O-ORGANISMS
OF THE
MAN
MOUTH
MILLER

HRUINUUTTUI
ARTES
LIBRARY
1817
VERITAS
UNIVERSITY OF MICHIGAN
MY PLURIBU
MUK
SCIENTIA
OF THE
TUEBOR
RIS PENINSULAM AMⱭT HAM
CIRCUMSPICE
ttc.
ARAWANAN WANDUANDAMANANA
DENTAL LIBRARY
MICRO-ORGANISMS OF THE HUMAN MOUTH.
THE
THE LOCAL AND GENERAL DISEASES WHICH ARE
CAUSED BY THEM.
WILLOUGHBY DO MILLER, D.D.S., M.D.,
PROFESSOR AT THE UNIVERSITY OF BERLIN.
***
BY
yton
WITH ONE HUNDRED AND TWENTY-EIGHT ILLUSTRATIONS, ONE
CHROMO-LITHOGRAPHIC AND TWO PHOTO-
MICROGRAPHIC PLATES.
*****
PHILADELPHIA :
THE S. S. WHITE DENTAL MFG. CO.
1890.
—AVORI
Copyright, 1890, by THE S. S. WHITE DENTAL MFG. CO.
*****,
·
**** Ja
4-23-49 LMS
Dental Library
gift
From the Library of
of Dr Fred C. Sizelan
4-22-49
added capy
.Temporary,
Dental Library
QR
47
.M653
cop. 4
PREFACE.
THE
HE impetus given to the study of bacteriology by the
introduction of the exact methods of bacteriological
investigation now in vogue, has led to discoveries in the domain
of dental and oral pathology which are of the greatest impor-
tance not to the dental surgeon alone but equally to the practi-
tioner of general medicine.
It has been established beyond all question that myriads of
and
micro-organisms are constantly present in the human mouth,
that these, under favorable circumstances, are capable of mani-
festing an action of the utmost significance upon the local as
well as the general health of the patient. Not alone are they
responsible for the vast majority of those diseases of the teeth
and contiguous parts which the dental surgeon is called upon to
treat, but they also give rise to other local and general disorders
of the most serious nature.
These various disturbances are produced partly by the direct
action of micro-organisms and their products upon the teeth and
the mucous membrane of the mouth, partly by constant swal-
lowing of large masses of bacteria, partly by carrying them into
the lungs, particularly in cases of violent inspiration, and, finally,
by their obtaining an entrance into the blood or lymph-vessels.
in the various ways described in Chapter XI.
The existence of a most excellent nursery for bacteria at the
V
Copyright, 1890, by THE S. S. WHITE DENTAL MFG. Co.
****
4-23-49 LMS
Dental Library
giph
From the Library of
of Dr Fred C. Sizelan
4-22-44
added copy
・Temporary.
Dental Library
QR
47
M653
cop. 4
PREFACE.
THE
HE impetus given to the study of bacteriology by the
introduction of the exact methods of bacteriological
investigation now in vogue, has led to discoveries in the domain
of dental and oral pathology which are of the greatest impor-
tance not to the dental surgeon alone but equally to the practi-
tioner of general medicine.
It has been established beyond all question that myriads of
micro-organisms are constantly present in the human mouth, and
that these, under favorable circumstances, are capable of mani-
festing an action of the utmost significance upon the local as
well as the general health of the patient. Not alone are they
responsible for the vast majority of those diseases of the teeth
and contiguous parts which the dental surgeon is called upon to
treat, but they also give rise to other local and general disorders
of the most serious nature.
These various disturbances are produced partly by the direct
action of micro-organisms and their products upon the teeth and
the mucous membrane of the mouth, partly by constant swal-
lowing of large masses of bacteria, partly by carrying them into
the lungs, particularly in cases of violent inspiration, and, finally,
by their obtaining an entrance into the blood or lymph-vessels
in the various ways described in Chapter XI.
The existence of a most excellent nursery for bacteria at the
Τ
vi
PREFACE.
very portal of the human body is a fact which has only recently
begun to receive the attention which its importance demands.
It has been my endeavor in the following pages to bring about
a better understanding of the nature and extent of bacteritic
growths in the human mouth, of the disastrous effects which
they are capable of producing, and, accordingly, a more proper
appreciation of the importance of dental surgery and dental
hygiene as a branch of general medicine.
The contents of the book consist chiefly of original investiga-
tions which, in part, have appeared in different American,
English, and German journals, and in part appear here for the
first time.
The first three chapters are designed more particularly for
those of my readers who may not have occupied themselves with
bacteriological studies, it being, in my opinion, utterly impossi-
ble for anyone to obtain a proper understanding of the action of
micro-organisms in the mouth without a knowledge of at least
the elementary principles lying at the foundation of the science
of bacteriology.
Of those works to which I am indebted for aid in my labor,
I wish to mention in particular the Lehrbuch der Mikroorgan-
ismen, by Flügge, and Die Fortschritte in der Lehre von den
pathogenen Mikroorganismen, by Baumgarten.
I take pleasure in acknowledging the very valuable assistance
rendered me by my friend Mr. Frank Thilly, of Cincinnati,
Ohio, in the preparation of the manuscript.
BERLIN, May, 1890.
THE AUTHOR.
LITERATURE
CONTENTS.
PART I.
GENERAL BACTERIOLOGICAL STUDIES, WITH SPECIAL REFER-
ENCE TO THE BACTERIA. OF THE HUMAN MOUTH.
CHAPTER I.
INTRODUCTORY
Short Outline of the Morphology and Biology of Bacteria
1. Forms of Bacteria
2. Cumulative Forms of Bacteria
3. Reproduction of Bacteria
4. The Origin of Bacteria
5. Life-Conditions of Bacteria
6. Influence of Various Conditions on the Growth of Bacteria
a. Action of Temperature
b. Action of Oxygen
c. Action of Acids and Alkalies
•
·
■
·
a. Lactic Acid Fermentation
6. Mannite Fermentation
d. Action of Light, Electricity, and Pressure
7. Antagonism among the Bacteria.
8. Self-Destruction of Bacteria
Vital Manifestations of Bacteria
I. Action of Bacteria upon the Living Vegetable or Animal Body
II. Action upon Lifeless Matter
1. Fermentation Bacteria
A. Fermentation of Carbohydrates
c. Dextrane Fermentation
d. Butyric Acid Fermentation
e. Diverse Fermentations
·
·
•
•
•
•
•
•
•
►
•
►
PAGE
xiii
PAGE
1
4
4
7
8
9
10
11
11
11
12
12
13
14
15
15
18
18
19
20
22
22
28393203598
vii
viii
CONTENTS.
B. Fermentation of Polyvalent Alcohols
C. Fermentation of Fats, Fatty Acids, and Oxyacids
D. Putrefaction.
Ptomaïnes
E. Oxidation of Alcohol to Acetic Acid
F. Ammoniacal Fermentation .
G. Nitrification and Denitrification
2. Chromogenic Bacteria
3. Aërogenic Bacteria
4. Saprogenic Bacteria (Bacteria of Putrefaction)
•
Definitions
Apparatus
Pure Culture
Line Cultures
Dilution Cultures.
CHAPTER II.
·
•
NUTRIENT MEDIA FOR BACTERIA IN THE ORAL CAVITY.
1. Saliva
2. The Buccal Mucus
3. Dead Epithelial Cells
4. Tooth-Cartilage
5. The Dental Pulp
6. Exudations of the Gums
7. Accumulation of Particles of Food
CHAPTER III.
•
•
•
·
•
•
►
•
•
Preparation of Nutrient Gelatine, or Agar-Agar
Examination of Micro-Organisms under the Microscope
Cover-Glass Preparations
Tissue Preparations
·
•
•
•
THE DEVELOPMENT OF THE STUDY OF MICRO-ORGANISMS IN THE ORAL·
CAVITY
Methods of Bacteriological Investigation.
•
•
+
14
•
•
·
•
•
Test-tube Cultures
Other Solid Culture Media
Liquid Media .
Application of the Above Methods to Cultivations from the Human
Mouth
·
•
•
•
•
·
PAGE
25
26
27
29
31
32
32
34
35
36
·
37
37
42
42
43
43
43
44
45
48
48
49
52
52
54
56
57
59
59
62
65
66
67
CONTENTS.
CHAPTER IV.
BIOLOGICAL STUDIES ON THE BACTERIA OF THE MOUTH
Mouth-Bacteria Proper-
Leptothrix buccalis :
Leptothrix innominata
•
CHAPTER V.
Bacillus buccalis maximus
Leptothrix buccalis maximu
Jodococcus vaginatus
Spirillum sputigenum
Spirochete dentium .
Mouth-Bacteria which are Uncultivable and whose Pathogenesis is un-
known
4. Diastatic Action of Mouth-Bacteria
5. Inverting Action of Mouth-Bacteria
MOUTH-BACTERIA AS EXCITERS OF FERMENTATION
General Remarks
A. Action of Mouth-Bacteria upon Carbohydrates
1. Lactic Acid Fermentation
Formation of Gas in Lactic Acid Fermentation
2. The Spontaneous Butyric Acid Fermentation.
3. The Acetic Acid Fermentation
CHAPTER VI.
•
•
·
Putrefaction as Cause of Decay
Chemical Theory of Dental Decay
·
·
Mouth-Bacteria which give a Blue or Violet Reaction with Iodine
Cultivable Mouth-Bacteria, partly Non-Pathogenic, partly of Unknown
Pathogenesis
Chromogenic Mouth-Bacteria
The Bacteria of Diseased Pulps
The Relation of Mouth-Bacteria to the Formation of Tartar
B. Action of the Mouth-Bacteria on Albuminous Substances
C. Fermentation of Fats and Fatty Acids in the Oral Cavity
D. Nitrification and Denitrification in the Mouth
·
•
•
•
-
A
•
•
D
•
•
•
·
•
ACTION OF THE PRODUCTS OF FERMENTATION ON THE DIFFERENT STRUC-
TURES OF THE MOUTH
The Decay of the Teeth
The Stagnation of Depraved Juices in the Teeth
Disturbances of Nutrition as Cause of Decay.
Inflammation Theory of Decay
Worm Theory of Caries.
100
•
ix
102
. 102
. 105
. 105
110
. 112
. 113
. 113
. 113
. 115
. 117
1 117
·
PAGE
68
69
70
72
73
74
74
75
80
•
80
82.
83
90
96
99
119
. 119
. 120
. 120
. 121
. 128
129
130
X
CONTENTS.
Parasitic Theory of Dental Decay
Electrical Theory of Decay
Diverse Causes of Caries .
a. Decay of Enamel
b. Decay of Dentine
c. Decay of the Cement
d. Decay of the Enamel-Cuticle
CHAPTER VII.
ORIGINAL INVESTIGATIONS ON THE DECAY OF THE TEETH
Introductory Remarks on the Histology and Chemistry of the Teeth
Chemical Composition of the Hard Dental Substance
Physical Phenomena of Dental Decay
·
a. Preparation of Specimens
b. Methods of Staining
4. Decay of Cement
•
Accompanying Phenomena of Dental Decay
1. Transparency of the Tissue in Dentai Decay
2. Pigmentation of the Tissue in Dental Decay.
Chemical Changes attending Decay of the Teeth
Microscopical Phenomena of Decay
1. Decay of the Enamel-Cuticle
2. Decay of Enamel
·
a. Preparation of Specimens
b. Appearances under the Microscope
3. Decay of Dentine
•
•
•
c. Appearances under the Microscope
Thickening of Neumann's Sheath
•
Decay, of Teeth worn on Plates
Artificial Decay
Caries of Animal Teeth
Spontaneous Healing of Dental Decay
•
A
ETIOLOGY OF DENTAL DECAY
The Micro-Organisms of Dental Decay
Predisposing Causes of Dental Caries
Influence of Civilization on Decay
·
CHAPTER VIII.
·
CHAPTER IX.
•
•
•
·
PROPHYLAXIS OF DENTAL DECAY
The Use of Antiseptics in the Prophylactic Treatment of Decay
The Antiseptic Action of Filling-Materials
The Action of Tobacco upon the Teeth
The Sterilization of Teeth for the Purpose of Implantation
•
146
. 146
148
. 151
. 151
. 153
. 155
. 156
•
. 156
. 156
. 162
. 163
. 165
. 165
. 166
166
. 168
. 171
. 171
173
. 175
. 188
. 193
. 194
. 194
. 199
202
PAGE
. 132
•
135
. 144
•
•
•
•
·
•
•
205
214
. 216
218
•
·
. 223
225
. 237
. 246
247
CONTENTS.
xi
PART II.
THE PATHOGENIC MOUTH-BACTERIA, AND THE DISEASES
WHICH THEY PRODUCE.
CHAPTER X.
THE BUCCAL SECRETIONS AS CARRIERS OF TOXIC SUBSTANCES AND OF
PARASITIC EXCITANTS OF DISEASES
Toxic Properties of Mixed Human Saliva.
Pathogenic Bacteria of the Human Mouth
1. Non-cultivable Pathogenic Mouth-Bacteria
2. Cultivable Pathogenic Mouth-Bacteria
a. Micrococcus of Sputum Septicemia
b. Bacillus crassus sputigen us
Biondi's Mouth-Bacteria .
·
e. Bacillus salivarius septicus
f. Coccus salivarius septicus
g. Streptococcus septo-pyæmicus.
h. Staphylococcus salivarius pyogenes
Original Investigations on Pathogenic Mouth-Bacteria
i. Micrococcus gingivæ pyogenes
k. Bacterium gingivæ pyogenes
1. Bacillus dentalis viridans
m. Bacillus pulpæ pyogenes.
c. Staphylococcus pyogenes aureus and albus. Streptococcus pyogenes
d. Micrococcus tetragenus
•
•
:
•
•
·
·
T
•
•
·
•
•
253
254
. 256
. 257
•
259
. 259
·
•
►
CHAPTER XI.
INTRANCE-PORTALS OF THE PATHOGENIC MOUTH-BACTERIA
274
1. Invasion of Pathogenic Mouth-Bacteria following Mechanical Injuries. 274
2. Gangrenous Tooth- Pulps as Centers of Infection
285
3. Complaints caused by the Direct Action of Bacteria upon the Mucous
Membrane of the Mouth and Pharynx
4. Pulmonary Diseases caused by the Inspiration of Germs from the Oral
Cavity
5. Complaints of the Digestive Tract caused by Mouth-Bacteria
Gas-forming Bacteria of the Stomach
. 262
263
. 265
. 265
. 266
. 266
. 266
. 267
. 268
270
271
. 272
. 273
·
•
•
•
•
Morphology
6. Points of Attack furnished by a Lack of Resistance in the Soft Tissues
of the Mouth
PAGE
299
300
313
. 317
a. Limited Suppurative Processes at the Margin of the Gums
b. Abscess-Formation resulting from Impeded Eruption of Wisdom-
Teeth
c. Pyorrhoea Alveolaris
Original Investigations concerning Pyorrhoea Alveolaris
•
·
295
319
319
320
. 321
. 328
xii
CONTENTS.
d. Stomatomycosis sarcinica
e. Mycosis tonsillaris benigna.
•
C
·
f. Stomacace
g. Stomatitis phlegmonosa, ulcerosa, etc.
7. Infections resulting from the Accumulation of the Excitants of Diph-
theria, Syphilis, Typhus, etc., in the Oral Cavity
Actinomycosis
CHAPTER XII.
SUPPLEMENTARY REMARKS ON BUD-, MOULD-, AND ANIMAL FUNGI
Bud-Fungi
Mould-Fungi
Mycetozoa, Animal-Fungi or Fungous Animals
INDEX OF AUTHORS
GENERAL INDEX
•
·
334
. 385
335
•
PAGE
384
337
. 339
·
. 343
343
349
351
•
a
355
359
LITERATURE.
¹ DE BARY. Vergl. Morphologie und Biologie der Pilze. S. 490.
2 FLÜGGE. Die Mikroorganismen. Leipzig, 1886. S. 76.
3 FRANK. Leunis' Synopsis der drei Naturreiche. Bd. III. Specielle
Botanik, Kryptogamen. 2842.
4 ZOPF. Die Spaltpilze. S. 1.
5 CORNIL et BABES. Les Bactéries. P. 173.
6 EHRENBERG. Organisation, Systematik und geographisches Verhältniss der
Infusionsthierchen. Berlin, 1830. Die Infusionsthierchen als vollkommene
Organismen. Leipzig, 1838.
7 LEEUWENHOEK. Opera omnia sive arcana naturæ ope microscopiorum
exactissimorum detecta. 1722.
8 NENCKI. Beiträge zur Biologie der Spaltpilze. 1880.
9 COHN und MENDELSOHN. Cohn's Beiträge. Bd. III, Heft 1.
10 R. KOCH. Aetiologie der Wundinfectionskrankheiten. Leipzig, 1878. S. 46.
11 G. KLEMPERER. Ueber die Beziehung der Mikroorganismen zur Eiterung.
Aus dem Laboratorium der 2. medicinischen Klinik zu Berlin. Zeitschr, f. klin.
Med. 1885. Bd. X, S. 158.)
12 D. BIONDI. Contribuzione all' etiologia della suppurazione. (La Riforma
medica, 1886. No. 34-36.)
18 A. ZUCKERMANN. Ueber die Ursache der Eiterung. (Centralbl. f. Bacterio-
logie und Parasitenkunde. 1887. Bd. I, No. 17.)
14 KREIBOHM und ROSENBACH. Experimentelle Beiträge zur Frage: Kann
Eiterung ohne Mitbetheiligung, etc. (Archiv f. klin. Chirur. 1888. Bd.
XXXVII, S. 737.)
15 GRAWITZ und W. DE BARY. Ueber die Ursachen der subcutanen Ent-
zündung und Eiterung. (Virchow's Archiv. Bd. CVIII, S. 67.)
16 SCHEURLEN. Weitere Untersuchungen über die Entstehung der Eiterung,
ihr Verhältniss zu den Ptomaïnen und zur Blutgerinnung. (Fortschritte d.
Medicin. 1887. No. 23, S. 762.)
17 NATHAN. Archiv f. klin. Chirurgie. Bd. XXXVII, Heft 4.
18 GRAWITZ. Beitrag zur Theorie der Eiterung. (Virchow's Archiv. Bd.
CXVI, Heft 1, S. 116.)
19 HOPPE-SEYLER. Physiologische Chemie.
20 MILLER. Ueber Gährungsvorgänge im Verdauungstractus und die dabei
betheiligten Spaltpilze. (Deutsche med. Wochenschr. 1885. No. 49.)
21 FLÜGGE. Die Mikroorganismen. Leipzig, 1886.
xiii
xiv
LITERATURE.
22 PASTEUR. Annales de Chimie et Physiologie. 1857.
23 HUEPPE. Ueber die Zersetzung der Milch. (Mitth. a. d. Reichsgesundheitsamt.
Bd. II, S. 307.)
24 BLACK. Gelatine-forming Micro-organisms. (Independent Practitioner. 1886.
P. 546.)
25 PRAZMOWSKI. Untersuchungen über die Entwickelung und Fermentwirkung
einiger Bacterienarten. Leipzig, 1880.
26 BRIEGER.
Ueber Spaltungsproducte der Bacterien. (Zeitschr. f. physiol.
Chemie. Bd. VIII, Heft 4 und Bd. IX, Heft
27 FITZ. Berichte der Chem. Gesell. 1873, Bd. VI, S. 48; 1876, Bd. IX, 2, S.
1348; 1878, Bd. XI, S. 42; 1879, Bd. XII, 1, S. 474; 1880, Bd. XIII, 1, S.
1309; 1882, Bd. XV, 1, S. 867; 1883, Bd. XVI, S. 844; 1884, Bd. XVII, S.
1189.
28 BOUTROUX. Sur la fermentation lactique. (Comptes rendus. Bd. LXXXVI,
P. 605.
1878.)
29 FLÜGGE.
•
Die Mikroorganismen. S. 486.
Ueber die Zersetzung der Gelatine und des Eiweisses bei der Fäul-
Bern, 1876.
30 NENCKI.
niss u. s w.
31 BRIEGER.
Ueber Ptomaïne. Weitere Untersuchungen über dieselben,
1885, und Untersuchungen über Ptomaïne. 3. Theil.
1886.
32 VAUGUAN. Ueber die Anwesenheit von Tyrotoxikon in giftigem Speiseeise
und in giftiger Milch, seine wahrscheinliche Beziehung zur Cholera infantumn.
(Archiv f. Hygiene. Bd. VII, S. 420.)
33 HANSEN. Contributions à la connaissance des organismes qui peuvent se
trouver dans la bière et la moût de bière et y vivre. (Meddelser fra Carlsberg-
laboratoriet. 1879. Heft 2.)
34 W. LEUBE und E. GRESER. Ueber die harnstoffzersetzenden Pilze im Urin.
(Virchow's Archiv. Bd. C, S. 555.)
35 SCHLÜSING und MÜNTZ. Comptes rendus. Bd. LXXXIX, Pp. 891 et
1074; Bd. LXXXIV, P. 301; Bd. LXXVII, Pp. 203, 353.
36 GAYON et DUPETIT. Comptes rendus. 1882. Bd. XCV, Pp. 664, 1365.
37 DEHÉRAIN et MAQUENNE. Sur la réduction des nitrates, etc. (Comptes
rendus. 1882. II. Bd. XCV, Pp. 691, 732, 854.)
38 HERAEUS. Ueber das Verhalten der Bacterien im Brunnenwasser. (Zeitschr.
1. Hygiene. Bd. I.)
P. 50 )
39 WARRINGTON. Journal of the Chem. Society. August, 1888. P. 727.
40 BINZ. Arzneimittellehre. S. 197, 198.
11 LIBORIUS, FLÜGGE. Die Mikroorganismen.
S. 455.
42 HOPPE-SEYLER. Physiologische Chemie. S. 188.
43 ELLENBERGER und HOFMEISTER. Der Speichel der Wiederkäuer. (Bericht
über das Veterinärwesen im Königreich Sachsen. 1885. S. 119.)
44 THE SAME. Die Function der Speicheldrüsen der Haussäugethiere. (Archiv
f. wissensch. u. prakt. Thierheilk. 11. 1885.)
15 Roux. Gazz. med. veterin. di Milano. 1871. (See Hoppe-Seyler 19.)
46 HERMANN. Physiologie. S. 94.
47 KIRK.
A Contribution to the Etiology of Erosion. (Dental Cosmos.. 1887. ·
LITERATURE.
XV
48 LEEUWENHOEK. Opera omnia, etc. Bd. II, S. 40, 1722.
49 MANDL. Comptes rendus hebd. des Séances de l'Académie des Sciences.
Bd. XVII, P. 213..
50 BUHLMANN. Müller's Archiv f. Anatomie. 1840.
51 HENLE. Pathologische Untersuchungen. 1840.
52 ERDL. Allgemeine Zeitung f. Chirurgie von Rohatzsch. 1843. No. 19. S. 159.
53 FICINUS. Ueber das Ausfallen der Zähne. (Walter's und Ammon's Journal
für Chirurgie, etc. 1847. Bd. VI, Heft 1.)
54 ROBIN. Histoire naturelle des végétaux parasites. 1853.
55 ROBIN. Des végétaux qui croissent sur les animaux vivants. Paris, 1847.
P. 42.
56 KLENCKE. Die Verderbniss der Zähne. Leipzig, 1850.
57 HALLIER. Die pflanzlichen Parasiten, etc. Leipzig, 1866.
58 LEBER und ROTTENSTEIN. Ueber d. Caries der Zähne. Berlin, 1867.
59 VIGNAL. Recherches sur les Microorganismes de la bouche. (Archives de
physiol. norm. et pathol. 1886. No. 8.)
60 MILLER. Zur Kenntniss der Bakterien der Mundhöhle. (Deutsche med.
Wochenschr. 1884. No. 47.)
61 LEWIS. Lancet. September, 1884.
62 MILLER. Ueber einen Zahn-Spaltpilz, Leptothrix gigantea. (Berichte der
Botanischen Gesellschaft. 1883. S. 224.)
63 MILLER. Biological Studies on the Fungi of the Human Mouth. (Indep.
Practitioner. 1885. Pp. 227, 283.)
64 BLACK. Trans. of Ill. State Dental Society. 1886.
65 WATT. Chemical Essays.
66 VIGNAL. La France médicale. Août 25, 1887.
67 HUEPPE. Deutsche med. Wochenschr. 1884.
Nos. 48, 49.
68 ESCHERICH. Die Darmbacterien des Säuglings. 1886.
69 BAGINSKY. Deutsche med. Wochenschr. 1888.
No. 20.
70 KRÄUTERMANN. Sicherer Augen- und Zahnarzt. 1732. (See Schlenker 72.)
71 BOURDET. Recherches et observations sur toutes les parties de l'art du den-
tiste. 1757. P. 95.
72 SCHLENKER Die Verderbniss der Zähne
73 v. CARABELLI.
Handbuch der Zahnheilkunde.
74 EUSTACHIUS. Opuscula anatomica et de dentibus.
75 JOHN HUNTER.
Diseases of the Teeth, etc. 1778.
The History and Treatment of the Diseases of the Teeth and
Virchow's Archiv. Bd. XLI, S. 441.
1
1574.
76 JOSEPH FOX.
Gums.
1806.
77 THOMAS BELL.
Anatomy, Physiology, and Diseases of the Teeth: 1831.
78 E. NEUMANN. Ueber das Wesen der Zahnverderbniss. (Archiv f. klin.
Chirurgie. Bd. VI, Heft 1, S. 117.)
79 HERTZ.
80 KÖCKER. Principles of Dental Surgery. P. 111.
81 HEITZMANN and BOEDECKER. Inflammation of Dentine (Eburnitis). (Indep.
Pract. 1886. P. 120.)
82 THE SAME. Contributions to the History of the Development of the Teeth.
(Indep. Pract. May, 1887, to July, 1888.)
B
xvi
LITERATURE.
89 FRANK ABBOTT. Caries of the Human Teeth. (Dental Cosmos. 1879.
February, March, April.)
84 HEITZMANN. New England Journal of Dentistry. Vol. I, P. 193.
85 FAUCHARD. Le chirurgien-dentiste.
Paris, 1728, 1746, 1786.
86 PFAFF. Abhandlung von den Zähnen. 1756.
87 LINDERER. Handbuch der Zahnheilkunde. 1837 and 1842.
88 W. ROBERTSON. A Practical Treatise on the Human Teeth, etc. 1835.
89 ROGNARD. Gaz. des hôpit. 1888.
90 MAGITOT. La salive. Paris, 1867.
91 WEDL. Pathologie der Zähne.
1870.
Dental Surgery. 1873. P. 734.
92 J. TOMES.
93 J. TAFT. Operative Dentistry.
94 MAGITOT.
Etudes et expériences sur la salive. Paris, 1867.
!
95 MILLES and UNDERWOOD. Transact. Internat. Med. Congr.
1881.
96 AD. WEIL. Vorträge, gehalten zu München in der Sitzung des ärztlichen
Vereins. 1880. S. 187.
97 ARKÖVY.
Diagnostik der Zahnkrankheiten.
98 BASTYR. Oesterreichisch-Ung. Vierteljahrsschr. f. Zahnheilk. 1885-86. S. 355.
99 A. GYSI. Dental Cosmos. 1887. No. 4.
100 W. X. SUDDUTH. Indep. Pract. 1888. P. 579.
101 PEIRCE. Ibid. 1888. P. 583.
102 G. ALLAN. Internat. Dent. Journal. 1889. No. 3.
103 BLACK. Dental Caries. (American System of Dentistry. Vol. I. 1886.)
104 BRIDGMAN. Trans. Odont. Soc. of Great Britain. 1861-63.
Vol. III, P. 369.
105 CHASE. Correspondenzbl. f. Zahnärzte. 1880. S. 190.
106 MILLER. Dental Cosmos. 1881 P. 91.
107 J. TOMES. A System of Dental Surgery. 2d Edition.
108 MAGITOT. Recherches sur la carie des dents. 1871.
109 J. and C. S. TOMES. Dental Surgery. 2d Edition.
110 WEDL. Pathologie der Zähne. S. 334.
111 (). WALKHOFF. Mikroskopische Untersuchungen über pathologische
Veränderungen des Dentins. (Monatsschr. f. Zahnheilk. 1885. S. 12.)
112 BLACK. American System of Dentistry. Vol. I, P. 741.
P. 720.
1873. P. 722.
113 F. J. CLARK. Indep. Pract. 1883. P. 134.
114 ALFRED GYSI. Dental Caries under the Microscope. (Dental Cosmos.
April, 1887.)
115 A. WEIL. Zur Histologie der Zahnpulpa. (Habilitationsschrift. Mün-
chen, 1887.)
116 MILLER. Einfluss der Mikroorganismen auf die Caries der menschlichen
Zähne. (Archiv für experimentelle Pathologie. Bd. XVI. 1882.)
117 J. and C. S. TOMES. Dental Surgery. 1887. 3d Edition. P. 246.
118 THE SAME. Ibid. 2d Edition. P. 301.
119 MILLES and UNDERWOOD.
1884 P. 222.
120 ATKINSON. Indep. Pract. 1888.
121 ELLENBERGER und HOFMEISTER.
Bd. XI, S. 162.
Trans. of the Odont. Soc. of Great Britain.
Pp. 580, 581.
Archiv f. wissensch, u. prakt. Thierheilk.
LITERATURE.
xvii
122 HESSE.
Deutsche med. Wochenschr.
1885.
No. 24.
128 COLEMAN. Trans. of the Odont. Soc. of Great Britain. 1861 to 1863. P. 82.
124 BRIDGMAN. Ibid. P. 369.
120 MM. GALIPPE et VIGNAL. Note sur les microorganismes de la carie den-
taire. (L'Odontologie. Mars, 1889.)
126 MAGITOT. Traité de la carie dentaire.; 1867. P. 60.
127 MUMMERY.
Vol. II, P. 7.
128 W. C. BARRETT.
Trans. of the Odont. Soc. of Great Britain. New Series. 1870.
An Examination of the Condition of the Teeth of Certain
Prehistoric Races. (Indep. Pract. October, 1883.)
Prehistoric Teeth.
Prehistoric Teeth.
129 MILLER.
(Ibid. 1884. P. 40.)
130 BLACK. American Systein of Dentistry. P. 730.
131 KOCH. Ueber Desinfection. (Mittheilungen aus dem Kaiserl. Gesundheit-
samt. Bd. I, S. 234.)
132 BLACK. Antiseptics. (Dental Review. 1889. Nos. 2 and 3.)
133 v. KaczorOWSKI, Der aetiologische Zusammenhang zwischen Entzün-
dung des Zahnfleisches und anderweitigen Erkrankungen. (Deutsche med. Wo-
chenschr. 1885. Nos. 33, 34, 35.)
184 WITZEL.
Deutsche Zahnheilkunde in Vorträgen. Heft 4, S. 99 u. f.
135 BUSCH. Verhandlungen der deutschen odontologischen Gesellschaft. Bd. I.
136 MILLER. Indep. Pract. June, 1884.
187 TASSINARI. Centralblatt für Bacteriologie und Parasitenkunde. ¡ 1888. Bd.
IV, S. 449.
188 HUNTER.
139 LETTSOM.
140 STRICKER.
141 EBERLE. Die Verdauung. 1834. S. 34.
142 SENATOR. Untersuchungen über d. fieberhaften Process. 1873. S. 6.
143 RAYNAUD et LANNELONGUE. Bulletin de l'Académie de méd. 18 Janvier,
1881.
144 PASTEUR. Ibid., 18 et 25 Janvier, 1881.
145 VULPIAN. Ibid., 29 Mars, 1881.
116 STERNBERG. Bulletin of the National Board of Health. April 30, 1881.
147 GRIFFIN. Archivio per le scienze mediche. Vol. V, Fasc. 3..
148 GAGLIO et DI MATTEI. Sulla non essistenza di una proprietà tossica della
saliva umana. (Arch. per le scienze med. 1882. Vol. VI, Fasc. 1.
Centralbl. f. klin. Med. 1883. S. 261.)
Referat im
149 A. FRÄNKEL. Verhandl. d. 3. Congr. f. innere Med. 1884.
150 MILLER. Deutsche med.. Wochenschr. 1884. No. 25.
161 KLEIN.
Ein Beitrag zur Kenntniss der Pneumokokken.
med. Wissensch. 1884. No. 30. S. 529.)
152 KREIBOHM. Flügge, Mikroorganismen. S. 257.
153 A. FRANKEL. Zeitschr. f. klin. Med. 1886. Bd. X, S. 401.
154 BaumgarteN. Lehrbuch d. pathol. Mykologie. 1888. S. 245.
155 KREIBOHм. Lit. 152. S. 260.
A Treatise on the Venereal Disease. 1786. P. 391.
Transactions of the Medical Society of London. Aug. 2, 1786.
Die Bedeutung des Mundspeichels. 1889. S. 138.
156 BLACK. Indep. Pract. August, 1887.
157 KOCH. Mitth. a. d. Kais. Gesundheitsamt. Bd. II, S. 42.
(Centralbl. f.
xviii
LITERATURE.
158 GAFFKY.
v. Langenbeck's Archiv. Bd. XXVIII, Heft 3, S. 500.
159 BIONDI. Breslauer ärztliche Zeitschr. September, 1887. No. 18.
160 ZAKHAREVITSCH. Vrach No. 34. S. 523.
161 BAUME. Lehrbuch der Zahnheilkunde. S. 644.
162 v. MOSETIG-MOORBor. Oesterr.-Ung. Vierteljahrsschr. f. Zahnheilkunde.
(From the Deutsche med.
Ein Fall von acuter Osteomyelitis des Unterkiefers mit tödt-
(Osterr.- Ung. Vierteljahrsschr. f. Zahnheilk. 1887. Heft 1.)
Archives of Dentistry. November, 1886.
1885.
Heft 2.
163 ZAWADZKI.
Wochenschr.)
164 v. METNITZ.
lichem Ausgange.
165 CONRAD.
Gaz. lekarska. 1886. No. 8.
166 RITTER. Deutsche Monatsschrift f. Zahnheilkunde.
107 PARREIDT.
Zahnheilk.
168 BUSCH.
169 PORRE. Dental Record. October, 1887.
July, 1888.
Ibid.
170 BAKER.
171 PONCET.
Gaz. des Hôpit. No. 19.
172 FRIPP. Dental Record. August, 1887.
December, 1886.
Zur Antiseptik beim Zahnausziehen. (Deutsche Monatsschr. f.
Heft 7, S. 254.)
1888.
Deutsche med. Wochenschr. 1885. No. 24.
178 RITTER.
Monatsschr. f. Zahnheilk. 1886.
No. 8.
174 COOPMAN. Correspondenzbl. f. Zahnärzte. Januar, 1888. S. 56.
175 MARSHALL. Dental Cosmos. December, 1888. P. 891.
176 PIETRZIKOWSKI. Oesterr.- Ung. Vierteljahrsschr. für Zahnheilk. 1886. S.
363.
177 HARRISON ALLEN. Dental Cosmos. 1874. P. 569.
178 SCHMID.
179 RITTER. Correspondenzbl. f. Zahnärzte. October, 1888.
180 GALIPPE. Die infectiöse arthro-dentäre Gingivitis. 1888. (Uebersetzung
von Manassewitsch.)
181 ODENTHAL.
Cariöse Zähne als Eingangspforte infectiösen Materials und
Ursache chronischer Lymphdrüsenschwellungen am Halse. (Inaugural disser-
tation. Bonn, 1887.)
182 UNGAR. Sitzung der Niederrhein. Gesellschaft für Natur und Heilkunde
zu Bonn, 1884. Mai 17.
Oesterr.- Ung. Vierteljahrsschr. f. Zahnheilk. 1885. Heft 1.
183 v. BERGMANN. Erkrankungen der Lymphdrüsen. (Gerhardt's Handbuch
der Kinderkrankheiten. Bd. VI, Abth. 1, S. 253, 254.)
Diagnostik der Zahnkrankheiten.
184 ARKŮVY.
185 ROTHMANN. Patho-Histologie der Zahnpulpa, etc. 1888.
186 JAFFÉ. Lungengangrän, durch einen verschluckten Kirschkern erzeugt.
Allgem. med. Zeitung. 1886. S. 233.)
187 LEYDEN und JAFFÉ. Ueber putride (fœtide) Sputa. (Deutsches Archiv f.
klin. Med. 1867. Bd. II, S. 488.)
188 JAMES ISRAEL. Ein Beitrag zur Pathogenese der Lungenaktinomykose.
(Archiv f. klin. Chir. 1886. Bd. XXXIV, Heft 1, S. 160.)
189 BAUMGARTEN. Jahresbericht. 1 Jahrgang. S. 142.
190 BAGINSKY. Deutsche med. Wochenschr. 1888. No. 20.
191 BEDNAR. Krankheiten der Neugeborenen und Säuglinge. 1854. S. 54.
LITERATURE.
xix
· 192 HENOCH.
Kinderheilkunde.
Klinik der Unterleibskrankheiten, S. 589 und Beiträge zur
Bd. I, S. 111, und Bd. II, S. 309.
198 NAUNYN. Ueber das Verhältniss der Magengährungen zur mechanischen
Magen-Insufficienz. (Archiv f. klin. Med. Bd. XXXI, S. 225.)
S. 869.
194 LEUBE. Archiv f. klin. Med. Bd. XXXIII, S. 4.
195 DE BARY. Zur Kenntniss der niederen Organismen im Mageninhalte.
(Archiv f. exper. Pathol. u. Pharmakol. 1886.
1886. Bd. XX, S. 248.)
Wagner's Hand wörterbuch der Physiol. Bd. III.
196 FRERICHS.
1 Abth.
197 EWALD.
Die Lehre von der Verdauung. 1886. S. 104.
198 ESCHERICH. Beiträge zur antiseptischen Behandlungsmethode der Magen-
Darmerkrankungen des Säuglings. (Therap. Monatshefte. 1887. S. 390) und
Die desinficirende Behandlungsmethode der Magen-Darmkrankheiten des Säug-
lingsalters. (Centralbl. f. Bacteriol. u. Parasitenkunde. 1887. Bd. II, No. 21.)
199 MINKOWSKI. Ueber die Gährungen im Magen. 1888.
200 MILLER. Deutsche med. Wochenschrift. 1885. No. 49.
Flügge. Mikroorganismen. 1885. S. 590.
201 MACFADYAN.
202 SUCKS DOrf. Das quantitative Vorkommen von Spaltpilzen im mensch-
I
lichen Darmcanal. (Archiv f. Hygiene. 1886. Bd. IV.)
203 BAUMGARTEN. Centralbl. f. klin. Med.
204 MILLER. Deutsche med. Wochenschr.
1884, No. 2.
1885, No. 49.
1886, No. 6.
205 KOCH. Zweite Serie zur Erörterung der Cholerafrage. (Deutsche med. Wo-
chenschr. 1885. No. 19, etc.)
206 PEDLEY.
On the Pathology of Riggs's Disease. (Dental Record. May,
1887)
207 BLAND SUTTON. Ibid. May, 1887.
208 REEVE. Indep. Pract. Vol. VI, P. 367.
209 PATTERSON.
4
Dental Cosmos. 1885.
1885. P. 669.
210 BENNETT. Dental Record. May, 1887.
Pp. 229, 233.
211 ARKOVY. Diagnostik der Zahnkrankheiten. 1885. S. 232.
Krankheiten der Mundhöhle, des Rachens und der Nase.
Mitth. a. d. Kais. Gesundheitsamt. Bd. II, S. 480.
212 SCHECH.
218 LÖFFLER.
214 BULKLEY. On the Dangers arising from Syphilis in the Practice of Den-
tistry
215 DULLES Medical and Surgical Reporter. January, 1878.
216 OTIS. Lectures on Syphilis. New York, 1887. P. 102,
217 LANCERAUX. Proceedings Académie de Médicine de Paris. (L'Union Médi-
cale.
1889. P. 655.)
218 GIOVANNI. Lo Sperimentale. 1889. P. 262.
219 LELOIR.
Leçons sur la Syphilis. 1886. P. 62.
220 LYDSTON. Journal of the American Medical Association. 1886. P. 654.
221 RODDICK. Montreal Medical Journal. August, 1888. P. 93.
222 PARKER.
February, 1890.
Western Dental Journal.
228 BOLLINGER.
Centralbl. f. d. med. Wissensch. 1877. No. 27.
224 BOSTRÖM. Verh. d. Congr. f. innere Med. Wiesbaden, 1885. S. 94.
225 JAMES ISRAEL. Neue Beobachtungen aus dem Gebiet der Mykose des
Menschen. (Virchow's Archiv. 1878. Bd. LXXIV,
S. 15.)
}
XX
LITERATURE.
226 PONFICK. Ueber eine wahrscheinlich mykotische Form von Wirbelcaries.
(Berliner klin. Wochenschr. 1879. S. 345.)
227 JAMES ISRAEL. Klinische Beiträge zur Aktinomykose des Menschen 1885.
228 HOCHENEGG. Zur Casuistik der Aktinomykose des Menschen. (Wiener
med. Presse. 1887. No. 16–18.)
229 ROTTER.
Demonstration von Impfaktinomykose. (Tagebl. der Naturfor-
scher-Versammlung. Wiesbaden, 1887. S. 272)
230 PARTSCH. Einige neue Fälle von Aktinomykose des Menschen. (Deutsche
Zietschr. f. Chirurgie. 1886. Bd. XXIII, S. 498.)
231 MOOSBRUGGER. Ueber die Aktinomykose des Menschen. (See Baumgar-
ten's Jahresbericht, 1886. S. 317.)
232 ROSER.
Deutsche med. Wochenschr. 1886. No. 22. S. 369.
293 BRAUN. Ueber Aktinomykose des Menschen.
234 LAURENT. Handbuch der ges. Medicin. S. 263.
235 PLAUT.
Neue Beiträge zur systematischen Stellung des Soorpilzes in der
Botanik. Leipzig, 1887.
236 KLEMPERER. Ueber die Natur des Soorpilzes. (Centralblatt für klin. Med.
1885. No. 50. S. 849.)
287 BAGINSKY. Ueber Soorculturen. (Deutsche med. Wochenschr. 1885. No.
50. S. 866.)
238 GRAWITZ. Ueber die Parasiten des Soors, etc. (Virchow's Archiv. 1886.
Bd. CIII, S. 393.)
239 FRANKEL. Grundriss der Bacterienkunde.
240 ZOPF. Pilzthiere oder Schleimpilze. 1885.
241 DE BARY. Morphologie und Biologie der Pilze. 1884. S. 458.
242 WORONIN. Pringsheim's Jahrbücher für Wissensch. Botanik. 1878. Bd.
XI.
243 KOCH. Mitth. aus d. Kais. Gesundheitsamt. 1881. Bd. I.
244 EIDAM. Allg. landwirthschaft. Zeitung. 1880. No. 97.
245 FLÜGGE. Die Mikroorganismen. S. 110.
246 BaumgarteN. Lehrb. d. path. Mykologie. 1888. S. 72.
PART I.
GENERAL BACTERIOLOGICAL STUDIES,
WITH
SPECIAL REFERENCE TO THE BACTERIA
OF THE HUMAN MOUTH.
THE MICRO-ORGANISMS OF THE HUMAN MOUTH.
Plants.
CHAPTER I.
*
P
INTRODUCTORY.
FUNGI belong to that class of Cryptogamia which are desig-
nated as Thallophyta (Thallophytes).
Their position in the vegetable kingdom may be indicated by
the following classification:
(Cryptogams,
flowerless plants
reproducing chiefly
by spores.
Phanerogams,
flowering plants
reproducing by
seeds.
(Thallophytes,
Leafy
Cryptogams.
Fungi,
Algæ,
Lichens.
The Cryptogams differ from the Phanerogams in the absence
of flowers, and in that they do not propagate themselves by
means of seeds, in which the future plant is already present in
embryo, but by means of spores, i.e. by simple bodies or cells,
which show no differentiation corresponding to the parts of the
future plant.
As leaf-bearing Cryptogams, we designate those spore-forming
1
1
2
THE MICRO-ORGANISMS OF THE HUMAN MOUTH.
plants which have leaves, stems, and often also roots. These
represent a higher stage of development than the Thallophytes,
inasmuch as the latter do not have the parts mentioned.
Thallophytes are very commonly divided into Fungi, Algæ,
and Lichens: Fungi being characterized as cells without chloro-
phy!, which subsist on preformed organic substances; Algæ as
cells with chlorophyl, living on inorganic substances; Lichens as
a combination of cells with and without chlorophyl, also living
on inorganic substances.
This classification has, however, recently been justly pro-
nounced untenable, since it is not possible to make the presence
or absence of chlorophyl a criterion for determining the fungal
or non-fungal character of any growth. The fungi comprise not
only Thallophytes without, but also such with chlorophyl, and
indeed some of the most characteristic members of this group
of Thallophytes contain chlorophyl (de Bary¹). Secondly, fungi
and alge show so marked a similarity in regard to their mor-
phology and conditions of reproduction, that a separation on the
chlorophyl basis alone scarcely seems desirable. In the third
place, recent investigations have demonstrated with considerable
certainty that lichens are not entitled to recognition as a sepa-
rate group of organisms, being nothing more than a mixture of
fungi and algæ, in which the former live as parasites upon the
latter (Flügge²). Again, the view has been steadily gaining
ground that bacteria have very little in common with the pure
fungi, and accordingly should not be classed, with them.
For the present I have, however, retained the old division,
particularly as the question of arranging and classifying the
Thallophytes has not yet been definitely settled.
(See Lit.
1, 2, 3, 4.)
From a hygienic point of view we recognize four chief groups
of fungi:
Schizomycetes.
Hyphomycetes.
Blastomycetes.
Mycetozoa.
1. Fission-fungi (Bacteria)
2. Mould- or Thread-fungi (Fungi proper,
Moulds)
3. Bud-fungi (Yeast-fungi, Yeast)
4. Animal-fungi (Pilzthiere)
INTRODUCTORY.
3
Of these four groups, bacteria command by far the greatest
interest. They are the chief agents in the production of those
intense decompositions designated as fermentation, putrefaction,
etc. By this means they not only prevent the accumulation of
dead animal and vegetable matter upon the earth's surface, but,
at the same time, produce from the complicated organic sub-
stances of the latter the simple compounds, carbonic acid (CO₂)
and ammonia (NH), which are absolutely necessary to the con-
tinuance of a chlorophyl-bearing vegetation.
Without these processes all higher vegetation, and conse-
quently all animal life, would in the course of time become ex-
tinct. Unfortunately, however, the activity of the bacteria is
by no means restricted to the performance of this important rôle
in the household of nature. They are also capable of exerting
a most deleterious influence on the living animal body, and have
been recognized as the exciting cause of the majority of all dis-
eases to which mankind is subject.
Mould-fungi (Moulds), although very widely distributed in
nature, do not by far play so important a part as the fission-
fungi. They do not produce as intense decompositions of organic
substances, nor, with the exception of certain cutaneous diseases,
are they capable of bringing about such disturbances in the
human body as result from the invasion of fission-fungi. Many
diseases of plants and of lower animals (insects) have, however,
been traced to the agency of mould-fungi.
-
Bud-fungi (yeast-fungi) exert even less disturbing influence
on human life than moulds; with the single exception of
thrush, no disease is at present known to be due to their action.
Our knowledge of the physiological and hygienic significance
of the "animal-fungi" is, as yet, very inaccurate.
The lower Mycetozoa (Monadina) occur as parasites on algæ
and fungi, as well as on higher plants. They have also been
found in enormous quantities in the human intestines, in dis-
eased as well as in healthy conditions, without it being possible
to assign to them an indubitably pathogenic action.
4
THE MICRO-ORGANISMS OF THE HUMAN MOUTH.
SHORT OUTLINE OF THE MORPHOLOGY AND BIOLOGY
OF BACTERIA.
Bacteria are microscopic, spherical or elongated, unicellular
organisms, which live upon preformed organic substances, and
increase by fissation, or through the medium of spores.
Each cell possesses a cell-membrane and protoplasmic contents;
the latter is usually homogeneous, seldom containing vacuoles
or granules (Beggiatoa). The deposits of lime-salts, so common
with other Thallophytes, have been but very rarely observed in
growths of bacteria.
Many kinds of bacteria possess the power of locomotion, and
consequently were formerly often classed among the infusoria.
The size of the cells of the different kinds of bacteria varies
very considerably, nor are the cells of one and the same kind
always of the same size. The micrococcus of progressive sup-
puration in rabbits has a diameter of only 0.15μ*; several mil-
lions of this micro-organism could easily dance, if not upon the
point, at least upon the head of a pin. On the other hand, Beg-
giatoa mirabilis is 35μ thick, and Spirochete plicatilis attains a
length of 225μ or millimeter.
D
1. FORMS OF BACTERIA.
According to de Bary, the chief forms of bacteria are:
1. Cocci: isodiametric, or at least but very slightly uniaxially
elongated single cells.
2. Rod-forms: uniaxially elongated, cylindrical, less frequently
spindle-shaped cells, or short chains of the same.
3. Screw-forms: rods which are twisted after the pattern of a
corkscrew, partly with shallow, partly with steep spirals.
To the first group (coccus-forms) belong:
a. Micrococci: cells spherical, or nearly so (Fig. 1, a, c. d).
b. Macrococci, Megacocci: remarkably large cocci.
c. Diplococci: biscuit-shaped cells, which arise during the
fissation of cocci (Fig. 1, b).
It would probably be more correct to consider diplococci
simply as transition-forms.
*uinikro-millimeter Togo inillimeter.
MORPHOLOGY AND BIOLOGY OF BACTERIA.
5
LO
a
h
664
To the second group (rod-forms) belong:
d. Bacilli: rods, i.e. cells, whose longitudinal axis visibly
exceeds the transverse (Fig. 1, p).
b
m
t
s
K
n
FIG. 1.
Al
d
1/
110
1
.....
W
00040
V
I
120108
g
00
00 00 00
p
---··
r
FORMS OF BACTERIA.
a. Cocci. b, Diplococci. c, Cluster-cocci (Staphylococci). d, Coccus chains (Streptococci,
Torula). e. Surface-shaped colonies (Merismopedia). f, Packet-shaped colonies (Sarcina). 9,
A double coccus chain produced by a single fissation of each member in a direction at right
angles to the long axis of the chain. h, Vibriones. i, k, Spirilla. 7, Spirochetes. m, Spiro-
monades. n, Spirulina. o, Cladothrix. p, Rods (bai'i). q,
q, Clostridium. r, Leptothrix
(threads). 7, Articulated threads. 8, Rhabdomonas. t, u, v, Zoogloea. (In part after Flügge
& Zopf.)
e. Clostridium: spindle-shaped cells (Fig. 1, q).
f. Leptothrix: thread-shaped cells, or chains of cells (Fig. 1,
r, 1').
f


