corresponding inharmony of the facial lines. While probably the greatest harm results from the premature loss of the second deciduous molar or canine in either arch, the principle applies to the loss of any of the deciduous teeth, the difference being only in degree. The mechanical influence of the deciduous teeth in the development of the dental arches is so important that they should not only by all means be retained their full normal period, but, if they become affected by caries, their full mesio-distal diameters should be restored by suitable fillings after sufficient separation. Likewise, if a deciduous tooth be lost through the premature absorption of its root, the full space occupied by it should be maintained by some suitable retaining device. Prolonged Retention of Deciduous Teeth. — One or more of the deciduous teeth are occasionally retained beyond the normal period. In this event the succeeding tooth will either be prevented from erupting or will be deflected to a malposition. ETIOLOGY OF MAL-OCCLUSION. 709 Loss of Permanent Teeth. — What has already been stated in regard to the mechanical influence of the deciduous teeth in assisting the nor- mal development of the dental arches and promotion of harmony of the facial lines is equally applicable to the permanent teeth up to the period of their full eruption, or until the last of the molars have taken their positions. This is a point of such importance that it should be carefully considered by all teachers and students. If one or more of the per- manent teeth anterior to erupting molars be extracted, the wedging process, so necessary in developing the arch, serves only to close the space thus made, and there will be no carrying forward of the teeth and process. The evil effects already enumerated as arising from unequal development of the two arches. will follow. It should also be borne in mind that the interdependence of the teeth is so great at all times that Fig. 628. the loss of one or more at any period in their history must have a marked influence on the remaining teeth. Tardy Eruption of Permanent Teeth. — It occasionally happens that a tooth, with or without apparent cause, fails to erupt, and remains imbedded in the alveolar process for months, or even years. Usually the space is partially or wholly closed by the adjoining teeth. The impac- tion of the canine is the most common of any of the teeth, owing to the fact that it erupts after both its mesial and distal associates, and must in all cases meet more or less resistance from them. If, later, efforts toward eruption occur, the tooth must necessarily be deflected, or force other teeth into malposition. Supernumerary Teeth. — Supernumerary teeth, as their name implies, are anomalies, or extra teeth above the normal number of thirty-two. In outline they rarely resemble any of the typical tooth forms, being most 710 ORTHODONTIA. commonly peg-shaped or conical. Although they may erupt in any part of the dental arches, or even nearly cover the entire vault of the upper arch, as shown in a model in the writer's collection, and also in two or three other well-known cases, their favorite location is between the cen- tral incisors, in the region of the laterals, or in the bucco-embrasial spaces between the molars. The reason for their appearance is not clearly established. Habits. — The habit of sucking the thumb, lip, or tongue, so fre- quently formed by young children, while rarely causing displacement of the deciduous teeth, will, if persisted in during the eruption of the per- manent incisors, cause their marked mal-occlusion. In the case of thumb-sucking, fortunately, the habit is usually broken before any marked evil effects result, so that cases where mal-occlusion Fig. 629. has really resulted from this habit are rare and easily recognized. The upper incisors and canines are always drawn forward and to one side, according as the thumb of the right or left hand has been used, while pressure from the back of the thumb upon the lower incisors causes their marked displacement lingually. These cases are frequently confounded with those of protrusion belonging to Division 1 of Class II. The condi- tions and results are very different, the latter being mouth-breathers, the former, never, as such action would be an impossibility. This is illus- trated in the difficulty which infants experience in nursing while suffering from temporary obstruction of the nasal passages resulting from coryza. The pernicious habit of biting the lower lip, or pressing the occlusal edges of the upper teeth against its outer surface, has a tendency to move ETIOLOGY OF MAL-OCCLUSION. 711 the upper centrals forward, thus lessening their natural resistance to the narrowing of the lateral halves of the arch. Such a case is shown in Fig. 628. In this case the mal-occlusion was easily reduced, but the habit of biting the lip was still persisted in for a period of nearly two years, necessitating the continued wearing of the retaining device for that length of time. This habit is more common than seems to be generally supposed, is often extremely difficult to over- come, and probably accounts for many ultimate failures in tooth regu- lating. It is always a marked accompaniment of cases belonging to Division 1 of Class II. and its subdivision, and unless it be overcome Fig. 630. and the normal functions of the lips regained, the incisors cannot be kept in their normal positions. Another habit, though quite rare, that of resting the tongue between the upper and lower incisors, produces the effect shown in Fig. 629. The pressure upon the incisal edges prevents full eruption and holds the teeth in infra-occlusion, while the molars, being held apart much of the time, lengthen into positions of supra-occlusion from lack of resistance. Nasal Obstructions. — When there is normal nasal respiration and normal relations of the dental arches, the teeth, and the muscles, the 712 ORTHODONTIA. conditions are such as to perfectly maintain the equilibrium and the mutual support necessary to the normal development of the teeth and jaws. Should nasal obstructions occur in the developing child, induc- ing habitual mouth-breathing, immediately the equilibrium is disturbed, the lips and muscles are placed on a different tension, and pressure upon the arches, instead of being equal, is localized, being greater than normal at some points and less at others. No matter how strenuously it may he denied, mal-occlusion of the teeth and abnormalities in the formation of the bones of the jaws naturally follow. The undeveloped nose and adjacent region of the face, the vacant look, the short upper lip, the open mouth, and irregular teeth of the mouth-breather are common sights familiar to all (Fig. 630). Alveolar Process and Peridental Membrane. The importance of a thorough knowledge of the alveolar process and peridental membrane is perhaps greater in orthodontia than in any other branch of dentistry, for to the orthodontist these tissues are secondary only in importance to the teeth themselves ; and it is largely owing to our intelligent comprehension