6
THE MICRO-ORGANISMS OF THE HUMAN MOUTH.
g. Beggiatoa: long, thick, rigid threads, which deposit grains
of sulphur in their protoplasm.
h. Crenothrix: thread-forming water-fungi, whose threads
(which may be either unicellular or composed of chains of cocci
and rods) are inclosed by a sheath, and increase in diameter
from base to apex.
i. Cladothrix: thread-forming bacteria with false branchings
(pseudo-branchings), (Fig. 1, 0).
Some writers question the correctness of classing Beggiatoa,
Crenothrix, and Cladothrix under bacteria.
To the third group (screw-forms) belong:
j. Vibriones: rods or threads with a slight undulating curve
or twist (Fig. 1, h).
k. Spirilla: rigid rods and threads with pronounced screw-
like windings (Fig. 1, i, k).
1. Spirochetes: flexible threads with narrow, unequal wind-
ings, sometimes as many as sixty in one thread (Fig. 1, 1). The
genera Vibrio, Spirillum, Spirochete, are not separated from
each other by any sharp line of division; an organism which
one would describe as a vibrio might by another be. desig-
nated as a spirillum; what one terms spirillum another calls
spirochete, etc. Furthermore, micro-organisms belonging to
the second group not unfrequently show a slight curve or twist
in some of their cells, without thereby being entitled to be placed
among the screw-forms.
Threads, whose ends are wound about each other like a braid
of hair, have been termed Spirulina (Fig. 1, u).
Each of the three fundamental forms (spheres, rods, and
screws) is subject to extensive modifications, according to the
circumstances under which it is cultivated, and it is not always
easy to determine whether the particular organism under exam-
ination should be classed as a coccus or a bacillus, as a bacillus
or a vibrio, etc. Whether these modifications can be carried so
far by any condition or conditions of cultivation that a micro-
organism normally occurring in any one of the three funda-
mental forms is transformed into another (for example a coccus
into a bacillus), or that a monomorphous organism becomes
pleomorph, is a question upon which much has been said pro
MORPHOLOGY AND BIOLOGY OF BACTERIA.
7
and con, but which we cannot discuss here. Suffice it to say,
that at present the great mass of evidence points to the conclu-
sion that such transformations cannot be brought about in the
manner indicated. On the other hand, there are many kinds
of bacteria that manifest two or all of the fundamental forms
at the same time. These have been designated as pleomorphous,
in contradistinction to those which produce only one form
(monomorphous). (See Zopf.)
4
The following forms are classed by Zopf and others among
the bacteria; Flügge speaks of them as being of doubtful rela-
tion to the bacteria, while Cornil and Babes 5 make of some of
them a sort of connecting link between the bacteria and infu-
soria:
1. Monades: large, spherical, oval, or short cylindrical cells,
provided with cilia, often in pairs (Fig. 1, m).
2. Rhabdomonas: large spindle-shaped ciliated cells (Fig. 1, s).
3. Spiromonas: leaf-like, flat cells, "twisted around an imag-
inary axis in the direction of their length."
2. CUMULATIVE FORMS OF BACTERIA.
Besides these forms of the single cells, we recognize various
configurations which result from the accumulation or combi-
nation of several cells. These are:
1. Thread-forms or Chain-forms: i.c. forms produced by a suc-
cession of single cells. To these belong:
a. Streptococci (Chain-cocci): cocci which appear chiefly
in chains, sometimes improperly called Torula (Fig. 1, d).
b. Leptothrix: long, articulated threads, composed of single
cells (cocci or rods), (Fig. 1, r').
2. Cluster-forms, i.e. groups, produced by the aggregation of
cells without definite arrangement, particularly Staphylococci,*
which are mostly found in clusters (Fig. 1, c).
3. Surface- or Mass-forms, which are produced by fissation in
two or three directions, such as merismopedia: plate-shaped
colonies, produced by fissation in two directions (Fig. 1, e), and
*σrapvλh, A clus'er of grapes
8
THE MICRO-ORGANISMS OF THE HUMAN MOUTH.
sarcina: packet-shaped groups, produced by fissation in three
directions (Fig. 1, ƒ).
4. Zooglœa-forms, produced by the gelatinization of the mem-
branes of the accumulated cells, in such a way that the latter
become imbedded in a mass of jelly (Palmella- or Zooglœa-con-
dition, Fig. 1, t, u, v). Where the jelly is very thick and carti-
laginous, the term Ascococcus is applied; where only the outer
layers of a Zooglea are gelatinized, the term Clathrocystis.
Threads, or pieces of threads, imbedded in round masses of jelly,
have been named Myconostoc (Fig. 1, t, u).
Pseudo-branching (Cladothrix) may also be regarded as a
cumulative form (Fig. 1, 0).
3. REPRODUCTION OF BACTERIA.
The reproduction of bacteria takes place in three different
ways: by fissation, in the same manner as seen in the infusoria
00088
0888380
ĥ
FIG 2.
THREADS.
(Aftor Zopf.)
0 8 38 8:
0088%
PROLIFERATION OF BACTERIA BY FISSATION.
a and d, Fissation in one direction; b, in two; c, in throo directions.
FIG. 3.
1>110 1912
a
b
SPORE-FORMATION IN RODS AND
FIG. 4.
10 0 0 0 0
FORMATION OF SPORES IN
BACILLUS BUTYRICUS.
A, Germination of a sporo.
(After Prazmowski.)
(Fig. 2), by spores (Figs. 3 and 4),
or by the separation of certain
cells from their original cyclus,
and their development into new combinations, morphologically
MORPHOLOGY AND BIOLOGY OF BACTERIA.
9
identical with those from which they sprang. By some these
cells are called cocci, by others spores (arthrospores).
The spores (Fig. 3) are spherical or ovoidal bodies, with sharp
contours and strongly refractive contents. They are formed
chiefly in media of which the available nourishment for bacteria
has been already, for the most part, consumed. Considered from
a hygienic stand-point they are of great interest, since they
offer more resistance to influences of every nature (chemical,
thermal, etc.) than the vegetative cells (as the active growing cells
may be designated in contradistinction to the inactive, resting,
spores). Formation of spores has been observed in various rod-
and some screw-forms, and recently also in the case of a micro-
coccus. Bacteria with endogenous spore-formation are called
endospore; those without endogenous spore-formation are called
arthrospore.
4. THE ORIGIN OF BACTERIA.
It has long been known that various kinds of bacteria are
found in the atmosphere, water, soil, etc. This fact was first
established by Ehrenberg (1828), although Leeuwenhoek' had
observed microscopic organisms in the human mouth as early
as 1675. Regarding their origin, a long and violent dispute
was carried on for many years between those who claimed
that they were produced spontaneously in solutions of organic
matter (generatio spontanea, sive æquivoca, abiogenesis), and those
who believed that they could originate only from pre-existing
germs. The exact methods of sterilization practiced in the last.
ten years have alone made it possible to establish the fact beyond
all question, that the proposition "omnis cellula e cellula" is
quite as applicable to these low forms of life as to the higher.
animal organism. The appearance of bacteria in solutions sup-
posed to have been sterilized, simply proves that the latter were
either not thoroughly sterilized in the beginning, or that they
were afterwards infected from without.
The question whether the number of species of bacteria re-
mains constant, or whether, in the course of centuries, through
the propagation of varieties in the Darwinian sense, new species
·
10
THE MICRO-ORGANISMS OF THE HUMAN MOUTH.
arise, has not been finally decided. The tendency seems to be
to accept the latter view, although positive evidence for the
origin of new species has not yet been adduced.
5. LIFE-CONDITIONS OF BACTERIA.
I designate as life-conditions of bacteria those circumstances
relative to food, air, temperature, etc., which are indispensable
to their development.
Nencki's analysis gives for bacteria the following chemical
composition: water 84.81 per cent., albumen 13.03 per cent.,
fat 1.20 per cent., ashes 0.64 per cent., undetermined residue
0.22 per cent.
8
According to this analysis a nutrient solution for bacteria
should be composed of albumen, carbohydrates, and small
quantities of salts; a conclusion which has been completely
confirmed by experience, which has taught that such solutions.
invariably form the best culture media.
The juices and accumulations in the human mouth at all times
present such a medium. Artificially it may be prepared in dif-
ferent ways, perhaps most easily by means of the following mix-
ture: water 100.0, peptone 2.0, sugar 1.0, beef extract 1.5.
The solid culture media introduced by Koch, which are pre-
pared by the addition of gelatine or agar-agar, are similarly com-
posed.
The composition and concentration of the culture medium are of
the greatest importance. The organic substances, albumen, pep-
tone, sugar, etc., are without question the most suitable culture
media, although formerly mineral solutions were extensively
used. One of these, recommended by Nägeli, has the following
composition: water 100 c.cm., tartrate of ammonia 1.0, phos-
phate of potassium 0.1, sulphate of magnesium 0.02, chloride of
calcium 0.01. Such mineral solutions are, however, as a rule,
by no means so well adapted to culture experiments as the media
now in use.
For each species of bacteria there seems to be a certain con-
centration of the culture medium best suited to its growth,
although it has not as yet been possible to establish definite laws
MORPHOLOGY AND BIOLOGY OF BACTERIA.
11
governing this principle, or to say just what degree of concen
tration is best adapted to each. So much, however, is certain,
that whereas no degree of dilution protects culture media against
bacteria, a too large proportion of solid matter or a too small
proportion of water impedes, or entirely prevents, their develop-
ment.
The chief condition for the formation of spores appears to be
an at least partial exhaustion of the available nourishment in
the solution, while a certain influence is also exerted by its tem-
perature and composition. The first condition is presented in
most perfect form by the necrotic tooth-pulp, a fact which, on
account of its great importance, will be referred to at more
length in a later chapter.
6. INFLUENCE OF VARIOUS CONDITIONS ON THE GROWTH OF
BACTERIA.
a. Action of Temperature.
Temperature naturally exerts an unlimited influence upon the
vegetation of bacteria. That temperature which permits the
most rapid increase (designated as the optimum) varies consid-
erably for the different kinds, for the most, however, ranging
between 25° and 40° C. Above 40° the development rapidly
diminishes, and ceases almost or entirely at 41°; below 5º,
on the other hand, proliferation takes place very slowly, if at all.
Many bacteria will not grow at a temperature below 20°; some
even not under 30° C.
The temperature most favorable for the majority of bacteria,
particularly for the pathogenic varieties, is 37° or 38° C. In this
respect, again, the oral cavity presents an excellent culture me-
dium.
b. Action of Oxygen.
The access of atmospheric air exerts special influence upon
the vegetation of bacteria. In accordance with this fact, we
distinguish three groups of bacteria. For the development of
the first, oxygen is absolutely necessary; they are called aërobic.
Bacteria of the second group thrive better without oxygen, or
12
THE MICRO-ORGANISMS OF THE HUMAN MOUTH.
even absolutely demand the exclusion of air for their develop-
ment; they are called anaerobic. The third group of bacteria
flourish either with or without oxygen, at least for a certain
length of time; Hueppe characterizes them as facultatively an-
aerobic. Most bacteria appear to belong to the first group, but
comparatively few purely anaerobic bacteria being at present
known.
The capability of certain bacteria to proliferate and to mani-
fest their specific action without access of air, may explain the
progress of tooth caries under air-tight fillings, in cases where
the softened dentine was not thoroughly removed before insert-
ing the filling.
c. Action of Acids and Alkalies.
Acids and alkalies, especially the former, even in very dilute
solutions, retard the development of bacteria. Some species,
however, show important deviations from this rule; thus, for
example, the acetic acid bacterium grows best in an excess of one
to two per cent. of acetic acid, while Micrococcus urea will
bear a high degree of alkalinity. A bacterium which I have
examined produces in solutions of carbohydrates 0.75 per
cent. of lactic acid, but perishes in this solution in a few days,
through the action of its own product. With comparatively
few exceptions, a neutral medium is best adapted to the develop-
ment of bacteria.
d. Action of Light, Electricity, and Pressure.
Light, electricity, and pressure have very little or no influence
upon the development of bacteria, nor upon their specific vital
manifestations. (See Cohn and Mendelsohn.") The assertion
that combined fillings of tin and gold, or of amalgam and gold,
etc., prevent the development of bacteria by means of the elec-
tricity which they produce, is utterly without scientific founda-
tion.
That even weak electric currents sometimes appear to have a
slight retarding action upon the development of bacteria, may
be easily demonstrated by the following simple experiment:
MORPHOLOGY AND BIOLOGY OF BACTERIA.
13
A tube of culture gelatine is richly infected with a bacte-
rium which grows rapidly at room temperature without liquefy-
ing the gelatine; it is then poured upon a glass plate in the cus-
tomary manner. While the gelatine is still liquid, place upon
the plate a metallic strip, one end of which is composed of tin,
the other of gold.
On the border of the tin, a retardation in the development of
the bacteria will be observed; the gelatine remains clear (Fig. 5).
In a few days the tin (electro-positive pole) will appear sur-
rounded by a white zone 10 to 30 mm. in diameter; the reaction
FIG. 5

APPARENT PREVENTION OF THE GROWTH OF BACTERIA BY
ELECTRIC ACTION.
a, Gold; b, Tin, on a plate of culture gelatine. In the parts indicated
Reaction around
by the white color no development of bacteria occurs.
the tin strongly acid; around the gold alkaline.
in this zone will be found to be strongly acid. The retardation.
in the development is to be ascribed not to the electricity, but to
the acid.
1
On the border of the gold the reaction will be found to be
alkaline. The development of the bacteria is here also retarded,
but much less than on the margin of the tin (the electro-positive
pole).
7. ANTAGONISM AMONG THE BACTERIA.
The principle of the struggle for existence and of natural
selection plays an important, though not fully understood, part
in the life of bacteria. If we bring a number of different kinds
14
THE MICRO-ORGANISMS OF THE HUMAN MOUTH.
of bacteria into a common culture medium, it will be found that
they do not all develop with equal rapidity; one kind will
always attain the supremacy. If we infect a second nutrient
medium with this culture and continue the operation through a
series of generations, we may find that at last only one kind
remains, the others having been crowded out. It depends upon
the composition of the solution, the temperature, and various
other conditions, as to which species will gain the victory. It
may also happen that at first one kind prevails, and that later,
through a change in the character of the medium, another kind
gains the upper hand; or again, in one part of the medium-
for example, on the surface-one kind may prevail, in another
part another. In the human mouth this struggle for existence
seems to play an important part; otherwise we should invariably
expect to find a much larger number of different kinds of bac-
teria than are actually present. The attempt to make use of
this principle in therapeutics, by bringing large numbers of
harmless bacteria into the human body in order to drive out
others of a pathogenic nature (Cantani), has hitherto not been
accompanied by the results which we had been led to hope for.
8. SELF-DESTRUCTION OF BACTERIA.
The growth and ferment activity of bacteria are always more
or less influenced by their own waste products. Lactic acid fer-
mentation not only ceases when the acidity of the solution has
reached 0.75 to 0.80 per cent., but the bacteria themselves are
often destroyed by the action of the acid which they have pro-
duced. The vital action of yeast cells is also hemmed by the
alcohol which accumulates in the solution, and for the same
reason the ammoniac fermentation of urine ceases when the
amount of ammonium carbonate produced amounts to 13 per
cent. (Flügge).
Some products of putrefaction appear to exert a similar action
the life of bacteria. Up to the present, however, it has
upon
not been possible to determine with certainty to which of the
many products of putrefaction this action is to be ascribed.
VITAL MANIFESTATIONS OF BACTERIA.
15
VITAL MANIFESTATIONS OF BACTERIA.
As vital manifestations of bacteria, are to be considered all
those phenomena which are excited by their presence in the sub-
strata which they inhabit. It is immaterial whether the latter
consist of dead substances, or of living animal or vegetable organ-
isms.
I. ACTION OF BACTERIA UPON THE LIVING VEGETABLE
OR ANIMAL BODY.
It is a belief of very old date, which found expression in the
writings of Varro as early as the first century B.C., that diseases
of an epidemic character are produced by some invisible living
element, a contagium vivum, contagium animatum; not, however,
until the first quarter of the present century, was this belief
placed on a scientific basis by the celebrated physician and nat-
uralist, IIufeland. In the year 1835 it received a strong actual
support by the discovery of Bassi that a fatal disease of the silk-
worm (muscardine), was produced by a mould-fungus (Botrytis
Bassiana). A few years later de Bary, Kühn and others, estab-
lished the parasitic nature of a number of diseases in grain, and
in the years 1851 to 1857, Rayer, Brauell, and Pollender fol-
lowed with the discovery of the anthrax bacillus. From this
time on, the attention of physicians and naturalists has been con-
stantly directed more and more to these low forms of life as the
exciting causes of disease. Micro-organisms were found to be
present in various disorders, and finally, within the last few years,
since the introduction of Koch's well-known culture methods,
the parasitic nature of a large number of diseases has been in-
dubitably established.
I will here name only anthrax, relapsing fever, abdominal
typhus, lepra, gonorrhea, tuberculosis, lupus, cholera, pneumo-
nia, syphilis, malaria, glanders, erysipelas, diphtheria, puerperal
fever, and suppurative processes.
We distinguish bacteria according to their action upon living
bodies, as (1) pathogenic and (2) non-pathogenic. Pathogenic
are all micro-organisms which, when brought into contact with
any part of a living organism under favorable conditions, multi-
ply and give rise to either local or general disturbances.
D
16
THE MICRO-ORGANISMS OF THE HUMAN MOUTH.
No sharp line of distinction can, however, be drawn between
pathogenic and non-pathogenic bacteria, for every bacterium.
brought into the animal organism in sufficiently large masses will
be able to maintain itself for a certain length of time and to
excite more or less inflammatory reaction.
Pathogenic in a high degree are those bacteria which, like the
anthrax bacillus, produce dangerous disturbances, even though
singly inoculated into the organism; very slightly pathogenic
are those which can cause disturbances only when introduced
in large quantities. Non-pathogenic are those, which, brought
into the organism in large numbers, soon disappear without
having produced any apparent disturbance.
Pathogenic bacteria exert very different and diverse influences
upon different species of animals. An animal of one species
may manifest symptoms of disorder soon after inoculation,
while members of another species may remain altogether unaf
fected by it. Even different varieties of one and the same species.
do not always manifest the same degree of susceptibility when
inoculated with the same bacterium; e.g. house mice inoculated
with the bacillus of mouse septicemia in a skin pocket suc-
cumb within forty to sixty hours, whereas field mice suffer no
inconvenience from the inoculation. Koch 10 explains this phe-
nomenon by the difference of the blood of these two nearly
related varieties.
A species or variety is consequently said to be either suscep-
tible (disposed) or unsusceptible (immune, refractory). With
every animal the degree of susceptibility varies at different times,
according to the condition of the body at the time being (tempo-
rary susceptibility). Furthermore, since in all epidemics the dis-
ease does not rage everywhere with equal severity, but attains its
greatest intensity at certain circumscribed points or localities, it is
customary to speak also of a local disposition or susceptibility.
Bacteria are further divided into parasitic: such as live in or
upon living organisms, and saprophytic: such as are confined to
dead substances. Most parasitic bacteria, however, are also
able to live upon dead matter, and may consequently be culti-
vated in artificial media, while on the other hand pure sapro-
phytes occasionally take on the habitus of parasites.
VITAL MANIFESTATIONS OF BACTERIA.
17
Such parasites as thrive only in or upon living organisms are
classed by de Bary as strictly obligatory parasites. To this class-
several species occurring in the oral cavity seem to belong. Sap-
rophytes which find their conditions of existence fulfilled only
in dead substances, are called obligatory saprophytes. Parasites
which occur in the interior of an organism are called endophytic;
those which vegetate only on the surface, epiphytic. Bacteria
which on being introduced into the human or animal organism
lead to formation of pus, are designated as pyogenic.
Very careful investigations made by Klemperer,¹¹ Biondi,¹2
Zuckermann, and many others, have led to the conclusion that
"chemical irritants, when free from micro-organisms, cannot
produce suppuration." Kreibohm and Rosenbach, Grawitz and
de Bary 15 obtained other results. According to them, certain
chemical substances, as oil of turpentine, ammonia, nitrate of
silver, etc., may under favorable conditions call forth suppura-
tion. Scheuerlen 16 was also able to cause suppuration by the
action of an alkaloid of putrefaction (cadaverine), without the
agency of micro-organisms. Nathan " repeated the experiments
of Grawitz and de Bary, and also found that suppuration took
place after injections of oil of turpentine, ammonia, and nitrate
of silver; in all cases, however, he was able by means of the
culture method to establish the presence of micro-organisms.
Nevertheless Grawitz,18 in a subsequent communication, main-
tains the correctness of his previous conclusions.
17
It has been suggested that these conflicting results may be ex-
plained by the fact that different investigators have made use of
different animals in their experiments. While the advocates of
the theory no suppuration without micro-organisms, have used
chiefly rabbits, guinea-pigs and rats, Kreibohm and others em-
ployed dogs.
As the matter stands at present, the burden of proof seems to
be in favor of the view that, in case of dogs at least, certain sub-
stances may, under specified conditions, produce suppuration
without the agency of micro-organisms.
2
14
18
THE MICRO-ORGANISMS OF THE HUMAN MOUTH.
II. ACTION UPON LIFELESS MATTER.
Bacteria are furthermore designated, with reference to their
action upon the substratum, as:
1. Zymogenic, or fermentation bacteria.
2. Chromogenic, or color-forming bacteria.
3. Aërogenic, or gas-forming bacteria.
4. Saprogenic, or putrefaction bacteria.
1. Fermentation Bacteria.
Ferment bacteria are such as bring about those changes in
the substratum which have been designated as fermentation.
According to Hoppe-Seyler, these changes are intense decom-
positions of complicated organic compounds, through which sub-
stances arise "which have together less heat of combustion
than those bodies out of which they were formed." By others,
fermentation is described as a process of decomposition, which
is inaugurated and continued by a substance called a ferment,
without the ferment itself suffering any change; this kind of
action is frequently designated as catalysis, κατάλυσις (καταλύω)
dissolution. During the process of fermentation the medium
gradually loses its nutritive power; it becomes used up. The
substances which are thereby produced are very numerous, and
of very different character. Many of them, the ptomaïnes, have
exceedingly poisonous properties. It is highly probable that all
bacteria, pathogenic as well as non-pathogenic, when brought
into a suitable substratum, possess the property of producing
changes which must be designated as fermentation. The fermen-
tation of nitrogenous, and more particularly of albuminous
substances, which is accompanied by the development of large
quantities of gaseous and stinking products, is called putrefactive
fermentation, or simply putrefaction, and the bacteria causing
this kind of fermentation are putrefactive or saprogenic bacteria.
Many years ago I20 called attention to the fact that the course of
the fermentation frequently depends more upon the substratum
than upon the micro-organism. Bacteria which grow upon white
of egg, producing an intensely offensive smell and a strong alka-
line reaction, when brought into carbohydrates exhibit entirely
19
VITAL MANIFESTATIONS OF BACTERIA.
19
different phenomena, viz. acid reaction and total absence of bad
smell.
We cannot therefore draw a sharp line between putrefactive
and fermentative bacteria. According to my observation there
are but a limited number of bacteria which will, under all circum-
stances, produce putrefaction. These might be called obligatory
saprogenic bacteria, in contradistinction to those which produce
putrefaction only under certain specified conditions; these latter
might be called facultatively saprogenic..
Bacteria produce a series of well-characterized fermentations,
whose nature has, however, in many points not yet been fully
explained. These fermentations are, according to Flügge's classi-
fication :21
A. Fermentation of carbohydrates.
B. Fermentation of the polyvalent alcohols.
C. Fermentation of fatty acids.
D. Putrefaction.
E. Oxidation of alcohol to acetic acid. To these we add:
F. Ammoniacal fermentation.
G. Diverse processes of oxidation and reduction first observed
in the soil, but probably going on under various other conditions.
A. Fermentation of Carbohydrates.
Carbohydrates, when acted upon by different bacteria, undergo
a series of fermentations which may be considered under the
following heads:
a. Lactic acid fermentation.
•
b. Mannite, or mucous fermentation.
c. Dextrane fermentation.
d. Butyric acid fermentation.
e. Diverse fermentations which cannot be classed under the
above heads.
Among the carbohydrates, the sugars in particular are ferment-
able in a high degree; other carbohydrates, however, as dextrine,
starch, cellulose, etc., may also undergo fermentation under the
action of certain micro-organisms. Tappeiner (Flügge 2) observed
a fermentative decomposition of cellulose in the alimentary canal
20
THE MICRO-ORGANISMS OF THE HUMAN MOUTH.
of ruminants; also two kinds of cellulose fermentation in artificial
mixtures. The former took place in neutral 1 per cent. beef extract
solutions, in which purified cotton or paper pulp was suspended,
carbonic acid, marsh gas, and small quantities of sulphuretted hy-
drogen, aldehyde, isobutyric acid, and acetic acid being formed;
the latter in alkaline beef-extract solutions, carbonic acid and
hydrogen being formed, with the same by-products as before.
Nothing at all is known concerning the occurrence of such fer-
mentations in the human mouth. They might possibly come
into consideration in the decomposition of cotton used in the
treatment of teeth.
a. Lactic Acid Fermentation.
Lactic acid fermentation of carbohydrates takes place sponta-
neously in milk, in the juice of the sugar-beet, in the accumu-
lations in the oral cavity, etc., and may be artificially induced by
a large number of different bacteria in saccharine solutions. It
proceeds most rapidly at a temperature of from 30°-38° C. The
course of the fermentation varies greatly, according to the bac-
terium by which it is produced. Sometimes there seems to be a
perfectly even decomposition of the molecules of sugar into two
molecules of lactic acid, according to the equation C6H12O6 (grape
sugar)=2C,HO, (lactic acid), no appreciable quantity of car-
bonic acid or hydrogen being formed. At other times the fer-
mentation is of a more violent nature, large quantities of carbonic
acid and hydrogen being formed, with other by-products, as
acetic, formic, succinic, and possibly butyric acid.
It is usually assumed that lactic acid fermentation must always
be accompanied by a development of carbonic acid. I was, how-
ever, struck by the fact that in certain cultures an evolution of
gas always failed to take place. In order to arrive at a positive
conclusion in regard to this point, I undertook an experiment
in a large glass vessel containing a liter of beef-extract-sugar-
solution, which I inoculated with a small piece of carious den-
tine. Then a rubber cork, carrying a bent glass rod, was coated
with sealing-wax and pressed into the heated opening of the
glass vessel, thus hermetically sealing it. The vessel, being
placed in the incubator, exhibited after a few hours a rapid de-
3
VITAL MANIFESTATIONS OF BACTERIA.
21
velopment of bacteria and an acid reaction. No bubbles of gas
were seen to be ascending through the solution, or to have
accumulated upon its surface, as is frequently the case in such
cultures. Hereupon the end of the escape-tube was made to
dip into lime-water, in which the smallest quantity of CO, escap-
ing from the flask would be readily detected by the cloudiness.
occasioned by the formation of the carbonate of lime, but after
twelve hours no cloudiness had appeared. I then heated the
flask, in order to drive out any carbonic acid possibly formed;
the lime-water, however, still remained clear. I repeated this
experiment with an apparatus for collecting the gas over mer-
cury. In a culture in which 1.75 grams of lactic acid were pro-
duced, only one little bubble of gas was collected, which might
as well have been caused by an imperceptible rise in the temper-
ature of the incubator as by actual gas formation.
From these experiments I can draw no other conclusion than
that the fermentation produced by the micro-organisms in ques-
tion is not accompanied by development of carbonic acid. This
process, writes Flügge (Lit. 2, p. 483), which wholly fails to evolve
gases, does not meet the requirements of the ordinary definition
of fermentation, and can consequently not be considered as such.
The fermentation ceased in all cases which I have thus far
examined, when the substratum showed 0.75 per cent. of acid.
In the mouth, however, the fermentation can proceed without
interruption, since the acid formed is either washed away or
combines with the lime of the teeth and tartar.
As early as 1857, Pasteur 22 showed that the transformation of
sugar into lactic acid depended upon the presence of a species.
of micro-organism.
The name of Bacillus acidi lactici (lactic acid bacterium) has
been given to a bacillus, first cultivated by Hueppe,23 from sour
milk. Although very many different bacteria are known which
possess the power of converting carbohydrates into lactic acid,
it is thought that Hueppe's bacterium should be designated as
the lactic acid bacterium, since it is "by far the most frequent
cause of spontaneous lactic acid fermentation."
This bacillus forms short, plump rods, from 1-1.7μ long and
0.3-0.4p thick; it is immotile, forms spores. Below 10° C.
22
THE MICRO-ORGANISMS OF THE HUMAN MOUTH.
and above 45.5° C. all development ceases, the optimum lying
between 35° and 42° C. It possesses inverting action, and trans-
forms not only dextrose, but also cane-sugar, milk-sugar, and
mannite into lactic acid. Its ferment-action is regularly accom-
panied by the development of carbonic acid.
It is not improbable that this bacillus plays an essential part
in fermentations of the human mouth. The frequency of its
occurrence in the oral cavity has, however, not yet been deter-
mined, although I have several times cultivated a micro-organism
from the mouth which, in point of morphology and physiology,
seems to be identical with Hueppe's bacterium.
b. Mannite Fermentation.
Mannite fermentation (mucous or gum fermentation) is caused
by an exceedingly small coccus (Micrococcus viscosus) which
grows in chains in various saccharine beverages, in wine, beer,
etc., and in saccharine juices. In consequence of the fermenta-
tion these liquids become slimy, viscous (stringy).
24
The products of fermentation are a kind of gum (viscose),
closely resembling dextrine, also mannite and carbonic acid. The
optimum of temperature is 30° C. Black 2 observed a similar
fermentation, caused by the action of various mouth-bacteria
(micrococci) in saccharine solutions. One coccus, occurring in
chains, cultivated in peptone bouillon with 2 per cent. of sugar,
gelatinized" the fluid so entirely in twenty-four hours that it
did not run out when the tube was inverted. The optimum of
temperature was above 100° F. The products of fermentation
were not examined. This fermentation, which is most probably
a kind of gum fermentation, explains, according to Black, the
mucous coating on the teeth and tongue in case of sordes in fever.
c. Dextrane Fermentation.
2
Dextrane fermentation occurs spontaneously under the action
of a micrococcus, Leuconostoc mesenterioïdes, in the juice of the
beet and in the molasses of sugar factories, and can also be in-
duced artificially in saccharine solutions. The masses of bacteria
(zooglœa) form a jelly of cartilaginous consistency, which com-
pletely fills the vessels containing the molasses. The products.
66
VITAL MANIFESTATIONS OF BACTERIA.
23
1
of fermentation are a jelly-like substance, dextrane and carbonic
acid. The optimum of temperature lies between 25°-35° C. As
cane-sugar is easily inverted, it serves the purpose of fermentation
as well as grape-sugar.
d. Butyric Acid Fermentation.
Few trustworthy observations have been made in regard to
the butyric acid fermentation of carbohydrates. The experi-
ments of Fitz, and more recently those of Flügge, have made it
appear probable that several species of bacteria are able to cause
a fermentation of carbohydrates, in which butyric acid results as
с
0
FIG. 6.

0
1оооов
ло 0 0 0
b
a
1%
P

BACILLUS BUTYRICUS.
a, b, Tadpole- and Spindle-shapes, partly with spores; c, Zoogloea condition.
A, Germination of a spore. (After Prazmowski.)
the principal product. These seem to be, for the most part, an-
aërobic, which makes it difficult to obtain them in pure culture.
Butyric acid, as well as lactic acid fermentation, was formerly
supposed to be due to the action of a single organism. This bac-
terium of butyric acid fermentation (Bacillus butyricus, Clostrid-
ium butyricum, Vibrion butyrique, etc.), whose morphology,
development, etc., have been thoroughly investigated by Praz-
mowski,25 appears in.form of rods from 2-12μ long and about 1.0μ
broad, either single or in long chains, or in zooglcea (Fig. 6);
frequently the rods grow out into long threads. During spore-
formation the cells exhibit peculiar changes of form; spindle,
ellipsoidal, or tadpole shapes appear, which in certain parts
BAN
24
THE MICRO-ORGANISMS OF THE HUMAN MOUTH.
attain to a diameter of 2.6p. (Fig. 6, a, b.) The plasma of the
cells is thereby condensed and becomes highly refractive; the
membrane also appears considerably thickened. This change
of form is soon followed by the formation of the spores. The
Bacillus butyricus is typically anaerobic; access of air impedes
or entirely prevents its development and fermentative action.
In solutions of carbohydrates (starch, sugar, dextrine), and of
lactates, this micro-organism produces butyric acid under evolu-
tion of carbonic acid and hydrogen. The fermentation is most
intense when air is excluded; optimum temperature, 35° to 40° C.
The butyric acid fungus shows a peculiar reaction in regard to
iodine, which is also incidental to several other bacteria. "Under
certain conditions it gives rise to a compound which is colored
blue to dark violet by iodine, and which consequently is to be
regarded as an analogon of starch." This reaction occurs when
the micro-organism is cultivated in solutions of starch, cellulose,
glycerine, and lactate of lime, rarely when solutions containing
dextrine and sugar are made use of. The young rods are colored
blue, the older ones dark violet; some only in scattered transverse
zones, others in continuo. The reaction depends also upon the
intensity of the fermentation.
The conditions obtaining in some parts of the human mouth
are not adverse to the development of the butyric acid bacterium;
hitherto, however, no proof has been adduced for the statement,
regularly found in hand-books of dentistry, that butyric acid is
formed in the oral cavity. In the first place, no micro-organism
has as yet been discovered in the mouth which gives rise to this
fermentation, nor has any trace of butyric acid ever been detected
in it. In regard to this point, however, experiments of a suffi-
ciently exhaustive nature are still wanting.
That butyric acid may be formed in the oral cavity as a
by-product in lactic acid fermentation, is at least highly probable.
The fermentation of a large quantity of saliva and starch yielded
about 2.0 c.cm. of lactic acid, and a few drops of a liquid faintly
sinelling of butyric acid, but the quantity was too small to allow
of a more accurate determination.
3
VITAL MANIFESTATIONS OF BACTERIA.
25
e. Diverse Fermentations.
Brieger 26 examined a number of bacteria, especially patho-
genic, in regard to their products of decomposition. A coccus
which occurs in the human fæces always splits 3 per cent. cane-
or grape-sugar solutions in the same manner, producing ethyl-
alcohol within the short space of twenty-four hours. Traces of
acetic acid are also appreciable. A pathogenic bacillus, also found
in the fæces, forms in grape-sugar solutions propionic acid, accom-
panied by minute quantities of acetic acid. The coccus of pneu-
monia decomposes cane- and grape-sugar solutions into acetic
acid, and very minute quantities of formic acid, under evolution
of large quantities of carbonic acid. (The solutions had been
saturated with freshly precipitated carbonate of lime.)
Typhus bacilli split grape-sugar solutions, or starch, into
acetic and lactic acids, and ethyl alcohol. Staphylococcus pyo-
genes aureus, when cultivated in bouillon containing glycogen
(3:100) and a quantity of freshly precipitated carbonate of lime,
forms very small quantities of organic acids (principally oxalic
acid).
Fitz 27 has also observed several carbohydrate fermentations;
among others, one in which ethyl alcohol appeared as chief pro-
duct. As products of milk-sugar fermentation, he found ethyl
alcohol and other substances not further determined. Cane-
sugar yielded butyl alcohol, butyric acid, and traces of lactic and
succinic acids. Starch yielded butyric and acetic acid; inuline,
which fermented as easily as starch, gave alcohol and volatile
acids.
Boutroux 28 found gluconic acid as a product of the fermenta-
tion of milk-sugar.
B. Fermentation of Polyvalent Alcohols.
In his communications concerning "schizomycetes fermenta-
tions," Fitz has described a number of different fermentations of
polyvalent alcohols: glycerine, erythrite, mannite, dulcite, and
quercite. Glycerine yielded normal butyl alcohol, with profuse
generation of carbonic acid and hydrogen, normal butyric acid,
and traces of a higher fatty acid (probably capronic).
26
THE MICRO-ORGANISMS OF THE HUMAN MOUTH.
A second experiment showed as chief product capronic acid,
and as by-products butyric and lactic acids. In other cases of
glycerine fermentation Fitz discovered traces of acetic acid, with
butyl alcohol as principal product. The Bacillus butyricus fer-
mented glycerine, so that butyric acid, as well as acetic, capronic,
and lactic acids, were formed. Different experiments with ery-
thrite yielded alcohol, butyric, acetic, also traces of formic and
succinic acids. Mannite yielded butyl and ethyl alcohol, butyric
and succinic acids, with a variable quantity of capronic, acetic,
lactic, and formic acids. Dulcite gave many volatile and some
non-volatile acids; quercite gave normal butyric acid, etc.
Fitz probably employed impure cultures in all his experi-
ments, which would explain the large number of products of
fermentation. It is not to be supposed that these fermentations
play an important part in the mouth, as the necessary nutrients
are not present in sufficient quantities, or in part are altogether
wanting.
C. Fermentation of Fats, Fatty Acids, and Oxyacids.
Fats exposed to the air soon become rancid, as is well known,
and give off a more or less strongly marked odor of fatty acids.
This change is due to a decomposition of the fats into glycerine
and fatty acid, under the action of micro-organisms.
The following fatty and oxyacids and their salts are also fer-
mentable: formic and acetic acids, lactic acid (oxypropionic acid),
glycerinic acid, malic (oxysuccinic) acid, tartaric (dioxysuccinic
acid, citric (oxytricarballylic) acid.
=
Formate of lime yields CaCO3, CO2, and H;
Acetate of lime yields CaCO3, CO2, and CH4.
According to Fitz, lactate of lime undergoes four different
fermentations. In the first are formed propionic acid, and as
by-products, acetic and succinic acids and alcohol; in the second,
propionic and valeric acids; in the third, butyric and propionic
acids; in the fourth, butyric acid, with ethyl and butylic alcohol
as by-products.
Glycerate of lime produces tartrate of lime, with succinic acid.
and ethyl alcohol as by-products; according to Fitz, also acetic
acid and traces of formic and succinic acids.
VITAL MANIFESTATIONS OF BACTERIA.
27
Malate of lime also undergoes several kinds of fermentation,
forming propionic, butyric, acetic, and lactic acids.
Tartrate of lime yields propionic or butyric acid, and, accord-
ing to Fitz, alcohol, acetic, and traces of succinic acids.
Finally, citrate of lime yields acetic acid, with ethyl alcohol
and succinic acid as by-products. (See Flügge, Micro-organisms,
p. 489.)
In accordance with the various fermentative processes specified
in the foregoing pages, a particle of starch introduced into the oral
cavity would undergo about the following successive changes: In
the first place it is, in part at least, transformed into grape-sugar
by the diastase of the saliva (ptyaline). This, in turn, is split into
lactic acid through the action of various bacteria in the mouth.
The lactic acid unites with the lime of the teeth, or tartar, form-
ing lactate of lime. The latter, according to the investigations
of Fitz and others just referred to, may then undergo various
fermentations, giving rise to new acid products and to the for-
mation of the corresponding lime-salts, from which, by still other
processes of fermentation, acids are again derived. The process,
however, most probably ceases after the formation of lactate of
lime.
D. Putrefaction.
When the decomposition of a culture medium is accompanied
by the development of stinking, for the most part gaseous pro-
ducts, ammonia, sulphuretted hydrogen (NH, SH₂), etc., the
process is commonly designated as putrefaction. Albuminous
substances are especially liable to putrefaction; also the albu-
minoids (glue-giving substances), peptones, and lastly, some sub-
stances related to the albuminous bodies,-leucine, tyrosine,
indol, etc.
*
It is evident, however, that this definition by no means involves
a precise chemical or bacterio-chemical process, and that the
presence or absence of stinking gases cannot be made an absolute
criterion by which to judge of the real nature of the changes
going on in a medium containing bacteria.
The appearance of putrefactive products in any fermentation
does not depend alone upon the kind of fermentation and the
28
THE MICRO-ORGANISMS OF THE HUMAN MOUTH.
kind of bacterium, but more especially upon simultaneously
occurring processes which have little or nothing whatever to do
with the decomposition of the decaying substance. If, for instance,
a tooth-pulp decomposes in a closed root-canal, an incredible
amount of bad-smelling gas may be formed, so that on opening
the pulp-chamber the whole room will be impregnated with the
odor. But if a tooth-pulp is allowed to decompose in the open
air, hardly any disagreeable smell will be noticed, although the
decomposition of the nutrient medium caused by the fungi may
be identical in both cases. In the latter case, under free access
of air, those products of putrefaction which are accountable for
the offensive odor are further decomposed (oxidized) by the
oxygen of the air, which is activated by the hydrogen liberated
during the process of decomposition; they consequently do not
manifest their presence at all. Where, however, the access of
air is limited, or the air altogether excluded, the oxidation of
these products cannot take place and they escape unchanged
from the solution. The products of fermentation remain the
same in both cases, but their subsequent fate is different.
A solution of white of egg, infected with saliva and kept at
blood temperature, soon gives rise to a stinking smell and an
alkaline reaction (NH, and SH). But upon addition of about
2 per cent. of cane-sugar to a similarly infected solution, no bad
smell will be detected; free NH, and SH, are not evolved; the
reaction is acid. Nevertheless, we have no reason to doubt that
the white of egg undergoes the same decomposition in both cases.
The products arising from the decomposition of these albu-
minous substances are very numerous. According to Flügge,29
they are: carbonic acid, hydrogen, free nitrogen, sulphuretted
hydrogen, phosphuretted hydrogen, marsh gas, formic, acetic,
butyric, valeric, palmitic, acrylic, crotonic, glycolic, lactic, and
valerolactanic acids; oxalic and succinic acids, leucine, glycocoll,
glutaminic, asparaginic, and amidostearinic acids; ammonia,
carbonate of ammonia, sulphide of ammonia; numerous amine
bases, propylamine, trimethylamine, etc.; indol, scatol, scatol-
carbonic acid; tyrosine and its derivatives of the aromatic series,
and lastly the ptomaïnes.
The large number of acids included in this list does not by
G
.
VITAL MANIFESTATIONS OF BACTERIA.
29
any means justify the assumption that a putrefying mixture must
have an acid reaction; this is not the case, for the simultaneously
formed basic products are more than sufficient to neutralize the
acids, so that the resulting reaction is alkaline. We must further
consider that by no means are all of the substances named gen-
erated in every process of putrefaction. The number of ascer
tained putrefactive products of the individual bacteria seldom
exceeds six, they being generally stinking gases (H₂S, etc.),
ammonia, peptone, trimethylamine, and fatty acids; reaction
alkaline.
Ptomaïnes.
This name has been given to certain nitrogenous waste pro-
ducts of bacteria, closely resembling vegetable alkaloids, which are
formed in putrefying mixtures. As they were found repeatedly,
and at first chiefly in decaying corpses, Selmi called thẻm pto-
maïnes (лτμα, corpse). According to Brieger, the principal
authority on this subject, and upon whose exposition my remarks
are based, Panum was the first to isolate a chemical putrid poi-
son, a ptomaïne. The alkaloid of Panum had an action upon the
animal body similar to that of snake-poison and curare. Then
Schmiedeberg and Bergmann obtained from putrefying yeast a
very minute quantity of a substance acting toxically on frogs
and dogs, which they called "sepsine." Zuelzer and Sonnen-
schein isolated a substance from macerated corpses which acted
like atropine, and Rörsch and Fasbender one showing properties
similar to digitaline.
Furthermore, there were gained from corpses an oil having the
odor of propylamine, a substance resembling coniin, " septicine,"
an amorphous base similar to nicotine, and aqueous extracts
with action like that of curare. Selmi obtained non-crystalline
products, which, in regard to their reaction and toxic properties,
might have been mistaken for morphine, coniine, atropine, or
delphinine. A strychnine-like base was also found in putrid
maize, and von Nencki 30 obtained in chemically pure condition
a ptomaïne isomeric with collidine.
ja
In 1883, Brieger 31 began his experiments with the basic pro-
ducts of putrefaction, which soon proved very successful. From
30
THE MICRO-ORGANISMS OF THE HUMAN MOUTH.
putrefied meat, fish, glue, and yeast, from old cheese and digest-
ing fibrine, and from pure cultures of pathogenic bacteria, he
isolated a large number of ptomaïnes, some of which were found
to be non-poisonous, others poisonous in the highest degree. Of
the poisonous ptomaïnes, the following are deserving of particu-
lar mention:
1. Peptotoxine, gained from fibrin, casein, brain-matter, liver,
and muscular tissue.
2. Neurine, from putrefied meat.
3. A base similar to ethylenediamine, from putrefied fish.
4. Muscarine, from the same source.
5. Mydaleïne, and another not distinctly defined ptomaïne,
from putrefying parts of corpses.
6. A ptomaïne having toxical effects on guinea-pigs, found in
cultures of typhus bacilli on meat-pap, which did not present
any of the characteristic symptoms of putrefaction; also another
poison called typhotoxicon.
7. Tetanin, from cultures containing principally tetanus bacilli.
This base, which is formed along with profuse quantities of am-
monia, produced the same symptoms in mice, frogs, and guinea-
pigs, which accompany tetanus in man.
The following ptomaïnes were designated as non-poisonous :
1. Neuridine, in putrefying cheese, meat, and glue.
2. Gadinine, in putrefying fish.
3–6. Cadaverine, putrescine, saprine, choline, in putrefying
parts of corpses.
Brieger furthermore isolated a non-poisonous base from cul-
tures of Staphylococcus pyogenes aureus on meat-pap. Pure
cultures of Streptococcus pyogenes yielded, besides the normal
components of meat (xanthine, etc.), especially large quantities
of trimethylamine.
Vaughan 32 isolated a poisonous alkaloid, which he called tyro-
toxicon, from a cheese which had occasioned extensive poisoning,
as well as from the milk and cream used in the preparation of
vanilla ice-cream, which had also proved poisonous.
The question now arises whether the products which may
possibly be formed in an unclean mouth can exert any deleter-
ious influence on the mucous membrane of the oral cavity, or
VITAL MANIFESTATIONS OF BACTERIA.
31
upon the general state of health, and whether the alkaloids which
doubtless form in putrid pulps have any irritating action upon
the peridental tissues. The fact, established by Odenthal, that
glandular swellings in the region of the lower jaw occur espe-
cially as concomitants of dental caries, seems to justify the
assumption that the resorption of the putrefactive products
attending the decomposition of a tooth-pulp is an important
agent in the above-named disturbance.
·
1
E. Oxidation of Alcohol to Acetic Acid.
The exciting cause of acetic acid fermentation, the vinegar
fungus (Mycoderma aceti), usually appears in the form of cocci,
or diplococci, either singly or in chains (Fig. 7). According to
Hansen,33 Zopf, and others, it also grows in rod and leptothrix
forms. The formation of very long chains and so-called invo-
luted forms is specially characteristic of the vinegar fungus
(Fig. 7, a). It grows best at 30° to 35° C.,
and forms a covering or pellicle on the sur-
face of fermenting liquids, which attains a
thickness of 50 to 100 mm. The cells of this
fungus transfer the oxygen of the air to the
medium, and thus possess the specific faculty
of oxidizing the alcohol in fermented liquors
to acetic acid; C₂Н¸‚ OH+0₂=CH„, COOH
+H₂O. The fermentation takes place most
rapidly when a minute quantity of acetic
acid (1 to 2 per cent.) is already present.
More than 10 per cent. prevents the continu-
ance of the fermentation; under 10° C. and
over 35° C. the formation of acetic acid
ceases. The deficiency of alcohol and the high temperature
render the occurrence of the specific acetous fermentation in the
mouth highly improbable.
51
2
2
An oxidation of alcohol to acetic acid also occurs in a certain
degree when alcohol is exposed to the air on large surfaces
(wood shavings); also when the oxygen is transferred to the
alcohol by means of sponge platinum. For obvious reasons this
process does not occur in the mouth.
000
FIG. 7
oooo
oooor
фос