and handling of these tissues that we are enabled to successfully correct malpositions of the teeth. It is unnecessary to here enter into an extended discussion of these structures. No thoughtful person can study the arrangement of the fibres of the peridental membrane without being impressed with their wonderful perfection of adaptation for resisting the various tooth movements inci- dent to occlusion and mastication, and a knowledge of this arrangement is of peculiar interest to the orthodontist, enabling him to better com- prehend not only the amount of force required and difficulties to be overcome in moving teeth, but the necessary anchorage to be gained from teeth in performing the operation, as well as a far better insight into the problems of retention. Tissue Changes Incident to Tooth Movement. — When force is exerted upon the teeth to be moved two principal changes take place in the alveolar process : first, a bending of the process ; second, absorp- tion of the process in advance of the moving tooth and deposition of bone behind it. These changes vary greatly according to the age of the patient, in different patients of the same age, in the direction of movement, and also in the rapidity of movement. In youth, or before the bone has become dense, it permits of much bending, so that incisors may be moved out of inlock in a few hours, or the lateral halves of the arch may be widened in a very few days, ALVEOLAR PROCESS AND PERIDENTAL MEMBRANE. 713 or before much absorption could have taken place in advance of the moving tooth. In further proof of this the process will be found upon examination to be intact about the roots, not only on the labial side, or in front of the moving tooth, but on the lingual, or opposite, side as well, it having been dragged after the moving tooth. This is easily explained when we remember the cancellous structure of the bone, the inelasticity of the fibres of the peridental membrane, and their very strong attachment to it. While more or less springing of the bone is probably always an accompaniment of tooth movement, yet in proportion as the bone becomes dense with age, so the modification of the process attendant upon tooth movement changes from springing to the slower action of absorption and the still more slow deposition of bone. Coincident with the changes in the bone there are also pronounced changes taking place in the peridental membrane. As force is exerted on the moving tooth the membrane is compressed in front of it, between it and the wall of the socket, while a greater tension of the fibres of the membrane takes place on the opposite side. As a result of this tension and compression the nerves of the membrane are impinged upon, causing a greater or less sense of pain, which, as a result of the slight movement of the tooth and temporary paralysis of the nerves from pressure, subsides more or less quickly according to the amount of inflammation present. As a result of this pressure the absorbent cells, or osteoclasts, are stimulated to increase in number and activity. They immediately engage in the absorption of the portion of bone most involved in the movement, as well as of the bone attachments of the fibres on greatest tension. While these changes are taking place the osteoblasts have become active, and have begun filling up the depression and reattaching the fibres by the redeposition of bone. But as this is a much slower process than that of absorption, the tooth is found to be more or less loose in its socket at the completion of its movement, as well as long after, necessitating its being supported by means of the retaining devices until the deposition of bone shall be complete and a perfect socket reformed for its support in its new position. If a tooth be elevated in its socket, the principal change involves the peridental membrane. The fibres at the end directly resisting this movement are severed, and the oblique or suspensory fibres are stretched and recurved upon themselves. The result of the partial withdrawal of the conical root is increased space, not only at the end, but also on the sides of the root, so that there is considerable freedom of movement 714 ORTHODONTIA. of the tooth, necessitating the deposition of bone over the entire surface of its socket, as well as increase of height of margin and a reorganiza- tion of the entire system of fibres. This explains the necessity for such protracted suspensory retention, and the comparative ease with which the movement may be performed. In the movement of depression — the most difficult tooth movement — the bone must be absorbed by the osteoclasts over the entire surface of the alveolus to allow for the advance of the root of conical form. The fibres of lateral support are stretched and placed on different angles, while the suspensory fibres are also stretched and severed at their points of attachment to the bone, thereby necessitating more dis- turbance of tissues and requiring more force and time than any other of the seven movements. In the rotation of a tooth, as probably most of the fibres indirectly tend to prevent the tooth from turning in its socket, and, in addition, there are an unusual number at the four angles so arranged as to directly resist such action, little springing or bending of the process is probable, the principal change being the absorption of the fibres and bone involved along the entire length of the root, thus accounting for the great force necessary for performing this movement. In all cases of tooth movement a large number of the fibres of the membrane remain on tension long after the movement is complete, the force they exert tending to draw the tooth back to its original position, thus necessitating considerable support from the retaining devices until the tissues have become thoroughly re-established in harmony with the tooth in its new position. In accomplishing the movement of teeth lingually, labially (or buc- cally), mesially or distally, the principal change is in the position of the crown of the tooth, it being tipped into its correct position. The usual supposition is that the tooth in the alveolar process acts as a lever, the crown, or long end of the lever, moving in one direction, and the apex of the root in the opposite direction. To make clear these sup- posed changes, and especially the extent of the movement of the apex, writers have frequently used the illustration of a post driven about one- third its length into the earth. If force be exerted at right angles to a side of the post near its top, the post will act as a lever in the dis- placement of the soil, the two ends of the lever moving in opposite directions, and the pivotal point being somewhere near the beginning of the last third of the imbedded portion. The illustration is a poor one and very misleading, as the mechanical conditions are very different. Doubtless this would be the result if the tooth, like the post, had but one resistant substance and that equally distributed in all directions about its root, but, as is shown by a study ALVEOLAR PROCESS AND PERIDENTAL MEMBRANE. 715 of the alveolar process, the bone varies greatly in thickness over dif- ferent portions of the root and in different teeth, so the amount of dis- placement of the apex of the root of a tooth depends, oftentimes, upon the location and the movement of the tooth, and whether one tooth or a number in the same region are being moved in the same direction. In reality there may be little or no displacement of the apex, or there may be considerable. In the first place the alveolar process is not a level plane, like that in which the post is implanted, but a projection or high ridge, of elastic structure, and admits of some bending laterally, its susceptibility to this action increasing proportionately as we approach the top. The pronounced bending of the process is a matter of common observation in efforts at extraction. Again, the mechanical difference in the attachment of the post to the soil and the tooth to the alveolar process is such as to still further add greatly to the difference in the results of their respective movements. As the apex of the root is implanted deeply in the bone, which is greatly thickened in its lingual direction and reinforced by the strong cortical layer of the alveolar process, its movement lingually could not well take place as a result of springing. This movement is further strongly resisted by the innumerable inelastic fibres that encapsule the apex, radiating in all directions for its firmest possible attachment to the bone, their ends being enclosed in its structure. So in the labial movement of the crown, the lingual movement of the apex of the root is not only resisted by the bone in front, but also behind and on each side, by reason of its attachment, while with the end of the post little, if any, resistance is offered by the soil behind or on either side, but only by that in front. Another difference. The force for the movement of the post is applied remote from the fulcrum, while the force exerted on the tooth by the ligature is applied close to the fulcrum, or at a point best calcu- lated to facilitate the bending of the alveolar process in the labial direction. Again, unlike the post, several teeth may be associated in the move- ment, which adds still further to the possibilities of the labial, as w^ell as adding correspondingly to the impossibilities of the lingual move- ment of their apices. In the lingual movement of incisors there is often considerable labial movement of the apices of their roots, owing to the lesser resistance offered by their thin covering of bone and the much greater thickness of bone on the lingual surfaces of the roots. This result is often noticed following the reduction of protruding incisors, as in cases belonging to Division 1 and its subdivision of Class II. 716 ORTHODONTIA. In the similar movements of the upper eanines and premolars, prac- tically the same changes in the positions of the roots follow. In the movement buccally of the upper molars there is bending or absorption of the outer plate, the palatal roots are elevated in their sockets to make easier the tipping of the crown, with probably no movement at the apices of the buccal roots, unless it be that they are forced deeper into their sockets. In the lingual movement of the same teeth there is more or less bending of the process, the forcing deeper into its socket of the palatal root, with perhaps some elevation in their sockets of the buccal roots. In the same movements of the lower molars there is greater displace- ment of the apices of the roots in the opposite direction from which the crowns are moved, owing to the great thickness of the buccal plate of the alveolar process. In the movement of teeth mesially or distally there can be little or no bending of the labial and lingual plates, the chief resistance now being offered by the septa and the peridental attachments, and the movement of the teeth more nearly resembles the movement of the post, the apex moving slightly in the opposite direction from the crown, as in Fig. 678. The Pulp. — While the pulp of the tooth is a tissue more or less involved in tooth movement, when the operation is properly performed this tissue is practically undisturbed and should suffer no real injury. On the other hand, its normal function may be so interfered with as to cause it to suffer marked disturbance and even complete devitalization, especially if the movement be conducted too rapidly, or the force be too abruptly applied. The principal danger, however, arises from conges- tion and inflammation of the tissues of the apical region, causing the partial or complete strangulation of the vascular supply to the pulp. In view of these facts, it should be our aim to prevent, so far as pos- sible, all tendency toward inflammation. If the pulp becomes partially congested, as is usually evinced by a slight change in color, as shown through the enamel, and by sensitiveness to thermal changes, the tooth should be allowed to remain passive for several days, when, usually, these symptoms will subside. The writer has noticed several instances where these symptoms have been markedly manifest, and have wholly subsided under palliative treatment. Sometimes, however, complete devitalization will follow, and while the death of the pulp under these conditions is to be regretted, the consequences are not of sufficient importance to occasion any more regret than when devitalization is found necessary in the treat- ment of teeth for caries. The principal evil following the death of the pulp in these cases is the possible permanent discoloration of the crown, which is more liable ALVEOLAR PROCESS AND PERIDENTAL MEMBRANE. 717 to follow the speedy death from strangulation than the slow devitaliza- tion from the encroachment of caries. For this reason, whenever com- plete devitalization of the pulp is apparent, it should be immediately removed, the tooth treated, and the canal filled after the best pre- scribed methods, when the further movement of the tooth may be conducted with probably no greater fear of inflammation than if the pulp were intact. It is often desirable to perform tooth movement soon after the erup- tion of the teeth, or at a time before the root is fully formed, the end of the root then having a broad, funnel-shaped opening. If the movement be intelligently performed, the pulp at this age should suffer no greater disturbance than when the root is fully calcified. In fact, there is less probability of strangulation and death than later, when the foramen is greatly diminished in size. Physiological Changes Subsequent to Tooth Movement. — So far we have considered the physiological changes which take place in the tissues during tooth movement, but we must remember that certain very important changes also occur subsequent to tooth movement. To better understand these changes we must keep in mind the conditions previ- ously existing. The development of mal-occlusion is gradual, and, in proportion as the positions of the teeth deviate from the normal, a corre- sponding deviation is necessitated in the development of the alveolar process, and, to a