"
0
0
1
O
0
OO
o
Ooc
Ja
BACTERIUM OF ACETIC
ACID FERMENTATION
(MYCODERMA ACETI).
a, Involution forms.
32
THE MICRO-ORGANISMS OF THE HUMAN MOUTH.
1
F. Ammoniacal Fermentation.
Various bacteria, Ascococcus Billrothii, Micrococcus ureæ,
Bacillus ureæ, etc., occasion a fermentation of urea leading to the
formation of carbonate of ammonia, and imparting an intensely
alkaline reaction to the solution. W. Leube and E. Greser 34
obtained pure cultures of four different bacteria which have the
power to decompose urea. Two of them, a small bacillus
(Bacterium urea) and a coccus (Micrococcus urea), showed
intense urea-decomposing properties. The other two possessed
this property in a less marked degree. Lungsarcina also effected
an intense decomposition of urea.
G. Nitrification and Denitrification.
35
Finally, certain processes of oxidation and reduction which
take place in the soil have been found to be due to the presence
of micro-organisms, and must consequently be classed under fer-
mentations. Schlösing and Müntz 3 established this fact for the
case of natural nitrification, which, according to their experi-
ments, must be regarded as a process of fermentation, resulting
from the action of a specific micro-organism. In their experi-
ments they used filtered and sterilized drainage-water (l'eau
d'égout), or weak alkaline solutions containing mineral sub-
stances, a salt of ammonia, and organic matter. When these
solutions were sterilized, infected with soil and exposed to the air,
a nitrate-forming fermentation ensued, which was occasioned by
very small oblong microbes (ferment, nitrique). Continuous
exclusion of air destroyed the ferment nitrique; it occurs very
extensively, but was not found in the atmosphere.
The conditions for the consummation of this process are (1)
access of oxygen, (2) a certain degree of humidity, (3) weak
alkalinity, and (4) the presence of organic matter, Below 5° C.
nitrification proceeds very slowly; at a higher temperature the
intensity of the fermentation increases, until 37° C. is reached,
which represents the maximum. At a still higher temperature
it decreases rapidly, and at 50° C. (!) yields but minute quanti-
ties of nitrates.
On the other hand, Gayon and Dupetit 36 found four different.
VITAL MANIFESTATIONS OF BACTERIA.
33
microbes which reduced nitrates, sometimes to nitrites, some-
times to ammonia, nitrogen, and nitrous oxide (denitrification.)
Drainage-water, to which saltpetre was added (0.02 to 1 litre),
infected with spoiled urine, showed a gradual decrease of the
nitrate under development of numerous microbes.
When the culture was sterilized, or chloroform, or any other
antiseptic added to it, no process of reduction took place. The
presence of organic matter and a limited access of air were the
conditions of fermentation. The optimum of temperature was
found to lie between 35° and 40° C.
Salicylic acid, in antiseptic doses, did not impede the process of
reduction, but soon disappeared itself. Nitrates of sodium, am-
monium, and calcium were reduced in the same way as nitrates
of potassium. Dehérain and Maquenne obtained similar results.
Their first experiment yielded the following figures for one hun-
dred parts of the gas formed:
37
CO,
2
80.5
N₂O
8.2
2
N 11.3
The second experiment yielded-
CO₂ 67.3
Η 31.5
N 1.2
These processes of oxidation and reduction have also recently
been observed in pure cultures.
38
It appears from Heraeus's investigations that they may be
occasioned by a large number of different species of bacteria.
He made experiments with several known kinds, and also with
twelve unknown kinds, which he cultivated from water, soil,
etc. Of the latter, two reduced nitric acid to nitrous acid and
ammonia, and converted urea into carbonate of ammonia. Two
consumed nitric acid without reduction; one of them transform-
ing urea into salts of ammonia, the other not. None of these
twelve varieties manifested any oxidizing influence. Heraeus
succeeded, however, in isolating, from garden soil, two species
which led to the formation of nitrous acid in saccharine solu-
tions, in urine, etc.
:
3
34
THE MICRO-ORGANISMS OF THE HUMAN MOUTH.
The following well-known species also showed the power of ox-
idation Micrococcus (Bacillus) prodigiosus, typhus and anthrax
bacilli, Finkler-Prior's and Denecke's spirilla, Staphylococcus
citreus. Brieger's and Miller's bacteria yielded inconstant
results. Contrary to Schlösing and Müntz, Heraeus found these
organisms in the atmosphere also. The latter declares Pasteur's
"anaërobium" to be untenable; there are, on the contrary, bac-
teria which call forth reductions under all circumstances, as well
as those which occasion oxidations.
Wherever bacteria find a favorable nutrient medium, in con-
centrated urine, saccharine solutions, meat-juices, that is,
wherever there are large quantities of organic matter,—the
reducing bacteria will preponderate; but wherever the condition
of the nutrient medium prevents rapid proliferation, the oxidiz-
ing bacteria will gain the ascendency.
Warrington 39 was able to note only a reduction of nitrates to
nitrites; gaseous products did not appear. His experiments with
artificial mixtures showed but minute traces of nitrification.
Fresh corpses, imbedded in powdered charcoal, are said not to
putrefy, but to decay in such a way that after several months
only bones and fat remain, while the charcoal contains a quantity
of nitric acid.40 We probably have here to do with a process sim-
ilar to or identical with nitrification, the oxygen condensed in
the charcoal taking the place of the atmospheric air. The ques-
tion whether these processes occur in the human mouth will be
discussed in Chapter V. It appears to me not at all improbable
that the appearance of nitrous acid in the oral cavity is due to
the reduction of nitrates.
2. Chromogenic Bacteria.
Many kinds of bacteria occasion so-called pigment fermen-
tations in which coloring-matter is produced; green, red, and
yellow colors predominate, brown, blue, and violet being of
less frequent occurrence. The colors sometimes appear in the
membrane or protoplasm of the cells, which is usually the case
with bacteria that form yellow coloring-matter. More frequently,
only the culture medium becomes colored, the cells remaining
colorless. This is the case with all bacteria that form green color-
VITAL MANIFESTATIONS OF BACTERIA.
35
ing matter, with the exception, perhaps, of Bacterium chlorinum
(Engelmann) and Bacillus virens (van Tieghem). Access of
atmospheric air is essential to the production of pigment fer-
mentation.
H. Kronecker first called attention to a liquefying bacillus
whose cultures in bouillon showed no color when the access of
air was limited, but when shaken with air an intensely green
color instantly appeared. I have noted a similar
result in the case of other bacteria. Liborius #1
proved for a large number of pigment bacteria
"that all these coloring-matters are formed only
where there is free access of air."
41
Chromogenic bacteria are widely distributed in
nature. When a plate of nutritive agar-agar is
exposed to the air for some time, and then kept in
a moist chamber, colonies of various kinds of
chromogenic bacteria generally develop upon it.
They have their representatives among the patho-
genic, as well as the non-pathogenic organisms.
3. Aërogenic Bacteria.
Various kinds of gases, CO₂, H, N, SH₂, CH4,
NH,, etc., are often formed as waste products of
bacteria, as well as of fungi in general. Accord-
ing to Flügge, the functional activity of the lower
fungi must always be accompanied by the develop-
ment of CO2. Nevertheless the quantity of CO2
evolved from many cultures is excessively small,
and is to be considered as a product of intermolec-
ular respiration only (see also page 20).
FIG. 8.

C
AMA
CULTURE OF A
GAS-FORMING
BACTERIUM
FROM THE
STOMACH, IN
BREAD-SUGAR
GELATINE.
One day old.
½: 1.
In fermentations of carbohydrates, lactic and
butyric acid, mannite and cellulose fermentations,
and various others, CO2, H, and CH, are princi-
pally or exclusively formed, the former often in
such quantities that the course of the fermentation is exceed-
ingly violent (Fig. 8).
The fermentation of albuminous substances (putrefaction) is
36
THE MICRO-ORGANISMS OF THE HUMAN MOUTH.
1
accompanied by the development of CO2, H, N, SH₂, PH, CH,
NH₂. In cellulose fermentations CO2, H, and CH4, in alcohol
fermentations CO2 and H are produced.
The formation of gas occasions manifold disorders in the human
stomach and intestinal tract. In putrefying pulps it is the fre-
quent cause of periostitis and abscess formation, since the gases.
generated force their way through the apical foramen or even
carry particles of the putrid pulp along with them, thereby
causing a severe irritation of the pericementum.
4. Saprogenic Bacteria (Bacteria of Putrefaction).
This term has been applied to such bacteria as are endowed
with intense putrefactive properties. They occur among the
saprophytes, as well as among the parasites. Many pathogenic
bacteria possess saprogenic properties; thus, for example, Bacil-
lus saprogenes (I, II, III), Bacillus pyogenes fœtidus, Brieger
bacillus, etc. The cause of putrefaction lies in the faculty pos-
sessed by many, if not by most, bacteria, of decomposing albu-
minous substances in such a manner as to give rise to character-
istic products of decomposition. (See Putrefaction, page 27.)
CHAPTER II.
NUTRIENT MEDIA FOR BACTERIA IN THE ORAL CAVITY.
THE organic and inorganic substances found in the mouth,
which may serve as nutriment for micro-organisms, are the fol-
lowing:
1. Normal saliva.
2. Buccal mucus.
3. Dead epithelium.
4. Dental tissue softened by acids.
5. Exposed pulps.
6. Exudations of the gums, conditioned by the irritation of
tartar, etc.
7. Accumulation of particles of food.
1. SALIVA.
Normal, human, mixed saliva is a colorless liquid, usually
slightly clouded by epithelium; it is more or less slimy, slippery,
and viscous, differing with different individuals. Normally the
submaxillary and sublingual glands furnish a viscous secretion,
whereas that of the parotid is more dilute. In healthy persons
it has a weak alkaline or neutral reaction; its specific gravity is
1.002 to 1.006. Under the conditions mentioned in Chapter VIII,
the reaction frequently becomes acid. If kept standing, especially
at blood temperature, it will putrefy sooner or later, according to
the amount of organic matter it contains; in the presence of
starch or sugar no real putrefaction takes place, but a process
of fermentation ensues, giving rise to an acid reaction and sour
smell, accompanied by the formation of carbonic acid.
37
38
THE MICRO-ORGANISMS OF THE HUMAN MOUTH.
The analysis of C. Schmidt and Jacubowitsch gives the fol-
lowing chemical ingredients of human saliva :
Water
Soluble organic substances
Epithelium
Sulphocyanide of potassium
Chloride of calcium (KCl) and chloride of sodium
(NaCl)
Other inorganic salts
Water
Dry substance
Organic substance
Mineral salts
Salts
water
·
果
​1000.00
The composition of the saliva of such animals as have been
particularly studied with reference to this point, differs essentially
from that of human beings. According to Ellenberger and
Hofmeister, the parotid saliva contains in 1000 parts:
a. in horses:
b. in cows:
CINA
CO, alkali
3
soluble in
Phosphates of the
alkalies and sul-
phates
CaCO, insoluble in
water
991.613
8.387
2.429
5.958
4.580
2.364
1.775
0.441
1.378.
42
Water
Dry substance
Organic substance
Mineral salts .
Salts
soluble
water
CINa
CO, alkali.
3
3
water
in
Sulphates and phos-
phates of alkalies
CaCO, insoluble in
995.16
1.34
1.62
0.06
0.84
0.98
990.000
10.000
0.400
9.600
9.550
0.440
7.460
1.650
0.050
The great amount of carbonate of the alkalies is specially note-
worthy; it imparts a strong alkaline reaction to animal saliva,
and is well calculated to neutralize such acids as may be formed.
in the animal mouth, thus tending to prevent the appearance of
caries.
Ellenberger and Hofmeister 43, 44 have carefully examined the
saliva of various animals (domestic mammals). According to
NUTRIENT MEDIA FOR BACTERIA IN THE ORAL CAVITY. 39
their researches, all the glands of the oral cavity of horses, cattle,
sheep, pigs, and dogs contain a ferment which converts starch-
paste into sugar and dextrine, while soluble modifications of
starch appear as intermediate stages. The saliva of cattle, sheep,
dogs, rabbits, etc., as well as that of horses and cows, differs
essentially from human saliva, in the strong alkaline reaction.
The inorganic ingredients (salts) contained in human saliva
are, besides chloride of potassium and chloride of sodium, com-
binations of carbonic and phosphoric acids with calcium, potas-
sium, natrium, and magnesium, calcium and natrium carbonate
preponderating (Hoppe-Seyler). Clear saliva exposed to the air
becomes cloudy through the precipitation of carbonate of lime
(Hoppe-Seyler), a fact which should be borne in mind in any
attempt to account for the formation of tartar. Human saliva
also contains slight traces of a nitrous compound, as is shown.
by the appearance of a blue color upon adding saliva slightly
acidified with very dilute sulphuric acid to a dilute solution of
iodide of potassium containing starch. The presence of nitrites
in the human saliva is probably to be accounted for by a reduc-
tion of the nitrates introduced into the mouth with food and
drink.
If human saliva from an unclean mouth be acidified with
muriatic acid, and a small quantity of chloride of iron added, a
beautiful red color almost always appears, which indicates a com-
pound of sulphocyanogen. The manner in which this compound
is formed in the human mouth is unknown. It has been supposed
to have some connection with carious teeth, or, according to
others, with smoking; the latter view is unquestionably erro-
neous, for I have repeatedly found the above-mentioned combi-
nation in the mouths of non-smokers.
The human saliva, as may be readily seen from the analysis,
is very poor in organic ingredients. It contains traces of an
albuminous substance which is coagulated by heat, also invaria-
bly a small quantity of mucine; in the saliva of dogs 0.662–2.604
grams were found in 1000 (Hoppe-Seyler). Consequently, the
saliva turns slightly yellow when boiled with nitric acid, changing
to orange upon the addition of an alkali. The addition of sul-
phate of copper (CuSO) and caustic potash (KHO) produces
40
THE MICRO-ORGANISMS OF THE HUMAN MOUTH.
•
a violet color. Alcohol, acetic acid, etc., cause a white flaky or
fibrous precipitate.
Lastly, human saliva invariably contains a diastatic ferment,
called ptyaline, which is identical with that found in the secre-
tion of the pancreatic glands, in the juices of the stomach and
intestines, in blood-corpuscles, in the liver, in the secretion of the
tonsils, etc. This ferment also occurs in the saliva of guinea-
pigs and rabbits, rarely in that of dogs (Hoppe-Seyler); Roux 15
failed to detect it in the saliva of horses. Ellenberger and Hof-
meister, on the other hand, invariably found ptyaline in the
saliva of dogs and horses.
Through the action of ptyaline, starch is converted into dex-
trine and a kind of sugar (called ptyalose by Nasse), which is
directly fermentable and has the property of reducing the oxide
of copper. The process of saccharification begins instantly, so
that it is immaterial for the ensuing fermentation whether the
saliva be mixed with starch or with sugar. Theoretically, the
acid reaction would set in at the same time and with equal in-
tensity in both cases. Indeed, it seems as if saliva mixed with
starch ferments not only sooner, but also forms a larger quantity
of acid than sugar. (See Chapter VIII.)
Ptyaline is able to convert comparatively large, though not
unlimited, quantities of amylum into sugar. In an experiment
made by Krüger, 4.672 grams of amylum were converted into
ptyalose by 1 gram of pancreatic juice, within the space of thirty
minutes. Now, since 1 gram of pancreatic juice contains only
0.014 of organic matter, of which, again, the ferment represents
but a small fraction, it is evident that 1 gram of the ferment can
transform a multiple of 314 grams of amylum into sugar in half
an hour. Ptyaline differs from the vegetable diastase, (1) in the
dissimilarity in the sugars formed; in the latter case, not ptya-
lose, but maltose, is produced; (2) in respect to the very differ-
ent temperatures at which the ferments are most active, ptyaline
acting most rapidly at 35° to 40° C., vegetable diastase at 70° C.
A sufficient quantity of pure saliva for the purpose of experi-
mentation may be obtained, after very thoroughly cleansing the
teeth and entire oral cavity, by placing a crystal of muriate of
cocaine upon the back of the tongue or by painting the surface
NUTRIENT MEDIA FOR BACTERIA IN THE ORAL CAVITY. 41
of the tongue and cheeks with sulphuric ether. If the mouth
is then held wide open over a glass or porcelain vessel, the saliva
will flow out in clear thin drops from the parotid or in long,
viscous streams from the sublingual and submaxillary glands.
Saliva thus obtained is but slightly clouded, but forms a white
precipitate when left standing. If a small quantity of this
precipitate be placed upon an object-glass in a drop of water,
covered with a cover-glass and a small drop of dilute sulphuric
acid allowed to flow underneath, a formation of gas-bubbles will
be observed (CO2), while under 20 to 40 diameters the needles
characteristic of sulphate of lime will appear. By means of
molybdate of ammonia, phosphoric acid may also be easily de-
tected in this precipitate. The latter, therefore, consists partly
of carbonates and partly of phosphates (lime-salts), and sufficiently
explains the formation of tartar. There is, consequently, no
need of having recourse to the theory, which for various reasons
is untenable, that tartar consists of the calcareous remains of
bacteria.
Pure saliva exposed to the air undergoes putrefaction, not as
rapidly, however, as is generally asserted in text-books of phys-
iology; on the contrary, sometimes very slowly, so that no bad
smell may be detected before several days have elapsed. Only
when the saliva is mixed with organic matter from the mouth
does it soon show marked signs of putrefaction.
This may be easily understood when we take into considera-
tion the fact that human saliva contains only about 0.15 per cent.
of organic matter, and is, therefore, but a very indifferent cul-
ture medium for bacteria, since experience has taught that a
good culture medium must contain a much greater quantity of
organic matter. As before mentioned, if sugar is added to the
saliva no sign of putrefaction will appear, but a fermentation
takes place which engenders an acid reaction and a sour smell.
The view, entertained by many dentists, that saliva possesses
antiseptic properties, seems to me to be unfounded. Those con-
stituents of human saliva which have antiseptic properties are
present in too small quantities to be able in any way to impede
the development of bacteria. The fact that the human mouth is
so favorable a place of habitation for so many kinds of bacteria, is
#7
42
THE MICRO-ORGANISMS OF THE HUMAN MOUTH.
of itself sufficient to prove the absolute incongruity of such an
idea. What would we think of a man who would put a piece
of meat in saliva, in the hope of keeping it from decay? The
comparative rarity of diseases of the gums, in spite of the large
number of bacteria in the mouth, is due, not to the antiseptic
action of the saliva, but to the great power of resistance of the
gums, and to their comparative unsusceptibility to infectious
agents. It is well known that in removing tartar from badly kept
teeth we often wound the gums with impunity, in a manner
which on other parts of the body would be very likely to lead to
a serious infection.
rf
2. THE BUCCAL MUCUS.
The secretion of the mucus-glands of the mouth is identical
with the mucus secreted by the submaxillary and sublingual
glands, which gives the saliva of these glands its viscous and
slippery character.
Hermann 16 calls the mucus "a clear, slimy, viscous alkaline
fluid"; according to others, it has an acid reaction; most proba-
bly the reaction of mucus, as well as of saliva, is subject to
variations dependent upon the general state of health. (See
also Chapter VIII.)
47
It is so difficult to obtain a pure secretion of the mucus-glands,
that the method proposed' by Kirk seems to be the only means
of determining the reaction with any degree of certainty, for a
large number of cases. Mucus mixes with water without being
dissolved, is equally insoluble in alcohol, ether, chloroform, and
dilute mineral acids; soluble, on the other hand, in dilute alka-
lies and excess of mineral acids. It does not coagulate when
boiled, belongs to the albuminoids, and serves as a nutrient for
bacteria.
3. DEAD EPITHELIAL CELLS.
These cells, for the most part from the surface of the mucous
membrane, form a flaky precipitate in saliva left standing, or are
deposited, mixed with mucus and particles of food, upon the teeth,
particularly in places which are not exposed to the friction of
mastication. Under the microscope they appear as flat, irreg-
►
;
NUTRIENT MEDIA FOR BACTERIA IN THE ORAL CAVITY. 43
ular, many-sided cells, which are frequently covered with bac-
teria, especially in vitiated or spoiled saliva (Fig. 9). The fact
that these cells are often found in a state of partial destruction
|
by bacteria would seem
to indicate that they form
a not unfavorable nutrient
for certain kinds at least,
a view which is also sup-
ported by the chemical
analysis.
•
O
FIG. 9.

4. TOOTH-CARTILAGE.
The organic matrix of
dentine belongs to the glue-
giving substances. When
decalcified dentine is
boiled for any length of
time, a gelatinous material is obtained, which solidifies on cooling.
Dry gelatine from dentine forms an odorless and colorless, or
faintly yellowish mass, like bone-glue, which swells up in cold
water, dissolves easily in hot, but is insoluble in alcohol and
ether. At blood temperature dentine gelatine, like other gluey
substances, is easily decomposed by bacteria, and my personal
experience has shown it to be a good medium for culture
experiments.
EPITHELIAL SCALES FROM THE ORAL CAVITY.
Partly destroyed by cocci. Ca. 500: 1.
5. THE DENTAL PULP.
On account of its delicate structure and the abundance of
blood, the dental pulp presents an exceedingly favorable nutri-
ent medium, and therefore very easily putrefies. By means of
a dead pulp spontaneous inoculations (auto-infections) readily
occur, from which very dangerous local or general poisonings
may result.
6. EXUDATIONS OF THE GUMS.
The gums, when irritated by accumulations of tartar or food,
or by sharp edges, protruding fillings, roots, etc., furnish par-
44
THE MICRO-ORGANISMS OF THE HUMAN MOUTH.
"
ticularly favorable conditions of nutrition for certain species of
bacteria. The apparently strictly obligatory parasitic bacteria of
the mouth, Spirochete dentium and Spirillum sputigenum, find
here the peculiar conditions essential to their development. It
is a very interesting fact, and one showing what a powerful
influence the nature of the culture medium may have upon the
growth of bacteria, that though numberless attempts have been
made to construct a culture medium adapted to the wants of
these bacteria, they have all signally failed, so exactly must the
natural conditions be imitated before they can be induced to
grow.
7. ACCUMULATION OF PARTICLES OF FOOD.
The chief source of nutrition for the oral bacteria is, however,
furnished by the particles of food collecting between the teeth,
or in fissures, depressions, cavities of decay, etc., or adhering
even to their free surfaces. These, consisting chiefly of albu-
minous substances and carbohydrates, mixed with the other
nutrient matter mentioned under 1 to 6, present an almost per-
fect culture medium for bacteria.
After these introductory remarks, we shall now proceed to
the study of the bacteria of the human mouth, a subject which
has justly attracted a vast deal of attention in dental, as well as
in medical circles, within the last few years.
CHAPTER III.
THE DEVELOPMENT OF THE STUDY OF MICRO-ORGANISMS IN THE ORAL
CAVITY.
THE celebrated Dutch scientist, Leeuwenhoek,48 was the first to
observe that microscopically small organisms exist in the human
mouth in great numbers. In a treatise bearing the date 1683,
he gives descriptions and diagrams of several kinds of bacteria
from the mouth, which show that the inferiority of his instru-
ments compared with those now in use did not prevent his ob-
taining a very fair view, par-
ticularly of Spirillum sputige-
num. In spite of the utmost
care which Leeuwenhoek be-
stowed upon the teeth and oral
cavity, quo fit, ut dentes mei
adeo puri maneant et candidi, ut
paucos mihi coætaneos hoc pacto
raro videas, nec gingivæ meæ
unquam sanguinem emit-
tant," he was nevertheless able
to detect five different kinds of
animalcula in a certain white
matter between the teeth.
"Ac
fere semper magna cum admira-
tione vidi dictæ illi materiæ inesse
multa exigua admodum animalcula jucundissimo modo se moventia."
Leeuwenhoek's diagrams are reproduced in Fig. 10. The
micro-organism marked g will immediately be recognized as
the Spirillum sputigenum, now so well known. While convers-
ing with an old man, Leeuwenhoek noticed the rather deplorable
Y
66
FIG. 10.
00
• 0
"ANIMALCULA" FROM THE MOUTH.
g, Spirillum sputigenum.
(After Leeuwenhoek.)
45
46
THE MICRO-ORGANISMS OF THE HUMAN MOUTH.
condition of his teeth and asked him when he had last brushed
them, to which the latter replied that he was not in the habit of
brushing his teeth at all. Leeuwenhoek, who never allowed any
opportunity to pass by unheeded, immediately made the request
to be allowed to make an examination of the old man's saliva
and of the greasy deposit ("materia alba") upon his teeth. In
this deposit he found so many animalcula, "ut tota aqua vivere
videatur." This observation agrees perfectly with our present
knowledge as to the occurrence of mobile bacteria (Spirillum
sputigenum, etc.) in the oral. cavity.
Lebeaume compared tartar, as the breeding-place and habita-
tion of these animalcula, to coral formations. Mandl 49 supposes
tartar to form through the accumulations of the calcareous
remains of vibrios, which he describes as rod-vibrios. Heat,
spirituous liquors, and muriatic acid were found to destroy them.
Bühlmann 50 observed the thread-forming bacteria of the mouth
and called them simply fibers, without expressing any definite
opinion concerning their animal or vegetable nature.
Henle 51
was the first to give expression to the view that these
buccal organisms were of a vegetable nature.
Erdl 52 (1843) treated carious teeth with muriatic acid, thereby
loosening from the crown of the tooth a delicate, colorless mem-
brane, composed of cells, which, in his opinion, is of a parasitic
nature (vide Chapter VI).
A considerable advance in the study of the micro-organisms
of the human mouth, as well as of the mouths of various domes-
tic animals, was made by Ficinus,53 a physician of Dresden, from
whose dissertation on this subject the following passage is taken:
"If a small quantity of the yellowish-white slimy substance
found upon every tooth is brought under the microscope, fibers
of a peculiar nature will be found, which have already been
mentioned by Leeuwenhoek and drawn by Bühlmann. Between
these lie dense masses of very small granules, epithelial cells,
and mucus corpuscles. Occasionally a few infusoria, which have
accidentally entered the mouth with food and drink, move across
the field of vision. The interstices remaining between the masses
of granular substance, when examined under high power and by
good light (particularly on addition of a little water or saliva),
¦
DEVELOPMENT OF THE STUDY OF MICRO-ORGANISMS.
47
afford the surprising revelation of a large number of small
roundish, or oblong bodies, which wander about with lively, rota-
tory movements. Only when their motion abates, particularly
when they arrive at objects which afford them nutriment, can
their shape be more accurately distinguished.
"In the contraction in the middle of the body a lip-like pro-
tuberance may sometimes be observed, which I suppose to be
the mouth, since it guides the organism in its approach to objects.
It is, therefore, a hairless, probably also mailed, infusorium with
an abdominal aperture, whose exterior is not unlike that of the
paramecium and the kolpoda."
о
Во
•
FIG. 11.

©
BO
وره
TOOTH-ANIMALCULA (ZAHNTHIERCHEN) AND
BÜHLMANN'S FIBERS.
a, b, c, Zahnthierchen with abdominal aperture.
(After Klencke.)
Ficinus proposed for these animalcula the generic name Den-
ticola.
Robin 54, 55 (1847) called them Leptothrix buccalis, and classed
them among the algae.
56
Klencke continued the researches of Bühlmann and Ficinus,
and furnished us with drawings of these tooth-animalcula (Zahn-
thierchen), as well as of the denticolæ or fibers of Bühlmann, sup-
posed to be produced by the coalition of the animalcula. They
are reproduced in Fig. 11. These diagrams are also interesting,
because they exemplify the great influence which a preconceived
notion may exert upon what is seen under the microscope.
Klencke had learned from Ficinus that the tooth-animalcula pre-
sumably possessed an abdominal aperture (Fig. 11, a, b, c), and
he consequently, not doubting the correctness of Ficinus's
observation, saw it very distinctly.
<.
48
THE MICRO-ORGANISMS OF THE HUMAN MOUTH.
METHODS OF BACTERIOLOGICAL INVESTIGATION.
It was not my design, when I began the preparation of this
book, to present even a summary of the various methods
employed in bacteriological investigations. These have be-
come so numerous within the last few years that an exhaust-
ive treatment of the subject is a work of itself, and must be
sought in treatises devoted to that alone. For these reasons
I passed over this important matter in the German edition,
with a bare mention. Since, however, some have expressed dis-
appointment at this omission, I have concluded to present in
this edition a brief summary of the most important methods
now in use. This task I now undertake all the more willingly,
because I am convinced that some of my readers in the dental
and medical professions may in this way obtain a certain knowl-
edge of the methods of bacteriological experimentation, which
they would not do if they were obliged to consult a separate
work for that purpose, and furthermore, because for every one, a
knowledge of at least the fundamental principles of research
very much facilitates the ready understanding of the results
obtained by them. I must repeat, however, that it is only the
most important and most commonly used methods that I pro-
pose briefly to consider here. In the first place, let me say that
there is at present no science which opens up so broad and fruit-
ful fields of study, and is so accessible to every one, as the sci-
ence of bacteriology. Of course, we often find ourselves con-
fronted by an apparently insoluble problem; but on the whole
the study of bacteriology compared with that of chemistry is,
we may almost say, child's play. This is testified to by the fact
that a course of six weeks usually suffices to put one in pos-
session of nearly all the important methods of bacteriological
research. The application of the methods, however, sometimes
involves an immense amount of time, and hard, patient labor.
DEFINITIONS OF A FEW TERMS USED IN THE FOLLOWING PAGES.
Agar-agar: the name given to various algæ growing on the
coast of the East Indian archipelago, particularly Gracilaria
lichenoïdes, Euchema spinosum, Gigartina speciosa, etc., which
METHODS OF BACTERIOLOGICAL INVESTIGATION.
49
+
on boiling with water yield a jelly that solidifies at temperatures
above that of the human body.
Platinum needle: a piece of platinum wire, about two and one-
half inches long, with one end melted into the end of a glass
rod (Fig. 12).
Fig. 12.


PLATINUM NEEDLES.
Damp chamber: a shallow glass vessel whose bottom is cov-
ered by a piece of wet bibulous paper, and over which a second
somewhat larger vessel is inverted (Fig. 13, b); or the arrange-
ment illustrated in Fig. 13, a, may be used. Damp chambers
may, however, be constructed of almost any two vessels,-for
example, of two soup-plates.
FIG. 13 a.
Colony: a cryptogamous growth on the surface of, or within
a layer of solid nutritive material, proceeding from one cell and
FIG. 18 b.

בשוב.
DAMP CHAMBERS.
IMPENEKUCIN
consisting of a number of cells, varying from a few to myriads.
The larger colonies are plainly visible to the naked eye, and
their color, form, structure, density, etc., furnish a ready means
for distinguishing between different kinds of micro-organisms
without the aid of the microscope, or often when even the
microscope fails to furnish the necessary information.
APPARATUS.
The accessories absolutely necessary for beginning work in
bacteriology are very few and inexpensive. I began work with
4
50
THE MICRO-ORGANISMS OF THE HUMAN MOUTH.
:
an outfit which cost about twenty dollars (of course not includ-
ing microscope), and gradually added one instrument after
another.
For one hundred and twenty-five dollars a laboratory may be
furnished with about all the apparatus necessary for carrying
on extensive general work, including the incubator and micro-
tome, but not the microscope.
Following is a list of the most essential apparatus :
1. A microscope. I would recommend those who are anxious
to obtain a microscope at the least possible momentary expense
by all means to procure a good stand, with two objectives of low
power, and the necessary oculars to give a magnification of 200
to 300 diameters. With these one may carry on a very exten-
sive series of bacteriological investigations; in fact, with help
of the methods of pure culture, one can accomplish very much
without a microscope at all.
When, however, the question of the morphology and mode of
development of bacteria, or their distribution in tissues, etc., is
to be considered, an oil-immersion lens will be necessary (price
$25 to $150). It is poor policy to buy a cheap stand, because it
will soon be out of order, and when subsequently one wishes to
complete the apparatus by adding new lenses, etc., it will be
found inadequate, and will have to be thrown away.
2. An incubator: zinc, $12.50; copper, $35 to $100.
3. A hot-air sterilizer for glass plates, etc., $6.
4. A steam sterilizer (Koch's Dampfcylinder), $6.
5. A spiral burner (automatic), $5.
6. A thermo regulator, $5 to $10.
7. A microtome with freezing arrangement (complete), $30.
8. Two gas-burners, $2.
9. Two dozen glass plates and benches, $1.50.
10. Six damp chambers, $3.
11. Leveling apparatus, for pouring cultures (complete), $4.
This apparatus consists of a tripod supported by three screws,
two shallow glass vessels, one slightly smaller, resting upon three
corks placed upon the bottom of the larger, a perfectly plane glass
cover, and a spirit-level. In use, the glass cover is first adjusted
and made perfectly horizontal by the help of the spirit-level and
METHODS OF BACTERIOLOGICAL INVESTIGATION.
51
tripod; it is then removed, and the inner vessel filled with cold
(iced) water and the cover replaced. The outer vessel acts
simply as a receiver for the excess of water in the inner. A
small glass plate placed upon the cover is not only horizontal, but
is also cooled, so that in pouring the gelatine upon it there is no
P
FIG. 14.

LEVELING APPARATUS.
For pouring culture-materials.
danger of its running off at one side. For pouring agar-agar
the simpler form of the apparatus represented in Fig. 14 should
be used.
12. A pair of scales (0.1–20.0 grams), a water-bath, one dozen
small glass dishes and watch-glasses, one dozen Petri'sche
Schalen (miniature damp chambers), measuring-glass, pipette,
test tubes, bottles of various size for holding preparations, also
some with ground stoppers for staining materials, a wash-bottle,
object- and cover-glasses, a few hollow object-glasses for drop-
cultures, various-sized porcelain evaporating-dishes, two platinum
needles, brushes, spatula, filters, filter-paper, cotton, wire baskets
for culture-tubes, scissors, pincers; further, for inoculation ex-
periments, a sterilizable syringe, two vaccination-needles, mice-
cages, etc.
The principal reagents made use of in staining bacteria are
absolute alcohol, aniline water,* cedar oil, oil of cloves, Gram's
solution (iodine 1, iodide of potassium 2, distilled water 300),
various staining materials, of which the most important are
* A saturated solution of aniline oil in water, made by thoroughly shaking
four parts aniline in one hundred parts water, then filtering.
52
THE MICRO-ORGANISMS OF THE HUMAN MOUTH.
fuchsine, methylene blue, methyl violet, gentian violet, vesuvine
(in concentrated alcoholic solutions, to be diluted on using), bis-
marck brown (aqueous solution).
In preparing tissues for examination, naturally the various
hardening, fixing, decalcifying, imbedding, and mounting solu-
tions may be required which are used in general histological
work, although most tissues may be cut and stained with excel-
lent results in the simple manner described in connection with
the preparation of decayed dentine. For staining tissues, picro-
carmine and picro-lithio-carmine receive the preference.
PURE CULTURE.
G
By a pure culture we understand a cryptogamous growth in
which only one kind of micro-organism is represented. For ex-
ample, a culture containing only cells which belong in the develop-
mental cyclus of the tubercle bacillus, is a pure culture of that
bacillus. As soon, however, as a single cell of another species finds
its way into the culture, it becomes an impure culture. Passing
over the various methods which were formerly employed for
obtaining pure cultures in liquids (fractional and dilution cul-
tures of Klebs, Nägeli, etc.), we will describe in brief only the
methods of cultivating micro-organisms on solid media, intro-
duced by Vittadini and Brefeld, and perfected by Koch.
I will confine myself to the two methods most commonly
employed for cultivating on gelatine or agar-agar. These are:
1, line cultures; 2, dilution cultures.
Line Cultures.
The principle of line cultures may be made clear by the fol-
lowing illustration: Suppose we were to dip a wet glass rod into
a bag containing a mixture of timothy and clover seeds, so that
a vast number of seeds of both kinds adhere to the rod, and
then draw it over prepared ground; at first, great numbers of
seeds will be left in the wake of the rod; gradually, however,
they will become less and less, until at last only single seeds may
be deposited. When these seeds grow, we will have in the first
part of the track a mixture of timothy and clover, but in the
METHODS OF BACTERIOLOGICAL INVESTIGATION.
53
last part separate stocks of timothy and clover, growing singly,
or in pure cultures. To apply this method to the cultivation
of bacteria, let us suppose that we wish to obtain a pure
culture of the bacteria from the white deposit about the necks
of the teeth. We proceed in the following manner: Having
melted a tube of nutritive agar-
agar, we carefully remove the
cotton stopper, hold the mouth
of the tube for a moment in the
flame of a Bunsen burner, to
destroy all germs sticking to it,
then pour the material upon a
sterilized glass plate, using the
apparatus No. 11. As soon as
this has stiffened, which takes
place in about one or two min-
utes, we take up some of the de-
posit upon the point of a ster-
ilized platinum needle, draw it
lightly over the surface of the
culture medium ten or fifteen
times, and place the plate in a
damp chamber at the tempera-
ture of the human body. In
the course of a day or two
we will invariably find that
an abundant growth has taken
place along the lines. On the
first line it will be very thick,
and on each succeeding line it
will gradually become thinner,
till on the last line the growth
will appear only as a few iso-
lated points (Fig. 15). These points usually represent pure
cultures. If they are not pure, they can be made so by vacci-
nating from them a second plate in the manner just indicated.
A portion of a culture made in this manner is represented in
Fig. 15. In making line cultures on nutritive gelatine we pro-
C
ъ
}
10.
de
e
19
ཤ༔--་
}
FIG. 15.
1803 (NDING, SELA
S
Compounds Br
o༠༠བ---་
000.000-.
~·Õ··· •—1271
38.
LINE CULTURE ON NUTRITIVE
AGAR-AGAR.
a
The number of colonies in each line
gradually decreases from a to b, until in
the last line we have only twelve to fifteen
colonies in which at least three different
micro-organisms are represented, the col-
onies c, d, and e plainly differing from each
other to the naked eye. The first colony
in the third line from a is a mould. Nat-
ural size.
+

54
THE MICRO-ORGANISMS OF THE HUMAN MOUTH.
ceed in exactly the same manner, except that the cultures must
be kept at a temperature just below that at which the gelatine
used liquefies. Instead of the ordinary glass plates, Petri'sche
Schalen may often be used to great advantage.
Dilution Cultures.
We may illustrate the principle of dilution cultures in the fol-
lowing manner: Suppose we have a handful of seeds of various
kinds which are invisible to the naked eye, and we are given the
task to separate the seeds, or at least to obtain pure cultures of
a
des ramilitky:
FIG. 16.

ob
ɗ B
Tay
~
SECOND DILUTION OF A GELATINE-CULTURE FROM THE WHITE
DEPOSIT ON THE TEETH.
a, very small; b, medium-sized; c, very large, round colonies;
d, irregular colony. The different sizes represent different
rapiditios of growth. Culture three days old.
them. We may accomplish the task in the following manner:
We go out to the field and cast the seed broadcast upon the
ground which has been prepared for the sowing, wait till they
spring up and ripen, then gather the different plants which are
produced into separate heaps. In this way we obtain pure cul-
tures of all the different plants represented in the original hand-
ful of invisible seeds.
In applying this principle to the pure cultivation of micro-
organisms we proceed as follows: Having melted three tubes
METHODS OF BACTERIOLOGICAL INVESTIGATION.
55
of nutrient gelatine by gently warming them over a gas flame,
we transfer to one of them, on the point of a platinum needle, a
small quantity of the material which we wish to examine, and
shake the gelatine gently to distribute the micro-organisms
throughout the mass. The quantity of soil in one tube is,
however, so small, and the organisms would lie so closely
together that we would not be able, as a rule, to distinguish
between the separate colonies. We consequently transfer, on
a loop of platinum wire, three or four small drops or beads
from the first tube (first dilution) to a second tube (second
d
FIG. 17.