greater or less degree, in the bones of the jaws, vault of the arch, the nasal tract, and the muscles of the face. All being out of harmony, the tendency is usually to favor still greater inharmony, or departure from the normal, as growth and development progress. After the crowns of the teeth have been moved into correct positions in the line of occlusion and harmony of the occlusal planes has been estab- lished, the positions of the teeth and function of the occlusal planes have been so changed as to exert a different influence upon the bones and mus- cles. The tendency now is to assist and stimulate nature to efforts toward the rearrangement of these tissues and their normal growth and develop- ment, in accordance with the demands of the teeth in their new positions and with her original design. Evidences are common throughout sur- gery of nature's wonderful inherent power to remedy her defects, and of her prompt response as soon as favorable conditions for self-assertion have been established. The natural changes following; the intelligent correction of mal-occlusion are often pronounced and gratifying. The cognizance of the possibilities of these changes should in many instances modify our plan of treatment from what it would be were we ignorant of them. Very frequently where there has been change of position of a number of teeth, especially in both arches, some may occupy planes of greater elevation than others, or the cusps of some 718 ORTHODONTIA. may not occupy exactly normal mesio-distal relations ; but if we have succeeded in placing the teeth so that the inclined planes of their occlusal surfaces favor their normal positions, their proper heights and relations will gradually become established as a result of occlusion. In some cases the incisors may apparently be much too short, but after a few weeks or months, when the posterior teeth shall have become settled in their new positions, the length of overbite of incisors will be normal. Another noticeable and most important change is that following the movement labially of the crowns of a number of incisors, as in Fig. 631, the crowded and bunched positions of the incisors have pro- duced marked arrest in the development of the alveolar process in the region of their apices, so that after correction they are found to stand at a very pronounced angle, with an abnormal depression in the region of the apices of their roots (Fig. 632), and an apparent overprominence of the lip, often suggesting the impossibility of their being maintained in such positions and the desirability of extraction in order to reduce Fir;. 031. Fig. 632. this prominence. But in a large percentage of cases the apparent prominence is due to lack of development of the alveolar process and the lingual positions of the apices of the roots, which have developed thus in accordance with the demands of the teeth in mal-occlusion. The crowns of the teeth now being in normal occlusion, nature is stimulated to continue the development of the alveolar process, and to shift labially to normal positions the apices of the roots, so that in due time there will be the full normal contour of the alveolar process and the teeth will stand at a normal angle, the result being a corresponding improvement in the contour of the face in the region of the base of the nose — a far better result than could have taken place had extraction been resorted to. The changes here outlined are shown to have taken place in Fig. 633, which represents a model of the corrected case three years later than that shown in Fig. 632. The discovery 1 of the fact that the nutrition of the structures will ' Angle, Mal-occlusion of the Teeth and Fractures of the Maxilla?, sixth edition. ALVEOLAE PROCESS AND PERIDENTAL MEMBRANE. 719 be so stimulated as to develop the alveolar process and actually shift the apices of the roots of the teeth amounts to an important step in the evolution of this science, for it makes inexcusable the sacrifice of teeth in order to provide room in the arches for the teeth that remain. It is well, however, to remember that this subsequent development is very active and quick to respond in youth, or during the period of eruption of the incisors and for some years later, but that it diminishes in activity in proportion to the age of the patient, until, after the age of maturity, it is doubtful whether any perceptible filling in of the bone takes place — another strong evidence of the importance of the movement of teeth in early youth. It is quite probable that in the case above cited, while the develop- ment of the alveolar process was progressing, a change in the positions of the crowns of the teeth of both arches was also being effected, there being a slight movement distally on account of the increase of lip pressure due to the more prominent positions of the incisors. This, Fig. 033. however, could not have occurred unless there had been full normal function of the lips, accompanied by habitual nasal breathing. Again, where one or both of the lateral halves of the upper arch have developed with the teeth in lingual occlusion, the result is to pre- vent the normal development and width of the arch, as in Fig. 732. It will be observed that force incident to mastication is brought to bear upon the crowns at an abnormal angle to their axes, with pro- nounced perversion in the development of the alveolar process and of the jaws, abnormal height of the vault of the arch, and greatly marred facial lines. Following the labial tipping of the crowns of the upper molars and the lingual tipping of those of the lower arch, the force of occlusion will be received at the proper angle with the axes of the teeth, or prin- cipally upon the buccal cusps of the lower molars and lingual cusps of the upper molars. In this case, as in all similar cases, marked changes followed. The 'width of the face in the region of the upper 720 ORTHODONTIA. jaw was perceptibly increased, and diminished in that of the lower, with a corresponding improvement in the vault of the arch and function of the nose, which continued until probably normal proportions were established. There are also noticeable changes following the reduction of marked prominence of the upper incisors, as in those cases belonging to Division 1 of Class II. As the crowns of the incisors are moved lingually the apices of the roots, as we have already noted, are moved to some extent in the opposite direction, which is evinced by more or less of a fluted appearance of the alveolar process in the region of their apices, and to some extent, a greater prominence of the lip in the region of the base of the nose. But if normal function of the nose and lip has been established, there will follow a return of the apices to their normal, positions, with corresponding normal development of the alveolar process surrounding them, and a corresponding lessening of the prominence of the tissues at the base of the nose. Other changes following tooth movement are mentioned in connec- tion with cases discussed under Treatment. Models. The first step in the study of all cases preparatory