α
e
b
COLONIES FROM THE PLATE ILLUSTRATED IN FIG. 15,
UNDER A POWER OF FIFTY DIAMETERS.
a, b, c, d, Colonies of four kinds of bacteria;
e, Mould colony.
dilution), and if thought necessary six to eight beads from the
second to a third tube (third dilution). We now pour the con-
tents of the three tubes upon three separate plates, which are
put into a damp chamber as soon as the gelatine has solidified.
If the plates are examined after about forty-eight hours, we
will find, as a rule, that the first dilution has become completely
opaque, through the development of innumerable colonies; the
second plate will appear thickly studded (Fig. 16) with mostly
whitish points (colonies), while the third plate will show but
very few colonies, or possibly none at all. The number of
56
THE MICRO-ORGANISMS OF THE HUMAN MOUTH.
colonies on the different plates will of course depend upon
the number in the original material. In these colonies we
have pure cultures or growths of all the different organisms
present in the material used, as far as they are cultivable in
gelatine. At this time, but much better a day or two later, it
may be seen by the unaided eye (better, naturally, under a low
power of the microscope) that the colonies do not all present
the same appearance. In color they may be white, yellowish,
dirty white, gray, brownish gray, brown, orange, red, etc., or
they may impart color to the gelatine; they may be perfectly
round or irregular, thick or thin, transparent or opaque, moist
or dry, homogeneous or knotty, soft or cartilaginous, etc. Some
liquefy the gelatine, others do not. Under the microscope, other
differences of structure not discernible to the naked eye may be
made out. (See Fig. 17.) By transferring one or more colonies
of each kind to tubes of gelatine or agar-agar, as described
below, we obtain larger, pure growths, in a form in which they
may be kept a greater length of time without becoming impure.
TEST-TUBE CULTURES.
When it is desired to obtain pure growths in larger masses,
and in a form in which they may be kept for a longer time, we
make use of the so-called tube cultures. These are obtained by
inoculating tubes of nutrient gelatine or agar-agar with sepa-
rate colonies, either from line or dilution cultures. Placing the
plate under a low power of the microscope (50 diameters), we
adjust an isolated colony, which we pick up with the bent point
of a platinum needle directly under the microscope (an opera-
tion which requires some practice), and transfer at once to the
tube, puncturing the gelatine with the needle to a depth of
about one and a half inches, the tube being held in the left hand,
with the mouth downward, to prevent the falling in of germs
from the air. Larger colonies may be picked up without the
aid of the microscope, provided only we have satisfied ourselves
beforehand by the microscopic examination that the colony is
really isolated, and that no small colony of some other species,
invisible to the naked eye, is lying near it. These test-tube
growths also generally furnish a ready means of distinguishing
METHODS OF BACTERIOLOGICAL INVESTIGATION.
57
between different species (Fig. 18, and plate, Figs. 1-4), although
sometimes two different organisms grow so nearly alike that
they cannot be distinguished by this means alone.
FIG. 18.



HRIGE
VIENMORJENESTENSION IN
3 a.
2 α..
1 a:
TEST-TUBE CULTURES OF THREE DIFFERENT BACTERIA.
All of same age.
Pure cultures in bouillon are obtained in the same manner,
though in this case we naturally cannot invert the tube, and
particular caution is requisite to prevent impurification during
the process of inoculation.
·
OTHER SOLID CULTURE MEDIA.
It sometimes happens that two different micro-organisms, culti-
vated on gelatine or agar-agar, present characteristics of growth
so similar to each other that it is not possible to distinguish be-
tween them, or that they do not grow at all on these media. In
such cases we have recourse to other media, such as coagulated
blood-serum, boiled potato, boiled egg, starch-paste, etc. I can-
not enter into a description of the method of preparing blood-
serum. Any one wishing to undertake this by no means very
easy task, must refer to the works on this subject. I would
certainly advise any one, unless he needs a very large quantity
of the material, to buy it, if possible, already prepared. It is
congealed, after sterilization, in shallow glass vessels, or in
58
THE MICRO-ORGANISMS OF THE HUMAN MOUTH.
test tubes placed obliquely, so as to obtain the greatest possible
surface. Only line or puncture cultures can be made with this
material; it is particularly adapted to the cultivation of the
tubercle bacillus, the bacillus of glanders, and some other patho-
genic micro-organisms.
Boiled potato is a medium of great value in the determina-
tion of bacteria. No medium, however, requires greater care in
preparation and after-treatment than this, in order to obtain sat-
isfactory results. Any sound potato which does not become mealy,
or crack open on boiling, will do for the purpose; it is first thor-
oughly washed and brushed, and all defective spots and deep eyes
being removed, it is placed for one hour in a 5 to 1000 solution of
bichloride of mercury, then in a steam sterilizer for one-half an
hour to one hour. In the mean time the damp chamber is sterilized,
and the bottom lined with filter-paper wet with sublimate solu-
tion, 5 to 1000. The potatoes are, while hot, removed from the
sterilizer with sterilized forceps, cut into halves with a cold ster-
ilized knife, and placed directly upon the sublimate paper (the
cut surface up) and the cell closed. Potato sections prepared in
this way should remain unchanged indefinitely. When the potato
has become cool, the cover of the cell is carefully removed, and
the micro-organism which is to be cultivated is spread upon a
space about as large as a dime, in the center of the section. Micro-
organisms which morphologically, as well as in their reaction
upon gelatine, agar-agar, and blood-serum, show no appreciable
differences, may sometimes be easily distinguished by aid of the
potato culture.
The potato can seldom be used to prepare
pure cultures. It is chiefly used as a reagent in distinguishing
between growths already in pure culture. For example, all
comma bacilli yet discovered grow on potato, except the one
found by Deneke in old cheese, which does not develop at all
on potato, and is thereby at once distinguished as an entirely
different bacterium.
Eggs may often be used to great advantage. They are pre-
pared as follows: The fresh egg is placed in sublimate, 5 to 1000,.
for ten minutes, then in the steam sterilizer for one hour. The
cell for eggs is prepared as for potatoes, except that a sterilized
glass plate, resting on a glass bench, is placed in the bottom to
METHODS OF BACTERIOLOGICAL INVESTIGATION.
59
具
​support the egg sections.
sections. As the egg must be handled with the
fingers, the hands must be thoroughly washed, then soaked in
sublimate, 5 to 1000, and then washed again in absolute alcohol, to
remove the sublimate. The eggs are shelled while still hot, and
cut into two, three, or four sections. They are vaccinated in
points, upon the white; the yellow is not so well adapted to cul-
ture experiments, since it cannot be cut with a smooth surface.
I always keep on hand sections of potato and egg, also tubes
of gelatine, agar-agar, and blood-serum; and when in my prac-
tice particularly good material, or anything uncommon, presents
itself, a portion of it is at once transferred to these different cul-
ture media, so that it is pretty sure to develop in one of them
at least. For example, I have several times met with a bacterium
in the human mouth which produces a yellowish coloring-mat-
ter, and which absolutely refuses to grow on anything which I
have tried, except potato.
LIQUID MEDIA.
For studying the various processes of decomposition, fermenta-
tion, putrefaction, etc., brought about by bacteria, a great variety
of liquid media have been employed. One which I have used
extensively consists of water 100.0, peptone 2.0, sugar 1.0, beef
extract 1.5, with occasional additions of starch. This I have
found very well adapted to the culture and study of many oral
bacteria. Other media are milk, urine, bread-juice, juice of
fruits, decoctions or watery extracts of various plants or grains,
saliva (to which, however, nutrient material must be added), etc.
These may also be combined with each other in various propor-
tions.
•
APPLICATION OF THE ABOVE METHODS TO CULTIVATIONS FROM
THE HUMAN MOUTH.
For general work on the bacteria of the oral cavity the best
medium, in my opinion, is presented by neutral beef-water-pep-
tone-sugar-agar-agar. On this medium I first make line cul-
tures (which may be supplemented by dilution cultures at the
same time), and then for the further study of the micro-organ-
isms cultivated I make dilution cultures on gelatine, etc. It often
60
THE MICRO-ORGANISMS OF THE HUMAN MOUTH.
happens, however, that bacteria which we have obtained on agar-
agar do not grow at all on gelatine, because of the low tempera-
ture at which it must be kept, just as it may also happen that
cultures made from the saliva on gelatine may develop nothing
whatever, although the saliva at the time may have contained
bacteria enough. If, therefore, I wish to obtain cultures from the
deposits or accumulations, secretions, etc., of the human mouth,
I make line cultures on agar-agar, either alone or supplemented
by dilution cultures on gelatine. For particular purposes, as in
the attempt to cultivate the Spirillum sputigenum, etc., I would
of course employ various other materials.
Pure cultures of the bacteria of tooth-decay I obtain by the follow-
ing method, which varies somewhat, according to whether we
wish to secure cultures from the surface or from the deeper part
of the dentine: In the former case, after having removed the
remains of food from the cavity of decay, I scratch out a small
portion of the decomposing dentine with a sterilized excavator;
this is then transferred to a plate of agar-agar in the manner
above described. To obtain a pure culture from the deeper
parts of the dentine, I first wash the tooth in a stream of pure
water and place it for some minutes in a 5 per cent. solution
of carbolic acid, also brushing carefully with the same solution,
so as perfectly to remove all traces of food and to destroy those
bacteria which are found only on the surface. I then dry the tooth
with sterilized bibulous paper, and remove the outer layers of
decayed dentine with a sterilized, spoon-shaped excavator. With
a second excavator I remove a second layer, with a third a third
layer, and so on, till I arrive near to the border of the sound
dentine; or, I undercut the decayed dentine at one side of the
cavity with a sharp instrument, and, grasping the detached edge
with a strong pair of pliers, I shell out the largest part of the
decayed matter in one piece. In either case I then detach a
small portion of the decayed dentine from the bottom of the
cavity, and place it in a drop of sterilized water, where it is torn
to pieces with two stiff needles, or fine excavators. With these
pieces, and with the water, the agar-agar plate is then inoculated.
At the same time dilution cultures may be made upon plates
of nutritive gelatine. These must of course be kept at a lower
METHODS OF BACTERIOLOGICAL INVESTIGATION.
61
temperature, in consequence of which the bacteria do not develop
so rapidly as they do on the agar-agar plates; sometimes no
development whatever takes place. The thought naturally pre-
sents itself to every one, that the bacteria growing in the deeper
parts of dentine may not develop under free access of air.
Accordingly, small pieces of decayed dentine should be placed
in tubes of melted gelatine or agar-agar, and allowed to sink
to different distances from the surface, where, on the medium.
becoming solid, they obtain but a very limited supply of air.
To obtain a pure culture from a gangrenous pulp, I carefully
cleanse and sterilize the tooth as before, so as to be absolutely
sure that no living germs are present upon the surface; I then
split the tooth by means of a pair of sterilized incising forceps.
Very often the tooth may be split without the forceps coming
into contact with the pulp, in which case the pulp, or portions
of it, may be lifted from its bed by means of a nerve-needle,
and transferred to a drop or two of water or gelatine. It is then
torn or picked to pieces so as to liberate the bacteria, after
which it may be drawn several times across the surface of the
agar-agar, or the inoculations may be made from the water.
For such micro-organisms as grow at low temperatures, gela-
tine forms a much more convenient material than agar-agar;
furthermore, differences of growth are much more readily recog-
nized on gelatine than on agar-agar. Consequently, we should
not rely upon cultures on agar-agar alone, but all of the bacteria
which we succeed in cultivating on agar-agar we should likewise
attempt to cultivate on gelatine. The majority of them will
grow, though by no means all of them.
The great advantage possessed by the solid culture media
over liquid media, consists in the fact that each germ must re-
main at the point where it is at the time the media becomes
solid. A number of different kinds of micro-organisms, there-
fore, on a plate of gelatine, may develop without mixing together,
each one remaining as a pure culture, whereas in liquids they
would naturally mix, thereby causing an impure culture.
62
THE MICRO-ORGANISMS OF THE HUMAN MOUTH.
3
PREPARATION OF NUTRIENT GELATINE, OR AGAR-AGAR.
Having prepared the solution which we wish to make the
base of our nutrient gelatine, we add to 100 grams of the solu-
tion 5 to 10, or even 20 grams, of the finest gelatine cut into
small pieces, and allow it to stand one-half hour to one hour,
when the gelatine should be completely dissolved by gently
warming the solution, and carbonate of sodium carefully added
until the reaction becomes neutral, or very slightly alkaline.
It is then boiled for about an hour, in order to effect a com-
plete precipitation of the salts and coagulable substances (other-
wise the medium when done will appear cloudy), and while
hot filtered directly into test tubes, or into flasks from which
it may subsequently be transferred to the tubes, each tube re-
ceiving about one and one-half to two inches. The tubes are
then exposed to steam at a temperature of 100° C. in the steam
sterilizer for one-quarter to one-half hour. Twelve hours later
they are again exposed for the same length of time, which will
usually suffice to effect a complete sterilization of the contents.
A solution which I have used very frequently consisted of
water 100.0, peptone 2.0, sugar 1.0, beef-extract 1.5, to which five
to twenty grams of gelatine is added, according to the strength
required. In summer 20 per cent. will often be found neces-
sary to prevent melting of the cultures at room temperature.
The beef-water-peptone-gelatine now so extensively used is made
in the following manner: "One-half kilogram of good, finely
minced meat, is covered with 1 liter of distilled water, well mixed
and left for twenty-four hours in the refrigerator. It is then
pressed through gauze, and enough distilled water added to bring
the quantity up to 1 liter. To this water we add 10 grams of
dry peptone, 5 grams of table-salt, and 50 to 100 grams of gela-
tine" (Hüppe). As a universal culture material for oral bacteria
this is improved by the addition of 10 grams of sugar. The
further preparation is conducted in the manner described above.
Nutrient agar-agar is prepared in the same way as nutrient
gelatine, except that only 1 to 2 per cent. of agar-agar is added,
instead of 5 to 20 per cent.
•
Naturally, every intelligent experimenter will be able to vary
the culture medium according to the circumstances, bearing in
METHODS OF BACTERIOLOGICAL INVESTIGATION.
63
1
mind that for many bacteria it is absolutely necessary that the
character of the artificial culture medium be very similar to that
of the substratum in which they are naturally found.
There are many kinds of bacteria which have not yet been
cultivated, and which are therefore styled strictly obligatory par-
asitic, which I doubt not would grow well enough if we were
able to prepare a medium for them identical with their natural
nutriment.
Except for especial purposes, I would not advise any one whose
time is so limited as that of a dentist or medical practitioner to
attempt to make his own gelatine or agar-agar, as he will save
much time in purchasing it already made.
Having obtained a pure culture of any given micro-organism,
the further study of it is to be directed to the following points:
1. Its morphology, development, etc., as revealed by high
powers of the microscope.
2. The characteristics of its growth on different nutrient
media.
3. Its behavior in regard to atmospheric oxygen.
4. Its physiological action (fermentation, putrefaction).
5. Does it possess diastatic, hydrolitic (inverting), or pepton-
izing action?
6. Does it form coloring-matter?
7. How is it affected by various antiseptics?
8. Does it possess pathogenic properties, and if so, what are
they?
The first question is answered by direct microscopical obser-
vation of stained and unstained specimens, with the help of
good, homogeneous immersion lenses, particular attention being
paid to the production or non-production of spores, since this is
a matter not alone of botanical, but also of great hygienic inter-
est, inasmuch as the resistance of a bacterium to devitalizing
agents is to a great degree determined by the presence or absence
of spores. A knowledge of the morphology and development
of a bacterium is not, however, essential to the study of questions
2 to 8. Pure cultures may be obtained and all desirable experi-
64
THE MICRO-ORGANISMS OF THE HUMAN MOUTH.
ments made without a knowledge of the form of the given
bacterium.
Question 2 is to be answered by examining the pure culture
on various nutrient media with the naked eye, or under weak
magnifying power.
Question 3 is most easily answered by placing a thin glass plate
or sheet of mica, on the plate culture; if the bacterium be aerobic,
it will flourish only till the oxygen in the gelatine is consumed;
the colonies will consequently present a stunted appearance. If
it be anaërobic, the colonies under the mica will grow faster
than the uncovered ones. The experiment may also be made
in vessels from which the air has been exhausted, or in which
it has been replaced by hydrogen.
Question 4 is decided by cultures on different media, prin-
cipally on carbohydrates, then on albuminous substances, or in
mixtures of both, as they generally occur in the mouth.
In order to answer question 5, cultures are made (a) in amyla-
ceous substances, which, when the culture has obtained its full
growth, are to be tested for sugar; (b) in solutions containing
cane-sugar, which are tested for dextrose, levulose, etc., or as to a
change in their rotatory power; (c) in solutions of albumen, which
are then tested for peptone, or on coagulated albumen, which
liquefies when the bacteria have a peptonizing action. We must
watch the course of the fermentation, its duration, and especially
note whether acids are generated or not, and what they are.
Question 6 is naturally decided by ocular inspection.
Question 7 by the usual disinfecting experiments, some of
which may be found described in full in Chapter IX.
The pathogenesis (question 8) must be determined by experi-
ments on living animals, for which purpose mice, rabbits, and
guinea-pigs are most commonly made use of; less frequently
dogs, fowls, or even sheep, calves, etc.
The material may be introduced into the animal body-
1. In form of powder, by inhalation.
2. With the food.
;
3. By cutaneous inoculations (performed by slightly scratch-
ing the purified skin with a sharp instrument charged with the
material to be tested).
METHODS OF BACTERIOLOGICAL INVESTIGATION.
65
4. By subcutaneous inoculations. The hair is shaved or cut off
and the skin cleansed at some point which cannot be licked or
scratched by the animal, a fold of skin pulled up with the pincette,
and a slight incision made with a pair of sterilized scissors. The
skin is then loosened from the subcutaneous tissue so as to form
a small pocket, into which the material is brought on the point
of an instrument or platinum wire.
5. By intravenous inoculations, best made in rabbits by inject-
ing the large vein at the base of the ear.
6. By injecting the material directly into the pleural or the
abdominal cavity.
Less frequently, more difficult operations are undertaken for
injecting or applying the material to various internal parts of the
body,-for example, into the duodenum, to avoid the action of
the gastric juice.
EXAMINATION OF MICRO-ORGANISMS UNDER THE MICROSCOPE.
Bacteria are frequently examined in a fresh (living) condition,
in order to determine whether they are motile or not, but more
particularly to study their mode of development. A small
quantity of the material to be examined is brought upon a glass
slide in a drop of pure water, and covered with a cover-glass,
when it is ready for examination under the microscope. For a
more careful study the method of hanging-drops is used. A
drop of bouillon on a cover-glass is inoculated with a very
minute quantity of the material (pure culture), and the cover-
glass placed with the drop on the under side upon the concavity
of a hollow object-glass (Fig. 18 a), the sides of the cover being
FIG. 18 a.
DROP-CULTURE.
then fixed to the slide (object-glass) by means of wax, fat, or
paraffine, to prevent evaporation. The development of the bac-
teria may be observed for hours in succession. If it is desired
to maintain a constant temperature above that of the room, the
heatable object-table may be used.
5
66
THE MICRO-ORGANISMS OF THE HUMAN MOUTH.
The study of bacteria in an unstained condition is, however,
always attended with considerable difficulty, and their detection
and differentiation in tissues, or when mixed with various organic
matters, is sometimes impossible. These difficulties are in a great
measure, and in fact usually, entirely overcome by first properly
staining the micro-organisms with some one of the basic aniline
stains above mentioned.
For examining bacteria in liquids we employ the
Cover-Glass Preparations.
A minute quantity of the material to be examined (pure cul-
ture, or any soft substance supposed to contain bacteria) is spread
over the surface of a cover-glass in a small drop of water and
allowed to dry in the air (or the material is crushed in water
between two cover-glasses, which are then pulled apart so that
each receives a coating). The glass is then slowly passed three
times through the flame of a spirit lamp or Bunsen burner, to
fix the material, and two to three drops of the stain (aqueous
solution) applied by means of a glass rod. The staining requires
from thirty seconds to ten minutes; by tilting the glass to one side
it is easy to see when the preparation has taken on the coloring-
matter. The excess of staining matter is then removed with a
gentle stream of water, or by floating the cover-glass in a vessel
of pure water, when the preparation may be placed upon a slide
and examined under the microscope. For permanent prepara-
tions the cover-glass, after washing, is dried and mounted in
Canada balsam.
In order to stain the spores, float the cover-glass from ten min-
utes to one hour on a hot concentrated solution of fuchsine in ani-
line water, wash off the excess of coloring-matter, and treat the
preparation for a few seconds or minutes with absolute alcohol
containing a trace of fuchsine. Then stain in the usual manner
with methylene blue (Hueppe). The bacilli appear blue, the
spores red. Instead of fuchsine and methylene blue, methyl
violet and vesuvine may be used.
METHODS OF BACTERIOLOGICAL INVESTIGATION.
67
Tissue Preparations.
It would lead us too far to attempt to give an idea of all the
many methods employed in staining bacteria in tissues. I refer
accordingly to only one or two:
Löffler's method. The sections are brought for a few minutes
into the strong alkaline solution (concentrated alcoholic solu-
tion of methylene blue 30 c.cm., caustic potash (1 : 10,000)
100 c.cm.), then they are washed in 0.5 per cent. acetic acid, de-
hydrated in absolute alcohol, cleared up in oil of cedar, and
mounted in Canada balsam.
Gram's method. Sections are placed first in alcohol, then in
the aniline water-gentian violet solution a few minutes, then in
the iodine solution for one to three minutes, then in absolute
alcohol till they lose all visible color. Clear up in oil of cloves,
and mount in Canada balsam; or, better, after Günther, stain one
minute, the iodine solution (page 51) two minutes, alcohol one-
half minute, 3 per cent. hydrochloric acid in alcohol exactly ten
seconds, then alcohol, oil of cloves, etc.
To obtain double coloring, bring the sections, stained in gen-
tian violet, from the alcohol into an aqueous solution of vesuvine
for some minutes, then again into absolute alcohol, clear up, and
mount in Canada balsam.
Ta
CHAPTER IV.
BIOLOGICAL STUDIES ON THE BACTERIA OF THE MOUTH.
If we compare the life-conditions of bacteria as described in
Chapter I. with the conditions prevailing in the human mouth,
it becomes evident that the oral cavity must be an excellent
breeding-place for these organisms. It is equally clear that both
their number and variety are continually being augmented by new
germs which enter with the air, food, and drink. In the course.
of a few years hundreds of kinds of bacteria would therefore
become established in the mouth, if the majority of them did
not perish, sooner or later, in the struggle for existence. Any
one, therefore, who continues the search for oral bacteria, by
means of the modern culture-methods, for a long period of time,
will continually meet with new kinds, until at last all cultivable
micro-organisms, whose germs occur in the air, in food and
drink, will have been found in the oral cavity. Within the
last few years I have isolated more than one hundred different
kinds of bacteria from the juices and deposits in the mouth.
A number of these were identical with well-known and widely
distributed species (for example, hay bacillus, potato bacillus,
lactic acid bacillus, bacillus of green pus, Micrococcus tetragenus,
Mycoderma aceti, Staphylococcus pyogenes aureus and albus,
etc.), while others appeared to be new kinds, although I was not
able, on account of the great number, to attempt in every case to
establish the identity or non-identity with known species.
It must be supposed that the occurrence of many of these
bacteria in the mouth was purely accidental, that they had
entered the oral cavity but shortly before the examination was
made, and disappeared again soon after. Some years ago, I found
68
BIOLOGICAL STUDIES ON THE BACTERIA OF THE MOUTH.
69
in the mouth of a patient suffering from acute gingivitis, a
spirillum very similar to, if not identical with, the bacillus of
Finkler-Prior. Repeated efforts, made a few days later, to
obtain this bacterium from the same mouth, proved futile.
In a
like manner I was able to isolate the vinegar bacterium from my
own saliva, after having drank a glass of beer in which this par-
ticular organism was present in large numbers; on the follow-
ing day my endeavors to find it failed, doubtless because this
bacterium cannot bear the high temperature of the mouth for
any length of time.
There are, however, a number of bacteria which almost
invariably occur in every mouth, and which may be termed
MOUTH BACTERIA PROPER.
These are:
1. Leptothrix innominata.
2. Bacillus buccalis maximus.
3. Leptothrix buccalis maxima.
4. Jodococcus vaginatus.
5. Spirillum sputigenum.
6. Spirochete dentium (denticola).
These bacteria occur in every mouth; sometimes even an
almost pure culture of No. 5 is found. They all have the pecul-
iarity that they will not grow on any of the usual culture media.
All endeavors at cultivation—and thousands have been made-
proved unsuccessful. I have myself made hundreds of attempts
to cultivate them on all the various solid and fluid media. For
these experiments I had excellent material. My errand-boy had
a very carious right inferior molar, covered with tartar and
deposits, the surrounding gum being slightly inflamed. In the
cavity I found an almost pure culture of Spirillum sputigenum,
and on the margin of the gum one of Spirochete dentium.
During several months I made cultures almost daily; first, I
tried the usual Koch nutrient media, beef-water-peptone-gela-
tine, blood-serum, agar-agar, potato, etc. These experiments not
succeeding, I varied the media by adding different substances,
such as sugar, starch, etc., and by using saliva instead of water
as a solvent. I also employed weak alkaline and acid, as well as
710
THE MICRO-ORGANISMS OF THE HUMAN MOUTH.
neutral media. Finally, I adapted my experiments to the boy's
food, and made up a mixture whose composition showed the
greatest possible similarity to the contents of the cavity. I fur-
thermore tried dentine glue instead of gelatine, which I pro-
cured by boiling decalcified teeth. Nevertheless, all these
attempts remained fruitless. Only line cultures afforded a very
limited growth, but the colonies never developed more than
fifteen to twenty cells, and a transference to a second plate
proved futile, no further growth taking place. Vignal's experi-
ments in reference to this question will be mentioned later.
It is very easy, as has been done by a writer in the October
number of the Oest. Ungar. Vierteljahrsschrift für Zahnheilkunde,
1889, who signs himself л, to account for the failure to culti-
vate these micro-organisms on the assumption that they are
strictly parasitic (vide page 17), and consequently cannot, under
any condition, grow when separated from their host. I find it,
however, more reasonable to explain the failure on the simple
ground that these bacteria are very sensible to slight changes in
the culture media, and that no one has yet succeeded in construct-
ing an artificial medium sufficiently similar to that found in cer-
tain mouths to admit of their cultivation. I have by no means
given up the hope of yet obtaining cultures of these most inter-
esting forms.
We must guard against the very common error of considering
every thread-forming organism which occurs in the oral cavity,
or is obtained in pure culture from the juices of the mouth, as
"Leptothrix buccalis," inasmuch as threads are formed by various
micro-organisms.
Leptothrix buccalis.
Leptothrix buccalis is a name chosen by Robin 5 for those
organisms in the human mouth which were formerly described
as animalcula, tooth-animalcules, Bühlmann's fibers, denticolæ,
Almost every living organism occurring in the mouth was
designated by this common name.
Hallier," and many of his successors up to the present time,
adopted this view. The motile bacteria of the mouth were
BIOLOGICAL STUDIES ON THE BACTERIA OF THE MOUTH.
71
regarded as the swarm-spores of Leptothrix buccalis, the immo-
tile (cocci, etc.) as the spores at rest. "Elements of Leptothrix
buccalis" were found everywhere.
Leber and Rottenstein 58 considered "a beautiful violet color
produced by iodine and acids" as characteristic of Leptothrix
buccalis, but we may easily convince ourselves that several
bacteria possessing this reaction occur in the mouth, and conse-
quently this does not especially characterize any particular kind.
Leptothrix buccalis is now usually described as long, thin,
apparently inarticulate threads, etc., while mouth-bacteria which
show the iodine reaction are distinctly and regularly articulated.
Vignal 59 has obtained in pure culture from the mouth a bac-
terium which he calls Leptothrix buccalis. It is characterized
by "la présence à l'intérieur des bâtonnets de cloisons transversales
sur les préparations colorées avec les couleurs d'aniline." Robin,55 on
the contrary, writes, "On ne remarque pas trace d'articulation dans ·
toute leur longueur." It is not stated whether this micro-organism
cultivated by Vignal shows the iodine reaction or not. In short,
the name Leptothrix buccalis designates no particular organism
possessing peculiar characteristics, and the name deserves to be
retained as little as "denticola," "Bühlmann's fibers," etc.; the
more so, since it has always been the expression for an obscure
and erroneous conception. Morphologically, as well as physi-
ologically considered, Leptothrix buccalis has been regarded as
a veritable wonder. It has been said to perforate and split up
teeth, its elements to cause all kinds of diseases in the oral cav-
ity, to penetrate into the lungs, the stomach, and other parts of
the body, and everywhere to manifest a destructive influence.
As absolutely nothing was known concerning the biology and
pathogenesis of this organism, all sorts of wonderful properties
were ascribed to it. It is therefore high time to banish this
confusing name from bacteriological writings.* For those
bacteria growing in threads, whose biology is too little known
to define their relation to other mouth-bacteria, or to form a
* Equally objectionable is the inclination of some observers to class everything
showing a slight contraction in the middle as Bacterium termo. This is also a
term which, on account of its application by different authors to very different
organisms, might well be dispensed with.
72
THE MICRO-ORGANISMS OF THE HUMAN MOUTH.
separate group with distinct characteristics, I propose the provis-
ional name of
Leptothrix innominata.
Leptothrix innominata in this sense is found in the soft, white
deposit on the teeth (Leeuwenhoek's materia alba). It invar-
iably occurs in every mouth, but by no means always in the
same numbers. In one case it may be found in masses, in
another but very sparingly. If
a portion of this white deposit
mixed with water be brought
under the microscope, we see
different sized heaps, apparently
consisting of small, round gran-
ules, from whose margins thin,
more or less zigzagged threads
project (Fig. 19). These gran-
ular masses form the so-called
"matrix of Leptothrix buc-
calis," and were formerly re-
garded as its spores; they
are, however, partly micrococci,
which have no genetic connec-
tion with the threads, and partly only crossings of the threads
themselves. The length of the threads varies considerably; they
are from 0.5 to 0.8μ broad, twisted and tortuous, immotile, inar-
ticulated; they generally show an irregular course, and often
appear degenerated, or even lifeless. Many shorter threads or
rods will also be found, that resemble fragments of the threads,
and may be regarded as such, or as younger cells.
If a small quantity of the white deposit is brought into a drop
of a solution of iodine in iodide of potassium slightly acidulated
with lactic acid, it will be observed (under about 350 diameters)
that the larger part of this substance, consisting of epithelium,
masses of micrococci, and diverse rod- and thread-shaped organ-
isms, assumes a faint yellowish or yellow color, as do also the
irregular projecting threads of Leptothrix innominata.
As a rule, however, we find also chains of cocci, either scat-
b
FIG. 19.

a
****
是
​въ
b
GROUP OF BACTERIA FROM THE HUMAN
MOUTH.
a, Leptothrix innominata; b. Various Rod-
and Coccus-forms.
G
BIOLOGICAL STUDIES ON THE BACTERIA OF THE MOUTH.
73
tered or in small groups, and thick bacilli, distinctly colored blue
violet. These two kinds, which I have entitled Jodococcus vagi-
natus, and Bacillus buccalis
maximus, I shall now de-
scribe more at length. Other
mouth-bacteria with a simi-
lar reaction are mentioned
below..
Bacillus buccalis maximus
Z
a
а
+
appears in the shape of iso-
lated bacilli or threads, but
much oftener as tufts of
threads, parallel to or cross-
ing each other, from 30 to
150μ long, and distinctly ar-
ticulated (Fig. 20). The rods
are from 2 to 10μ long, some-
times even longer, and from
1 to 1.3μ broad. This bacterium is therefore the largest occurring
FIG. 21.
a
i
L
ADIT
FIG. 20.

FASCICLE OF BACILLUS BUCCALIS MAXIMUS.
Colored with the iodine solution. 400: 1.
UDIE
BACILLUS BUCOALIS MAXIMUS.
After treatment with iodine solution. 1800: 1.
1
G

a
in the mouth; it has a very regular contour, and usually the
same thickness throughout. (b, Fig. 21, is an exception.)
74
THE MICRO-ORGANISMS OF THE HUMAN MOUTH.
Not all the cells of this bacterium show the iodine reaction, a
statement which applies equally well to most bacteria that turn
blue on the addition of iodine. The majority of them, how-
ever, respond very distinctly to the test, becoming stained brown
violet, either throughout (Fig. 21, a) or only in isolated places
(Fig. 21, 6). I have not observed this bacillus in the dentinal
tubules; indeed, its size would seem to oppose a barrier to its
entrance into the tubules. The size, the distinct and regular
articulation, the absence of the zigzag windings, as well as the
iodine reaction before mentioned, hinder me from admitting
this micro-organism into the cyclus of the above-described Lep-
tothrix innominata.
Leptothrix buccalis maxima.
There is also found in the mucous deposits upon the teeth quite
a large number of long, thick, straight, or curved filaments,
which show a marked resemblance of form to Bacillus buccalis
maximus, except as regards the joints, which are, perhaps, some-
what shorter in the latter. These cells do not give the iodine.
reaction. Whether they are, therefore, to be regarded as a differ-
ent variety, or as cells of the same variety, in which the substance
which assumes the blue color is not yet formed (possibly younger
cells), must for the present remain undecided. I have called
this organism Leptothrix buccalis maxima.
Jodococcus vaginatus.
This micro-organism occurs in consid-
erable numbers in all unclean mouths.
Only in the case of two children, aged five
and eight years respectively, have I failed
to find it. It appears singly or in chains
of from 4 to 10 cells, longer being rarely
seen. The chains are furnished with a
sheath in which the cells appear as flat
disks, or as more rounded, even square shapes, which some-
times show a great likeness to tetrads (Fig. 22). The chains
have a diameter of 0.75p. Occasionally chains are found in
CALINA
GUILFORD
FIG. 22.
HIKHE
amm
JODOCOCCUS VAGINATUS.
1100: 1.
BIOLOGICAL STUDIES ON THE BACTERIA OF THE MOUTH. 75
which one or more cells are missing, i.e. have escaped from the
sheath; others again, whose sheaths have burst, while the
separate members have not entirely severed their connection with
the chain. Sometimes the remains of the broken sheath may be
easily detected; it does not show the iodine reaction, but remains
colorless, or becomes yellowish after the continued action of the
reagent. The contents of the cells are always stained dark blue
to violet by iodine.
Spirillum sputigenum.
Spirillum sputigenum also occurs in every mouth, but in vary-
ing proportions. In mouths properly cared for it will be found
only in very small numbers; in neglected mouths, however, it
often exists in enormous masses. If a small quantity of the soft
deposit on the margin of the inflamed gums is taken from an
unclean mouth and brought under the microscope, we some-
times find an almost pure culture of Spirillum sputigenum, or of
Spirochete dentium. The former occurs in the shape of rods,
curved like commas, which show very active spiral movements.
By the growth of the rods, where fissation does not occur,
or when the separate rods remain connected with each other,
S-forms and short spirals are produced. (See Figs. 23 to 29.)
This bacillus was regarded by Lewis, Klein, and others as
identical with the cholera bacillus, a view which a more careful
study of these two morphologically similar organisms will show
to be incorrect. I have given an exposition of the real relation
of the curved bacilli in the oral cavity to the cholera bacillus, in
the Deutsche med. Wochenschr.60 From this source I quote the
following: Prof. Lewis's communication on comma bacilli in the
human mouth has added extraordinary interest to the study of
the fungi of the oral cavity. As is known, Lewis discovered(?)
a curved bacillus in the mucus of the mouth, which in form, size,
and color-reaction is said to correspond to the cholera bacillus
and consequently to be identical with it. Its occurrence in the
mouth is, however, by no means a discovery of Prof. Lewis's,
but a long-known fact. I mentioned it in the Transactions of the
Botanical Society, 1883, p. 224, and expressed the opinion that
it belonged in the cyclus of development of Spirochete dentium,
61
76
THE MICRO-ORGANISMS OF THE HUMAN MOUTH.
since I was able now and then to find cells of this organism,
which were composed of a series of short comma-like joints, in
my own specimens.62 The fact that the comma bacilli of the
mouth take up coloring matter so much more easily than do the
Spirochetes, does not, however, favor this supposition. I have
also referred to this spirillum in Klebs's Archives for 1882, Vol.
XVI, where a diagram of it will be found on Plate VII, Fig. 2.
Furthermore, F. Y. Clark regarded it as the cause of dental
caries as early as 1879, and called it "dental bacterium." He
describes it as "half U-shaped, having screw-like movements.”
According to my experience it is to be found in every mouth,
FIG. 23.
FIG. 24.

:
KyFans
****
CURVED BACILLI, SPIRILLA, ETC.,
FROM THE MOUTH.
1100: 1.
•
2.95
Mini
برده و یاده
T
CURVED
BACILLI IN A
DENTINAL
CANAL.
1100: 1.
mixed with numerous other bacteria (Fig. 23). It frequently
occurs in extraordinary numbers, exceeding all other forms put
together, especially in cases where for some reason or other
a slight hyperemia of the gums has supervened. If a pointed
instrument be introduced under the reddened gums, any desirable
quantity of comma bacilli and Spirochetes may always be ob-
tained. Between the teeth and in cavities of decay I have found
it much more rarely. Now and then variously curved and
twisted micro-organisms are met with in the dentinal tubules ;
the irregularity of the curves leads us to the inference that in
most of such cases they are due only to the contracted space
which does not admit of the organisms growing in straight lines
(Fig. 24). Although I obtained nearly pure material in several
1
BIOLOGICAL STUDIES ON THE BACteria of tHE MOUTH. 77
cases, and used all possible kinds of nutrient media, I did not suc-
ceed in producing the slightest growth of this fungus. On gela-
tine and agar-agar with beef-extract, calf's broth, and beef-water-
peptone, saliva, etc., also in fluid media at various temperatures,
no development ever took place.
This fact alone is quite sufficient to establish the total differ-
ence of the organisms under consideration from the cholera
bacillus, which, as is well known, grows very well on artificial
culture-media. It is, however, to be hoped that a pure culture
may yet be procured, since it is in itself an organism of great
interest. But Spirillum sputigenum is not the only fungus occur-
ring in the human mouth which produces curved rods. Another
kind, not difficult to cultivate, occurs in
short, plump, tapering rods, generally united
in pairs, some of which show a slight cur-
vature (Fig. 41); this is particularly observed
in rods undergoing fissation. This bacterium
is motile, grows well at room temperature,
and quickly liquefies the gelatine.
A third mouth-bacterium, which I have
already described in the Independent Prac-
titioner 63 and in No. 36 of the Deutsche med.
Wochenschr., 1884, occurs in the form of
delicate rods of varying length, sometimes
straight and sometimes so curved as to form the arc of a circle,
two rods together making the letter O (Fig. 25). The cells vary
in form to such an extent that I first supposed I had an impure
culture before me; the attempt to separate them, however, did
not succeed. Later, on observing various forms on one thread
(Fig. 25, c), I became convinced that they belonged to the same
fungus. The rods show every degree of curvature, from the
straight to the semicircular. Two united rods sometimes form
an S-, more frequently an O-shaped figure; in some cases the
rods are so combined that they are scarcely distinguishable from
cocci (Fig. 25, b). By the fissation of the rods, chains of cocci are
formed, as is best seen in old cultures. No formation of spores
was observed, and, examined in a hanging drop of bouillon, the
rods displayed no motion.
یم
FIG 25.
གག
reaub
HALF-CIRCULAR RODS
FROM A CULTURE OF
THE E-BACILLUS
OF MILLER.
1100: 1.
78
THE MICRO-ORGANISMS OF THE HUMAN MOUTH.
On account of its slow growth on gelatine, its pure culture
from saliva or dentine is connected with many difficulties. Cul-
tures made of microscopically pure material offer nothing re-
markable, as I have stated in a former communication. No
growth occurs on the surface, nor does a liquefaction or evapo-
ration of the gelatine take place. Its identity with the cholera
bacillus is, therefore, quite out of the question. A true spirillum
which possesses much more similarity to the comma bacillus of
cholera asiatica, both morphologically and in the manner of its
growth, I obtained from the human mouth in pure culture some
five years ago. The isolation of this bacterium was accomplished
in two cases by the use of coagulated beef-blood serum.
The
FIG. 26.
"
125
एग
(
COMMA- AND S-FORMS FROM A PURE CUL-
TURE OF A BACILLUS FOUND IN THE
HUMAN MOUTH, PROBABLY FINK-
LER-PRIOR BACILLUS.
1100: 1.
FIG. 27.

SPIRILLUM FORMS OF THE BACILLUS
REPRESENTED IN FIG. 26.
1100: 1.
material from which the cultures were made was, in each case,
found under the margin of inflamed gums, in unhealthy mouths.
Morphologically, this bacillus is very similar to the other well-
known comma bacilli, occurring as commata, either singly or
in twos (Fig. 26), or in spirillum form (Fig. 27). In old cultures
on gelatine, all the commata sometimes grow out into spirilla,
giving a pure spirillum culture. Cultivated on plates of beef-
water-peptone-gelatine, at 20° C., they appear after twenty hours
(in the second dilution), under a power of 100 diameters, as per-
fectly round, finely granular colonies, with a smooth border and
brown color; in the same time the first dilution will be com-
pletely liquefied. They liquefy coagulated blood-serum with
great energy, as do the other comma bacilli. On the surface of
agar-agar they form a yellowish coating, and convert the medium,
BIOLOGICAL STUDIES ON THE BACTERIA OF THE MOUTH. 79
superficially only, into a paste. They grow slowly on boiled
potato. I have, consequently, not yet been able to establish any
definite peculiarity of growth. The reactions of this bacillus are
such as at once establish the fact that it is altogether a different
organism from the comma bacillus of Koch. It possesses, on
the other hand, many of the peculiarities of the Finkler-Prior
bacillus. Whether it is identical with this organism has never
been determined beyond all doubt, though most bacteriologists
believe it to be so.
It must be remarked that this organism is not the one which
is constantly to be found in every mouth. This grows rapidly
on ten per cent. gelatine, while the latter appears to be unable to
grow at all on the same medium.
Not one of the many forms of micro-organisms, curved or
otherwise, which I have obtained in pure culture from the human
mouth, is for a moment to be mistaken for the bacillus of Koch.
I have before shown that micro-organisms occur in the mouth,
which are not destroyed by a solution of artificial gastric juice,
so that they may pass through the stomach into the intestines.
and still retain their power of reproduction.
That this should also be the case with curved
bacilli occurring in the mouth, is not at all impos-
sible. On the contrary, it is to be expected that,
under certain conditions, they will be able to pro-
liferate in abnormally large numbers in the intes-
tines.
FIG 28.
- 18.
In my own fæces, during a slight diarrhoea,
curved bacilli, as well as Spirochetes, were found
in small numbers (Fig. 28), but they proved as
uncultivable as the similar bacilli of the mouth.
As a matter of course, the simple occurrence of a curved rod in
the evacuations will not prove its specific character.
The above examples will suffice to demonstrate the existence of
various screw-forms, which bear no more relation to each other
than do the various species that occur in the form of cocci. They
further show that the form of a fungus alone by no means always
entitles us to draw conclusions as to its specific character. In
doubtful cases this point can be decided by pure cultures alone.
CURVED
BACILLI AND
SPIRILLA FROM
THE FACES.
1100: 1.
80
THE MICRO-ORGANISMS OF THE HUMAN MOUTH.
Spirochete dentium.
Spirochete denticola (Spirochete dentium, tooth spirochete) is
not found in decaying dentine, but in the same places in which
Spirillum sputigenum is found, i.c., under the margins of the
gums, when they are covered with a dirty de-
posit and slightly inflamed,-in other words,
in cases of gingivitis marginalis. This bac-
terium exhibits spirals from 8-25μ long, of
very irregular windings and unequal thick-
ness, which manifest a great difference in their
affinity for coloring-matter. The thicker
ones usually take it up much more readily
than the thin ones; they also have fewer and
broader windings (Fig. 29).
It is a question whether we have not to
deal with two different organisms, the thicker
of which may possibly represent a stage of
development of Spirillum sputigenum. The
development and pathogenesis of Spirochete
dentium is as obscure as that of the other above-mentioned
uncultivable mouth-bacteria. Neither do we know anything
definite as to their vital conditions and manifestations (fermenta-
tion, pathogenic action, etc.).
FIG. 29.

SCREW-FORMS
(SPIRILLA AND SPIRO-
CHETES) FROM THE
MOUTH.
1100: 1.
MOUTH-BACTERIA WHICH ARE UNCULTIVABLE AND WHOSE PATHO-
GENESIS IS UNKNOWN.
Under this head belong all the mouth-bacteria proper, as well
as a bacterium of enormous dimensions which I discovered in
great numbers in the mouth of a dog suffering from pyor-
rhœa alveolaris, and which I have designated by the name Lepto-
thrix gigantea (Fig. 30). It appears in forms of tufts or fascicles
whose threads diverge from a point of adhesion in different
directions, somewhat like those of Crenothrix. It forms cocci,
rods and threads, and therefore belongs to the pleomorphous
bacteria. The threads of the same tuft may vary considerably
in thickness, some relatively very thin, others very thick. The
larger threads often show a difference in diameter between the
BIOLOGICAL STUDIES ON THE BACTERIA OF THE MOUTH. 81
FIG. 30.

LEPTOTHRIX GIGANTEA.
From the mouth of a dog suffering from pyorrhoea alveolaris.
540: 1.
6
82
THE MICRO-ORGANISMS OF THE HUMAN MOUTH.
base and point; they sometimes appear straight, sometimes
irregularly curved, sometimes twisted in regular spirals either
throughout or only at the point or base. Now and then a spirulina
may be observed. I have not been able to determine whether
this fungus has any causal relation to the disease.
The question arises whether this organism may not also occur
on the teeth of other carnivora, or even of phytophagous mam-
mals. In order to determine this point, I examined the teeth of
various animals and found very frequently leptothrix-like fungi
in the mouths of sheep, cattle, pigs, horses, and so forth.
It can be determined by pure culture alone whether these
species of Leptothrix, occurring in different animals, are identical
or not. Some of them, at least, show morphologically great simi-
larity; in general, however, those of the cat and rabbit seem to
be more delicate and thin than those of the dog.
MOUTH-BACTERIA WHICH GIVE A BLUE OR VIOLET REACTION WITH
IODINE.
Besides the Bacillus buccalis maximus and Jodococcus vagi-
natus, the following mouth-bacteria may be mentioned which
give the iodine reaction described above:
a. A micro-organism which I shall for the present term Jodo-
coccus magnus; large cocci or diplococci of differ-
ent sizes (Fig. 31). I first succeeded in obtaining
a pure culture of this micro-organism on a medium
composed of equal parts of agar-agar gelatine and
a solution of dentine glue sufficiently thick to
become stiff at room temperature. In addition to
these ingredients, the medium contained 1.5 per
cent. of sugar and 1.5 per cent. of starch. If a
small quantity of the soft deposit upon the necks.
of teeth be brought upon this medium after the manner employed
in making line-cultures, a copious growth of different micro-
organisms will be observed in twenty-four to forty-eight hours,
if kept at the temperature of the human body. We now pour
a slightly acidulated solution of iodine in iodide of potassium
upon the plate. The culture-medium itself becomes bluish, most
of the colonies yellowish; some individual points, however, often
FIG. 31.
00
JODOCOCCUS
MAGNUS.
800: 1.
BIOLOGICAL STUDIES ON THE BACTERIA OF THE MOUTH. 83
display a violet color, and if the latter are immediately trans-
ferred to a new plate a pure culture of the given bacterium may
be easily obtained. The brief period of action of the iodine
solution does not destroy these organisms, at least not all of them,
and consequently its application affords an excellent means of
determining and isolating them. They also flourish on ordinary
nutrient agar-agar, but not on gelatine at room temperature.
The reaction is best observed in media containing sugar, less
plainly in amylaceous media. When cultivated on the latter, the
colonies often show concentric variously-colored rings, thereby
giving rise to very delicate and pretty patterns.
In form and in reaction this micrococcus exactly coincides
with one which is found in carious dentine, and which produces.
the violet color characteristic of decayed dentine on addition of
the iodine solution. The same has hitherto, without any defi-
nite reason, been considered as "elements of Leptothrix buccalis."
The cells of the Jodococcus magnus are on the average larger
than those of the coccus occurring in dentine; yet the difference
is not so great that it may not be explained by the great dissimi-
larity in the conditions of growth.
b. A small micrococcus, of which I have succeeded in obtain-
ing a pure culture recently, which, however, I have not more.
closely examined. It also gives a blue to violet color with iodine.
c. A micrococcus which gives a beautiful pink color under the
action of iodine. I have observed a slight development of this
bacterium on nutrient agar-agar, but have not been able to per-
petuate it in pure culture.
Other bacteria, which are colored slightly blue or violet by
iodine, also occur in the mouth. Their reaction is, however, too
slight to justify a further examination in this connection.
I have furthermore obtained in pure cultures two yeast-fungi
from the mouth, which show characteristic reactions with iodine.
CULTIVABLE MOUTH-BACTERIA, PARTLY NON-PATHOGENIC, PARTLY
OF UNKNOWN PATHOGENESIS.
The great number of different kinds of bacteria which have
been obtained in pure culture from the mouth has hitherto made
their classification impossible. We are also unable, with few
84.
THE MICRO-ORGANISMS OF THE HUMAN MOUTH.
exceptions, to state which of these bacteria occur most frequently
in the mouth, or under what conditions the different kinds
develop best. Any one who makes an extensive series of culture
experiments will soon be overwhelmed with such a quantity of
material that it will be impossible for him to work it up with
the desired thoroughness. I have myself made the mistake,
which I think others have made, of attempting the impracticable
FIG. 32.
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h
VARIOUS FORMS OF BACTERIA FROM THE MOUTH.
a, c, o, Screw-forms; b, Cocci; d, Rods; e, Coccus-chain with sheath; i, Coccus-chain (Strep-
tococci); f, Rod-chains; h, Various thread-forms.
task of examining all the species which I have isolated, instead
of concentrating my attention upon individual cases and study-
ing them thoroughly. Consequently only general results have
been obtained, and the researches of different authors have
repeated, instead of complementing each other. Some confusion
therefore exists in our conceptions of mouth-bacteria, which can
only be cleared up by an enormous amount of labor.
With the exception of Cladothrix and Beggiatoa, all of the most.
common species of bacteria have their representatives in the oral
cavity (Fig. 32).
BIOLOGICAL STUDIES ON THE BACTERIA OF THE MOUTH. 85
Up to 1885, I had isolated twenty-two different kinds of bacteria
from the human mouth. A number of these are represented in
Figs. 33 to 44. In these figures b represents the form of the re-
spective colonies, on 10 per cent. gelatine, slightly magnified.
Ten of the twenty-two kinds mentioned appear in the form
of cocci; four of these are reproduced in Figs. 33-36: they are
of different dimensions, from very small, round cells (Fig. 33)
to remarkably large cocci, " macrococci" (Fig. 36).
FIG. 33.
α
a
FIG. 37.
a
FIG. 40.
2,8
b
b
FIG. 34.
a
b
FIG. 38.
a
FIG. 41.
b
FIG. 35.
a
FIG. 36.
a
a
ارد
By
FIG. 42
FIG. 39.
a
b
b
Five appeared as short rods (Figs. 37, 38), six as somewhat
longer rods (Figs. 39, 40). A curved species, which liquefied
gelatine and produced a green coloring-matter, was designated
by the name Vibrio viridans (Fig. 41). One species (Fig. 42)
formed spirilla, another developed into long threads (Fig. 43).
One again formed long jointed threads, some of which were fur-
nished with sheaths (Fig. 44). Of thirty species cultivated later,
eighteen were cocci, eleven rods, while one grew into threads.
In liquids three developed into rather long articulated or in-
86
:
THE MICRO-ORGANISMS OF THE HUMAN MOUTH.
articulated threads, one kind occurred in spirillum form, eight
were motile, fourteen immotile.
Formation of spores was observed in three cases only, the
others appearing to develop by fissation alone; eight liquefied
gelatine. Fourteen were cultivated on slices of potato, five of
them growing rapidly, one in particular soon spreading over the
whole surface of the slice and liquefying it completely to a depth
of one to two millimeters. The others did not thrive well on
potato. Of fifteen kinds which were cultivated on the white of
egg, four grew well, evolving considerable quantities of sulphu-
retted hydrogen (HS) and later ammonia (NH). The white
of egg was converted into a semi-transparent pasty mass, which
FIG. 43.
a
$
b
FIG. 44.

a
b
gradually disappeared. Seven grew slowly, and four not at all.
On sections of normal undecalcified dentine certain bacteria
seemed able to exist for some days, presumably till the organic
substance exposed on the surface of the section was consumed.
No growth occurred on enamel.
These bacteria showed, as far as they were examined, differ-
ences in relation to the action of atmospheric air. Ten of them
were strictly obligatory aërobic, growing only with free access
of air; four were not strictly obligatory aërobic, growing better,
but not exclusively, when air was admitted; eight were faculta-
tive aërobic, that is, they seemed to grow equally well with or
without oxygen.
If from the deposits about the necks of the teeth we make line-
*BIOLOGICAL STUDIES ON THE BACTERIA OF THE MOUTH. 87
cultures on beef-water-peptone-sugar agar-agar, certain bacteria
will develop with tolerable regularity. Of these I think the
following worthy of mention:
1. A micro-organism occurring in somewhat irregular cocci
or diplococci, singly or in chains (Fig. 45). It produces small,
prominent, shining colonies resembling in older cultures tiny
glass beads; these colonies are further charac-
terized by their cartilaginous consistency, and
by the fact that they cannot be taken up with the
point of the needle, but run ahead of it on the
surface of the plate. Under a low power the
colonies appear roundish, very dark, lustrous,
frequently having a villous margin and a black
pattern within (Fig. 46). These two last char- AsCOCOCCUS BUCCALIS.
acteristics are not, however, constant.
1100 1.
2. A bacterium which appears in the form of unequally large
cocci (Fig. 47). It forms small round or roundish, very thin colo-
FIG. 46.
COLONY OF ASCOCOCCUS BUC-
CALIS 3 DAYS OLD.
i
70: 1.
*
FIG. 47.
FIG. 45.
CELLS OF THE MOUTH-BACTE-
RIUM DESCRIBED UNDER 2.
1100: 1.
FIG. 48.


SECTOR OF A COLONY OF THE
MOUTH-BACTERIUM DE-
SCRIBED Under 2.
3 DAYS OLD. 200:1.
nies, without a distinct margin, which are quite colorless or tinged
but faintly yellowish-gray when examined under the microscope.
The separate cocci are visible under a power of about 200 diam-
eters, the whole colony appearing coarsely granular, and the short
chains of cocci or separate cocci protruding over the margin.
Fig. 48 shows the sector of a colony under about 200 diameters.
3. A third bacterium appears as oval cocci, mostly in pairs
or chains (Fig. 49). It also forms thin, small colonies, hardly
88
THE MICRO-ORGANISMS OF THE HUMAN MOUTH.
visible to the naked eye; under weak power without distinct
outlines or wholly transparent at the margin, becoming denser
toward the center, which has a grayish color. Under 320 diam-
eters the sector of a colony has the appearance represented in
Fig. 50. I have named this bacterium Micrococcus nexifer on ac-
count of the loops formed by the chains of cocci in pure culture.
4. A bacterium somewhat less frequent, which appears under
the microscope as scattered, unequally large, irregular colonies,
composed of a few cells. These colonies are without distinct
form, dark gray: micrococci.
5. The bacterium which I mention as the fifth is conspicuous
to the naked eye for the size of its colonies. It appears in almost
all cultures, but in comparatively small numbers. To the naked
eye the colonies appear milky-white; under the microscope they
show a gray margin and a yellowish to dark-brown center wholly
opaque. The margin of the colony is occasionally indented and
strongly refractive. Morphology: beautiful round cocci in dense
masses.
FIG. 49.
MICROCOCCUS
NEXIFER.
1100: 1.
FIG. 50.

SECTOR OF A COLONY OF MICRO-
COCCUS NEXIFER 3 DAYS OLD.
320: 1.
6. A micro-organism which is remarkable for its very charac-
teristic growth may often be found on culture-plates, whether
inoculated from the secretions of the oral cavity or from decayed
dentine. It forms colorless, transparent, prominent colonies,
which obtain a height of 1.5 millimeter and a breadth of from
2.5 to 4 millimeters, having the consistency of paste. Under the
microscope the separate cells in form of chains of cocci are dis-
tinctly visible, lying scattered in this paste.
< BIOLOGICAL STUDIES ON THE BACTERIA OF THE MOUTH. 89
7. I have found the Jodococcus magnus in almost all cases in
which I have particularly searched for it in the secretions of the
mouth.
These bacteria, cultivated in saccharine solutions, bring about
fermentation, accompanied by a strong acid reaction. Experi-
ments undertaken for the purpose of determining their other
physiological characteristics are not yet concluded. Various other
coccus and bacillus kinds are less constant; some of them are
shown in Figs. 33 to 44. Colonies of yeast-fungi may almost
invariably be found on plates inoculated from the human mouth.
I have, however, made no attempt to examine them more closely.
(See Chapter XII.)
W. Vignal ("Recherches sur les microorganismes de la
bouche," Archives de Physiologie norm. et pathol., 1886, No. 8) has
made very extensive and exact experiments upon the bacteria
of the mouth. In his communication, which is accompanied
by very instructive illustrations, he describes seventeen different
kinds of bacteria found in the mouth and obtained by him in pure
culture. Some of these were identical with well-known species,
while others were new to him.
Concerning the frequency with which the various bacteria ex-
amined occur in the human mouth, Vignal makes the following
determination, for which, however, he claims only approximate
accuracy. Most frequently of all he found Bacterium termo,
then Bacillus e (Bacillus ulna?) etc., in the following order:
1. Bacterium termo.
2. Bacillus e (Bacillus ulna?).
3. Potato bacillus.
4. Coccus a (d of Miller?).
5. Bacillus b.
6. Bacillus d.
7. Bacillus c (Bacillus alvei?).
8. Bacillus subtilis.
9. Staphylococcus pyogenes albus.
10. Staphylococcus pyogenes aureus.
11. Bacillus i.
12. Bacillus f.
+
13. Bacillus j.
90
THE MICRO-ORGANISMS OF THE HUMAN MOUTH.
14. Bacillus g.
15. Bacillus h.
16. Leptothrix.
Vignal's table is characterized by the predominance of bacilli.
With the exception of the two pyogenic bacteria, he met with
but a single coccus form (Coccus a), while other investigators-
Black, Biondi, Gysi, and myself-found a preponderance of
coccus forms. An examination of a few preparations derived
from mucous tooth deposits or carious dentine will, as a rule,
show a prevalence of micrococci.
This difference in the results of different investigators can be
explained, I think, by the circumstance that Vignal cultivated all
of his bacteria on gelatine. Since, however, very many mouth-
bacteria do not grow on gelatine, cultures made upon agar-agar
may lead to different results.
G
64
In America, Black has entered upon the study of the micro-
organisms of the human mouth with great zeal. He describes
among others Streptococcus continuosus, Staphylococcus medius,
Staphylococcus magnus, Coccus cumulus minor (probably Sarcina or
Micrococcus tetragenus), and a "gelatine-forming" organism,
Bacillus gelatogenes. (See page 22.)
CHROMOGENIC MOUTH-BACTERIA.
:
It needs scarcely to be remarked that many theories have been
proposed to account for the various colors presented by decayed
dentine. The best known is that of Watt,65 which attributes
these colors to the action of various mineral acids, supposed to
be concerned in the production of caries. Another view assigns
the chief rôle to articles of food, drink, etc., which do certainly
sometimes produce discoloration of the decayed as well as of the
healthy tooth-tissue.
Others, again, would have us believe that the color comes from
within and is one of the results of the vital reaction of the tooth-
substance itself. Black seeks to account for the discoloration
by the impregnation of the carious tissue with sulphides, while,
finally, the view has not been wanting in advocates that certain
bacteria which possess the property of forming various coloring
BIOLOGICAL STUDIES ON THE BACTERIA OF THE MOUTH. 91
matters are the chief factors in bringing about the pigmentation
in question.
The following presentation of the characteristics of the color-
forming bacteria of the human mouth, as far as they have as yet
been revealed to us by actual research, is undertaken in the hope
of determining how far they are accountable for the work which
has been assigned to them.
Chromogenic bacteria are widely distributed in nature. A
plate of gelatine exposed to impure air for a short time will
almost invariably develop one or more colored colonies; green,
various shades of yellow, brown, red, being sometimes represented
on the same plate. Such being the case, it must naturally
happen that these bacteria often find their way into the human
mouth with food, drink, and chiefly with the air. As matter
of fact, they are by no means seldom met with in the oral cavity.
As a rule, the colorless bacteria predominate in the human
mouth to such an extent that the chromogenic bacteria, if
present, cannot be detected; occasionally, however, they may be
easily recognized even by the naked eye. I have observed a
brick-red color more frequently than any other, on the lingual
surface of the lower front teeth and on the buccal surface of the
molar teeth.
When this organism has once become established in the
mouth, it does not readily allow itself to be expelled. I have in
my practice a number of patients in whose mouths I have
watched its growth for six to eight years. One case which par-
ticularly interested me was that of four children, brothers and
sisters, aged about ten to seventeen years, for whom I repeatedly
removed the brick-colored deposit on the lower incisors only to
see it faithfully return in the course of a few weeks. Having
recently had occasion to examine the mouth of the mother, I
found the same deposit, from which I conclude that there is
some constitutional peculiarity about these children, inherited
from the mother, which renders the secretions of their mouths
peculiarly adapted to the needs of this organism.
Attempts to cultivate the bacterium of brick-colored deposit
have been unsuccessful, although I did succeed in isolating from
the mouth an organism which produces about the same color
92
THE MICRO-ORGANISMS OF THE HUMAN MOUTH.
(Fig. 1, Plate III). My present opinion, however, is that the one
I obtained is not the one I have been seeking.
A number of times I have found cavities of decay, usually
dark brown, in which the surface of the dentine was colored
with a bright yellow mass of cheesy consistency. I have not
been able to obtain a pure culture of this bacterium on gelatine,
though I have repeatedly observed a slight growth on potatoes.
Any one who will keep a lookout for the two appearances
just described will certainly see them. A case which was inter-
esting in more than one respect occurred at the polyclinic of the
Dental Institute at Berlin, some time ago. A man presented
himself, having a swelling on the right side of the face, almost
as large as a man's fist, connected with the inferior wisdom-
tooth (impeded eruption). The larger portion of the surface of
the mouth and tongue was covered with a canary-yellow deposit,
which could not be accounted for by anything that the patient
had taken into his mouth.
found a bacillus in the pus which was evacuated upon the
extraction of the tooth, and also in the yellow layer upon the
surface of the cheeks and gums, which reproduced the same
color in pure cultures, and besides showed considerable patho-
genic action. I had no opportunity to see the patient again,
consequently do not know the result of the infection.
A pure
culture of this micro-organism on gelatine is seen in Fig. 2 of the
plate.
I have found in the human mouth and isolated no less than
eight different kinds of bacteria which produce a yellow pigment,
not including the well-known yellow sarcina. These bacteria
are themselves yellow, but do not impart any color to the culture-
medium.
I have made a great many attempts to cultivate the supposed
bacterium of greenstain, but so far without success. I have
indeed isolated five different species of bacteria from the mouth
which impart a green color to the culture-media, although themselves
colorless, and all of which grow well on the usual media, but I
do not bring any of them into causal connection with the green-
stain, since, as far as my observation goes, the bacterium of
greenstain, if there be such a thing, does not grow on gelatine.
BIOLOGICAL STUDIES ON THE BACTERIA OF THE MOUTH. 93
I found one of these in the contents of an alveolar abscess; it
grew with tolerable rapidity, liquefying the gelatine. If culti-
vated without the presence of oxygen, no color is developed, but
if the culture is shaken with air, it will in a few seconds assume
a beautiful green color. I found the second in a cavity of decay,
and the other three in my search for the supposed bacterium of
pyorrhoea alveolaris; they are colorless, but impart a beautiful
opalescent color to the gelatine, one of them having at the
beginning a decidedly bluish tinge. A pure culture of one of
these is seen in Fig. 3 of the plate. It is, however, impossible
in the lithograph to reproduce the beautiful opalescent color of
this growth. The cultures of one bacterium obtained from the
mouth have a red color on the surface, but are colorless beneath
the surface (Fig. 1, plate); the protoplasm of the living cells con-
tains the coloring-matter, and no color is imparted to the gela-
tine. Another has a reddish color, also confined to the bacteria
themselves. Cultures of still another have a decided brownish
color (Fig. 4, plate); it liquefies the gelatine, and sinks to the
bottom as a brownish irregular mass.
I have recently isolated a bacterium from the mouth occurring
in form of long large rods and jointed threads, which, cultivated
on the surface of nutritive agar-agar, imparts to the medium, in
the course of a few weeks, a yellowish-brown color which grad-
ually darkens and extends deeper into the substratum as the age
of the culture increases. To this bacterium, whose character-
istics I have not yet sufficiently investigated, I have assigned the
name, Bacillus fuscans.
I shall not enter into a discussion of the biology of these bac-
teria. At present we are interested in the question as to what
part they may take, if any, in the production of the various colors
or shades of color in carious dentine.
Of all the chromogenic bacteria above referred to, only the
ones represented in Fig. 4 of the plate and the one described as
Bacillus fuscans could be looked upon as taking any direct part
in the pigmentation of carious dentine. These, however, as far
as we know at present, do not occur with sufficient constancy in
the mouth to admit of assigning an important rôle to them.
The green-producing bacteria, which I have named Bacteria
94
THE MICRO-ORGANISMS OF THE HUMAN MOUTH.
viridantia, are excluded, because green dentine does not occur.
Those which assume a yellow color (Bacteria flavescentia) cannot
be looked upon as the direct cause of the yellow shade of carious
dentine, because the color is confined to the micro-organisms
themselves, the medium on which they are cultivated becoming
very little, if at all, stained. In the case of dentine, the relations
are exactly the opposite; the dentine becomes stained, while the
micro-organisms remain colorless (white). This is probably well
known to those who have made a few sections of carious dentine.
-
The following experiment may serve to furnish an idea of the
manner in which the pigmentation of the carious tooth-tissue
may be brought about.
I inoculated a tube of culture-gelatine with a bacterium ob-
tained from decayed dentine; almost any bacterium which lique-
fies the gelatine would, however, have served the same purpose.
In about two weeks the gelatine was completely melted and a
white mass of bacteria lay on the bottom of the tube.
At the beginning of the experiment the gelatine had only the
slight yellowish tinge often present in culture gelatine. Soon,
however, a yellowish-brown color made its appearance, which
gradually became darker even after all life had disappeared from
the culture, until at the end of ten weeks the whole mass of
melted gelatine had a deep brownish color.
A very old dry culture presented about the color of the black
spots (so-called caries nigra) often seen on the approximal sur-
faces of teeth where caries once began and then ceased after the
removal of the approximating tooth. Organic matter under-
going decomposition assumes, as is well known, a dark color,
and the same is true of decaying dentine. The colors charac-
teristic of decaying dentine do not exist in the very beginning
of the decay, but appear subsequently. The more recent or
acute the decay, the less the discoloration; the older or more
chronic the decay, the deeper the color.
There is, however, another factor which may play a part in
the discoloration of dentine, more particularly in teeth contain-
ing dead pulps; the latter sometimes become intensely black,
and it is to these in particular that the following suggestion re-
fers. My attention was some time since called to the fact that
་
A
BIOLOGICAL STUDIES ON THE BACTERIA OF THE MOUTH. 95
recent experiments had demonstrated the presence of iron in a
variety of tissues where it had not previously been detected.
This discovery led to the thought that iron might be present in
the dental pulp, and that in such case the black color of the
putrid pulps might be accounted for by the formation of the sul-
phide of iron. I made a few preliminary experiments relating
to this question, the results of which I here give. The tests were
made in the following manner: A tooth was cracked in a porce-
lain mortar, so as to thoroughly expose the pulp, and then placed
in a mixture of dilute hydrochloric acid, to which was added a
small proportion of a 10 per cent. solution of ferrocyanide of
potassium. The hydrochloric acid, as well as the water used
for diluting it, must be free from iron; neither must any iron
instrument be brought in contact with the freshly-broken sur-
faces of the tooth. Those parts of the tooth containing iron,
even in minute quantities, will, after an exposure of from one to
sixty minutes, assume a blue color-Prussian blue being formed.
One source of error is introduced in the necessary use of an iron
instrument in extracting the tooth, but this will only affect those
points on the external surface of the tooth with which the forceps
come in contact, and may therefore be easily eliminated.
I have found iron (1) constantly in Nasmyth's membrane
(probably only as a deposit from external sources); (2) in the
dental pulp, though not constantly; (3) in carious dentine almost
constantly, a bright blue line often forming on the border
between the decalcified and normal tissue,—a rather remarkable
appearance for which I can at present attempt no explanation; (4)
in enamel, particularly around the margin of cavities of decay.*
It seems, consequently, not impossible that the sulphide of iron
which would be formed during putrefaction of the pulp may have
something to do with the discoloration of the same. Whether
sulphide of iron may be formed through decay of the dentine or
enamel in sufficient quantity to aid in discoloring the same, I
cannot say; at present I doubt it. Further experiments may
furnish an answer to this question.
* Traces of iron have been detected (as is well known) ly chemical analysis
in both dentine and enamel.
96
THE MICRO-ORGANISMS OF THE HUMAN MOUTH.
THE BACTERIA OF DISEASED PULPS.
In the mouth we find certain conditions which are presented
by no other part of the human body, in that a direct way is fur-
nished for parasites through the medium of root-canals and
diseased tooth-pulps into the deeper parts (Fig. 51).
The question arises, Is this way equally passable for all bac-
teria and under all circumstances, or are there only certain kinds
which find a suitable culture-medium
in different conditions of the pulp, and
are thereby enabled to effect the pas-
sage through it to the apex of the root
or to the periapical tissue?
As far as I know, nothing has as yet
been ascertained in regard to this point,
and I can here only communicate the
results of my own investigations, which
have, in fact, as yet but begun.
We have reason to suppose that in
the living pulp, for instance in the case
of chronic pulpitis, as well as in all
suppurative inflammations of the pulp,
chiefly bacteria of a pathogenic nature
may obtain a footing, since in such cases.
these find the most suitable nutrient
medium, and that the more harmless
parasites of the human mouth, on the other hand, would prefer
the dead organic matter of the oral cavity. It has, moreover,
appeared to me that in cultures from such pulps I have not,
as a rule, found the large number of different kinds of bacteria
which may usually be found in the mouth.
FIG. 51.

CROSS-SECTION THROUGH
THE LOWER JAW WITH HALF
OF A DECAYED PREMOLAR IN
SITU, showing how germs of in-
fection may pass from the mouth
directly into the spongy portion
of the bone.
Ma
Again, since the access of air, particularly in case of closed
pulp-chambers, is very limited, we would expect to find a pre-
ponderance of anaerobic or of facultative anaërobic bacteria.
In regard to this point, also, experimental evidence is wanting.
In the third place, in case the pulp-chamber has not been
opened, the entire store of nutrient material being soon consumed,
the bacteria may perish from want of nourishment, or even be
at
BIOLOGICAL STUDIES ON THE BACTERIA OF THE MOUTH. 97
destroyed by their own products, or finally they may enter upon
the state of spores.
It may, therefore, readily occur that a putrid pulp does not
contain a single bacterium capable of development.
Of seventeen necrotic tooth-pulps which I have examined
with reference to this question, I found seven without living (at
least without cultivable) bacteria. Attention has already been
called to the fact that the dental pulp presents in a high degree
the conditions essential to the formation of spores; and since
spores possess high power of resistance, the antiseptic treatment
of root-canals is thereby rendered more difficult.
In order to determine whether a necrotic pulp contains living
bacteria or not, we proceed in the following manner. Taking a
freshly extracted tooth (the best are such whose pulp-chambers
have not been opened), we first cleanse it by placing it for a
short time in a solution of sublimate 5: 1000; then carefully
wash it with sterilized water to remove the sublimate, dry it
with sterilized paper, and split it with sterilized forceps. The
pulp is then removed with a sterilized needle and brought into
the culture-medium, in which it is crushed, the solution being
repeatedly shaken in order to distribute the organisms equally
throughout. From this a second or even a third dilution is made,
and the number of colonies determined in the usual manner.
Experiments 1 to 5 were made on gelatine, the others on agar-
agar at a temperature from 37° to 38° C.
From Pulp 1
66
66
2.
66
66
66
(6
66
66
46
..
+
66
66 4
5
6
7
8
9
66 10
، ، 11
66
6.6
66
،،
66
со
6.
12, dry, black,
foul-smelling
4800
4800
235
0
0
275
0
3
0
4
.250,000
0
colonies developed.
،،
66
66
66
66
،،
66
66
66
66
6.6
66
•
66
66
66
66
،،
66
66
66
66
66
7
98
THE MICRO-ORGANISMS OF THE HUMAN MOUTH.
From Pulp 13, moist, bad-
smelling
14, almost dry,
black.
66
46
66
66
66
66
66
66
15, suppurating
16, black, liquefied,
very bad-smelling
17
2050
0
405
512
0
colonies developed.
،،
،،
66
66
66
66
،،
66
The fourth case is that in which the pulp-chamber is widely
opened, so as to permit the entrance of new culture-material
from the mouth. Processes of putrefaction or fermentation here
continually take place. In the lower part of the canal, at least,
the same organisms are present which are found in the other
part of the oral cavity, with the exception of such whose growth
depends upon the presence of more or less inflamed gums.
The subject of the bacteria of the diseased pulp is one which
has as yet but little occupied the attention of bacteriologists,
consequently little definite is known about them; nor has any
classification of them been made. A series of experiments which
I myself began in this direction had to be broken off on account
of want of time.
The general infections which are brought about by inocula-
tion with the bacteria of diseased tooth-pulps will be treated of
in Chapter XI.
It often happens that a tooth, which has occasioned no disturb-
ance for years, in spite of a necrotic pulp, will exhibit a severe
inflammation of the pericementum a few hours after the pulp-
chamber has been opened for the purpose of removing the
remains of the pulp and filling the root-canals.
An attempt has been made to ascribe this very unpleasant
result to an infection of the pulp occasioned by germs from the
air. When the pulp-chamber is opened, air is supposed to rush
´in, carrying bacteria along with it. These excite decomposition
of the contents of the root-canal, thereby giving origin to an
inflammation of the pericementum. This idea deserves to be
ranked among the many other wonderful theories of olden times.
Every practitioner in dentistry knows very well that air or
BIOLOGICAL STUDIES ON THE BACTERIA OF THE MOUTH. 99
gas often enough escapes as soon as an opening is made into
a pulp-chamber containing a gangrenous pulp. No one, how-
ever, as far as I am aware, has observed that the air enters the
pulp-chamber under such conditions.
It would indeed be difficult to explain how a vacuum could
exist in the canal of a root. Granted, however, that a partial
vacuum did exist at the time the pulp-chamber was opened, and
that ten cubic millimeters of air were admitted into the pulp-
chamber (which is a large estimate), how many organisms would
likely be introduced with it?
The number of micro-organisms in a given quantity of air
depends of course upon the purity of the air, and consequently
varies according to the locality. Pure air in Berlin was found
to contain, on the average, 0.1 to 0.5 bacteria per liter, and the
air in hospital wards, with seventeen or eighteen beds, to contain
2.4 and 2.7 per liter respectively.
Now, if we suppose the air of a dental office to contain double
the amount represented by the largest number found in pure
Berlin air, there will exist in one lirer, that is, in one million
cubic millimeters, one germ. Ten cubic millimeters would then
contain 1000 X 10 = 100000 germs.
T
The chances would then be that in one hundred thousand
operations of this kind the success of one would be endangered
by the entrance of one germ into the pulp-cavity. Whether this
one germ in such case could produce any disturbance, would
depend upon the existing circumstances.
The appearance of pericementitis after opening into a pulp-
chamber is due solely to the carelessness or helplessness of the
operator. He either forces particles of the putrid pulp through
the foramen apicale, or introduces new infected fermentable mat-
ter into the root-canal from without, or occasions an infection by
means of unclean instruments.
THE RELATION OF MOUTH-BACTERIA TO THE FORMATION OF TARTAR.
Since the discovery of the existence of great numbers of
microscopical organisms in the human mouth, repeated efforts
have been made to make them responsible for the formation of
tartar. Lebeaume compared tartar to coral; Mandl supposed it
100
THE MICRO-ORGANISMS OF THE HUMAN MOUTH.
:
to be caused by the accumulation of calcareous remains of
vibrios; Klebs, Galippe, and others express the opinion that
tartar is to be regarded as an excretion of micro-organisms.
There is such a vast difference between tartar and coral, as
well as between bacteria and coral-forming polyps, that Le-
beaume's comparison is certainly unwarranted, while the theory
of Klebs is an apparent contradiction of facts known to every
practitioner. As is well known, tartar is formed chiefly, some-
times exclusively, where the salivary glands discharge their pro-
ducts into the oral cavity, particularly on the lingual surfaces of
the lower incisors. In no other locality of the mouth have the
bacteria so little opportunity of gaining a foothold as at this par-
ticular point, since the tongue keeps these surfaces nearly free
from bacteria and soft deposits.
1
15
*
Moreover, the amount of tartar in a given mouth is in no wise
proportional to the number of bacteria contained in the same, nor
am I aware that calcareous deposits anyway resembling tartar
have been observed in pure cultures of mouth-bacteria.
Other considerations also seem to me to render this explana-
tion untenable. Tartar contains about 25 per cent. of organic
matter and 75 per cent. of salts (almost exclusively lime-salts;
bacteria, on the other hand, contain about 0.5 per cent. of
ashes, consequently the percentage of ashes in bacteria is equal
to but of. that in tartar; a formation of tartar, therefore, by
an accumulation of the calcareous remains of bacteria appears
to me to be out of the question.
Normal saliva contains calcium phosphate as well as carbon-
ate; these are held in solution in the blood and in the glands by
carbonic acid. When the saliva enters into the mouth, the
carbonic acid escapes and the lime-salts are precipitated. The
following experiment will demonstrate this process:
Small quantities of calcium phosphate and calcium carbonate
are brought into water charged with carbonic acid (a bottle of
soda-water serves the purpose very well), shaken at brief inter-
vals, and left standing until the water becomes quite clear. On
opening the bottle very carefully and permitting the carbonic
acid slowly to escape, the precipitation of the salts held in solu-
tion will produce a distinct cloudiness.
-
BIOLOGICAL STUDIES ON THE BACTERIA OF THE MOUTH. 101
At the June meeting of the Odontological Society of Great
Britain, 1889, Cunningham and Robinson presented impure
cultures of bacteria partly from the mouth, in which well-formed
crystals might easily be seen with the naked eye. The analysis
proved these crystals to consist of the double ammonium-mag-
nesium phosphate or triple phosphate (NH,,Mg,PO4, 2H,O).
The authors were of the opinion that "the deposition of tartar
on the teeth and the formation of some calculi in other parts of
the body may be due, in part at least, to this action." On a visit
of Dr. Cunningham to my laboratory a short time ago we ex-
amined a number of pure cultures from the mouth and found in
three cases, all from two to three months old, distinct crystalline
formations not imbedded in the growth, but projecting from it
into the pure gelatine or agar-agar.
As stated to Dr. Cunningham at the time, I am not quite
prepared to believe that this process has much to do with the
formation of tartar. Of course it remains for him to show
whether such crystals really are found in tartar, and whether
tartar actually contains the above-mentioned triple phosphate in
any considerable quantity.
A communication on the subject of salivary calculus by A.
C. Castle, in the January number of The Forcep, 1855, may be
of interest in this connection. He writes, "Microscopic examina-
tion discovers that this calculus exists in a crystalline state, and
by its irritating effects frequently causes what are supposed to be
neuralgic pains.
"The next form of salivary calculus is of a soft, friable, pul-
verant nature. It is of two kinds, the simple phosphate of lime,
and the ammoniaco-magnesia phosphate of lime, with the usual
combinations of animal matter, and oxalate of lime upon investi-
gation will be found to exist in large quantities in those subjects
where the oxalates exist in excess.
9.9
•
CHAPTER V.
102
MOUTH-BACTERIA AS EXCITERS OF FERMENTATION.
GENERAL REMARKS.
NUMEROUS experiments and investigations from the time of
Schwann to the present day, and particularly the exact methods
of bacteriological research employed within the last few years,
have demonstrated beyond all doubt that all processes of fermen-
tation and putrefaction depend upon the presence of microscopi-
cally small living organisms. Nevertheless, certain authors, not
in dental literature alone, are in the habit of completely disrc-
garding all the facts established in the last fifty years, putting
themselves back into the first half of the century and speaking
of putrefactive processes which are supposed to arise in some in-
explicable manner without the aid of micro-organisms, and to
yield certain products, among which bacteria themselves are not
unfrequently reckoned.
Apa
-
It is actually astonishing that the question, which is first, the
bacteria or the fermentation? can still claim the attention of any
mind, and that irrefutable facts can be entirely overlooked,
although handbooks of bacteriology are so numerous and widely
circulated that ample information may be easily obtained in re-
gard to these fundamental questions. We are constantly con-
fronted by the statement that the decomposition of certain sub-
stances may be effected by means of finely divided platinum,
that alcohol may be directly oxidized to acetic acid. Many
dentists also continue to refer to the possibility that acids may
develop during the putrefaction of organic substances in the
mouth without the participation of micro-organisms, and obsti-
nately ignore the fact that without micro-organisms the putre-
MOUTH-BACTERIA AS EXCITERS OF FERMENTATION. 103
faction of organic substances is altogether impossible. Others,
again, settle the question in a manner which they think should
be satisfactory to every one by the stereotyped assertion, "Bac-
teria are not the cause, but the result of fermentation."
Whoever is at all versed in the fundamental principles of
bacteriology will regard it as a matter of course that the process
of fermentation going on in the oral cavity offers no exception
to the rule that all fermentative and putrefactive processes are
conditioned by the presence of living micro-organisms. This
fact may be established experimentally by the following simple
tests:
Exp. 1. Add 2 per cent. of sugar or starch to fresh saliva,
and keep the mixture at blood temperature. It invariably be-
comes acid in four to five hours; or fill a glass tube two cm.
long and three mm. wide with starch, sterilize it, and fasten it to
a molar tooth in the mouth on going to bed; next morning the
contents of the tube will have a strong acid reaction. A cavity
in a tooth, or a piece of linen, which may be saturated with a
solution of starch, will answer the purpose as well as the glass
tube.
Erp. 2. Keep the mixture of saliva with starch or sugar for
one hour in the sterilizer at 100° C., and then place it in the in-
cubator; it does not become sour in four, nor in twenty-four
hours; in fact, not at all. We conclude that the agent which
caused the mixture in 1 to become sour (i.e., the ferment) is
rendered inactive by a temperature of 100° C.
Exp. 3. Heat the starch alone to 150° C. before mixing with
the saliva; the solution still becomes sour. Heat the saliva alone,
and the mixture does not become sour. Conclusion: the ferment
exists, not in the starch, but in the saliva.
We have now to determine the question, Is it an organized
ferment (micro-organisms), or is it an unorganized ferment
(ptyaline)?
This question is determined by the following experiments:
Exp. 4. From six to eight grams of saliva are agitated in a
test tube with as much sulphuric ether as it will take up, starch
added, and the whole put in the incubator. On examination
after a few hours, we will find sugar in the solution, but no acid;
104 THE MICRO-ORGANISMS OF THE HUMAN MOUTH.
N
in other words, the acid-forming ferment has been rendered
inactive, but the unorganized, sugar-forming ferment, not.
same.
Exp. 5. Instead of ether, enough carbolic acid is added to
make the solution one-half per cent. strong; the result is the
These two experiments show that the ptyaline of the
saliva (which was not injured by the presence of the ether or the
carbolic acid, as proved by the fact that it retained its diastatic
action) is not the cause of the acid reaction.
Exp. 6. According to Paschutin, ptyaline is devitalized by an
exposure of twenty minutes to a temperature of 67° C. Organ-
ized ferments could not be killed by the same means.
We ac-
cordingly subject a mixture of saliva and grape-sugar to the
given temperature for twenty minutes. We thereby destroy
the ptyaline; the mixture, nevertheless, becomes sour if allowed
to stand in the incubator for twenty hours.
This experiment confirms the result of experiments 4 and 5,
and we begin to suspect that we have to deal with an organized
ferment. This supposition is confirmed by the following experi-
ment:
Exp. 7. A small quantity of a perfectly sterilized solution of
sugar in saliva (1-40), in a test tube with cotton cork, is infected
from the mouth, or with carious dentine, as described above; in
twenty-four hours the solution will be acid; with a fraction of a
drop of this solution a second tube is infected; it will likewise
become acid; from this a third, etc.; each becomes acid in turn,
while the control tube (containing the same solution, not infected)
remains neutral.
The conclusion is plain that we have to do with a ferment
which is capable of reproducing itself; in other words, the agent
giving rise to acid fermentations in the juices of the human
mouth exists in the form of living organisms.
W
I have examined twenty-two different species of bacteria
which up to the year 1885 I had isolated out of the secretions,
etc., of the human mouth, in reference to their fermentative
action; and although, as may readily be seen, it was impos-
sible with so large a number of different organisms to carry out
the experiments to the desired degree of completion, I have
nevertheless obtained some results which may be of interest and
MOUTH-BACTeria as exciters of ferMENTATION.
105
may somewhat contribute to our knowledge of the different fer-
mentative processes in the human mouth and the diseases conse-
quent upon them.
The chief source of nourishment for micro-organisms in the
human mouth is furnished by two groups of substances, the
carbohydrates and the albuminous substances. Both are almost
invariably present in the human mouth in depressions, in fissures
of the teeth, or in the spaces between them, or finally upon their
free surfaces.
The carbohydrates undergo fermentations which lead to an
acid reaction of the medium, while decompositions of albumin-
ous substances are accompanied by an alkaline reaction. As a
rule, mixtures of both produce an acid reaction. The reaction,
which may be observed in any hidden recess of the human
mouth, depends, consequently, partly upon the nature of the
food present at the time, partly upon the kind of bacterium.
In the case of one bacterium which I examined with particular
reference to this question, I found that it caused a neutral reac-
tion when cultivated in a 3 per cent. solution of beef extract in
the presence of per cent. of sugar, while the reaction became
acid on increasing the quantity of sugar and alkaline upon
diminishing it. I shall revert to these facts in Chapter VIII, in-
asmuch as they explain a number of phenomena accompanying
dental caries.
A. ACTION OF MOUTH-BACTERIA UPON CARBOHYDRATES.
1. Lactic Acid Fermentation.
The action of bacteria upon carbohydrates is of the greatest
importance to the dentist in particular, to the medical practi-
tioner, and, in fact, to every one, inasmuch as the origin of decay,
with its evil consequences, depends upon it. Of the twenty-two
kinds of mouth-bacteria already mentioned, sixteen soon brought
about an acid reaction when cultivated in beef-extract-peptone-
sugar solutions, four produced an alkaline reaction under the
same conditions, while in case of two only the reaction remained
neutral.
In a later series of experiments, twenty-five mouth-bacteria,
thirteen stomach-bacteria, and fourteen bacteria from the intes-
106
THE MICRO-ORGANISMS OF THE HUMAN MOUTH.
tines were examined in regard to the reaction which they pro-
duce in saccharine solutions. Of the mouth-bacteria, sixteen
occasioned acid reaction, four alkaline, while five yielded incon-
stant results; the corresponding numbers for the stomach-bac-
teria were nine, two, and two; for the intestine-bacteria, six,
five, and three. The number of acidifying bacteria is therefore
comparatively larger in the stomach and mouth than in the in-
testines. Whether these relations are constant could, of course,
be established only by a larger number of experiments than I am
as yet able to record.
Cl
Cultures on sterilized milk give slightly different results. It
was furthermore found impossible to draw a sharp line between
those bacteria which produce an acid reaction and such as cause
an alkaline reaction, because in some cases the reaction was very
weak and changed during the course of the experiment, while
in others it was materially influenced by change in the amount
of sugar.
In consequence of the large number of bacteria experimented
upon, it was naturally not possible to undertake for each one a
qualitative determination of the acid which it produced. In
the case of eighteen different bacteria, however, the examination
was made, and in ten cases out of these eighteen lactic acid was
found. It was formerly believed that the lactic acid fermenta-
tion could be brought about by only one specific micro-organism,
which was designated as the lactic-acid fungus (Bacterium acidi
lactici). Some years ago I called attention to the fact that many
different bacteria are found in the human mouth which are
capable of forming lactic acid out of sugar, and it has now been
established by various investigators that this property, as well as
the inverting and peptonizing property, is very widely distributed
among bacteria. This fact offers an easy explanation for the
long-known constant presence of lactic acid in the stomach and
intestines.
↓
The determination of the acid was made partly by analysis, partly
by crystallization tests, and partly by the color test of Ewald.*
* Five to ten cc. of water plus one drop of chloride of iron plus two drops car-
bolic acid gives a violet color, which becomes yellow on addition of lactic acid
even in very minute quantities.
MOUTH-BACTERIA AS EXCITERS OF FERMENTATION.
107
By this simple reaction the detection of lactic acid, which is
otherwise often extremely difficult, is very much facilitated. Un-
fortunately, however, it cannot be applied under all conditions,
since not only lactic acid and its salts, but also tartaric acid,
malic acid, acetic acid, oxalic acid and its salts, as far as I have
examined them, and possibly some other substances not yet ex-
amined, give the same reaction. In order to produce the yellow
color, it is, in fact, only necessary to add to the violet solution a
small piece of fruit (apple, grape, plum, tomato), a few drops of
white wine (Mosel, etc.). All these acids must, of course, be
first excluded before the presence of lactic acid can be assumed
with absolute certainty.
In order to determine more accurately the acid formed in a
mixed fermentation of carbohydrates, as it occurs in the mouth,
a chemical analysis was made.
The method of carrying out such an analysis will now be given:
Two hundred cc. of fresh saliva are mixed with 2.0 starch and
allowed to stand forty-eight hours at blood temperature; the
mixture is then filtered, and heated to 100° C., to stop the
fermentation. This process is repeated until about a liter of the
solution has accumulated. It is then placed in a retort and
reduced to a volume of about 75 cc. It will be very strongly
acid. A few drops of this liquid added to a very thin solution
of methyl-violet, leave it unchanged; from this we conclude
that we have to deal with an organic acid, as an inorganic acid
would turn it first blue and then green. Since the acid did not
distill during the prolonged boiling, we may set it down as non-
volatile, hence a non-volatile organic acid. The distillate was
very slightly acid; we will call it distillate No. 1, as we wish to
refer to it again.
The solution was further reduced in volume to about 40 cc.
over the water-bath, and then transferred to a large glass vessel,
briskly shaken with one and one-half to two liters of sulphuric
ether, and allowed to stand until the ether became perfectly
transparent. This was then filtered into a large retort and dis-
tilled, proper precautions being observed to prevent accidents.
When the volume had been reduced to about 50 cc., the solution
was filtered into a porcelain vessel, and still further reduced over
108
THE MICRO-ORGANISMS OF THE HUMAN MOUTH.
the water-bath. A portion of the solution tested in the short
tube of a Mitscherlich double-shadow polaristrobometer gave, as
a mean of nine readings, a rotation of the plane of polarization
equal to 0.015 degree, or 0° 0.9'. In other words, the solution.
was optically inactive, the 0° 0.9' being far within the range of
the error of experiment, especially as the solution was not abso-
lutely transparent.
An excess of freshly prepared oxide of zinc was then added to
the solution, and the whole slowly and carefully boiled, water
being added as it was found ne-
cessary, till the reaction became
neutral, or nearly so, filtered
into a large glass evaporating
dish, and put away at the tem-
perature of the room for the salt
to crystallize. A drop of this
solution placed upon a glass
slide gave, upon crystallization,
the forms seen in Fig. 52, which
are at once recognized as crys-
tals of lactate of zinc. In a few
days a quantity of a whitish
crystalline powder had formed.
This was placed upon a filter,
the mother-liquid squeezed out, washed in absolute alcohol, dis-
solved in hot water, recrystallized and dried over sulphuric acid;
it then weighed 0.343. After exposing to a temperature of 100°
C., or a little more, till the weight became constant, it weighed
0.2816; it lost accordingly 17.9 per cent.* of water of crystalli-
zation, corresponding to three molecules of water. The salt was
then dissolved in water, the zinc precipitated as carbonate and
burned. The burned mass (zinc oxide) weighed 0.0970. We
have, consequently,—
FIG. 52.