to treatment is the taking of accurate impressions of the teeth, from which accurate articulating models of both arches are made. Such models not only assist in the classification and diagnosis of cases, but also aid in deter- mining the proper plan of treatment, and are also exceedingly valuable for reference during its continuation, for by comparing the models with the natural teeth at each visit of the patient we may not only keep posi- tively informed as to the exact movements of the malposed teeth, but any unfavorable movement of the anchor teeth may also be imme- diately detected. Accurate measurements of the extent of movement of any tooth or teeth may also be made at any time, with such models as a basis. Material for Impressions. — Models are only valuable in proportion as they are accurate, and the only models approximating accuracy are those made from plaster impressions. These models must show not only both arches and the relative positions of the teeth and cusps, as well as the vault of the arch, rugae, and gums, but must also correctly show as much of the roots and their positions as are indicated by the gums and alveolar process up to the point where the attachment of the muscles renders obscure the further shape of the jaw. Models sufficiently perfect cannot be made from impressions taken in modelling compound or other of the plastics. The shape of the jaw, together with the shapes and inclinations of MODELS. 721 the teeth, make the removal of a plastic impression, without change of form, impossible. The degree to which arrest of development of the alveolar process has taken place, especially in the region of the roots of the incisors, so important to accurately record in the model, can only be the merest supposition in a model made from a plastic impression. When the correct method of taking plaster impressions has been learned the operation occasions but little, if any, more trouble to the operator, or objection from patients than if one of the plastics were used. The Trays. — The writer's trays, shown in Figs. 634 and 635, are Fig. 635. best suited, being much higher than the ordinary trays. In taking an impression care should be taken to select a sufficiently large tray, which should be bent to conform more nearly to any peculiarity in the shape of the jaw; this will not injure the tray. 46 722 ORTHODONTIA. Taking the Impressions. — Good impression plaster is mixed in the usual way and carefully distributed, as shown in Fig. 636, the shape and height of the trays making but little impression material neces- sary. It will be observed that the greater amount is placed in the ante- rior part of the tray and made to extend over the outer edge of the rim, none being allowed in the vault of the tray. It is now placed squarely in position and the plaster allowed to rest evenly in contact with the occlusal edges of all the teeth, but not forced up into position. The lip is then raised, and the plaster extending outside of the rim of the tray is carried high up underneath it with the finger. This is to insure the expulsion of air, as well as a high impression. The tray is then forced up evenly until the points of the teeth touch, or nearly touch, the bottom of the tray, and steadily supported upon the end of the index-finger only. To expel the air from the cheeks they are now gently manipulated, but not drawn down, as to do this would force Fig. 636. down a portion of the plaster and prevent one of the important objects — viz., a very high impression. It should be allowed to remain in position until the plaster has become thoroughly set, which is very important, as the harder the plaster is allowed to become, the more perfect will be the impression. The tray is now loosened and taken away, leaving the impression in the mouth. It is essential that the tray should loosen easily from the impression ; hence the importance of its being kept clean, bright, and smooth. Two grooves are then scraped or cut in the hardened plaster on a line parallel with the canine teeth, but not cut quite through. Then with a quick pry with the point of a knife the anterior plate is loosened. The lateral pieces are then broken off with the thumb and finger, when the large piece covering the roof of the mouth alone will remain. This may be readily worked loose, and if the operation has been carefully MODELS. 723 performed the impression will consist of four pieces, although to have a much greater number would in no way injure it. After the pieces of the impression are dry they are united by means of wax, and should present the appearance illustrated in Fig. 637. This method of taking impressions preserves the fine points of the interdental spaces. We believe it to be the only practicable way of taking an accurate impression. In like manner the impression of the lower arch is taken, removed, and united, being careful to observe the essential points — namely, carry- ing the impression material, which has been built up and outside of the anterior part of the rim of the tray, well down beneath the lip with the Fro. 637. finger before forcing the tray home, then expelling the air by gradually working the cheeks while the tray is steadily held by the ends of two fingers of the left hand, one to rest on the top of each lateral half. Varnishing- the Impression. — The impressions being united, they should be coated very evenly with shellac varnish. At the expiration of half an hour, or when the varnish has become hard, a second coat should be applied over the occlusal surfaces of the teeth and rough points only, not over the smooth surfaces, especially the labial gum sur- faces. Dry again, and then apply over the entire impression a very thin, even coat of sandarac varnish. 1 1 It is important that both of these varnishes shall be of the proper consistence, which is difficult to describe. If too thin, the hard, glossy surface will be wanting, and it will be difficult to separate the impression without injury to the model. If too thick, all fine tracings of the impression will be obliterated. 724 ORTHODONTIA. The Models. — After drying for half an hour the impression will be ready for filling, which may be best accomplished, in order to insure expulsion of air-bubbles, by quickly and carefully painting the plaster into the tooth-cavities with a small camePs-hair brush, then rapidly fill- ing with a spatula, gently shaking the while (never jarring), after which it should be turned bottom upward on a glass slab. After the plaster has thoroughly set, the pieces of the impres- sion may usually be very readily separated in the same order in which they were removed from the mouth. Should any air-cavities be found in the model, they may be remedied by the artistic use of a delicate brush in the application of plaster of a creamy consistence. A cusp or broken tooth may in like manner be repaired. The models may now be trimmed, and not only will there be a surface as smooth as polished marble, but each cusp, all the interdental spaces, and the rugae, as well as the inclinations of the roots, and even the Fig. 638. Model plane. minute " stipples " of the gum, and the developmental lines of the enamel, will all be accurately and beautifully shown. Any coating of paint or varnish only detracts from the beauty of such models. The models should be trimmed according to lines of graceful propor- tions and artistic balance. Formerly this trimming was all done with a knife, and the proportions judged with the eye. Now the finer trimming is easily, quickly, and accurately accomplished by means of the model plane and combination square, shown in Fig. 638. The use of a plane for this work was first suggested by one of my students, Dr. F. S. McKay, but those procurable were almost useless, as, on account of being made of iron and rusting, they greatly discolored the models. The writer's plane, shown in the engraving, is made of brass, with blade of hard bronze, and effectually overcomes this, and the combining of the plane and rule is another feature of great convenience. After they are trimmed, the models should be carefully compared MODELS. 725 with the natural teeth, and the occlusal relations indicated by two or more pencil markings, so that the proper points of contact may after- ward be readily found. These serve the purpose much better than any form of an articulator. As soon as the teeth have been completely moved, another impression should be taken and models made. This is done after all appliances have been removed and the teeth thoroughly cleansed, and immediately previous to adjusting the retaining devices. These models are valuable for comparison with the natural teeth during the period of retention, as well as for future reference. It is also of advantage to have " study models " occasionally made during treatment and retention by pressing a piece of softened wax, about three-eighths of an inch deep, on to the occlusal edges of the teeth, to accurately show their positions and such appliances as may be upon them only. Fig. 639. Fig. 640. A collection of fine, accurate models is not only an incentive to keener interest and better work, but is a most valuable form of " library " in itself, in which many valuable phases of the subject are recorded that can never be reduced to writing. Models should never be mutilated by the fitting of bands and appli- ances. While they may serve as a basis for general measurements for the appliances, the fitting should always be done to the natural teeth. Photographs. — Quite as important as models are good photographs of the patients' faces, in which are represented full profile and front views in a simple, natural pose. These are far preferable and more relia- ble in judging the harmony and inharmony of the patient's face than is the plaster cast of the face. Skiagraphs. — Skiagraphs, now so easily and quickly made, are often of great value in settling all doubts as to whether teeth be missing, or 726 ORTHODONTIA. their exact locations and forms if merely imbedded. While these points may be determined in the majority of cases by careful inspection of the contour of the alveolar process, and digital pressure, together with the use of the exploring needle, yet where any doubt exists the skiagraph should be resorted to. Fig. 639 illustrates a case as revealed by the skiagraph where the canine is so deeply imbedded in the alveolar process as to baffle the ordinary methods of diagnosis. Fig. 640 shows the rare case of a missing permanent canine, the deciduous canine being nearly ready to drop out, its root having been almost wholly absorbed. The first premolar is about to erupt. Where any doubt exists on these points, the #-ray should promptly be employed to eliminate all guessing, so that we may positively know exactly what conditions exist. Regulating Appliances. Two plans are now followed in the designing and constructing of regulating appliances, the first based upon the belief that each case so radically differs from all other cases that an appliance must be invented and constructed from raw material to meet its special requirements. The second plan recognizes the division of mal-occlusion into a few clearly defined classes, having requirements of treatment clearly indi- cated, with fixed, standard forms of ready-made regulating appliances acting upon definite principles, which amply provide for all require- ments of all cases belonging to each class. The first plan is the one which has been most universally employed, and has come down to us from the earliest history of orthodontia ; indeed, much of the literature of the science consists of descriptions of appliances which have been invented to accomplish tooth movements in special cases, until some thousands are recorded, one author alone boasting of many hundred. Wliere something may be accomplished in the following of this plan, it should require no argument to prove that there are many reasons why it is most defective and unscientific. First, it necessitates that each dentist shall be an inventor, and it is well known that the inventive faculty is rather a natural gift than an acquirement, and that it can be exercised successfully only by a very few. Then, as all inventions if perfected must be experimented with, it must follow that each case so treated must be largely in the nature of an experiment, often necessitating many changes in the plan and construction of appliances. Hence all treatment upon such theory must be, and, in fact, has ever been, tedious and costly, and often of doubtful result. Second, another objection is that in following this plan, the construc- tion of appliances must necessarily be more or less crude and lacking REGULATING APPLIANCES. 727 in requisite proportions, for any instrument only reaches perfection as to size, proportion, temper, strength, and finish after much experiment- ing and repeated efforts toward perfection in manufacture. Finally, another objection more serious than all is that as the plan is empirical, with only a vague and indefinite basis from which to reason, the difficulties in teaching and practice become very great and the results greatly limited. After a life of practice the dentist follow- ing this plan must still be in a maze of experiments, and unable to impart much information that could be of assistance to those who may begin the practice after him. The second plan, as we have already stated, recognizes the practi- cability of fixed, standard forms of devices for the requirements of tooth movement necessary in all the various classes of mal-occlusion, the proper forms having been arrived at as a result of careful experi- mentation and close observation in a very large number of cases embracing the greatest variety of mal-occlusion. Instead of hand-made productions by the dentist, which, with his limited experience and meagre facilities, must always fall far short of the ideal, they are, like fine watches, made upon elaborate machinery by the most skilful workmen. If such appliances are practicable, it must become apparent to all thoughtful minds that the advantages from their use must be very great over the first plan, for, instead of being confronted with a confusing and almost