1JpR
+
T
ار
lo
CRYSTALS OF LACTATE OF ZINC.
Substance analyzed (a zinc salt) = 0.343
Oxide of zinc
0.097
The zinc oxide is seen to be equivalent to 28.2 per cent. of the
substance analyzed.
*Theoretically 18.2, or 0.3 per cent. more.
MOUTH-BACTERIA AS EXCITERS OF FERMENTATION.
109
The formula for the inactive ethylidene lactate of zinc is—
-5 3
C₂H₂O3)
C₂H₂O₂
Dried at ordinary temperature it contains 27.3 per cent. zinc
oxide. The result obtained from the analysis differs, therefore,
from that deduced from the formula by less than 1 per cent.,
and settles beyond doubt the fact that the substance analyzed
was the lactate of zinc, or that the acid generated by the fermen-
tation is lactic acid, or, more exactly, inactive ethylidene lactic
acid, since, as shown above, the acid solution was optically
inactive, and the zinc salt contained three molecules of water of
crystallization. The salt was furthermore soluble in sixty-two
parts water at 14° C.
I repeated the analysis with the following solution:
Water, 1000 cc.
Saliva, 300 cc.
} Zn + 8H₂O,= 248 + 54.
Bouillon, 200 cc., made by boiling 125 grams of beef ten
minutes in 300 cc. of water.
Sugar, 10.0.
This solution being slightly acid was neutralized with the car-
bonates of lime and sodium, sterilized, and infected from a pure
culture of the bacterium in question. It was treated throughout
exactly as above described, except that the zinc salt was con-
verted into the sulphide instead of the carbonate, and burned
with powdered sulphur in a stream of hydrogen. The result was:
Substance analyzed = 1.0540
Zinc sulphide
Zine
0.415
26.38 per cent.,
instead of 26.74 per cent., as deduced from the formula, a differ-
ence of only one-third of one per cent.
In this case the substance was dried at 100° C. before weigh-
ing, and the formula becomes-
C₂H₂O3
5 Zn
C₂H₂OS
-5 3
One more analysis was made, using-
Water, 1000 cc.
Liquid beef extract, 20 cc.
Sugar, 10.0.
243.
110
THE MICRO-ORGANISMS OF THE HUMAN MOUTH.
The result was the same, and need not be given; the two an-
alyses above described being abundantly sufficient to show that
the acid generated by the fungus in question is the common fer-
ment lactic acid. Distillate No. 1, referred to above, owed its
slight acidity, we now know, in part at least to lactic acid, since,
when an aqueous solution of lactic acid is boiled, a small fraction
of the acid goes over with the water. To ascertain, however,
whether any other acid, especially volatile, was present, the dis-
tillate was boiled with carbonate of lime, filtered, evaporated to
dryness, a small amount of dilute sulphuric acid added, and
heated in a retort over the water-bath; a few drops of an oily
acid came over, which, when taken upon the fingers, smelled like
butyric acid; the amount, however, was so small that no attempt
could be made to analyze it.
Among the products of fermentation of these bacteria I have
also found formic,* acetic, and butyric acids, the latter, however,
only in very small quantities. The greatest amount of acid which
I have as yet observed in lactic acid fermentation is 0.75 per
cent. Although the coefficient of separation of lactic acid is very
small compared to that of the inorganic acids, it is, nevertheless,
rather large when compared to that of other organic acids. My
investigations have convinced me that it is considerably increased
in syrupy solutions, so that instead of 10, the coefficient for
aqueous solutions, a multiple of 10 must be taken, large quanti-
ties of ether (one and a half to two liters) being necessary to
effect even an approximate extraction of the acids.
Formation of Gas in Lactic Acid Fermentation.
The fermentations which are brought about by different lactic
acid bacteria show great differences in respect to the amount of
gas evolved. I have already called attention to the fact that the
fermentations of carbohydrates frequently proceed without gen-
erating the least trace of gas. On the other hand, some of the
bacteria more recently examined formed very large quantities of
gas (CO, and H), so that the gelatine in the culture-tubes was
* The distillation with phosphoric acid was made very carefully over the water-
bath.
MOUTH-BACTERIA AS EXCITERS OF FERMENTATION.
111
completely torn to pieces, or a part of it even driven out of the
tube (Fig. 53). In some cases the pressure was even great enough
to burst the tube.
:
From this violent evolution of gas the conclusion was drawn
that it was not a pure lactic acid fermentation, corresponding to
the equation CH12O6=2C,H,O,, a conjecture
which was verified by the analysis, which revealed
the above-mentioned by-products, formic, acetic,
and butyric acids. During the fermentation of
half a liter of beef-extract-sugar solution I collected
two hundred and fifty cubic centimeters of gas
(CO), and H) in three hours.
2
I would call especial attention to five different
gas-forming bacteria, which invariably form large
gas-bubbles in the gelatine or tear it to pieces, as
is represented in the figure. One of these bacteria,
which generates considerable quantities of gas also
in albuminous substances, I found in the human
fæces as well as in a gangrenous tooth-pulp. Its
appearance in the latter place may help to explain
the frequent occurrence of dental abscesses. If a
tooth be filled before removing the necrotic pulp
and sterilizing the root-canals, the gas formed will
force itself through the foramen in the apex of the
root, or carry particles of the putrid pulp along
with it, causing irritation, if not immediate in-
flammation, of the pericementum.
It was formerly customary in such cases to bore
into the tooth at the neck in order to "ventilate
the nerve," that is, to permit the gases or other
products of putrefaction to escape. Several of
these bore-holes, which continually discharge pus,
stinking gases, etc., may sometimes be found in one mouth.
Of the other gas-forming bacteria I found three in the stomach
and one in the fæces; and it may be readily seen what unpleasant
results might accompany their profuse development in the
stomach or intestines.
These results of my investigations, which I published in 1884
FIG. 53.

WAV
CULTURE OF A
GAS-FORMING
BACTERIUM
FROM THE
STOMACH, IN
BREAD-SUGAR
GELATINE.
One day old.
1½: 1.
112
THE MICRO-ORGANISMS OF THE HUMAN MOUTH.
and 1885, have been verified by different investigators. Vignal
investigated the action of seventeen different mouth-bacteria cul-
tivated on various nutrient substances, particularly on such con-
taining carbohydrates. Seven of these micro-organisms dissolve
albumen, five cause it to swell up or make it transparent, ten
dissolve fibrin, four cause it to swell up and become transparent,
nine dissolve glutine, seven coagulate milk, six dissolve caseine,
three transform starch, nine convert lactose into lactic acid,
seven invert crystallized sugar, seven ferment glucose and
partially convert it into alcohol.
67
66
Hueppe also calls attention to the presence of lactic acid in
the oral cavity. He isolated two different micro-organisms (one
of which seems to be identical with one described by me), which
formed lactic acid in saccharine solutions.
As already mentioned above, by-products, such as butyric
acid, formic acid, acetic acid, etc., are often produced in lactic
acid fermentation of carbohydrates. But, as far as my observa-
tion goes, these by-products are produced in comparatively very
small quantities, so that they perform no important rôle in the
various processes in the human mouth. Moreover, direct state-
ments as to the detection of these acids in the human mouth are
entirely wanting in the literature of this subject. A great deal
has been said about butyric and acetic acids as causes of dental
decay. These statements, however, have no scientific founda-
tion whatever. Any other proof of the presence of these acids
in the human mouth than that which I myself have produced
has not been given.
2. The Spontaneous Butyric Acid Fermentation
does not appear to take place in the human mouth; at any rate,
the Bacillus butyricus has not been detected in it; furthermore,
the free access of air is not favorable to the development of this
bacterium. Whether other kinds of the butyric acid forming
bacteria, which are tolerably widespread in nature, occur in the
human mouth and there cause their characteristic fermentation,
is not known; the possibility is not to be excluded. I only affirm
that as yet the occurrence of butyric acid fermentation in the
human mouth has not been proved.
MOUTH-BACTERIA AS EXCITERS OF FERMENTATION. 113
3. The Acetic Acid Fermentation
68
certainly does not occur in the oral cavity, for the simple reason
that this fermentation cannot take place at a higher temperature
than 35° C.; besides, the necessary quantity of alcohol and of
acid essential to this fermentation is wanting. Escherich 6 dis-
covered in the intestinal tract of a child a micro-organism called
by him Bacterium lactis aërogenes, to which he ascribes the pure
lactic acid fermentation. According to Baginsky," however, it
develops only minute quantities of lactic acid and profuse quan-
tities of acetic acid. Nothing is known as to its occurrence
in the mouth. Among seven of the bacteria which Vignal ex-
amined, he found one which brought about a fermentation of
carbohydrates, by which, in addition to other products, alcohol
and carbonic acid were formed.
4. Diastatic Action of Mouth-Bacteria.
The bacteria which I examined very seldom displayed a dias-
tatic action. Indeed, out of nine different kinds I found but
one possessing a pronounced saccharifying action. This bacte-
rium formed from starch a kind of sugar having the power of
reducing the oxide of copper, and then further decomposed the
same under development of an acid reaction. It is frequently
asserted that a bacterium possesses a diastatic action, simply be-
cause it grows on slices of boiled potato. This assumption,
however, is inadmissible, inasmuch as the micro-organisms are
by no means restricted to the potato starch alone, but may also
derive nourishment from the albumen, sugar, etc., of the potato.
5. Inverting Action of Mouth-Bacteria.
Cane-sugar, C₁₂H22O11 (which is unfermentable, does not reduce
oxide of copper in alkaline solutions, and turns the plane of
polarization to the right), treated with a ferment, soluble in
water and contained in beer-yeast, higher plants, and apparently
also in many fungi, will, on the addition of water, be converted
into invert-sugar. The latter is a mixture of grape- and fruit-
8
114
THE MICRO-ORGANISMS OF THE HUMAN MOUTH.
sugar, which turns the plane of polarization to the left, reduces
cupric to cuprous oxide, and is directly fermentable.
C₁₂H22011 + H2O = C6H12O6+ C6H12O6
Cane-sugar. Water. Grape-sugar.
Fruit-sugar.
The ferment which occasions this conversion of cane-sugar,
designated as a hydrolytic decomposition, seems to be produced
by many mouth-bacteria, since under their action cane-sugar very
soon acquires the properties of invert-sugar.
That this conversion is really due to the action of an enzym
formed by and separable from the bacterium, I have, as I think,
proved in one case by the following experiment. A number of
cultures in Florence flasks having been made at the same time,
I was able after forty-eight hours to obtain the bacteria which
had collected at the bottom of the vessels in considerable quan-
tity. In this way I obtained about 10 c.cm. of a rather thick
pap. The organisms were then devitalized by 90 per cent.
alcohol, dried in a porcelain bowl, rubbed with sand, thoroughly
soaked in water, and filtered. The filtrate, or watery extract,
which must be clear, was added to a cane-sugar solution at
room temperature; this solution then showed in the long tube
of a Mitscherlich double-shadow polaristrobometer a rotation of
5.19 as the average of nine readings. The solution was left
standing in a damp chamber for four hours at 39° C., whereupon
it produced a rotation of 4.98. There was consequently a de-
crease of two-thirds of a degree, indicating a corresponding in-
version of the cane-sugar solution. The solution also caused a
slight reduction of an alkaline solution of sulphate of copper.
Many ferment bacteria of the mouth do not seem to be depend-
ent upon the presence of free oxygen for their fermentative
action. I have made cultures in which (1) the air was excluded
by a thick layer of oil; (2) in vessels from which the air had
been exhausted by a mercury air-pump; (3) in vessels which
had been freed from oxygen by an alkaline solution of pyrogallic
acid. It was ascertained that as much acid was generated in
these cases as when the air had free access. We must conclude
from the above that fermentation itself is not a process which re-
quires oxygen, since the traces of oxygen still present in these
experiments were entirely out of proportion to the acids formed.
[
MOUTH-BACTERIA AS EXCITERS OF FERMENTATION. 115
ን
B. ACTION OF THE MOUTH-BACTERIA ON ALBUMINOUS SUBSTANCES.
By far the majority of mouth-bacteria, in fact of all bacteria,
possess an action similar to pepsine, in converting (peptonizing)
coagulated albumen into soluble modifications. The essential
difference, however, consists in this: that, while pepsine exerts
its peptonizing action only in the presence of acids (especially
muriatic), bacteria exert it in neutral or alkaline media also.
The albuminous substances, therefore, even when insoluble, offer
an excellent nutrient medium for bacteria. The products arising
from the development of mouth-bacteria in albuminous media are
the same as those arising from putrefaction of organic substances
in general. These are chiefly bad-smelling gases, sulphuretted
hydrogen (SH), ammonia (NH3); further, CO₂, H,N, sulphide
of ammonia and the products mentioned on page 28. The re-
sultant reaction of all the products of any process of putrefaction
is, as far as my observations go, invariably alkaline.
In my experiments the albumen was so congealed in the test
tubes as to expose the largest possible surface, i.e., the tubes were
prepared in the same way as tubes of beef-blood serum. If
kept in a damp chamber to prevent drying up, the material may
be held ready for use for any desired length of time. Four of
the bacteria examined would not grow on this medium, six
exhibited but limited growth, while the others developed com-
paratively well, in some cases completely liquefying the albumen.
Whether these bacteria produce more peptone than is necessary
for their own nutrition, and whether and to what extent they
might thereby benefit the human body, is a very difficult prob-
lem. In a large quantity of coagulated white of egg inoculated
with a bacillus from the mouth, which showed intense putrefac-
tive properties, I was able on the third day to detect traces of
peptone by means of the biuret test.
In the presence of small quantities of sugar the characteristic
phenomena of putrefaction are much less pronounced, or are
altogether wanting. No bad-smelling products are formed, or,
if formed, they immediately undergo further changes, and an
acid reaction takes the place of the alkaline. I found that a bac-
terium, tested particularly in reference to this point, occasioned
a neutral reaction in the presence of per cent. of sugar when
116
THE MICRO-ORGANISMS OF THE HUMAN MOUTH.
cultivated in a 3 per cent, beef-extract solution. Increase of sugar
caused acid reaction, while a diminution rendered it alkaline.
The products arising from the process of assimilation and
growth of the living cells, or, in other words, their waste pro-
ducts, are such as impart an alkaline reaction to the medium;
those arising from the fermentation of sugar are acid. The
resulting reaction depends upon the predominance of the former
or the latter. In my opinion, no sharp distinction can be drawn
between fermentative and putrefactive bacteria, since many of
the former possess also a ferment which decomposes albumen
under formation of the characteristic products of putrefaction,
while, on the other hand, there are fungi which, though regarded
as putrefactive, when cultivated in saccharine solutions cause
them to ferment without displaying the slightest signs of putre-
faction.
One of the mouth-bacteria I examined rapidly dissolved boiled
white of egg, forming bad-smelling products, among which sul-
phuretted hydrogen and ammonia were easily detectable. It
also showed an inverting action, transforming cane-sugar into
dextrose and levulose; in the third place it decomposed fer-
mentable sugars into lactic acid with generation of carbonic acid;
it, fourthly, caused an acid reaction in an amylaceous beef-extract
solution, investing this solution at the same time with a slight
power of reducing cupric oxide; in other words, it exerts finally
a diastatic action also.
By-products presumably also arise in the last stages of these
various fermentations, making the transformations caused by one
and the same organism and the substances produced by it very
numerous. This fact explains the profusion of products which
may arise in putrefying mixtures, and makes the supposition
somewhat doubtful that the number of kinds of bacteria in a
fermenting mixture coincides with that of the products of fermen-
tation. The twenty to thirty different substances which may be
formed in an exposed putrefying mixture are not produced by
one organism alone; it is, however, not in accordance with the
facts to assume that each product or each stage requires a differ-
ent organism.
Pure putrefactive processes are found in those localities of the
!
pla
MOUTH-BACTERIA AS EXCITERS OF FERMENTATION.
117
oral cavity where no carbohydrates exist, or where their amount
is very insignificant as compared to that of the albuminous sub-
stances,—for example, in gangrenous pulps, also when particles
of meat decompose between the teeth. Pledgets of cotton
pressed slightly against the gums absorb the albuminous secre-
tion of the inflamed gums and very soon emit the disagreeable
odor of putrefaction. Ulceration or sloughing of the gums (sto-
macace, stomatitis ulcerosa, etc.) is, as is well known, likewise
accompanied by marked signs of putrefaction. It cannot be
doubted that putrefaction alkaloids, ptomaïnes, must be formed in
considerable quantities during the intense putrefactive and fer-
mentative processes which are too often observed in very unclean
mouths, but what part they play and what influence they have
on the local and general state of the body has not yet been fully
ascertained. (See Chapter XI.)
C. FERMENTATION OF FATS AND FATTY ACIDS IN THE ORAL
CAVITY.
Whether and under what conditions the fermentation of fats
and fatty acids (mentioned on page 26) takes place in the human
mouth I am not at present able to state. Since, however, the
salts most liable to cause fermentation (lime-salts, especially lac-
tate of lime) are constantly being formed, we have every reason
to suspect that such fermentations do there occur.
D. NITRIFICATION AND DENITRIFICATION IN THE MOUTH.
On page 30 I gave an account of various experiments which
have shown that fermentation processes in the soil, as well as in
artificial media, where there is free access of air, may lead to
the formation of nitrates from organic matter, and that, on the
other hand, nitrates may be reduced to nitrites or to am-
monia when the air is excluded. The formation of nitric acid
in the human mouth has, as will be known to many, been advo-
cated by Watt, the ammonia, undoubtedly formed in the mouth
in certain quantities by the putrefaction of albuminous substances,
becoming, according to his view, oxidized to nitric acid. This
assertion of Watt is, however, not based upon experimental
118
THE MICRO-ORGANISMS OF THE HUMAN MOUTH.
evidence. The question now arises whether, in the light of the
facts recorded above, such a process can occur in the mouth by
the agency of a "ferment nitrique"? This question can be solved
by experiment only. The fact that nitric acid does not occur in
the mouth in appreciable quantities speaks against it. Further-
more, the process of nitrification demands an abundant supply
of air, while the centers of fermentation in the mouth are but
sparingly supplied. The assumption that not oxidations but re-
ductions may take place in the human mouth to some extent is
much more in accordance with our knowledge of the conditions.
under which oxidizing or reducing processes may be effected by
bacteria.
The nitrous acid compound found with tolerable constancy in
mixed saliva we may presume to be formed by the reduction
(denitrification) of nitrates contained in water and in vegetable
nutrients.
It is, to say the least, very doubtful whether the fermentations
mentioned on page 27, in which lactic, acetic, butyric, and pro-
pionic acids, etc., are formed, take place in the oral cavity to any
considerable extent. No experiments have been made relating
to this matter.
CHAPTER VI.
f
ACTION OF THE PRODUCTS OF FERMENTATION ON THE DIFFERENT
STRUCTURES OF THE MOUTH.
Ir might appear from a superficial observation that the pro-
ducts formed by the above-mentioned fermentations, of which
one or more is constantly going on in the mouth, do not exert any,
or at most but a slight deleterious influence on the soft tissues.
Considerable quantities of food may remain in contact with the
mucous membrane of the gums and cheeks for some length of
time without exciting any apparent local disturbances, which
might not be explained by the mechanical irritation caused by
them. A more thorough examination, however, will enable us
to trace serious local and general diseases to the influence of
parasites in the mouth. These disorders will be discussed at
length in Part II. For the present I propose to consider that
particular action of the parasites and their products which has
as its result the most frequent and widespread of all diseases of
the human body,-
THE DECAY OF THE TEETH.
The destruction of the hard substances of the teeth, commonly
known as caries of the teeth, decay of the teeth, tooth-rot, etc.,
has, more than any other topic in the domain of dentistry, con-
tinued to excite the scientific interest of dentists and physicians
for more than two thousand years. The numerous theories
which have been held at different times concerning the origin
of dental decay prove that the problem is no easy one. Not one
of them has as yet been universally accepted. Among the causes
119
120
THE MICRO-ORGANISMS OF THE HUMAN MOUTH.
which have been assigned for decay of the teeth the following
are the most important:
1. Depraved juices accumulated in the teeth.
2. Disturbances of nutrition.
3. Inflammation.
4. Worms.
5. Putrefaction.
6. Chemical dissolution.
7. Parasites.
8. Electrolytic decomposition.
9. Diverse causes.
10. Chemico-parasitic influences.
THE STAGNATION OF DEPRAVED JUICES IN THE TEETH
was first designated by Hippocrates (456 B.c.) as the cause of
toothache.
Kraütermann70 (1732) gives a similar explanation of caries:
"The teeth are corroded by the great influx of the lymphæ acri-
oris. The fermento acri rodente in the hollow tooth reappears,
after being removed by the application of remedies."
This theory was held for many centuries. Bourdet" (1757)
also accepted it: "When the juices contained in the vessels of
the teeth are too thick, they stagnate, decay, and soon attack the
tooth."
Benj. Bell (1787), Serre (1788), Kappis (1794), and others?
accuse the juices carried to the teeth of playing an important
part in the origin of decay.*
72
DISTURBANCES OF NUTRITION AS CAUSE OF DECAY
are alluded to by Galen (131 A.D.). He says, "The lack of
nutrition makes the teeth weak, thin, and brittle. An excess of
nutrition excites a kind of inflammation similar to that of the
soft parts." A deficiency of nourishment not only causes the
tooth to die away, but also enlarges the cavities. Crumbling, cor-
* A detailed treatise of the old literature on diseases of the teeth is found in
Schlenker 72 and Carabelli. From these authors some of the following references
were obtained.
THE DECAY OF THE TEETH.
121
roded teeth are to be treated with astringents. Galen explained
the loosening of the teeth "by an excess of moisture, which
impairs the nerves.
"'"
This view is also held by Aëtius of Amida (550), partially,
too, by Ebn-Sina (Avicenna, 978-1036), and Serapion 73 (1002).
INFLAMMATION THEORY OF DECAY.
74
A great number of writers even up to the present time have
regarded tooth-decay as a process of inflammation. As early as
131 A.D., Galen mentions a kind of inflammation which is called
forth in the tooth by excessive nourishment. Eustachius (1574)
expresses himself more definitely: "Redundantia, quamvis dentes
substantiam duram habeant ac prope lapideam, similem in eis affec-
tionem excitat cujusmodi est circa carnosas partes inflammatio quod
sane ut admiratione dignum sit tamen ex alimenti copia accidere posse
et Galenus téstatur et ratio ipsa confirmat."
John Hunter7 (1778) approaches the inflammation theory
when he says (after having designated caries as mortification),
"I am apt to suspect that during life there is some operation
going on which produces a change in the diseased part."
Kappis (1794) expresses the same views.
76
Joseph Fox (1806) says, "The diseases to which the teeth are
subject have their origin in inflammation.'
""
Thomas Bell" (1831) characterizes caries of the teeth as gan-
grene, and says, "The true, proximate cause of dental gangrene
is inflammation."
E. Neumann,78 Hertz,79 Koecker,80 and others entertained the
same views.
Koecker writes, "Caries, in fact, is that state of the tooth in
which mortification has taken place in one part and inflamma-
tion in the part contiguous to it, the former originally produced
by the latter, and the latter continually kept up by the former."
In more recent times the inflammatory theory of dental decay
has derived its chief and almost only support from the contribu-
tions of Frank Abbott, Heitzmann, and Boedecker. These
authors have strenuously advocated the view that "there occurs
a primary inflammation in dentine independent of pulpitis or
81
122
THE MICRO-ORGANISMS OF THE HUMAN MOUTH.
pericementitis, running its course in the middle of the dentinal
tissue and leading, as all inflammatory processes do, either to a
new formation or to destruction by suppuration.
"Inflamma-
tion causes first a solution of the lime-salts, and afterward a
liquefaction of the basis-substance both in bone and dentinal
tissue. The result will be the appearance of globular spaces or
bay-like excavations which exhibit medullary corpuscles or some-
times clear protoplasmic masses corresponding to the embryonal
stage of the inflamed tissue."
"By the breaking apart
of these medullary corpuscles pus may be formed in the middle.
of the dentine, thus representing an abscess independently of the
pulp-tissue," or, on the other hand, a healing process may take
place through the redeposition of lime-salts. The reasons given
in support of this view do not appear to me to be such as admit
of a very close examination. The first reason is simply the as-
sertion that the hardening or consolidation, sometimes believed
to take place under fillings, is "the consequence of an inflam-
matory reaction of the dentine," and further, "instances are
not rare in which the insertion of an oxyphosphate, oxychloride,
or a gold filling gives rise to excruciating pain.
The
latter result is due to intense and acute inflammation of the
dentine."
""
It is not quite clear to me how the cases stated by Heitzmann
and Boedecker justify the conclusions which they draw from
them. We might say that the consolidation of the dentine is
due to a continued or even increased functional activity of the
dentinal fibrils; a number of facts might be, and have been,
brought forward in support of this statement, though some
oppose it; but to jump at once to inflammation of the dentine,
is making rather free with logic, to say the least.
Again, pain following the insertion of fillings may be due to
the mechanical or chemical insult to the exposed dentinal fibers,
or it may be due to the insult to the pulp itself. I cannot help
thinking that it is here also perfectly gratuitous to speak of
inflammation of the dentine. It is not proved by the cases
referred to.
The second argument of Heitzmann and Boedecker is based
upon the utterly mistaken idea that the ivory of elephants' tusks
THE DECAY OF THE TEETH.
123
has the property of healing wounds and of encapsuling musket-
balls without the intervention of the pulp or pericementum. In
regard to this point they write, "The present writers have had
no chance to study an elephant's tusk immediately after its in-
jury, but the illustrations, as given by Carl Wedl, are sufficient
for the assertion that all changes in the ivory are produced by an
inflammatory reaction around the foreign body driven into it."
Against this view, obtained from the examination of four wood-
cuts, we have the unanimous voice of Cuvier, Owen, Goodsir,
Murie, Tomes, and all the most recent writers on this subject.
I personally have examined not less than fifty-two cases of gun-
shot and lance wounds of elephants' tusks, and well-nigh one
hundred abscess-cavities, and, without entering into a discussion
of the question here, will simply state that not a single one of
all these cases affords the slightest indication of any inflammatory
reaction on the part of the ivory.
M
In the third place, Heitzmann and Boedecker attempt to
establish their views of inflammatory action in dentine through
microscopical investigations. They have found and illustrated in
the articles above referred to "excavations of the dentine which
are identical with those seen in the process of absorption of the
dentine of temporary teeth, and those of secondary dentine in
the neighborhood of an inflamed pulp." The thought naturally
occurs to every one that the authors have simple cases of absorp-
tion before them. They affirm, however, that the "diagnosis of
primary eburnitis was established by the presence of such exca-
vations in the middle of the dentine, without any connection with
the surface or the pulp-chamber of the tooth."
FIG. 53 a.
ጌ
a
It must be supposed that the connection or non-
connection of the excavation with the surface of the
tooth or pulp-chamber was established by macro-
scopical examination of the tooth before cutting or
by serial sections, since the occurrence of absorption
lacunæ in the middle of a preparation would, of
course, not exclude the possibility or probability of
an outlet on some other plane. For example, in the accompa-
nying diagram (Fig. 53 «), a root in which absorption is going
on at a, a section through the plane b would show excavations
t

124
THE MICRO-ORGANISMS OF THE HUMAN MOUTH.
in the middle of the dentine without connection with perice-
mentum. If primary inflammation of the dentine occurs as often
as we are to infer from the communications of Heitzmann and
Boedecker, then it is very strange that their observations have
not been confirmed by other investigators. One might think,
too, that by placing their preparations before the many compe-
tent microscopists in various parts of America the question could
be very soon settled beyond all doubt.
It is certainly owing to the authors to examine their prepara-
tions from a perfectly objective stand-point, and they also owe it
to us to place their preparations before us in order finally to dis-
pose of a subject of controversy which has already taken up
enough of the time of the profession. For my own part, having
spent not a little amount of time in the study of pathological
conditions in human dentine and in ivory, I am forced to accept.
the eburnitis theory of Heitzmann and Boedecker (the inflam-
mation, suppuration, and healing of dentine without the inter-
vention of the pericementum or pulp) with a great deal of reserve.
Not, however, having had the opportunity of examining a prepa-
ration from these gentlemen, I cannot give any definite opinion
as to my idea of the nature of the processes which they have
styled eburnitis, though I cannot get rid of a lurking suspicion
that it is nothing more than absorption.
Heitzmann and Boedecker 82 also claim that the views com-
monly held regarding the development of dentine and enamel
are false, Neither the odontoblasts nor the ameloblasts take part
directly in the formation of the dentine and enamel, but these
bodies first break up into medullary corpuscles, between which
the dentinal fibers are formed. It is not the place here to discuss
these views. They still await confirmation.
Abbott describes decay of a living tooth as "an inflam-
matory process which, beginning as a chemical process, in turn
reduces the tissues of the tooth into embryonic or medullary
elements evidently the same as, during the development of the
tooth, have shared in its formation and its development and
intensity are in direct proportion to the amount of living matter
which they contain as compared with other tissues.'
"Micrococci and leptothrix by no means produce caries; they
""
THE DECAY OF THE TEETH.
h
do not penetrate the cavities in the basis-substance of the tissues
of the tooth, but appear only as secondary formations, owing to
the decay of medullary elements."
Abbott's communication, from which these statements are
taken, is accompanied by a number of illustrations, of which
one is reproduced in Fig. 54, together with the explanation
accompanying it.
Ef
g
0
દો
b
FIG. 54.
CROSS-SECTION OF CARIOUS DENTINE. After Abbott.
h
g
]
125

a.
"At a certain distance from the decay the canaliculi look
unchanged, and each contains the central transverse section of
the dentinal fiber, with its delicate radiated offshoots (Fig. 54, «).
Nearer to the decay we meet with moderately enlarged canaliculi,
the center of which is occupied by a cluster of protoplasm, the
granules and threads of which have readily taken up the car-
mine (Fig. 54, b). One step farther we find the canaliculi con-
siderably enlarged, to double or treble their original size, and
they are filled with yellow protoplasm, plainly exhibiting the
net-like arrangement of the living matter (Fig. 54, c, c). The
126
THE MICRO-ORGANISMS OF THE HUMAN MOUTH.
most peripheral granules send delicate conical offshoots through
the surrounding light space toward the unchanged basis-sub-
stance. In some of the enlarged canaliculi, accumulations of
living matter are seen fully in the shape of nuclei. Sometimes
two or more such nuclei may be seen surrounded by a varying
amount of protoplasm (Fig. 54, d, d). Still nearer to the decay
the canaliculi are enlarged to ten or fifteen times their original
diameter, and the cavities thus produced are all filled with a
partly nucleated protoplasm (Fig. 54, e, e). Between the roundish
cavities we meet with longitudinal cavities, arisen from the con-
fluence of several cavities in one main direction (Fig. 54, f). The
cavities continue increasing in size, and form large spaces, with
rounded, bay-like boundaries, between which only scanty traces
of unchanged basis-substance are left (Fig. 54, 9, 9). Lastly, the
basis-substance has entirely disappeared, and only protoplasm is
visible in its place, either in the shape of multinuclear layers
or of irregular so-called medullary elements, with rather faint
marks of division (Fig. 54, h, h).”
So much for Abbott's explanation of the figure. But what,
in reality, are those cellular elements, clusters of protoplasm,
medullary elements, etc.? They are masses of micro-organisms
mixed with the débris of the decomposing dentine.
The discoveries of Abbott have received no confirmation,
whereas, on the other hand, the untenableness of the inflamma-
tory theory has been exposed by various authors. It is not
necessary therefore to call especial attention to the many points.
of Abbott's argument, which, in my judgment, are at variance
with indisputable facts. I will accordingly content myself with
a recital of the following oft-repeated facts, which cannot be
made to tally with the postulates of the inflammatory theory of
decay.
1. The elements which appear in inflammation of other tissues
of the animal body cannot be found in decayed dentine. Among
the thousands of preparations of decayed or decaying dentine
that I have examined, I have not found there anything which I
could identify with the process of inflammation, suppuration,
etc., illustrated by Heitzmann and Boedecker. The appear-
ances represented by these authors either do not occur at all in
¡
THE DECAY OF THE TEETH.
127
decay of the dentine, or so very seldom, that we could not for
a moment think of connecting them with the process of decay.
The mere detection of swelling or tumefaction of the dentinal
fibrils is no evidence that decay is the result of inflammatory
action. The custom of certain dental pathologists to assume
that every variation from the normal detected in the tissue is of
an inflammatory nature is about as rational as it would be for
the general histologist to ascribe the many post-mortem changes
which take place in delicate tissues, while being prepared for
examination, to inflammation.
I do not say that changes of a vital nature may not take place
in the dentinal fibrils as a result of the action of the decay-pro-
ducing agents, or in connection with inflammation of the pulp.
Indeed, it would be strange if the acids penetrating the dentine
and bathing the fibrils did not produce some change in them.
But it remains to be shown that in either case these changes
either produce decay or accelerate the process when once estab-
lished.
84
Heitzmann's & attempt to explain the inability of others to see
things under the microscope just as he sees them, on the ground
that they work with inferior lenses or that their eyes have not.
been properly educated, can scarcely be said to meet all the re-
quirements of a final argument. Anyone disposed to make use
of the same sort of argument might be led to inquire whether
Heitzmann and some of his followers have not sometimes seen
just a bit too well.
2. It is not possible to produce decay of the tooth, or anything
resembling decay, by means of any or all of those mechanical or
chemical agents which invariably produce inflammation in other
tissues.
We all know very well that we may file, grind, saw, bore, and
pound the living dentine, may break away large portions with
the forceps, or subject it to the action of the most irritating sub-
stances; indeed, we may do what we please with it, we cannot
produce in this way a trace of caries.
The operation of filling teeth is of itself a continued testimo-
nial to the inconsistency of the inflammatory theory of decay;
for we know very well what would result if we should bore a
128
THE MICRO-ORGANISMS OF THE HUMAN MOUTH.
**
hole in any tissue capable of inflammation (bone) and pound it
full of gold.
3. The liquefaction of the basis-substance, the melting together
of the tubules, the production of caverns, etc., characteristic of
decay, cannot be found when bacteria are not present.
4. Pulpless teeth and dead teeth worn on plates or as pivot
teeth are subject to decay in the same degree as teeth with living
pulps: they show also the same microscopical changes in the
structure.
5. It is possible to produce artificial changes of the dentine,
or, in other words, artificial decay, which under the microscope
cannot be distinguished from natural decay.
These facts are not here brought to notice for the first time,
and are probably well known to the advocates of the inflamma-
tory theory; they ignore them, however, completely, and thereby
admit their inability to answer them.
WORM THEORY OF CARIES.
For many centuries worms were regarded as an essential factor
in the origin of caries, and all sorts of remedies were employed
to drive them out. Thus, e.g., Scribonius 73 used fumigations.
against them; Ebn-Sina recommended for this purpose seeds of
henbane, leek, and onions. Musitanus 73 (1114), Kräutermann 70
(1732), Ringelmann (1824), Kremler, and many others took simi-
lar measures to get rid of the worms. Even to this day the worm
theory is not entirely abandoned. Among the lower classes in
many countries the belief prevails that worms are the source
of toothache, and Chinese dentists especially are said to under-
stand how to make superstition pay. When a patient with the
toothache presents himself, they are in the habit of making an
incision into the gums "to let the worms out." For this purpose
they employ an instrument which has a hollow handle filled with
artificial worms. When the incision is made, the operator, by a
dextrous turn of the instrument, drops the worms into the mouth;
the excitement of the patient and the loss of blood cause at least a
temporary relief. The worms are collected, dried, and are then
ready to be taken out of the next patient's gums. The Japanese
THE DECAY OF THE TEETH.
129
term for tooth-decay, or rather for a hollow tooth, is "mushi ba”
-mushi = worm, ba tooth, therefore a worm-tooth.
In Chinese, a hollow tooth is called "chung choo," which has
exactly the same meaning.
The existence of tooth-worms was called in question by Hol-
larius as early as 600. According to his idea, the worms are
nothing else than "particles of the henbane which fly off during
the fumigations."
It is rather difficult to understand how the first authorities in
the dental art should for so many centuries go on accepting burnt
particles of henbane or other vegetable substances for worms.
85
86
Peter Fauchard 8 (1728) also made futile efforts to discover the
worms. Pfaff (1756) saw worms on the gums, " particularly in
the case of very common people who are in the habit of eating
decaying cheese." He was "not able, however, to observe that
such worms had produced toothache by gnawing," although he
is willing to admit such a possibility.
PUTREFACTION AS CAUSE OF DECAY.
Putrefaction was specified as the cause of decay by Pfaff86
(1756). "Remains of food which undergo putrefaction between
the teeth occasion decay of the teeth." At the present time even,
many designate decay simply as tooth-rot (Zahnfäule) and regard
it as a process of putrefaction, overlooking the fact that an ex-
tracted tooth may be left an indefinite length of time in a putre-
fying mixture without showing any trace of decomposition.
Buda
Some years ago Mayr and Stockwell attempted to establish
the putrefaction theory of decay on a new basis. Bacteria were
said to grow into the tubules and to destroy or absorb the basis-
substance, whereupon the lime-salts fall apart. In conformity
with this theory, the analysis of carious dentine should not reveal
a decrease, but rather an increase of lime or a loss of organic
substance. In reality, the very reverse is the case, so that this
theory soon had to be abandoned.
9
130
THE MICRO-ORGANISMS OF THE HUMAN MOUTH.
CHEMICAL THEORY OF DENTAL DECAY.
Up to very recent times no theory of dental decay has enjoyed
the approbation of so large a number of distinguished odontolo-
gists as the chemical.
Paul of Ægina 73 (636) advises, "in order to preserve the
teeth, to take precautions against the spoiling of food in the
stomach (indigestion), since the frequent vomiting resulting from
it is very injurious to the teeth."
According to Carabelli, the first experiments on the action of
acids on the teeth were made by Berdmore (1771), who tested
the action of nitric and sulphuric acids. Pasch (1767), Bücking
(1782), Becker (1808), and Ringelmann (1824) attribute injurious
effects to sour food and acids. Linderer7 (1837) characterizes
caries as a purely chemical process. Robertson 88 combated the
inflammation theory. According to him, caries is a chemical
decomposition of the dental tissues by means of acids; the
latter are formed in the mouth by the dissolution of food-par-
ticles. Rognard 89 follows Robertson, and particularly mentions
sulphuric and nitric acids as products of the decomposition of
vegetable and animal substances. These acids are the cause of
the decay of the teeth.
Magitot⁹ writes, "Les considérations qui précèdent tendent à établir
que la carie dentaire résulte d'une altération purement chimique, exercée
sur l'émail et l'ivoire des dents," etc. Wedl91 also defends the chem-
ical theory; he regards the action of an acid as the chief cause of
caries in all cases where even the slightest traces of decalcification
are discernible.* The acid secretion of the gums, especially in
the cases of children and of women during pregnancy, and the
acidity of the saliva accompanying disorders of the digestion, de-
serve special mention. Leptothrix bears no direct relation to the
origin of caries.
Tomes 92 (1873) concludes "that caries is the effect of external
causes in which so-called 'vital' forces play no part; that it is
due to the solvent action of acids which have been generated by
fermentation going on in the mouth, the buccal mucus probably
*In my opinion, decay without decalcification, which Wedl here seems to
assume, does not occur.
W
131
THE DECAY OF THE TEETH.
playing no small part in the matter; and when once the dis-
integration is established in some congenitally defective point,
the accumulations of food and secretions in the oral cavity will
In
intensify the mischief by furnishing new supplies of acids."
the last edition of Tomes's work the phrase "organisms having
no small share in the matter" takes the place of "buccal mucus
probably playing no small part in the matter."
Watt has also made himself conspicuous by his obstinate de-
fence of the chemical theory. He refers the different colors of
carious dentine to the action of various mineral acids.
93
J. Taft also favors the chemical theory. "Acid mucus and
saliva, vitiated secretions, products of decomposition of animal
and vegetable matter in the mouth, and galvanic action, mineral
and vegetable acids," are, in his opinion, the chief causes of
dental decay.
Schlencker 72 writes, "Dental caries is therefore a purely chemi-
cal process. Be it repeated, where there is no acid, no caries is
possible."
Baume adheres to the chemical and opposes the parasitic
theory. "The fungi are the result of the caries” (!)
Comparative microscopical examinations of decayed dentine
and dentine simply decalcified by acids, and even a macroscopic
comparison of decayed teeth with teeth which have been acted
upon for a certain length of time by acids only, furnish sufficient
proof for the untenableness of the purely chemical theory. The
microscopic changes characteristic of decayed dentine as repre-
sented in Figs. 58-88 cannot be produced by any acid or acids.
It is not to be denied that such changes as the swelling or
tumefaction of the fresh or living dentinal fibrils may be brought
about by the action of acids, since all delicate organic tissues
suffer more or less change when acted upon by external agents.
But the enlargement of the dentinal tubules, the liquefaction of
the basis-substances, the confluence of the canals, and the forma-
tion of cavities in the dentine are absolutely inexplicable by the
action of acids in such a diluted state as they occur in the mouth.
By the action of sugar, as well as of various acids, Magitot⁹
succeeded in producing cavities in the dental tissues which were
very similar to those formed by decay. It is not difficult by the
{
132
THE MICRO-ORGANISMS OF THE HUMAN MOUTH.
action of almost any acid to produce cavities especially in enamel,
since by the decalcification the entire tissue of the enamel is de-
stroyed. Moreover, when the experiment is made in the air,
more or less discoloration appears. By such experiments, how-
ever, nothing more is proved than the universally recognized
fact that acids exert a decalcifying effect on dental tissue. The
identity of a destructive process in the tooth with decay itself
can be established by the microscope only.
G
But the untenableness of the purely chemical theory of decay
has been so strikingly and repeatedly demonstrated within the
last few years that it seems unnecessary to enter upon a closer
consideration of the subject here.
PARASITIC THEORY OF DENTAL DECAY.
52
It is not quite certain who was the first to accuse micro-organ-
isms of being concerned in the production of tooth-decay. The
credit of having originated this view is generally given to the
Dresden physician, Ficinus.53 Prof. Erdl, however, seems to have
been two years in advance of Ficinus. Erdl regards the "caries
materie" as parasites. This on its first appearance forms upon
the crown a delicate, colorless membrane composed of cells; later
these cells become more irregular and their nuclei more distinct.
But since Erdl employed muriatic acid to isolate his "caries
matter," it is quite probable that the delicate membrane which
he obtained was nothing else than Nasmyth's membrane. In
order to destroy these parasites and thereby hinder the progress
of the decay, Erdl recommends creasote and nitric acid. He
first applies creasote until the "caries matter" is impregnated
with it, then nitric acid, which immediately produces violent and
complete decomposition of the creasote, as well as of the parasites
saturated with it.
Ficinus 53 attributes decay to the action of his "denticolæ."
These proliferate in the enamel-cuticle, which they decompose;
they then attack the enamel, destroy the connection between the
enamel-prisms, and thus penetrate to the dentine, which they
cause to decay in the same manner.
Klencke 56 also describes a parasite, Protococcus dentalis, dis-
THE DECAY OF THE TEETH.
133
}
+
covered by him in the human mouth, which liquefies dentine
and enamel in pretty much the same manner as the fungus Meru-
lius lacrymans softens the wood of houses or furniture (?).
"We have, consequently, in this process, which I shall call
for sake of brevity destructio dentis vegetativa, a fungus which
softens and destroys dental substances and is nourished by their
chemical elements; this parasite is a true Protococcus dentalis."
Klencke assumed "four kinds of tooth-decay, viz: (1) cen-
tral decay, destructio sive dissolutio dentis centralis-s. inflam-
matoria; (2) peripheric vegetative decay (caries acuta), destructio
dentis vegetativa, caused by the tooth-fungus Protococcus den-
talis; (3) peripheric putrid decay, destructio s. colliquatio dentis
putrida―s. infusoria (caries acuta), caused by infusoria (dental
animalcula, denticolæ hominis); (4) disintegration of the tooth,
destructio dentis chemica (caries chronica)."
Leber and Rottenstein 58 deserve the credit of having placed
the parasitic theory of caries on a more solid basis. They re-
garded the commencement of caries as a purely chemical pro-
cess; but as soon as the dentine is superficially decalcified the
elements of the fungus Leptothrix buccalis penetrate the dentinal
tubules, enlarge them, and thereby facilitate the rapid penetration
of the acids. These authors discovered a reaction which for a
long time was thought to be characteristic of Leptothrix buccalis.
The elements of this fungus, treated with a slightly acidulated
solution of iodine in iodide of potassium, show a violet color.
Sections of carious dentine exhibit the same reaction. But, as
I have explained on page 71, Leptothrix buccalis, treated with
iodine, gives no, or at most a yellowish, color. The violet reac-
tion of the accumulations in the mouth, as well as of decayed
dentine, is occasioned by an entirely different organism.
The communication of Milles and Underwood presented be-
fore the Dental Section of the International Medical Congress
in London, 1881, served to revive the interest in the parasitic
theory of dental decay, which at that time appeared to be on the
wane. They noted the constant presence of micro-organisms in
decayed dentine, and the widening of the tubules produced by
them. They rejected the chemical theory of decay, and stated
their conviction that in the decay of the hard tooth-structures
134
THE MICRO-ORGANISMS OF THE HUMAN MOUTH.
"two factors have always been in operation: (1) the action of
acids, and (2) the action of germs." "This theory-which for
the sake of distinction may be called the septic-is rather an
amplification of the chemical theory than a contradiction of it.
Most probably the work of decalcification is entirely performed
by the action of acids, but these acids are, we think, secreted by
the germs themselves, and the organic fibrils upon which the
organisms feed and in which they multiply are the scene of the
manufacture of their characteristic acids, which in turn decalcify
the matrix and discolor the whole mass." It need not be said.
that the investigations of Milles and Underwood marked a great
step in advance of anything hitherto accomplished in this direc-
tion.
96
Ad. Weil writes, "Decay generally begins from without, and
must, therefore, first make its way through the enamel-cuticle.
I regard it as highly probable that this fungus (Lepto-
thrix buccalis) bores directly through it. The fungi now pro-
ceed farther into the enamel and force apart its prisms, gradually
breaking up its structure. From the enamel they penetrate into
the tubules of the dentine, which they often enlarge to three
times their natural size, at the same time extracting the lime-
salts."
ލ
97
Arkövy describes caries as "a breach of continuity of the hard
dental substance brought about by chemical action, in which the
invasion of nosogenous fungi play an essential part.”
98
Baštýr "As long as it cannot be shown that the appearances
observed in the decay of living teeth, decay of dead teeth in the
mouth, and artificial caries show any appreciable differences, so
long will every attempt to explain decay as a vital process be
very difficult."
Alfred Gysi: "As all my experiments and investigations on
this subject have presented facts which are consistent with this
theory (the chemico-parasitic), I accept it as a satisfactory explanȧ-
tion of dental caries."
Sudduth 100 says, "Dr. Miller's theory of the formation of cavi-
ties by the action of a digestive ferment upon the basis-substance
of dentine has been the only theory ever advanced that explains
the formation of cavities."
THE DECAY OF THE TEETH.
1
135
Peirce 101: "I am a firm believer in the fact that dental caries
cannot progress without these low forms of life."
Allan 102 The germ theory is the only one so far that clearly
and satisfactorily accounts for the acid." "The germ theory
fully explains the distended tubules and the broken-down basis-
substance."
:
Black 103 In this way the tubules become packed full of
organisms, and the surrounding dentine is always decalcified in
advance of the growth of the fungus by the lactic acid produced.
That this is the true explanation of the etiology of dental caries,
there is no longer a reasonable doubt."
ELECTRICAL THEORY OF DECAY.
A theory making decay of the teeth dependent upon galvanic
action was promulgated by Bridgman 10 in a prize essay before
the Odontological Society of Great Britain. The human mouth
is to be regarded as a galvanic battery; the individual teeth
represent the different elements, and the secretions of the mouth
a common electrolyte. Under normal conditions the crowns of
the teeth are electro-positive, the roots electro-negative. When,
however, the roots become exposed by recession of the gums,
the exposed portion must be electro-positive. In like manner
the pulp is electro-negative to the dentine and to the enamel of
the crown. To be consistent, Bridgman should have gone further
and pronounced the dentine negative to the enamel, the cement
negative to the dentine, and the enamel positive to the cement.
The electric current generated between the two parts produces
an electrolytic decomposition of the fluids of the mouth; the
acids (electro-negative) are given off on the surface of the crown
of the tooth (electro-positive) and cause decalcification. Further-
more, inasmuch as the "formation of the dentine is due to elec-
tro-voltaic action," so, too, the dentine may be directly pulled
down electrolytically and decomposed by the same force.
Bridgman's treatise won the prize offered by the Odontological
Society for the best essay on dental decay; it naturally excited
some notice at the time, but was not accepted with confidence.
We will not stop to consider the forty-five theses of Bridgman
136 THE MICRO-ORGANISMS OF THE HUMAN MOUTH.
separately; very few of them would bear a careful analysis, not
being based upon direct proof but upon certain principles or
beliefs which, in themselves doubtful enough, become still more
so when applied to the teeth. For example, he says, "The
condition and arrangement of the several layers (composing the
skin) are incontestably those of an electro-voltaic series," conse-
quently the pulp-vessels, together with the dentine and enamel,
also form an electro-voltaic series.
At present the electric theory is to be regarded rather as a
curiosity than as a theory of dental decay. Its promulgation had,
however, a secondary action which for a time was very strong,
and which is still felt to some extent at the present day; it may
consequently not be out of place to consider it at some length.
Prompted by Bridgman's exposition, experiments were under-
taken to determine the position of dentine in the electro-chemical
series. These experiments resulted in the establishment of the
following scale: Electro-negative-gold, amalgam, tin, gutta-
percha, dentine, oxychloride of zinc+electro-positive. From this
it follows that the highest electro-motive force, or the strongest
electrical action, is generated by a combination of gold and den-
tine; combination of amalgam and dentine yields a weaker
force; still weaker is that produced by a combination of gutta-
percha and dentine. On the strength of these and similar ex-
periments Chase 105 maintained that a tooth filled with gold would
necessarily soon become carious again on the margins of the cavity,
wherever the acid secretions of the mouth constantly bathe the
filling and the bordering tooth-substance. A tooth filled with
amalgam succumbs to this electro-chemical process less rapidly,
while one filled with tin still longer escapes destruction. The
comparative rapidity with which teeth filled with gold, amalgam,
and tin are destroyed is expressed by the numbers 100, 67, and
50. On the other hand, a tooth filled with oxychloride of zinc
becomes electró-negative by contact with this material, and is
therefore protected from the effects of acids (which are also
electro-negative).
Chase also succeeded in obtaining experimental evidence in
support of these calculations. He prepared pieces of ivory of
equal shape and size, bored a hole in each, and filled the holes
THE DECAY OF THE TEETH.
137
66
with different materials. After these pieces had been exposed
to the action of an acid for a week, he found that they had de-
creased in weight in the following gradation:
The piece filled with gold
66
66
66
66
66
66
66
66
،،
66
66
66
gutta-percha
oxychloride of zinc
From these results Chase concluded that gold is the worst of.
all filling-materials, and laid down his notorious proposition,
"Every tooth filled with a metal is a galvanic battery which
begins its work as soon as the surrounding liquid has an acid
reaction." Practitioners of repute actually discarded gold as a
filling-material on the strength of this unfounded statement.
It is necessary to grasp two fundamental facts in order to
understand the arguments upon which the electrical theory is
based.
1. When two heterogeneous metals (in general two chemically
dissimilar conductors) touch one another, a difference of potential
is produced between the two conductors, charging one of them
(electro-positive) with positive electricity, and the other (electro-
negative) with negative electricity in exactly equal amounts. In
this state, the former, the electro-positive, has an increased affinity
for electro-negative or acid bodies. The charge of electricity so
developed, as well as the increased chemical activity resulting
from it, is, however, very small.
66
"amalgam
tin
66
66
66
66
66
0.06
0.04
0.03
0.01
0.01.
0.00
wax
2. In any cell of a galvanic battery acid is set free at the
positive pole and alkali at the negative, and so long as the cur-
rent continues to flow, the positive pole (when not a noble
metal) continues to be acted upon by the acid so liberated.
Therefore, if we were to take a piece of zinc or a zinc model
of a tooth and make a gold filling in it or attach a piece of
gold to it, the zinc would be more rapidly attacked when im-
mersed in any electrolyte than when no other metal was in con-
tact with it, and for two reasons: (1) because the whole surface
of the zinc would become electro-positive by contact with gold,
and would therefore more rapidly decompose a solution and
138
THE MICRO-ORGANISMS OF THE HUMAN MOUTH.
take the acid constituents to itself. This action is inconsiderable
as compared with the following, (2) because the electric current
generated between the two metals would liberate acid over the
whole surface of the zinc, by which the action upon the zinc
would be still much more increased. We see, then, if teeth were
made of zinc, what disastrous results would follow their filling
with gold.
But can we, without further question, assume that the same
takes place even to a limited extent, or to any extent whatever,
when a natural tooth is filled with gold or any other metal?
In other words, do any two substances when brought into
contact assume a difference of potential, or can any two sub-
stances act as the generating plates of an electric element? An
article in the Correspondenz-Blatt für Zahnärzte, translated from
the Practitioner, contains the statement that a galvanic battery
may be constructed with almost any two different substances
whatever. It is only necessary that one of them be more readily
acted upon chemically than the other.
A stick of wood and a piece of mica are two substances which
fulfill the above condition, but we would try in vain to form an
electric element by use of them; we would equally fail with
sealing-wax and glass, or with gold and glass, even though both
substances might be entirely consumed in the attempt. But
what condition necessary to the production of an electric current
is wanting in the above cases?
Conductivity. When two chemically dissimilar substances
are made to touch one another, they do not assume a difference
of potential or become charged with electricity if one (or both)
of them is a non-conductor, and no electric current can be pro-
duced by the use of any two chemically dissimilar substances if
one (or both) of them is a non-conductor. Tooth-bone is a non-
conductor, and consequently cannot become electro-positive, or
be changed in potential by contact with gold, and cannot act as
the pole of a cell when immersed in an acid or salt solution.
I say that tooth-bone is a non-conductor, though the fluids
with which the tooth is permeated are conductors.
It is necessary that the difference be thoroughly understood. A
silk thread, for instance, is a perfect non-conductor, but by dipping
THE DECAY OF THE TEETH.
139
1
a silk thread in a salt solution, or in any liquid which conducts,
we obtain a conductor. Now, it is not the particles of the thread
which transmit the current, but the particles of the liquid; and
if we were to bring a piece of metal in contact with this moistened
thread, the potential of the particles of silk would not be changed.
This is what we have in the living human tooth,-a non-con-
ductor permeated by a conductor. If we were able to construct
a tooth of glass and fill the pulp-cavity, the canals, and tubules
of that tooth with a 0.75 per cent. solution of table-salt (which
has about the same specific resistance as the tissues of the body),
then we would have an electrical instrument similar to a living
human tooth. Such an instrument would transmit a current of
electricity; in other words, it would be a conductor just as the
wet silk thread is, but the substance of the tooth-the glass-
could not receive any potential, even by contact with gold or
any other metal.
It has just been stated that dry dentine, as well as enamel, is
a non-conductor. Although the fact that the constituents of
which dentine is composed are themselves non-conductors justi-
fies this conclusion, it nevertheless appeared desirable to test the
question by direct experiment. This test was made in the follow-
ing manner:
A cross-section of dentine millimeter thick was inclosed in
a circuit of three Siemen's cells. The galvanometer used had a
multiplicator with 16,000 turns of wire and a resistance of 5000
Siemen's units. When the circuit was closed, not the slightest
deflection of the needle could be observed.
The section of dentine was placed between
the ends of two wires which had a diameter
*of 1.9 millimeter under a pressure of about
two grams to the square millimeter.
This experiment was then varied by inclos-
ing three sections in a circuit in a manner
illustrated in Fig. 55, so that the surface of
contact was three times as great and the resist-
ance consequently only one-third of that in the above experi-
The deflection remained, however, zero; in other words,
the resistance was infinitely great.
ment.
a
Deta
¿
C
FIG. 55.
B

تم
↑
A
140
THE MICRO-ORGANISMS OF THE HUMAN MOUTH.
¿
If, as we have stated, the conductivity of the living tooth for
electric currents depends entirely upon the liquids contained in
its pores, then dentine, which is more porous than enamel, should
show a less resistance than the latter; furthermore, a section of
dentine which cuts the canaliculi at right angles or nearly so
would have less resistance than one parallel with them, and
finally the resistance would increase with that of the liquid with
which the section is moistened.
In order to determine whether the resistances of dentine and
enamel, of cross-sections and longitudinal sections, in reality bear
the relations to each other demanded by the above condition, the
following tests were made:
The section whose resistance was to be determined was held
between the ends of two amalgamated zinc wires, which had a
diameter of 1.9 millimeter, under a constant pressure of about
two grams to the square millimeter. The
section of dentine, of a millimeter thick,
was moistened with a concentrated solution
of sulphate of zinc.
FIG. 56.
B
↑

0
Rh
III
The arrangement of the apparatus for de-
termining the resistance may be seen in the
accompanying figure (Fig. 56).
F
Here E denotes two Siemen's elements;
B, a mirror galvanometer after Wiedemann,
with 16,000 turns of wire and a resistance of
5000 Siemen's units, having an aperiodized
magnet ring after E. du Bois-Reymond; Rh, the rheostat; Wx,
the resistance to be determined; O, I, II, III, IV, denote the
connections with a round compensator after E. du Bois-Reymond
with the modifications of Christiani.
I
Wx
II
As result of the large number of experiments, I found that a
section of dentine millimeter thick, cutting the canali-
culi at right angles, had a resistance of about 1700 Siemen's
units; that a similar section, parallel or nearly so with the canali-
culi, had a resistance at the beginning of about 8050 Siemen's
units. As the piece began to dry, the resistance rapidly increased,
till it soon became infinitely great.
When the same sections were moistened with water, the re-
K
Badg
THE DECAY OF THE TEETH.
141
sistance was much greater; it could not, however, be definitely
determined on account of the polarization.
It may be easily shown by the following simple experiment
that the resistance of the enamel is much greater than that of the
dentine. Place one pole of a battery consisting of four Siemen's
cells upon the gums and the other upon the enamel of a sound
tooth, not the slightest sensation will be produced; if, however,
we place the second end upon the dentine or upon a metallic
filling in contact with the dentine, we will at once experience a
very unpleasant sensation.
There can be no doubt that there are electric currents in the
mouth whenever there are teeth with metallic fillings. These
currents do not, however, exist in such a manner between the
filling and the tooth-substance that the latter could in any way be
compared with the generating plate of a galvanic cell; they owe
their existence alone to the heterogeneity of the metallic fillings.
Electric currents will be produced on the surface of every
filling, even of a pure gold one, when the filling does not have
the same density in all parts. They flow from the denser to the
less dense points of the surface. If these currents were even
strong enough and durable enough to be considered as anything
more than infinitesimal, they still could have no injurious effect
upon the tooth deserving of mention, since it could rarely happen
that a great excess of them would be directed toward the margin
of the filling.
When two fillings of different materials, in the same tooth or
in approximating teeth touch each other, a current is produced,
which flows from the more oxidizable (electro-positive) metal
through the liquids of the mouth and tooth to the less oxidizable
electro-negative). These currents, by electrolytically decom-
posing the liquids of the mouth, may produce injurious effects
upon the teeth. Through them acid will be set free on the sur-
face of the electro-positive metal, which may attack the tooth at
the margin of the filling. This action, however, is very slight
at best, and appears to cease altogether as soon as the surface of
the positive pole becomes oxidized; in short, we have not found
in practice that such a process has any injurious effect upon the
teeth.
C
142
THE MICRO-ORGANISMS OF THE HUMAN MOUTH..
די
When gold plates with clamps of baser metal are put into the
mouth, a weak electric current is produced through which acid
may be liberated upon the clamp. This, in course of time, may
have a marked injurious effect upon the tooth with which it
comes in contact. This action may be demonstrated by the
following experiment: I attached a bicuspid by means of a plat-
inum wire, twisted around the neck of the same, to the positive
pole of a Siemen's battery of three cells, and a second bicuspid
in the same manner to the negative pole. The teeth were then
placed one in each arm of a U-shaped tube which was filled with
a 0.75 per cent. solution of chloride of sodium. The circuit con-
tained, for observing the current, a galvanometer possessing a
multiplicator of 1000 turns and a resistance of 200 Siemen's
units. On closing the circuit there followed a deflection of the
needle amounting to thirty-one degrees; after two weeks, the
deflection had decreased to eight degrees. On removing the
teeth from the solution it was found that the wire, by virtue of
the acid liberated upon its surface, had cut a groove about mm.
deep around the neck of the anode tooth. At the kathode tooth
no change was observed.
Electric currents may therefore occur in the mouth (1) when
a metallic filling has not the same density throughout; (2) when
two fillings of different metals touch; (3) when a plate is com-
posed of different alloys.
Dentine being, as shown by these experiments, an absolute
non-conductor of electricity, all these electric currents between
different parts of the teeth or between filling and tooth-substance
can have only an imaginary existence, and the results obtained
by Chase in the experiments referred to above must be erro-
neous. That they are utterly so may be easily determined by a
few carefully made experiments of the same nature.
I have made in all over twenty such experiments, with dif-
ferent substances and under varying conditions.106 The results
of ten of these experiments are given below, and each one may
draw his own conclusions from them. These ten were not
selected from the whole number, but each alternate one was
taken in the order in which they were made. The first series of
experiments I made with ivory, the second with dentine taken
THE DECAY OF THE TEETH.
143
from a fish tooth, the third with dentine from human teeth. The
pieces of human dentine were made in pairs, both members of
each pair being obtained from the same tooth by making a cross-
section of a sound, large molar, removing all traces of pulp-
cavity and of the enamel, and then dividing the section symmet-
rically into halves. In this way the two pieces of each pair were
as nearly alike as they could well be made.
In some of the experiments the pieces were filled with differ-
ent materials; in others they were suspended to equal depth in
the solution by means of wires of different metals and of silk
thread, the latter method being equivalent to making fillings of
the same materials, the silk thread corresponding to a filling of
wax; the wires were all of the same diameter. In the sixth
column of figures I have given the results which would have
obtained in accordance with the experiment of Chase, on the
theory that if gold causes a certain loss in weight, amalgam
will cause two-thirds the same; tin, one-half; gutta-percha, one-
sixth; wax, one-sixth, while the piece filled with zinc-oxychlo-
ride suffers no loss in weight. The balance used was capable of
noting a variation of two-tenths of a milligram.
SUBSTANCE.
1. Ivory
2.
44
1. Ivory
2.
3.
4.
5.
66
66
44
1. Dentine from
fish tooth
2 Dentine from
fish tooth
1. Dentine from
human tooth
2. Dentine from
human tooth
WEIGHT
IN MGS.
115.6
44
204.0
44
44
46
•
912.0
+6
39.3
""
SOLUTION.
Sulphuric
acid, 1 per
cent.
Sulphuric
acid, 1 per
cent.
Vinegar
"
"
44
46
66
I.
Acetic acid,
20 per cent.
Acetic acid,
20 per cent.
TIME.
Six weeks Gold wire
66
**
III.
Two weeks Gold wire
CA
SUSPENDED BY
66
Silk thread
V.
Lemon-juice | Eight days Gold wire
Silk thread
"C
Platinum wire
Copper
•
Tin
Silk thread
VII.
Ten days Gold wire
Silk thread
LOSS IN
WEIGHT.
30.6
31.1
76.0
76.4
76.5
75.0
76.8
248.0
244.0
5.0
4.6
COMPARI-
SON.
30.6
5.1
76.0
38.0
12.7

248.0
41.3

5.0
0.8
144
THE MICRO-ORrganisms of THE HUMAN MOUTH.
pelgalt media gef
SUBSTANCE.
1. Ivory
2.
2.
1. Ivory
3.
4.
**
3.
4.
ang tangga teme ve a g
44
44
1. Ivory
2.
46
C
+4
SALE e alle de gagn
1. Dentine from
human tooth
2. Dentine from
human tooth
1. Dentine from
human tooth
2. Dentine from
human tooth
1. A sound bi-
cuspid
2. A sound bi-
cuspid
WEIGHT
IN MGS.
201.5
46
Chak Makað takapor vet ar
pada ka ng mag party pages we make
201.5
66
66
..
195.5
+6
66
44
88.4
46
70.9
885.0
875 0
SOLUTION.
TIME.
Hydrochloric One week Gold wire
acid,
1/2
per cent.
Hydrochloric
acid, 2
per cent.
Sulphuric
acid, 2
per cent.
Sulphuric
acid, 2
per cent.
Sulphuric
acid, 2
per cent.
Sulphuric
acid, 2
per cent.
46
Acetic acid,
20 per ct.
Acetic acid,
20 per ct.
IX.
46
4.
Acetic acid,
dilute
Acetic acid,
dilute
XI.
One week
XIII.
Lemon-juice One week
44
66
44
66
16
46
XVII.
Lemon-juice Six days
66
64
SUSPENDED BY
Silk thread
66
Gold
Amalgam
Tin
XV.
Two weeks Gold
Gold
Amalgam
Tin
Zinc-oxychloride 6.5
Gold
LOSS IN COMPARI-
WEIGHT. SON.
53.3
53.3
Zinc-oxychloride
XIX.
Three w'ks Gold
54.0
7.5
69.0
Zinc-oxychloride 70.4
Zinc-oxychloride
7.3
6.3
13.5
Zinc-oxychloride 14.9
68.0
68.5
49.6
48.6
79.0
82.0
p
8.9

7.5
5.0
3.7
0.0

6.80
45.3
34.0
0.0

13.5
0.0

49.6
0.0

79.0
0.0
DIVERSE CAUSES OF CARIES.
Mechanical injuries, particularly such as are caused by sharp
or rough particles of food (splinters of bone), sharp tooth-powders,
sudden changes of temperature, climatic influences, humidity
of the air, use of tobacco, medicines, mineral waters, mercury,
mental exertion, the quality of the food, erosions, "salty,
acid, pointed or rough particles which irritate the very delicate
membranes of the alveoli or the nerve-filaments," etc., are men-
tioned by many as the cause of toothache.
1
THE DECAY OF THE TEETH.
145
Some also accuse sugar or strongly sugared beverages. Ovel-
grün 72 (1771), Pfaff 86 (1756), directed attention to the bad teeth
of confectioners, while Peter Forest72 (1597) pointed out the
occurrence of a similar malady in the case of apothecaries, "who
ruin their teeth with licking the juices."
Westcott holds that sugar is injurious only on account of its
fermentation products, viz, lactic and butyric acids. At present,
sugar is universally regarded by dentists as well as laymen as
injurious to the teeth. Many investigators, as Fauchard (1728),
Angermann (1806), Guttmann (1827), Desirabode 72 (1846), etc.,
distinguish external and internal or local and general causes.
Fauchard also mentions different forms of decay, such as scrofu-
lous, scorbutic, moist, dry, superficial, deep, etc.
As external causes, were mentioned mechanical, chemical, etc.;
as internal, bad juices, deformities, constitutional diseases, etc.
10
P
CHAPTER VII.
ORIGINAL INVESTIGATIONS ON THE DECAY OF THE TEETH.
INTRODUCTORY REMARKS ON THE HISTOLOGY AND CHEMISTRY OF
THE TEETH.
THE peculiar structure of the hard dental tissues, especially of
the dentine, not only determines to a great extent the manner in
which the change designated as decay advances in the tissues,
but also accounts for the microscopic appearances characteristic
of this disease, and also greatly influences the spreading of caries
in the tissues. I shall, therefore, as briefly as possible, call atten-
tion to those structural properties of enamel and dentine, which
are of special significance.
Furthermore, an intimate knowledge of the chemical compo-
sition of the hard dental tissues is requisite to an understanding
of the process of decay.
Dentine forms the chief constituent or fundament of the
human tooth, and retains approximately the original form of the
tooth after the removal of the enamel and cement. For our
purpose, dentine may be defined as a dense, glue-giving basis-
substance, impregnated with lime-salts and traversed by sheathed
tubules radiating from the pulp-chamber. These, the dentinal
tubules, have a diameter of 1.3-2.5μ; their average diameter is
consequently greater than that of bacteria, with the exception
of Crenothrix, Beggiatoa, and a few other species as yet not met
with in the human mouth. They are straight or slightly undu-
lating, and radiate from the pulp-chamber to the surface of the
dentine. They are not empty, but contain living matter, and,
by means of their many ramifications and anastomoses, form a
delicate net-work, particularly on the border of the enamel. The
146
Govt
HISTOLOGY AND CHEMISTRY OF THE TEETH.
147
quantity of organic substance near the enamel and cement may be
increased by numerous small interglobular spaces (stratum granu-
losum) filled with protoplasm. Larger interglobular spaces are
also often found in dentine, especially in teeth of poor structure.
The sheaths of the tubules are remarkable for their great
power of resistance to acids and to putrefying agents. Accord-
ing to Hoppe-Seyler," the tubules of many fossil teeth may be
sufficiently isolated as to permit of examination under the micro-
scope. The isolation is performed by extracting the lime-salts,
washing carefully with water to remove the salt and acids, then
boiling for a certain length of time in water.
The enamel covers the crown of the tooth somewhat like a
thimble. At the margin, that is, at the neck of the tooth, it is
very thin, thicker toward the grinding-surface, and thickest on
the cusps of the molars, where it sometimes has a thickness of
2.5 mm.
It is the hardest tissue of the human and animal body. Ac-
cording to Hoppe-Seyler, only the siliceous urinary calculi which
occur in ruminants, and, perhaps, the siliceous sheaths of bacil-
laria, exceed it in hardness.
print
In the fissures of molars and bicuspids, as well as in the fora-
mina cœca of molars and superior lateral incisors, the formation
of the enamel-cap is very imperfect. These localities conse-
quently form loci minoris resistentiæ which but feebly resist
the attack of caries. Indeed, they rather induce it by the reten-
tion of food-particles. The fissures, cracks, etc., of old enamel
act in the same way, although in a minor degree.
Morphologically, enamel consists of four- to six-sided straight
or undulating, usually parallel prisms, which are separated by
an extremely thin layer of intervening substance (binding sub-
stance). The spaces between the prismis are, however, under
normal conditions, by far too narrow to permit the entrance of
micro-organisms.
The enamel-cuticle (Nasmyth's membrane) forms a thin, trans-
parent, glueless layer on the crown of every tooth, in so far as
the latter is not worn down by mastication. It resembles the
sheaths of the dentinal tubules in the high power of resistance
which it shows to the action of acids and putrefactive agents.
148
THE MICRO-ORGANISMS OF THE HUMAN MOUTH.
The structure of cement is similar to that of bone, from which
it differs, however, particularly in the absence of Haversian
canals, which, if present in the cement, would naturally render
it far more susceptible to the action of external agents than it in
reality is.
The relation of Sharpey's fibers to the progress of decay in
the cement is very significant; they may accordingly claim espe-
cial mention. Without concerning ourselves about the genesis
of these so-called penetrating fibers, or fibers of Sharpey, it
may suffice to say that they indicate the presence of tubules or
canals running perpendicular to the longitudinal axis of the tooth,
present in all parts of the cement, but particularly numerous at
the neck of the tooth. In case of decay, the micro-organisms are
seen to penetrate these canals very much as they enter the den-
tinal tubules. They thereby facilitate the invasion of bacteria
into the interior of the cement, often making the course of
cement-decay very similar to that of dentine-decay.
CHEMICAL COMPOSITION OF THE HARD DENTAL SUBSTANCE.
Numerous analyses of the hard tooth-substance have been made
by different chemists. Some of the older ones, however, are un-
reliable, and the results obtained are at variance with each other.
cent.
Dentine contains a quantity of organic substance which is
subject to slight variations in different teeth; in very hard den-
tine it amounts to about 26 per cent., in very soft to 28.5 per
These variations, however, stand in no direct proportion
to the hardness of the dentine; that is to say, we find much
greater differences in the density of the dentine of different
teeth than we do in the percentage of lime-salts which they con-
tain. They probably do not relate to the normally formed
intertubular substance, but depend upon the composition of the
entire mass of dentine, including the tubules, interglobular
spaces, etc. For example, a tooth with wide tubules and large
interglobular spaces would, on analysis, give a higher percentage
of organic matter than a tooth with narrow tubules and smaller
interglobular spaces, even though the intertubular substance
should have exactly the same composition in both cases.
In like manner, differences in the proportion of organic matter
HISTOLOGY AND CHEMISTRY OF THE TEETH.
149
in the compact and spongy parts of one and the same bone are
not to be attributed to the bony matter itself, but to the whole
bone, including the contents of the lacunæ, Haversian canals,
etc. (Hoppe-Seyler).
f
;
In the compact matter of the femur of women aged ninety-
seven, eighty-eight, eighty-one, eighty, and twenty-two years re-
spectively, Fremy found the same quantity of organic substance
as in the case of a new-born female child.
In conformity with these and other similar results, Hoppe-
Seyler maintains the unchangeableness of the combinations
occurring in bone, dentine, etc. If Hoppe-Seyler's conception is
correct, the small increase of inorganic matter supposed to occur
in senile teeth is not to be explained by an increased amount of
lime-salts in the dentine, but must be attributed to a decrease in
the volume of the soft tissues of the dentine,-in other words,
by a formation of basis-substance at the expense of the tubular
substance. We shall recur to this question in our remarks upon
the transparency of dentine.
The organic constituent of dentine yields glutine when boiled
with water, and readily undergoes putrefaction.
The enamel contains but two to five per cent. of organic sub-
stance, and usually falls completely to pieces during decalcifica-
tion, unless special precautions are taken. This remnant of the
enamel-forming organ is of epithelial origin, and consequently
yields no glutine when boiled in water.
According to Hoppe-Seyler, bone, dentine, and enamel all
contain (PO),CaCO3, or 3[(PO4)2 Ca] CaCO3,-that is, saturated
calcium phosphate carbonate in a combination which corresponds
to apatite (PO4) Ca₁0Fl2.
6 10
The following analyses of the ashes of bone, dentine, and
enamel gave values which conform with this view:
Bone.*
Dentine.†
Ca
PO
37.99
54.91
CO
4.98
Fl
1.29(?)
Mg 0.83
According to Wildt.
4
3
Ca 37.54
56.05
4.79
PO₁
Cog
Enamel.†
Ca 38.31
56.20
5.60
0.47
PO
CO3
Cl
Mg 0.38
† Average of several analyses.
According to Hoppe-Seyler.
150
THE MICRO-ORGANISMS OF THE HUMAN MOUTH.
Notwithstanding the very considerable difficulties attending
the analysis, we notice a marked conformity between the values
found and those calculated from the atomic complex (PO4)6
CaCO3, since the latter demands Ca 38.83 per cent., PO, 55.34
per cent., CO, 5.83 per cent.
The question whether this combination has been brought to-
gether by the glue-giving substance (glutine) had to be answered
in the negative, as it also occurs in enamel which contains no
glutine.
Another question which has been broached by Hoppe-Seyler now
engages our attention: What is the relation of these salts to the
glue-giving basis-substance? Are they precipitated in the carti-
lage according to physical laws, or are they held together by means
of the organic substance, and do they enter into a chemical union
with it? This is a matter of importance for the understanding
of certain pathological phenomena exhibited by the teeth. As
emphasized above, the variations in the amount of salts in the
dentine are by no means great enough to explain the variations
in hardness. But in the case of a chemical union between the
organic and inorganic constituents of the tooth, we should expect
to find dentine hard or soft according as the union is firm or
unstable.
Unfortunately, our knowledge of the nature of the combina-
tions occurring in teeth is as yet very incomplete, nor does it at
present appear how we may approach this problem experiment-
ally. "No affinities are known which might make a chemical
union conceivable, nor do we know any physical conditions
which could explain the impregnation of the organic substance
with this calcium phosphate carbonate."
The density of the dentine cartilage is about 0.55, consequently
about equal to that of bone; this, by the way, shows that the
substance of the odontoblasts, as well as that of the osteoblasts,
must undergo a very great condensation during or before calcifi-
cation.
G
The density of the organic substance of enamel, on the other
hand, is only about 0.075. Regarded from this point, the forma-
tion of enamel is a process which essentially differs from the
formation of dentine and bone.
:
PHYSICAL PHENOMENA OF DENTAL DECAY.
151
裔
​PHYSICAL PHENOMENA OF DENTAL DECAY.
a. DECAY OF ENAMEL.
In making a study of the phenomena of dental decay which is
intended to be anywise complete, it will be necessary to subject
the physical, chemical, and microscopical changes of the tissues
involved to a rigid examination.
Let us begin with the physical phenomena of dental decay, in so
far as they are revealed by inspection with the unaided eye or by
examination with such simple instruments as excavators, probes,
etc. A clear insight into the macroscopical changes which occur
at the beginning of enamel-caries can be gained most easily from
a freshly extracted molar or bicuspid, decayed on the approximal
surface. Cases of fissure-decay are not serviceable for this pur-
pose, because the appearance of the decaying enamel is here
generally obscured by other processes occurring simultaneously
(precipitates, discolorations, etc.).
Suitable material is not always easily obtained, because teeth
showing the very first stages of decay are seldom extracted, and
because caries on the approximal surfaces of unextracted teeth
becomes apparent only after it has made considerable progress.
The opportunity of observing decay at its beginning is therefore
very rare.
As the first indication that the process of destruction has begun
on the external surface of the enamel, we notice that it has lost
its normal polish and transparency; then a white (not black) ir-
regular spot of chalky color appears; a sharp instrument (e.g.,
the point of a needle) will not easily glide over the surface, but
will readily detect the presence of a slight roughness caused by
a softening or disintegration of the enamel, by which it is
gradually changed into a soft cheesy powder. This dissolu-
tion of the enamel may be best observed when decay advances
from the dentine upon the inner surface of the enamel (secondary
decay); here the broken-down enamel-prisms cannot be washed
away, so that quite a thick layer of a perfectly white cheesy sub-
stance may often be found.
In primary decay the disorganized enamel-prisms are soon
mechanically washed away, whereby an excavation or cavity is
152
THE MICRO-ORGANISMS OF THE HUMAN MOUTH.
formed. The form of the cavity depends upon various circum-
stances, among others upon the breadth of the surface of contact
with the adjacent tooth, also in a high degree upon the structure
of the enamel; it is sometimes flat and broad with scarcely dis-
tinguishable margins, sometimes narrow and deep with sharp
ragged margins. Soon after the commencement of decay, a more
or less pronounced discoloration sets in. In my opinion the
view held by some that this discoloration is to be regarded as the
first sign of decay is based on an error which is to be explained
only on the supposition that the advocates of this view have not
examined decay in its earliest stages.
A discoloration of intact smooth enamel does not occur;
some change or other must have taken place in the enamel before
a discoloration can take place, and this change is nothing else
than a softening or decalcification of it.
This discoloration appears in very different grades; when the
decay proceeds very rapidly (caries acutissima), it is slight or
wholly wanting (white decay). In other cases, only the margin
of the enamel is colored brown to black while the center of the
cavity remains white. When the decay proceeds very slowly,
that is, when it is of long standing (caries chronica), the greater
part of the affected tissue is deep brown or black. This is also
the case where the progress of the decay has been interrupted,
as is often observed on the approximal surfaces of teeth which
have been exposed by extraction of the adjacent tooth. Such
cases are usually designated as caries nigra (black decay). This
badly-chosen term must, however, not mislead us to suppose that
we have to do here with an especial form of decay. As a matter
of fact, we are scarcely entitled to speak of such places as decay
at all, any more than we are to say that a man with a pock-
marked face has got the smallpox, because they do not indicate
that the process of decay is going on at the time being. They
are simply degenerated tissue which in the course of time has
become discolored by oxidation, precipitation, or other processes
of this nature. Decay-marks would be a much better name for
such spots.
S
PHYSICAL PHENOMENA OF DENTAL DECAY.
153
b. DECAY OF DENTINE.
By the progress of the above-described process the destruction
of the enamel spreads until the surface of the dentine is reached
(Fig. 57). Here the disease takes on a very different form, inas-
much as we no longer find
the tissue being changed into
a soft cheesy mass, but into a
tough cartilaginous substance
which does not readily fall to
pieces or yield to the slightest
friction, as does the decayed
enamel, but may retain its
form for some time. This
stage is designated as soften-
ing of dentine, and is condi-
tioned, as will be seen below,
by a more or less complete
decalcification of the dentine.
The softening spreads in all
directions in the dentine, with
a rapidity dependent upon the
intensity of the fermenta-
tion processes present in the
mouth and the physical and
chemical constitution of the
dentine.
SA
FIG. 57.

a
UNDERMINING ENAMEL DECAY.
The softened mass may
be
easily cut or peeled off with
a sharp instrument; upon a, Masses of bacteria lining the cavity. Circa 50 : 1.
pressure, it discharges a small
quantity of a liquid which in the great majority of cases will be
found to redden blue litmus-paper, i.e., to have an acid reaction.
The thickness of the softened layer varies considerably in
different cases, for reasons which will be fully discussed in
Chapter VIII. Very soon after the softening of the dentine its
disintegration or dissolution begins, leading to the formation of
a cavity in the dentine. The surface now appears uneven, soft,
151
THE MICRO ORGANISMS OF THE HUMAN MOUTH.
and porous, infiltratel and contaminated with particles of fer-
menting food, masses of bacteria, etc.
The discoloration of the dentine is brought about by the same
causes as that of the enamel; it also shows the same variations in
acute and chronic decay, and all shades, from the natural color of
dentine to black.
As the destructive process spreads more rapidly in dentine than
in enamel, the latter becomes usually more or less undermined,
and the cavity may acquire a shape resembling a short-necked
Florence flask (Fig. 58). The undermined
enamel-margins become dry and brittle, and
easily break off; it therefore not unfrequently
happens, particularly in case of extensive
decay on the approximal surface, that the
cover of enamel breaks under the pressure
exerted by mastication and reveals a large
previously invisible cavity. Or, decay pro-
ceeding from the grinding-surface of molars
destroys the greater part of the dentine, so that only a perforated
enamel-cap remains; this finally breaks into pieces at the neck
of the tooth, thereby completing the de-
struction of the crown. In rare cases,
caries beginning on the grinding-surface
seems to proceed particularly rapidly at
the border between enamel and dentine.
The bond of union between the two tis-
sues is weakened or destroyed, the enamel-
walls break away, while a large portion of
the decalcified dentine remains (Fig. 59).
In other cases, again, the destructive
process advances most rapidly along the
line of the dentinal tubules toward the
pulp. By this means a tube-shaped cavity
is formed, as is often observed on the
grinding-surface. These cases are usually
designated as penetrating decay. But
these terms, penetrating and undermining decay, must not mis-
lead us, for there is no specific form of decay which shows a
/
FIG. 58.
UNDERMINING DECAY.
Flask-shaped cavity.
HIN
AXIS ERMAL
sese.
FIG. 59.
DECAY OF A MILK-MOLar.
The enamel-walls are broken
off, while the dentine re-
mains standing.
4

PHYSICAL PHENOMENA OF DENTAL DECAY.
155.
particular tendency to penetrate toward the pulp, nor is there
one which especially avoids the pulp to spread laterally under
the enamel. The causes and the entire process are identical;
in both cases it depends only on the structure of the tooth,
whether the decay presents itself as penetrating or undermining.
In poorly developed teeth, with many interglobular spaces,
the destruction spreads rapidly on all sides under the enamel,
following the course of the interglobular zone, whereas when
the teeth are dense and completely dentinified the decay extends
more rapidly in the direction of the dentinal tubules. It is barely
possible that an infection with small cocci might cause the decay
to spread laterally more rapidly than an infection with large cocci
or bacilli, since the former could advance laterally through the
fine branches of the tubules, whereas the latter would be obliged
to keep more to the main track.
When the softened dentine is strongly saturated with liquids,
as is the case in caries acuta, it has been designated as caries
humida. The chronic form of dentine decay, in which the den-
tine is dry and brittle, is sometimes termed caries sicca.
C. DECAY OF THE CEMENT.
Decay of the cement frequently occurs at the neck of the
tooth. The layer of cement is, however, so thin here that the
characteristic phenomena of cement-caries scarcely become ap-
parent. Caries of the cement of the root occurs only when the
latter is exposed, and is therefore comparatively rare.
The roots of molars which are laid bare by the recession of the
gums and destruction of the periosteum show the greatest pref-
erence for decay.
Such roots are often covered with thick white or yellowish-
white deposits, consisting of food particles, dead epithelium,
mucus, and fungus masses, and not unfrequently present cases of
typical decay of the cement.
The first symptom of cement-decay is an abnormal roughness
or softness of the cement surface, which may be easily penetrated
or scraped off with an excavator.
This phenomenon, which is also nothing but the softening of
the cement, is followed by a loss of the surface-substance; thus
1
156
THE MICRO-ORGANISMS OF THE HUMAN MOUTH.
a cavity is produced, or rather a depression, since it has little
similarity with the cavities of the crown. Deep bulb-shaped
cavities are hardly ever formed; they are for the most part shal-
low, widely extended excavations, without a distinct margin.
This is due to the fact that there are no circumscribed points.
of retention or foci of decay on the roots, from which alone the
destruction could proceed. It therefore seldom happens that
decay beginning at the root spreads from the cement to the den-
tine and destroys the latter to such an extent that the root-pulp
is exposed.
I
A natural retention-center is formed at the point of bifurcation of
the molar roots where it has been exposed by recession of the gums,
and penetrating decay is consequently not seldom found here.
Discoloration has been erroneously regarded as the first stage
of cement-decay also. Exposed roots almost invariably become
more or less discolored in time, whether they are decayed or not,
especially when they are not kept clean.
d. DECAY OF THE ENAMEL-CUTICLE.
It is impossible to follow the process of decay in the delicate
membrane covering the crown of the tooth without the aid of
the microscope. All we can see with the naked eye is a more
or less pronounced discoloration surrounding the carious part of
the membrane which has been detached by strong acids. Fre-
quently a thickening and cloudiness are also detectable.
In pulpless and dead human teeth, even in artificial teeth
carved from walrus-teeth, decay exhibits the same physical phe-
nomena as in living teeth.
ACCOMPANYING PHENOMENA OF DENTAL DECAY.
As concomitant phenomena of dental decay I designate cer-
tain processes which manifest themselves either immediately or
some time after the appearance of decay, and which, in my opin-
ion, have been erroneously denominated as characteristics of it.
Those processes are: (1) transparency, (2) the pigmentation or
discoloration of the decayed tissue.
"Coincident with the development of the opacity and the
pigmental degeneration in the commencement of the carious
affection of the dentine, an increased translucency is observed,
ACCOMPANYING PHENOMENA of DENTAL DECAY.
157
frequently, in the portions adjacent to the boundary of the cari-
ous portion. With reflected light these portions have a horny
appearance, similar to that found in senile roots, and with trans-
mitted light they present hyaline bands and spots. The focus
vánkomatnly waterin
FIG. 60.
C.