limitless number of devices, which can at best only serve as general, vague, and often delusive patterns to him, the student has but to thoroughly familiarize himself with a few standard devices which he may quickly and easily apply. Again, familiarity with and repeated use of standard appliances add greatly to the possibilities of development of skill and judgment in their use, as in the case of the frequent use of favorite patterns of pluggers or excavators which have also been made by skilled experts. And whether or not ideal standard regulating appliances have yet been reached, the possibilities and positive advantages of the principle over the first plan are so marked that we think all teachers who are inter- ested in this branch should make effort toward that direction, rather than to assist in perpetuating a principle so obviously defective that it must be apparent to all that it is a positive hindrance to the real prog- ress of orthodontia. It is now well known that most of the real progress that has been made in dentistry and surgery, and, we may add, in orthodontia, has been since the dentist, surgeon, and orthodontist were relieved of this impractical task by experts who have produced instruments so perfect in design, construction, and finish as to be often in advance of their com- prehension and skill. 728 ORTHODONTIA. The writer's appliances, the description, plan of adjustment, and operation of which will be given farther on, are in direct keeping with the second plan just described. Materials for Construction. — The materials that have been used in the construction of devices for the regulation of teeth are legion — gold, silver, platinum, platinous gold, platinous silver, iridio-platinum, platinoid, aluminum, nickel silver, brass, copper, aluminum bronze, steel, iron, vulcanized rubber, India rubber, wood, silk, hemp, gut, and many combinations of these materials have all been used. None are ideal, yet most of them possess properties of more or less value. After years of experimenting the writer is convinced that the material most nearly filling all requirements is nickel silver. 1 Since its introduction by the writer some eighteen years ago for the manufacture of regulating appliances, it has largely supplanted all other metals for this purpose. Its great practical value becomes more and more apparent with familiarity in its use. It is very susceptible of skilful working, and may be developed to possess great strength and rigidity, or it may be given great elasticity. When properly annealed it is very malleable, yet sufficiently rigid to give it the excellent work- ing qualities so necessary in retention and in reinforcing anchorage. Rolled into a flat ribbon, if it be of the proper quality and properly treated in manufacture, it may be drawn by the band-forming pliers so tightly about a tooth as to conform to its surface with great accuracy, even though it be but three-thousandths of an inch in thickness, and yet it will be sufficiently rigid to withstand driving to place upon the tooth without crimping or changing form if care be used, in striking contrast to gold, silver, platinum, or other metals of the same thickness used for this purpose. Its surfaces are readily united by solder, and its fusing-point is so high that any of the various grades of gold or silver solder may be employed without fear of injuring the band by overheating, if care be taken and the proper flame used. So slow a conductor of heat is it that the excellent method of sol- dering by holding many of the pieces with the fingers may be employed, 2 again in sharp contrast to the other metals we have enumerated. It is susceptible to a high degree of polish, which should always be given to plain bands after setting, and which is lasting in many mouths. Sometimes these bands will assume a delicate bronze-like color, pleas- ing in appearance, and the w T riter has known of their being worn for 1 Nickel silver is an alloy of copper, nickel, and zinc, prepared in varying propor- tions, according to the use for which it is intended. 2 Introduced by the writer in the first edition of his work entitled The Angle System of Regulation and Retention of the Teeth. THE WRITERS APPLIANCES. 729 three years with no change of color. In a small percentage of mouths, however, they do become discolored, even to unsightliness. This fact has given rise to the only prejudice we know of against the use of nickel silver for regulating appliances ; but this objection is trivial in view of its many points of superiority. In those few mouths in which discoloration does take place, however, and where the wearing of the bands in retention for a long time is necessary, it may be better to use platinized gold for the bands. This is the writer's practice in occa- sional cases ; but if the orthodontist will insist on a reasonable degree of cleanliness on the part of the patient, occasionally devoting a few moments of attention to the cleansing of appliances and teeth himself with the soft-rubber disk and pumice, there will be little occasion for complaint. Again, the inexpensiveness of nickel silver brings it in sharp con- trast to gold and platinum, but it is its ideal working properties and not its cost that makes it the most desirable of all materials thus far dis- covered for the construction of regulating appliances. The Writer's Appliances. When the writer first brought out his so-called system of appliances mal-occlusion was yet unclassified, and the " special appliance for each case " method of treatment was the only one taught or practised. In an attempt to reduce the chaos of regulating appliances that cumbered the literature and hindered the progress of orthodontia to something like system and order, these appliances, designated as sets Nos. 1 and 2, with a few auxiliary parts, numbering some twenty in all, were introduced. By their use separately and in combinations it was presumed, and truly, that tooth movements could be much more quickly and easily performed, and with far less annoyance to the patient, than by means of the neces- sarily crude, clumsy, and frequently very inadequate hand-made metal devices, or the far more undesirable, painful, and filthy vulcanite plates, cribs, etc. With the greater development of the science, however, and especially since the classification of mal-occlusion, the writer has gradu- ally dispensed with the greater part of even these few appliances, until at the present time he uses practically but one, or three modifications of a single principle. This principle was given us nearly two hundred years ago by the famous French dentist, Fauchard, 1 and it has since been used in many modified forms. It is now known as the expansion arch, and in conjunction with clamp-bands for the anchor teeth, and the auxiliaries of plain or spurred bands, and wire and rubber ligatures, it is adequate for all necessary movements of all teeth in each arch 1 Le Chirurgien Dentiste ou Traite des Dents, Paris, 1728. 730 ORTHODONTIA. separately, as in Class I. cases, or for the simultaneous movement of all teeth in both arches when used in connection with the Baker anchorage, as in cases belonging to Classes II. and III. The writer's improvements of this appliance may briefly be said to consist in change of metal (nickel silver), modification of form and pro- portions, delicacy of temper, greater length of threading of sides for universal adjustment of size, in the material, style, and proportions of the parts entering into the anchor clamp-bands, and in the various attach- ments, some of which are modified and others newly devised. Important among these is the addition to the clamp-band of the long tubular sheath for the reception of the ends of the arch, which not only protects the Fig. 641. cheeks from abrasion by the threaded portion of the arch, but gives greater stability to the anchorage. Still others deemed very important are the friction sleeve of the sheath of the clamp-bands and extension flange of the arch nuts, the extension rib on the ribbed arch, the sheath hooks, for use in the Baker anchorage, and last and most important, the brass- wire ligatures, descriptions of all of which follow, in connection with instructions for their use. As before stated, there are three forms of the expansion arch. Fig. 641 represents the plain expansion arch E, which is a very elastic round bar, bent to conform approximately to the shape of an ideal dental arch. The sides of this arch are threaded and provided with nuts, which, with THE WRITER'S APPLIANCES. 731 the threaded portion of the arch, accurately fit the smooth-bore tubes of the X and D bands. One end of these nuts is elongated to form an extension flange, which accurately telescopes the friction sleeve of the sheaths of the D and X bands, as shown in the engraving. This form of nut adds another truly valuable improvement to the ex- pansion arch, as it enables us to make the exposed part of the nut very short and compact, at the same time giving greater length of thread and consequently greater strength. Its greatest value, however, is that this extension flange prevents the loosening of the nut by unscrewing Fig. 642. from friction with the tongue or cheek — a common annoyance since screw devices have been used in the mouth. This improvement is also made use of in the writer's jack- and traction-screws. Fig. 642 shows the ribbed expansion arch E, a later modification of the arch last shown, and differing from it only in that it is provided with a delicate rib on the periphery of the unthreaded portion, in which hook- like notches are to be made at desired points to prevent slipping of the wire ligatures. By this means the direction of force on the moving teeth is accurately controlled. It is a most important improvement to the arch. 732 ORTHODONTIA. Fig. 643 shows the third form of the arch, as used by the writer, known as the arch B. It is a smooth, threadless arch, similar in form and temper to the plain expansion arch E, though more limited in use. It is especially designed for use in connection with the Baker anchorage, Fig. 643. having a sheath-hook on each side for the reception of the rubber liga- tures. These little sheath-hooks, Fig. 644, may also be obtained separately for attachment to either of the other arches whenever it may be desired to employ them in connection with the Baker anchorage. Fig. 644. Fig. 645 represents six adjustable clamp-bands. Nos. 1 and 2 are plain, and are used both in regulation and retention. Nos. 3 and 4 are provided with strong-headed pins soldered to their screw-heads. These were especially designed for the treatment of fractures of the maxillae, for a consideration of which the student is referred to the sixth edition Fig. 645. of the writer's work on Mal-occlusion of the Teeth and Fractures of the Maxillaz. The X and D bands are provided with smooth-bore tubes soldered to their sides, into which the ends of the arches and the extension flange THE WRITERS APPLIANCES. 733 of the nuts accurately fit. The X bands are for bicuspids and the D bands for molars. 1 Fig. 646 shows three coils of band material from which plain bands for incisors, canines, or even premolars may be made, to serve as mediums Fig. 646. F of attachment to the arch through the wire ligatures. They are also very largely used in retaining devices. C and F are of the same width, being narrower than H, and F and H are of the same thickness, being Fig. 647. thicker than C. C is used only where a very thin, delicate band is required. F is used where a stronger band is needed, and has much more universal use. H is used principally for canine bands. Fig. 64S. / Fig. 647 represents the wire G, a section of very soft, smooth wire. For the making of spurs on bands, for the attaching of ligatures, or for retention it is indispensable. It is also used for reinforcing anchorage and for the moving of teeth, the latter being illustrated in Fig. 703. 1 For the varying sizes of molar teeth there are three sizes of D bands, although in the writer's practice the medium size alone meets all requirements of the permanent molars. The smaller size, however, is occasionally demanded on the deciduous molars. 734 ORTHODONTIA. Fig. 648 represents the retaining tubes R, which are used in detach- able connections, in reinforcing anchorage, in retention, etc. Fig. 649 represents the ligature wire, which is very soft, smooth, tough, strong, bright wire, especially prepared for the use of orthodon- tists. It comes in three sizes. The largest size is the preferable one for performing most tooth movements. The medium size is used where so great force is not required, or where the teeth are so close together Fig. 649. that the larger wire could only be passed between them with great diffi- culty. The smallest size is principally used to hold teeth passively to the arch after their movement is completed, while the movements of other teeth are being completed by means of the heavier ligatures. It is also sometimes used in connection with the retaining devices. Fig. 650 represents rubber for wedges, which are principally used to intensify pressure on some tooth of overprominence, or to assist in Fig. 650. yg IN. WIDE Vm\n. WIDE llll rotation. Figs. 684 and 685 show working combinations of these appliances. The following appliances are those which the writer has now practi- cally eliminated from his practice, not because they were inefficient to perform the tooth movements required of them, but because they were designed to act locally, so to speak, or only upon teeth that seemed " crooked," instead of to operate from the basis of occlusion, and hav- ing control of one tooth or of all teeth in one or both arches. But, as will be shown later, while not often used, they are still so necessary for some purposes that they cannot be wholly dispensed with. Their uses will be described later. THE WRITERS APPLIANCES. 735 Fig. 651 shows the jack-screw E and J. The first regulating jack- screw was invented by Dr. Dwindle, of New York, in 1848. This invention marked two important steps in the progress of this science. First, the introduction into orthodontia of one of the most compact yet Fig. 651. immmimmiim ©