PORTION OF A LONGITUDINAL GROUND SECTION THROUGH THE CROWN OF A MOLAR,
Showing two cavities of decay, with the transparent zones at c. (After Gysi.)
(Herd) of the caries is surrounded by a diaphanous halo. The
opaque, carious dentinal cone, therefore, is invested by a trans-
lucent zone, extending from the periphery toward the center;
around a more spherical, carious portion of the dentine a cres-
centic diaphanous halo is sometimes met with (Fig. 60). The
158
THE MICRO-ORGANISMS OF THE HUMAN MOUTH.
light portions, finally, vary exceedingly in respect of their
outlines, according to the form in which the carious limits are
extended, being radiated, kidney-shaped, etc." (Wedl.)
A true picture of transparency can be obtained only where
softening and pigmentation of the dentine have not yet taken
place; that is to say, where there is as yet no decay. The trans-
parent portion here forms a cone whose apex points toward the
·
むか
​RAN
FIG. 61.

a
a
BEGINNING DECAY OF ENAMEL WITH TRANSPARENT CONE OF DENTINE.
Under weak power.
pulp and whose sides run parallel with the dentinal tubules. In
as far as
most cases the transverse sections of these cones are,
my observations go, bounded by two opaque stripes (Fig. 61, a).
Under the microscope, the dentinal tubules within these stripes
are seen to be filled with irregular, angular granules or oblong
particles.
I have not been able to discover analogous phenomena in
ACCOMPANYING PHENOMENA OF DENTAL DECAY.
159
dead dentine. Through the kindness of the late Dr. Franz, I
obtained no fewer than three hundred human teeth which had
been worn in the mouth on plates. Nearly all of them showed
different degrees of decay. I split about sixty which seemed
specially suited for the purpose. One case only revealed a phe-
nomenon resembling transparency, but even in this one case it
was not possible to say that the change was not brought about
while the tooth was still living. Again, the appearance in ques-
tion is by no means peculiar to decay. We have seen that it
does not accompany decay of dead teeth, whereas it is very com-
mon in sound teeth which have been worn off, also in teeth
whose approximal surfaces have been slightly worn away by
friction. It is found particularly in senile teeth, whose entire
roots frequently become transparent, likewise in roots in the pro-
cess of resorption, etc.; everywhere, in short, where the living
dentinal fibers are slightly irritated. I have noticed a high degree
of transparency in the teeth of old dogs which have been ex-
tensively worn away. It does not show the remotest similarity
to decay, and, in fact, bears no direct relation to it, inasmuch as
it is absent in dead teeth, and very frequently occurs in a marked
degree and in typical forms in places where there is not a trace of
decay, and where decay, on the whole, very seldom occurs. The
same agents which produce decay may also occasion transparency
of dentine, which explains the frequent simultaneous appearance
of both phenomena.
•
The opacity of normal dentine is produced by the different
coefficients of refraction of its component parts. If two sub-
stances, whether transparent or not, of different refractive power
be mixed, an opaque substance will result, unless the one is
soluble in the other. Thus water and oil are both transparent,
but when mixed they are opaque. In a like manner the
opaque foam is composed of two transparent substances, air and
water. Furthermore, both glass and air are transparent, but
when glass is pulverized, that is to say mixed with air, an opaque
substance will result. The powdered glass can be made trans-
parent again, when another substance having the same coefficient
of refraction as glass is substituted for the air. Oil of cedar is
such a body (approximately). This poured upon powdered glass
"
›
160
THE MICRO-ORGANISMS OF THE HUMAN MOUTH.
restores its transparency.. Now, dentine consists, on the one
hand, of the basis-substance infiltrated with lime-salts, and on
the other of the dentinal tubules, with their contents; and since
both these constituents of dentine have different coefficients of
refraction, an opaque tissue is formed. We may diminish the
opacity—that is, increase the transparency-by filling the dentinal
tubules with a substance which has the same coefficient of re-.
fraction as the basis-substance, or by transforming the basis-sub-
stance so as to make it resemble the contents of the tubules in
respect to refraction.
In spite of the many attempts to account for the increased
transparency of the dentine under certain conditions, its true
cause has not yet been established with certainty. J. Tomes 107
and Magitot 108 explain transparency by the calcification of the
dentinal fibrils. Both authors regard it as the result of a vital
process-an attempt made by nature to impede the progress of
the disease. Later, Tomes 109 seems to have doubted the correct-
ness of his former views. C. Wedl 110 regards the transparency
occurring in dental decay as identical with that appearing in the
roots of senile teeth. He doubts the correctness of the calcifi-
cation theory, without giving further expression to his own.
Leber and Rottenstein 58 ascribe transparency to a partial de-
calcification of the dentine.
Schlenker 72 seems to be of the same opinion.
It has also been attempted to explain the transparency of the
dentine by the obliteration of the dentinal tubules brought about
by the swelling of the basis-structure.
Since, however, the swelling or expansion of a porous body is
not accompanied by obliteration of the pores, but, on the other
hand, naturally implies a corresponding enlargement of them, an
obliteration by swelling is a physical impossibility. According
to Walkhoff, "transparency has also been explained as the con-
sequence of micrococci." I have found no such view expressed
anywhere, either by Milles and Underwood or any other advo-
cate of the chemico-parasitical theory of decay.
111
Walkhoff concludes from his experiments "that transparency
must be regarded as a sclerotic action of the dentine-fibers, by
which they form new basis-substance at their own expense. Its
ACCOMPANYING PHENOMENA of DENTAL DECAY.
161
real nature is an increased and lasting physiological activity,
which calls forth over-production of intercellular matter at the
expense of the cells and primarily of their offshoots."
Black 112 disputes the view that transparency is to be looked
upon as the expression of a vital process. He appears to regard
it as the earliest stage of disintegration. According to the ob-
servations which I have made in reference to transparency, I
am inclined to accept the vital theory. In my opinion we must
choose here between two possibilities: either the basis-substance
is decalcified and a form of transparency thus brought about, or
the tubules are partially or completely filled with a substance
which has a similar action upon light as the intertubular sub-
stance. A decalcification, however, has most certainly not taken place
in the transparency in question; this is sufficiently proved by
chemical analysis, while on the other hand many facts point to
a vital process.
1. We know that the diameter of dentinal tubules in normal
condition is much greater near the pulp than at the border of the
enamel, and that it is much smaller in senile than in young teeth.
These facts point to a gradual decrease of the diameter of the
tubules after the dentine has already been formed. We also
know that chronic excitations of any kind lead to "secondary"
dentine formation on the inner surface of the dentine. May
they not, then, also lead to an acceleration of the formation in the
domain of the fibrils?
2. The microscopic examination of transparency shows as a
matter of fact a decrease in the diameter of the dentinal tubules
within the transparent zone. This at the same time signifies a
diminution in the size of the fibrils.
3. The transparency is characteristic of living dentine.
4. Chemical analysis gives results which agree with this
theory. According to my own determinations, dentine from the
transparent part of a number of teeth (about twenty-five) gave,
when dried at 102°-105° C., 71.9 per cent. ashes, while normal
dentine from the same teeth gave 72.1 per cent. A second calcu-
lation, made by a chemist, yielded for transparent dentine 69.5
per cent., and for the normal dentine from the same teeth 68.0.
We may conjecture from the rather small amount of ashes that
11
162
THE MICRO-ORGANISMS OF THE HUMAN MOUTH.
the dentine was not thoroughly dried before combustion; this
latter determination is therefore not quite reliable, but at any
rate shows that there is an increase rather than a decrease of
lime-salts. The general conception, however, that this theory is
compatible only with a high percentage of lime-salts is not quite
correct. A formation of new dentine, whether it be at the per-
iphery of the pulp or in the domain of the fibrils, does not occur
without a preceding solidification of the outer layer of the odon-
toblasts or fibrils. If, therefore, a new formation of dentine
takes place in the tubules at the expense of the dentinal fibrils,
this occasions not only an increase of lime-salts, but also simul-
taneously an increase of the glue-giving basis-substance.
may therefore have a consolidation of the dentine, although
analysis may not detect any marked increase in the percentage
of lime-salts. In conclusion, this theory must not be confounded
with the old calcification theory. The latter demands an im-
pregnation of the fibrils with lime-salts only, the former a partial
or total conversion of the fibrils into normal dentine.
↓
2. PIGMENTATION OF THE TISSUE IN DENTAL DECAY.
The pigmentation or discoloration usually attending decay of
enamel or dentine is another secondary process which has erro-
neously been viewed as a stage of decay. Every degree of dis-
coloration may be observed, from the normal color of the tissue
to a yellowish, yellow, yellowish-brown, dark-brown, black. In
the very first appearance of decay no discoloration is visible.
This absence of discoloration is especially remarkable in second-
ary caries of enamel, the tissue being converted into a perfectly
white powder.
Nor does rapid caries show any or but very little discoloration
in the deeper parts, while chronic caries always exhibits a dark
color, dark brown to black; in other words, the intensity of the
discoloration is in inverse proportion to the rapidity of the progress of
the disease. Besides, the discoloration of dentine does by no means
occur in decay only. Wherever the dentine is laid bare, it may
be more or less discolored in time. The black discoloration is
especially common in worn-off teeth, and, indeed, not only in the
case of smokers, but also of non-smokers, nor is it rare for the
CHEMICAL CHANGES ATTENDING DECAY OF THE TEETH. 163
teeth of dogs to show a deep brown to black discoloration.
Most authors concur in the view that the pigment arises from
without, and is conditioned by causes which have nothing to do
with the decay itself.
Watt explains it by the action of various mineral acids: mu-
riatic acid conditions the white, nitric acid the yellow, sulphuric
acid the brownish-black decay.
A
Clark 113 believes that the discoloration is called forth by the
color-forming power of bacteria.
Black 112 explains the discoloration by the settling of coloring-
matters into the partly decomposed tissue. These seem to be
derived chiefly from the dark sulphurets formed in the mouth
by the action of sulphuretted hydrogen upon such metallic ele-
ments as may be present. Others lay the blame on various foods
and stimulants, coffee, tobacco, etc.
■
It is not to be denied that smoking may occasion a dark dis-
coloration of dentine. It cannot, however, be the cause of pig-
mentation in dental caries, since the latter occurs in the cases of
persons who do not smoke. Then, again, dentine is colored
black also in the worn-off teeth of dogs; moreover, discoloration
of dentine and coal-black deposits are very common in teeth of
animals without decay.
In my judgment, the cause of discoloration in dental caries is
exactly the same as that of the discoloration of any other organic
substance which is decomposed by micro-organisms. This idea
is presented at length in the chapter on chromogenic mouth-
bacteria.
CHEMICAL CHANGES ATTENDING DECAY OF THE TEETH.
With very few exceptions, all investigators who have given any
attention to the study of the phenomena of dental decay have
been unanimous in the opinion that the softening of the dentine
is caused by the extraction of the lime-salts.
The fact that we have to do with a genuine process of decal-
cification is so patent that I would have no excuse for presenting
the experiments recorded below, if they were not of some value
in showing the comparative degrees of decalcification in decayed
dentine and in dentine artificially softened, as well as the com-
W
164
THE MICRO-ORGANISMS OF THE HUMAN MOUTH,
parative losses of the organic and inorganic constituents of the
dentine.
A large number of analyses were made by myself, as well as
by Dr. Jeserich, Prof. Liebreich, and others, in which decayed
dentine was compared with dentine softened in a fermenting
mixture of saliva and bread and in various acids. The results
obtained showed the process to be identical in all cases. (See
Dental Cosmos, 1883, p. 337.) In order to obtain results which
would show at the same time the amount of loss suffered by the
organic constituents of the dentine, I proceeded in the following
manner:
I procured three perfectly fresh teeth which contained large
quantities of carious dentine. These teeth were washed in a
gentle stream of water to remove all remains of food, and the
softened dentine removed in one piece with a spoon-shaped exca-
vator. The joint volume of the pieces was then determined by
an instrument specially constructed for the purpose, which gave
the volume at once in cubic millimeters, and also by the ordi-
nary picnometer. Then (from the same teeth) pieces of sound
dentine were procured whose volume was determined in the
same manner. The pieces were then dried for thirty hours at
105° C., and analyzed.
I give the result of one analysis:
187.2 cubic millimeters of sound dentine weighed 0.3600
"carious (6
66
66
66
66
0.0821
0.2779
Loss,
The sound dentine gave on analysis 72.1 per cent.
lime-salts
The carious dentine gave on analysis 26.3 per cent.
lime-salts
0.2595
0.0192
Loss, 0.2403
The sound dentine contained 27.9 organic matter=0.1004
66
carious
6.6
66
73.7
6.6.
(6
0.0605
Loss, 0.0399
MICROSCOPICAL PHENOMENA OF DECAY.
165
The carious dentine had accordingly lost on the whole seven-
ninths of its original mass, the lime-salts had lost twelve-thir-
teenths, and the organic matter two-fifths.
In plain words, the carious dentine had suffered an almost
complete decalcification, only one-thirteenth of the original
amount of lime-salts being still present. The organic matter
had suffered the comparatively small loss of two-fifths of its
original amount. This loss is no doubt attributable, for the
most part, to the direct action of the micro-organisms upon the
more completely decalcified portions of the carious dentine.
The results of these experiments are too plain to require fur-
ther explanation. They show an almost complete decalcification
of the carious dentine, and a comparatively small reduction of
the organic matter, also that the organic matter yields last to the
destroying agents.
MICROSCOPICAL PHENOMENA OF DECAY.
1. DECAY OF THE ENAMEL-CUTICLE.
If we subject a piece of Nasmyth's membrane perforated by
decay to a microscopic examination, we will find, in addition to
its discoloration and clefts,
an enormous number of
round and oblong densely
crowded bodies, which are
easily recognized as bacte-
ria, especially after staining
(Plate, Fig. 6). They are
sometimes so closely packed
that the membrane itself is
entirely lost to sight (Fig.
62). Wedl calls these cor-
puscles" the matrix of Lep-
tothrix buccalis." They have, however, most probably no ne-
cessary genetic connection with thread-forming mouth-bacteria,
but represent various kinds of bacteria, both monomorph and
pleomorph. They exert the same destructive influence upon the
enamel-cuticle as upon every organic substance; it loses its
transparency, appears thickened and cleft in all directions, and
LAMA
FIG. 62.

SMALL PIECE OF ENAMEL-CUTICLE
Converted into a mass of bacteria by decay. 300:1.
166
THE MICRO-ORGANISMS OF THE HUMAN MOUTH,
•
particularly at the margin of the cavity ragged and in a state of
dissolution: In the last stages of decay we see only a mass
of bacteria (cocci, rods and threads), which is held together by
the remnant of the membrane. The thickening of the mem-
brane is for the most part, I think, due to the accumulations of
bacteria. Sections of enamel in an early stage of caries, after
being stained with fuchsine, clearly show that the membrane is
loosened from the enamel on the decayed point, thickened and
invaded by masses of bacteria. The membrane in this condition
affords a matrix, that is, a point of retention, for bacteria, as well
as for very minute particles of food, and thereby accelerates the
progress of decay.
2. DECAY OF ENAMEL.
a. Preparation of Specimens.
The preparation of specimens of enamel suited for a study of
the process of decay is very difficult. It is well known that it
is impossible to decalcify enamel and to make sections of it with
the microtome. We are restricted to the study of ground sections,
and these necessarily give but an imperfect idea of the process,
because the largest part of the decayed enamel is lost in grinding.
Various methods have been proposed for the preparation of
microscopically thin ground sections. Whichever method be
applied, we first endeavor to split the tooth with a pair of split-
ting forceps in such a manner that the surface of cleavage passes
approximately through the center of the cavity (which, of
course,
does not always succeed) and grind down each half on a rough
corundum-wheel to the thickness of about 1 mm. ; or the whole
tooth is ground down from both sides, until the cavity is reached.
By the latter process we obtain only one lamella, and conse-
quently but one preparation, whereas the former yields two
preparations. These lamellæ are then ground under water on a
fine corundum-wheel as thin as possible without destroying too
much of the diseased tissue. A smooth, firm cork is best suited
for holding the piece against the wheel.
4MAT
The method of A. Weil (p. 171) may also be applied to advan-
tage, or we may follow the suggestion of Gysi: 114
MICROSCOPICAL PHENOMENA OF DECAY.
167
"Take a freshly-extracted tooth and grind it down with a
coarse corundum-wheel to a pretty thin lamella, according as a
transverse or a longitudinal section is desired. This lamella
should then be ground on one side perfectly even on a fine stone,
and then polished on the same side upon leather, coating with
some fine polishing-powder until no rays are visible on this side
anywhere. The lamella should then be cemented with the pol-
ished side down on a glass slide, such as is used for putting up
microscopical preparations, with some thick Canada balsanı,
which is easily softened by heating, and then firmly pressing the
lamella against the glass. Around the lamella are cemented
some exceedingly thin pieces of covering-glasses, as used in
microscopy.
سیر
D
"Practically it is best to cement on the other side of the glass
a piece of cork, so that the slide can be easily managed during
the further process of grinding. The lamella is then ground by
hand on a fine and perfectly flat stone until all the thin cover-
ing-glasses are evenly touched. By this process the lamella is
made of an equal thickness, with the covering-glasses cemented
around it.
"The cover-glass pieces are then removed and the lamella
ground still thinner; when thin enough, it generally detaches
itself. All this grinding must be done with water on a water-
stone. The final step is to polish it on this newly-ground side.
"The exceedingly thin plate procured in this manner should
then be washed in alcohol, and every particle of polishing-pow
der brushed off with a fine camel's-hair brush. The ground sec-
tion is now ready for mounting. For this purpose it is placed
in absolute alcohol for five minutes or longer, by which every
trace of water is removed. It is then transferred to oil of cloves.
to clear it; then placed on a clean glass slide, a drop of Canadà
balsam put on it, and covered with a thin cover-glass. The
preparation is now finished and ready for examination under
the microscope."
Charters White ("Elementary Microscopical Manipulation");
recommends rubbing down the sections between two plates of
ground glass, with the addition of some pumice-powder and
water; a method which is said to give very good results.
168
THE MICRO-ORGANISMS OF THE HUMAN MOUTH.
Preparations of enamel are to be stained in the same manner
as those of dentine. (See page 173.)
b. Appearances under the Microscope.
Microscopic examination of preparations of decayed enamel
brings to light in many preparations nothing more than a de-
pression (a loss of substance)
with uneven margins (Fig.
63), a more or less pro-
nounced pigmentation of the
enamel in the vicinity of the
depression, and a distinct
appearance of the transverse
striation of the enamel-
prisms (Fig. 64).
FIG. 63.

a
UNDERMINING ENAMEL DECAY.
a, Masses of bacteria lining the cavity. Circa 50:1.
FIG. 64.

PRONOUNCED STRIATION
THE PRISMS IN DECAY
OF ENAMEL.
250: 1.
or
In other better prepared
specimens the depression is.
seen to be filled with masses of micro-organisms which readily
take on coloring-matter; the margin of the cavity is indented, the
enamel cracked, the prisms falling to pieces. The spaces between
the loosened prisms are, in these cases, often filled with the same
fungal masses, whereas the latter never penetrate between the
prisms of normal enamel. In grinding, the masses of bacteria,
as well as the loosened prisms, are generally torn away.
MICROSCOPICAL PHENOMENA OF DECAY,
169
After the enamel has once been perforated by decay, its fur-
ther destruction proceeds principally from the inner surface.
This statement may at first seem strange, but will be found on
closer examination to be in accordance with the observed facts.
The remains of food accumulating in every dental cavity do not,
of course, attack the external, but the internal surface of the
enamel. We will find, furthermore, in nearly all large cavities
the decay extending from the dentine directly upon the inner
surface of the enamel.
This latter form of decay, which we designate as secondary
enamel-decay, is in many respects better suited for study than
the primary, inasmuch as the diseased tissue is not torn away by
mastication, etc., and not contaminated from without by foreign
bodies.
The extent of the secondary decay of the enamel naturally
corresponds to that of the dentine-decay; in large cavities on the
grinding-surface of molars, almost the entire inner surface of
the enamel may be found to be involved. Penetrating enamel-
decay proceeding from within is rare. I have observed such
cases usually in inferior mo-
lars, where decay proceeding
from the grinding-surface
perforates the enamel-wall
from the inner side, breaking
through the approximal wall
of enamel to the outside. In
secondary decay we find the
enamel-surface coated with a
white layer of softened enamel
sometimes mm. thick. If a
small quantity of this be
brought under the micro-
scope in water, it is seen to be
composed of enamel-prisms
mixed with large masses of bacteria (Fig. 65). These prisms lie
either singly or in groups; are 10-150μ long, and have sharp or
rough extremities. The transverse striation is distinctly marked.
In sections the margin appears indented, and the enamel-prisms
+
香味
​DELF
FIG. 65.

DISRUPTION OF THE PRISMS IN SECONDARY
ENAMEL-DECAY. 400: 1.
170
THE MICRO-ORGANISMS OF THE HUMAN MOUTH.
more or less dislocated. The whole looks as if the inter-prismatic
substance were dissolved, i.e., the connection between the prisms
$
FIG. 66.

SECONDARY ENAMEL-DECAY. a. partially docalcified enamel which has slightly taken on the
staining matter; b, zone of infected enamel showing masses of bacteria working their way into
the decalcifying tissuo. 70: 1.
FIG. 67.
1
destroyed. Sections of enamel in secondary decay often show the
bacteria forcing their way between the loosened prisms (Figs. 66,
67). About the same result is
obtained where normal enamel is
treated with diluted acids. The
destruction of the enamel as it
occurs in decay must be regarded
as essentially a parasitico-chemi-
cal process. The loosening of the
enamel-prisms is caused by acids
concerning whose origin there
can be no doubt; they arise in
the mouth by fermentation of
carbohydrates. The prisms thus
loosened are sometimes mechani-
cally removed; sometimes they remain on the spot, as in the case

A SMALL PORTION OF THE BORDER of
Fig. 66, showing the invasion of the dis-
cased enamel by bacilli..
MICROSCOPICAL PHENOMENA OF DECAY.
171
of secondary enamel-decay, until an opening is formed through:
which they escape. The bacteria directly participate in the pro-
cess, inasmuch as they invade the broken-down enamel, perhaps
drive the prisms farther apart, and destroy the remnant of organic
matter.. Micro-organisms do not exert a direct influence on nor-
mal enamel; their action upon the enamel in the first stage of
decay is therefore indirect,—that is, they act by means of the acids
which they produce. In the later stages of the process they exert
also a direct action upon the diseased tissue.
3. DECAY OF DENTINE.
a. Preparation of Specimens.
Various methods have been employed to prepare specimens
of decayed dentine for microscopic examination. In the first
place, ground sections of the decayed and the adjacent normal
dentine have been made, in the different manners described
for preparing sections of decayed enamel. Whoever has tried to
grind softened dentine or any soft tissue will easily understand
how difficult it is to obtain good specimens in this manner. Better
sections might, perhaps, be prepared by previously hardening the
decayed matter in absolute alcohol..
A method of grinding soft tissue, or a combination of soft and
hard tissue, which v. Koch applied in the case of mollusks, has
been employed by Weil 115 for grinding the soft tissues of the
teeth. Weil first placed the tissue (2-5 mm. thick sections of
the root or crown) into Müller's fluid, in order to fix the soft
parts, which requires six to seven weeks. The objects were then
thoroughly washed, and successively brought into a 30 per cent.,
50 per cent., and finally 70 per cent.. solution of alcohol to be
hardened. They were then cut into smaller pieces by a fine
bracket-saw, so as to facilitate the action of the coloring-matter
in the subsequent staining process, and again placed for some
time in a 70 per cent. solution of alcohol. He then stained
them, extracted the water by means of alcohol, clearing them
up in oil of cloves; the objects were then taken out of the oil,;
rinsed in pure xylol, and placed for at least twenty-four hours
172
THE MICRO-ORGANISMS OF THE HUMAN MOUTH.
in a large quantity of chloroform; then they came for an equal
length of time in a diluted solution of Canada balsam in chloro-
form, to which, after about twenty-four hours, was added as
much hardened Canada balsam as would dissolve in it.
་
Weil now placed the teeth in a porcelain vessel, added enough
of the solution to cover them, and then kept the solution over a
water-bath at 60°-70° C.,-later at 80°-90° C. until the mass.
when cooled became as hard as glass; the teeth were then care-
fully taken out, the superfluous balsam removed, and the speci-
mens were ready for grinding.
Sections of dentine are also frequently prepared as follows:
Rather thick ground sections are made comprising both the nor-
mal and softened tissue; these are decalcified in diluted acid
(chromic acid, etc.), and cut into microscopically thin sections by
the microtome. Such preparations have the great disadvantage
that we are not able to determine with certainty just where the
decayed tissue stops and the artificially decalcified begins; nor
can we tell exactly what changes of the dentine may have been
caused by the artificial decalcification.
Having made and examined several thousand microscopic prep-
arations of decayed dentine, I have found the following method
to be the most recommendable, both on account of its extreme
simplicity as on account of the excellence of the preparations
which it yields and the few reagents to which it is necessary to
subject the tissue.
Selecting a freshly-extracted decayed tooth, we wash out the
cavity only sufficiently to remove the particles of food, and
break away the margins of enamel so as to expose the softened
dentine as much as possible. Then with a sharp instrument we
dissect, so to speak, the decayed from the sound dentine, keep-
ing hard upon the latter; by this means we may easily shell out
nearly the whole of the softened dentine in one piece. Where
the decay has approached near to the pulp, it is very easy to ex-
tend the cut quite to the pulp-chamber, by which means a thin
layer of hard dentine will be contained in the mass removed.
The material thus gained is immediately cut on the freezing
microtome. It is well to freeze the tissue in an aqueous solu-
tion of gum-arabic instead of in water. Such a solution has a
!
MICROSCOPICAL PHENOMENA OF DECAY.
173
higher freezing-point than water, and does not become so hard,
By means of the freezing microtome several hundred very thin
cuts may be prepared in a very few moments.
The objection has been raised to this method that it permits of
securing sections of the softened dentine only, whereas we may
wish to see what, if any, changes have taken place in the other-
wise normal dentine just at or a little beyond the border of decal-
cification. I do not, however, attach much importance to this
point, because a study of a few preparations soon teaches us
that in the parts indicated but slight changes, or none at all,
can be detected; besides, it is not difficult, with the help of the
freezing microtome, from such pieces of dentine in which a thin
layer of unsoftened dentine has been cut out along with the de-
cayed, to make a few cuts containing both hard as well as de-
cayed dentine, although the edge of the knife will be somewhat
damaged by it. For the study of the phenomena of transparent
dentine, a number of ground sections should be made from teeth
in which the decay has made but little progress.
Unstained sections must be examined in water. But it is im-
peratively necessary to stain a large number of sections, especially
in order to study the distribution of the bacteria in the tissue and
the manner in which they demolish it.
b. Methods of Staining.
For the purpose of staining the tissue, picro-carmine or picro-
lithio-carmine is, according to my experience, most suitable. The
sections are placed in the concentrated solution for about fifteen
minutes, then in a mixture of alcohol 70, water 29, muriatic acid
1, where they may remain from fifteen minutes to five hours,
then for a short time into alcohol, to which have been added a
few crystals of picric acid (till it turns slightly yellow). They
are then cleared up in oil of cloves, and mounted in Canada bal-
sam or glycerine. The dentinal fibrils and sheaths are colored
red, the basis-substance pink, the bacteria light red, the decom-
posing parts yellow.
For staining the micro-organisms the basic aniline colors are
best suited, fuchsine and gentian-violet being, according to my
174 THE MICRO-ORGANISMS OF THE HUMAN MOUTH.
experience, preferable; methyl-violet, methylene-blue, and ve-
suvin not quite so good. The staining with fuchsine is carried
out in the following manner: Enough of a concentrated alco-
holic solution of fuchsine is added to water to turn it cherry-red.
In this solution the sections are allowed to remain for three to
L
J
five minutes, and are then placed (after Gram's method) for one
to three minutes into a solution of iodine 1.0, iodide of potas-
sium 2.0, distilled water 300.0. Then they are put into absolute
alcohol, which must be renewed as soon as it becomes red. In
the alcohol the color gradually disappears from the tissue, while
the bacteria retain it. The sections must not be left in the alco-
hol too long, otherwise the bacteria will also give up a portion
of their coloring-matter. Some experience is necessary in order
to take out the cuts at the proper time. From the alcohol they
are transferred to oil of cloves, then mounted in Canada balsam.
By this method the parts infiltrated with bacteria, or the bac-
teria themselves, are colored red; everything else appears un-
stained.
I have obtained equally good, and, in fact, I have sometimes
thought, better, results by simply treating the slightly overstained
cuts with absolute alcohol, though the process is somewhat longer,
it sometimes requiring an hour or more to decolorize the prepara-
tions, during which time the alcohol must be repeatedly changed.
The preparations, when taken from the alcohol, must not show
a diffuse staining, but rather a differential staining, some parts of
the preparation appearing to the naked eye quite colorless and
others bright red.
The other coloring-materials above mentioned are employed
in the same way as fuchsine. Remarkably beautiful prepara-
tions may be obtained in a very few minutes by employing Gün-
ther's modification of Gram's method with gentian-violet.
f
The cuts are brought from absolute alcohol for one to two
minutes in a deep violet solution of gentian-violet in aniline
water, then removed on the point of a platinum wire, lightly
touched to bibulous paper to remove the excess of coloring solu-
tion, placed for two minutes in the iodine-iodide of potassium
solution, one-half minute in alcohol, ten seconds in 3 per cent.
alcoholic solution of hydrochloric acid, then again one to five
MICROSCOPICAL PHENOMENA OF DECAY.
175
minutes in alcohol, then cleared in oil of cloves and mounted in
Canada balsam.
I have not given much attention to the double staining of
decayed dentine, but as far as my experience goes I have found
that double-stained preparations, while they show up" very well
under low powers, are not as good for study as the single-stained.
- Sections stained with gentian-violet may be after-stained by
transferring them from the last alcohol bath to a solution of
vesuvin one minute or picro-carmine, one to three minutes, after
which they must be returned to the alcohol, then to oil of
cloves, etc.
•
66
A very good double stain may often be obtained if the sections
colored with fuchsine are placed in a vesuvin solution for one to
five minutes, then rinsed in water, put into alcohol for a few
moments, then cleared up in oil of cloves and mounted in Can-
ada balsam. The bacteria appear red, the dentine appears yel-
lowish-brown. Double coloration does not, however, always
succeed, and requires some practice to obtain good results.
Ground sections are to be stained in the same way as the cuts.
*
c. Appearances under the Microscope.
Preparations colored with fuchsine, when examined under
very low power or even with the naked eye, show that the bac-
teria are not equally distributed throughout the mass of softened
dentine. Sections parallel to the dentinal tubules (longitudinal
sections) generally reveal on the outer margin
corresponding to the external layer of den-
tine a deep-red coloration, which gradually
diminishes toward the inner margin. Large
tracts of decayed tissue, especially at the
extremities of the specimen, often remain
entirely uncolored. This necessitates the
conclusion that the softening (decalcifica-
tion) of the dentine extends further than the
invasion of the micro-organisms. The ap-
pearance of comparatively large non-infected portions at the
extremities or sides of the specimen may be explained by the
accompanying diagram (Fig. 68).
FIG. 68.

b
UNDERMINING DECAY.
b, zone of softened
non-infected dentine.
176
THE MICRO-ORGANISMS OF THE HUMAN MOUTH.
This is intended to represent a case of undermining decay on
the grinding-surface of a molar; the enamel has been broken
through, and the softening (decalcification) has extended in all
directions in the dentine with about equal rapidity. The micro-
organisms, on the other hand, travel more readily in the direc-
tion of the dentinal tubules than at right angles to them, since
in the latter direction they can advance only through the tortu-
ous and narrow road of the fine branches of the tubuli. Conse-
quently, while the micro-organisms almost or quite keep up with
FIG. 69.

E
A
•
A CUT FROM A LARGE PIECE OF DECAYED DENTINE, left half only in outline. Shows at a an
unusually large non-infected zone of decayed dentine. 20:: 1..
the softening in the direction toward the pulp, they fall consid-
erably behind in the lateral directions, so that the invasion, par-
ticularly in the lateral direction, is usually much less extensive
than the softening.
Fig. 69 represents the appearance under a low power of a
preparation of decayed dentine in my possession.
Cases where there are many large interglobular spaces may
form an exception to the rule. In such cases, the bacteria, fol-
lowing the course of the interglobular spaces, can advance very
MICROSCOPICAL PHENOMENA OF DECAY.
177
•
rapidly in both directions underneath the enamel (Fig. 70),
though strangely enough, as first pointed out by Mummery, the
interglobular spaces are often peculiarly free from infection.
The presence of these non-infected areas in decaying dentine,
which I announced in 1883, was at first contradicted by some
authors. Now, however, it is universally acknowledged. Among
others, Watson writes, "I quite agree with Dr. Miller that there
are areas of softened, non-infected dentine which contain no or-
ganisms." In fact, they are so easily detected that I am at a
loss to understand how any investigator could have missed seeing
them at once.
Under a somewhat higher power (forty to sixty diameters) we
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INTERGLOBULAR SPACES FILLED WITH MICRO-
cocci. About 400 : 1.
:

may more easily follow the invasion. Occasionally we find that
a majority of the tubules are infiltrated to the same depth; usu-
ally, however, the parasites penetrate the different tubules to very
different depths. We also occasionally find that all or nearly all
the tubules are filled with bacteria at the surface, while in the
deeper parts only a few are infiltrated.
The advancing hordes of bacteria consequently present a very
irregular, zigzag front toward the pulp. Laterally, however,
the line separating the infected from the non-infected portions
of the decaying dentine often appears quite regular and sharply
defined (Fig. 71). These peculiarities are readily accounted for
by the structure of the invaded tissue.
12
178
THE MICRO-ORGANISMS OF THE HUMAN MOUTH.
I have found in one case only the very remarkable mode of
advance represented in Fig. 72. Here the invaders are seen
FIG. 71.

DECAYED DENTINE, showing that laterally the boundary between the infected and non-infected
parts may be very regular. Circa 40: 1.
a
KIINTEILGE
FIG. 72.

DECAYED DENTINE, showing an advance of the
bacteria in three columns. Circa 15 : 1.
1
to advance in a manner which I can only liken to an army of
men marching through a hostile country. Far in advance we

PLATE I.
FIG. 1.
Longitudinal section of decayed dentine, showing infection with micrococci,
bacilli and threads (mixed infection). 500: 1.
Phot'd by DR. CARL GÜNTHER, Berlin.
FIG. 2
Longitudinal section of decayed dentine, showing infection with micrococci.
500: 1.
MICROSCOPICAL PHENOMENA of DECAY.
179
see a very distinct line of pickets. This is followed by an interval
which in the language of bacteria might be put down at several
furlongs, since it is about one thousand times the length of an aver-
age-sized bacillus. Then comes the vanguard, and finally, after
another interval, the main body of the invading hordes. I was
not able to find any cause for this peculiar disposition of the forces.
X
A question which has often been mooted now arises: Can the
bacteria penetrate into normal dentine? This question must be
answered in the affirmative. Since the average diameter of the
dentinal tubules is greater than that of the bacteria found in the
mouth, it is but reasonable to conclude, a priori, that bacteria
may under certain circumstances make their way into the tu-
bules of apparently intact tissue. Under high power we also
often observe that a small number of bacteria, outposts, as it
FIG. 74.

FIG. 73.

MICROCOCCI PENETRATING THE CANALS
OF SOLID DENTINE, in a partially absorbed
and abscessed but not decayed root: 700: 1.
LONGITUDINAL SECTION
OF DECAYED DENTINE.
showing caverns, or foci
of liquefaction, filled with
bacteria. 150: 1.
were, have penetrated into the nor-
mal dentine without, however, pro-
ducing any visible changes.
We notice also in partly resorbed, abscessed roots, particularly
of milk-teeth (Fig. 73), that bacteria work themselves into the
open ends of exposed tubules for a short distance. The great
mass of bacteria, however, in decay of the dentine does not
even penetrate up to the normal dentine, much less into it.
From this it is evident that the proposition which I established in
180
THE MICRO-ORGANISMS OF THE HUMAN MOUTH.
1882 116 is correct in every respect: "The action of acids always
precedes the invasion of bacteria."
As is best seen in a longitudinal section under low power,
numerous rounded or oval masses of from ten to one hundred
micro-millimeters long and from five to fifty broad often appear
in the domain of the infected dentine (Fig. 74). The masses con-
sist of closely packed cells of bacteria, and correspond to the
more or less ample enlargement of one or more dentinal tubules,
by which the neighboring tubules are crowded together or bent
out of their course. If these masses attain larger dimensions, the
course of some of the tubules, together with the intervening basis-
substance, is interrupted for a certain distance, thus forming a
space or cavern in the dentine. These caverns being formed by
the dissolving of the basis-substance by peptonizing bacteria,
may be properly designated as liquefaction-foci.
Such foci do not al-
ways have the form
represented in Fig.
74; they may be
tapering, triangular,
crevice-shaped, etc.
The crevice-shaped
spaces frequently lie
obliquely to the den-
tinal tubules, pre-
senting the charac-
teristic appearance
UNIFORM EN- shown in Fig. 75.
LARGEMENT OF
In some specimens
all the tubules are
enlarged to nearly the
same extent (Fig. 76),
occasionally to three
or four times their normal size. This enlargement is caused
partly by the dislodgment of the neighboring tubules, partly by the
loss of the intertubular substance. Lastly, the destruction of the
intervening substance causes a confluence of two or more adjacent
tubules, producing long caverns running parallel to them. By the
FIG. 75.
DECAYED DENTINE WITH OBLIQUE
LIQUEFACTION-FOCI. Circa 400 : 1.
FIG. 76.


THE TUBULES
IN DECAYING
DENTINE.
MICROSCOPICAL PHENOMENA OF DECAY.
181
formation of caverns and by the fusion of adjacent caverns the
dentine is broken up, becomes porous, and is gradually de-
stroyed. The tubules are often attacked in groups, while others
lying between these groups may be wholly free from infection. In
other cases, however, every single canal is stuffed full of bacteria.
In Fig. 77 I have endeavored to reproduce an appearance
very commonly met with in decaying dentine. This specimen
Start
PRENEURSIZĘ
FIG. 77.
FIG 78.


DECAYED DENTINE SHOWING TOTAL
LIQUEFACTION OF
OF THE BASIS-SUB-
STANCE BY BACTERIA. 400: 1.
A SINGLE
TUBULE from
the preparation
illustrated in
Fig. 77.
clearly shows that the enlargement
of the tubules always found in
decayed dentine is due to the in-
fection, and that a gradual fusion
of the basis-substance may take
place, beginning with the separate tubules, until nothing remains
but a mass of bacteria held together by the remnant of the den-
tine. Fig. 78 shows a tubule from the same specimen under
high power.
In rare cases the action of the bacteria is mostly restricted to
the surface, and the dentine is gradually dissolved from the sur-
face downward, without the formation of caverns within the
dentine. I term this form of dissolution of dentine progressive
182
THE MICRO-ORGANISMS OF THE HUMAN MOUTH.
superficial dentine dissolution, in contradistinction to that form
represented in Figs. 74-78, which may be designated as paren-
chymatous dentine dissolution.
Not one of the morphological changes of dentine mentioned
takes place without a previous invasion of bacteria.
FRINGE OF LEPTOTHRIX THREADS on the border of a section of decayed dentine. 400:1.
In well-stained specimens the individual cells of the bacteria
are clearly visible under a power of 400-500 diameters; although
for a thorough study of the specimens oil immersion lenses and
Abbe's condenser are desirable. With their
assistance we see that the external margin of
the specimen consists of broken-down dental
tissue intermixed with enormous masses of mi-
crococci, bacilli, and leptothrix threads. The
latter often appear as fringes on the border of
the specimen (Fig. 79), but are not found along
the entire margin, while in some they are alto-
gether lacking. In many cases, no doubt, they
are torn away in preparing the specimens. It
is seldom that they penetrate the dentinal tu-
bules, unless the dissolution is already far
advanced, and even then they are to be found
mostly in the external layers. Tubules contain-
ing long, tortuous threads (Fig. 80) are there-
fore comparatively rare.
-
If we examine a somewhat deeper zone, we
usually find the tubules filled with micrococci and rods only, the
former decidedly preponderating. These two forms of bacteria
generally occur in separate tubules; thus we often see a tubule
FIG. 80.
FIG. 79.


SINGLE TUBULE
FILLED WITH
THREAD FORMS.
1100: 1.
-

PLATE II.
FIG. 1.
Diagonal section of decayed dentine. Infection with micrococci, bacilli and
screw-forms. 500: 1.
Phot'd by DR. CARL GÜNTHER, Berlin.
FIG. 2.
-7
Longitudinal section of dentine artificially decayed. Infection with bacilli..
500: 1.
MICROSCOPICAL PHENOMena of decAY.
183
FIG. 81.
stocked only with micrococci (Fig. 81), the adjacent one only
with rods (Fig. 82); there are, however, tubules packed with a
mixture of both (Fig. 83), while it rarely happens that one ex-
tremity of a tubule is filled with rods, the other with cocci.
We have consequently in decay of the teeth to do with a
so-called mix-infection (Fig. 84).
SINGLE TUBULE
FILLED WITH
COCCI.
1100: 1.
FIG. 82.
1
Tas
Yest
00.0
SINGLE TUBULE
FILLED WITH
Rods.
1100: 1.
FIG. 83.
дво
88
•
8
88
000
Pm
활동
​SINGLE TUBule
SHOWING A MIXED
INFECTION OR
INFECTION WITH A
PLEOMORPHOUS
BACTERIUM.
1100: 1.
PEAKMUS
*...
FIG. 84.

It is true that we often meet
with specimens which appear
to contain cocci alone (whether of one or of
different varieties the microscopic examination
does not tell). On the other hand, I have in
my possession a few preparations which exhibit
a pure bacillus infection, particularly in circum-
scribed portions.
This, however, must not lead us to believe
that there is a bacillus-decay and a micrococcus-
decay which are distinguished by characteristic phenomena;
decay caused by the different bacteria reveals no such distinc-
tions, consequently I do not consider it as proved that caries
chronica, acuta, acutissima, etc., are caused each by its own
specific bacterium.
In general that species of bacterium which possesses the
ANIM
DECAYED DENTINE
SHOWING A MIX-
INFECTION WITH
COCCI AND BA-
CILLI.
400 : 1.
184
THE MICRO-ORGANISMS OF THE HUMAN MOUTH.
!
highest ferment activity (in other words, acid-forming power)
and the highest peptonizing power (i.e., dissolving power for
albuminous substances) and is able to flourish with a limited
supply of air will, cæteris paribus, cause a more rapid destruction
of the tooth-substance than another having these qualities in a
minor degree. A mouth-bacterium which in respect to these
properties excels all others in such a degree as would be neces-
sary to explain the difference between caries acuta and caries.
chronica will most probably never be discovered. The rapid
advance of acute caries is to be explained rather by the resist-
lessness of the tooth's structure and the favorable conditions for
fermentation obtaining in the mouth.
Successfully stained cuts of decayed dentine furnish prepara-
tions which to the eye of the bacteriologist and pathologist are
not only of exceeding great beauty, but also demonstrate with
such clearness the intense action of micro-organisms upon den-
tine that no doubting Thomas can look at them and then have
the hardihood to deny their significance. In Fig. 85 I have en-
deavored to reproduce the microscopic appearance of a specimen
in my possession (and of which I presented duplicates to Dr.
Cunningham, of Cambridge, England, and to Dr. Allan, of New
York). If the reader can imagine the basis-substance in this
preparation stained yellowish-brown and the micro-organisms
red, and further take into account that by slightly lowering or
raising the tube of the microscope or by moving the prepara-
tion one constantly brings new and different pictures into focus,
and, lastly, that the most skilled draughtsman and xylographer
come very short of nature, he may then form some idea of the
beauty of this specimen. The dentine is completely riddled by
the masses of bacilli and threads.
A section cutting the tubules at right angles shows under a
power of three hundred diameters that the tubules filled with
micro-organisms are distended from one to four times their nor-
mal diameter, and that often two or more of the enlarged tubules
are converted into one by the liquefaction of the membranes and
the intervening substance (Fig. 86). This melting together of
the tubules increases as we near the outer border of the speci-
men (corresponding to the surface of the cavity) until it is no
MICROSCOPICAL PHENOMENA OF DECAY.
185
}
longer possible to distinguish the separate tubules; we then see
only irregular masses of bacteria, of different sizes, which are
more or less contaminated by the detritus (débris) of the de-
composing dentine. These impure masses are what Abbott
FIG. 85.
α
Z
с
Ъ

140
:
đ
1
LONGITUDINAL SECTION OF DECAYED DENTINE SHOWING INFECTION WITH ROD- AND
THREAD-FORMS. a, tubule distended, but walls still comparatively intact; b, d. tubular walls
broken through and the dentine in a state of complete dissolution; c, tubules out of focus. Circa
500: 1.
calls "embryonic elements." Since they are not homogeneous,
they take up the coloring-matter unequally at different points,
and therefore occasionally present figures that may bear a certain
faint resemblance to cells.
186
THE MICRO-ORGANISMS OF THE HUMAN MOUTH.
Fig. 87 represents an appearance frequently observed in cross-
sections. A number of adjacent tubules are enlarged to such an
extent that their walls finally touch or even flatten one another.
In such cases they form five- to six-sided prisms. The question
arises: What has become of the intertubular substance?
A slight compression of the intervening substance may doubt-
less be caused by the pressure from within the tubules, but its
total compression, as shown in Fig. 87, is altogether inconceiva-
ble. Now, since the micro-organisms cannot penetrate into the
intertubular substance through the intact dentinal sheath, the
above occurrence can be explained only by the hypothesis that
FIG. 86.
FIG. 87.


CROSS-SECTION OF DE-
CAYED DENTINE.
Showing the distention of
the tubuli and formation
of liquefaction-foci.
400: 1.
T
KN
CROSS-SECTION OF DECAYED
DENTINE.
The tubules through reciprocal
pressure have assumed the
shape of 5-6 sided prisms.
they form a pepsine-like diffusible ferment, which dissolves the
intervening substance, while Neumann's sheath remains intact.
I am not, however, at all sure that I have hit upon the right
explanation of this phenomenon.
In the deeper zones of decayed dentine the bacteria lie ex-
clusively in the tubules and their ramifications, and a direct in-
vasion of bacteria into the intertubular substance only excep-
tionally takes place; the dissolution of the latter progresses from
the surface or from the lumen of the tubules.
At the neck of the tooth the external layer of dentine is either
devoid of tubules, or they are so narrow that the entrance of the
bacteria is greatly impeded. Caries at the neck of the tooth con-
sequently presents phenomena which differ somewhat from those
of other parts. This applies especially to chronic dry caries at the
MICROSCOPICAL PHENOMENA OF DECAY.
187
neck of the tooth, which leads to intense pigmentation. Under
the microscope the external margin of a longitudinal section
exhibits a layer consisting of masses of bacteria from which
numerous leptothrix threads radiate. Below it the dentine
appears interspersed with many triangular fissures, with their
bases toward the border and their longer diameter parallel to the
tubules (Fig. 88).
The fissures are almost always filled with micro-organisms,
especially with cocci. I suspect that they are not formed by
FIG. 88.

Mind
APPEARANCE OF DECAY AT THE NECK OF THE TOOTH.
The fissures are filled with bacteria. Circa 50: 1.
bacteria, but by the contraction of the external layer of dentine,
and that masses of bacteria, as well as very small food-particles,
enter them afterward. Each fissure thus affords a point of re-
tention or a caries-center from which the infection of the dentine
proceeds.
Specimens stained with picrocarmine frequently exhibit pe-
culiar appearances, which cannot always be easily explained.
Longitudinal sections under three hundred diameters show on
the margin a reddish fringe of leptothrix threads, mingled with
188
THE MICRO-ORGANISMS OF THE HUMAN MOUTH.
micrococci, and below this a yellow layer about one-fourth of a
millimeter wide. Besides, the parts in a state of disintegration
are generally of a yellowish color. In the parts that are only
softened, but not infected, as well as in the masses of bacteria,
the red color prevails. Now and then scattered, greatly enlarged
tubules are seen to be filled with shining, yellow, homogeneous
contents, and only under a very high power does its granular
character become evident.
Cross-sections also often present a very peculiar appearance.
They reveal more or less numerous, scattered, greatly enlarged
tubules, filled with red-colored micrococci, and about as many
scattered, enlarged tubules of strongly refractive, homogeneous
yellowish contents (Plate III, Fig. 5). I am not able to state
why these various tubules are so differently affected by coloring
matter; it occurs in artificial as well as in natural decay.
Fuchsine specimens also occasionally exhibit tubules of deep
red, apparently homogeneous contents. In such cases it may be
shown that the specimens have been over-stained, which makes
it impossible to distinguish the closely-crowded cocci.
FIG. 89.
We now come to a series of phenomena which have been
widely discussed, but not yet definitely explained. They are (1)
the thickening of Neumann's sheaths;
(2) the breaking up of the dentinal
fibrils into rods (pipe-stems); (3) the
occurrence of granular, not vegetable,
elements in the tubules.

@
@
0
THICKENING OF NEUMANN'S SHEATH.
According to some authors, a thick-
ening of the walls of the dentinal tu-
bules (Fig. 89), that is, of Neumann's
sheaths, is an invariable accompaniment
of decay. According to Neumann, this
thickening proceeds until the lumen of the tubules is totally
obliterated, while Tomes assumes only partial obliteration. He
compares a dentinal tubule with its thickened walls to the stem
of a tobacco-pipe.
0%
THICKENING OF THE DENTAL
SHEATH.
(Neumann's sheath.)
(After Wedl.)
MICROSCOPICAL PHENOMENA OF DECAY.
189
Leber and Rottenstein, on the other hand, found not a con-
traction, but a distention of the tubules with thickened sheaths.
They examined several teeth made of the ivory of the hippo-
potamus, as well as three human teeth, worn on a plate, which
had become carious in the mouth, and discovered that the
microscopic changes of the dentine described above occur in such
teeth also. In all cases the tubules were more or less, sometimes
very extensively, dilated by a substance generally stained red by
carmine. The specimens from the ivory teeth particularly pre-
sented these changes in a very high degree.
Opinions vary greatly concerning the cause of this thickening.
Tomes 117 considers that "the diseased condition has, perhaps,
undone the work of development and thrown light on the ques-
tion how this was effected; it might almost be said to have re-
stored the outline of the formative cells: the tissue is to a certain
extent broken up into its histological elements. Under the
microscope the section looks as though it might have been built
up of multitudes of tobacco-pipe stems, united by an interven-
ing substance. Such is the condition when disorganization has
advanced up to a certain point; at a later period short lengths of
the walls of the tubes (dentinal sheaths, Zahnscheiden of Neu-
mann) are found isolated; and finally the whole tissue breaks
down into minute granular particles which are, by degrees,
washed away in the saliva."
Leber and Rottenstein 58 do not seem to be satisfied with their
own attempts to explain the thickening of Neumann's sheaths;
still it seemed to them most probable "that the thickening of
the walls of the dilated tubules is brought about mechanically
by the compression of the surrounding substance." In their
judgment, the thickening cannot be caused by acids.
I have examined numerous specimens of natural and artificial
decay stained with picrocarmine, fuchsine, hæmotoxylin, etc., and
indorse the view of Leber and Rottenstein, that a contraction
of the lumen of the dentinal tubules is seen only in cases where
it existed before the softening commenced. Further, that the
thickening of the dentinal sheath is not a vital process, since
it may be clearly observed in specimens of artificial decay.
This phenomenon might perhaps be explained, in part at least,
蠢
​:
190
THE MICRO-ORGANISMS OF THE HUMAN MOUTH.
by the pressure of the fungal masses in the tubules, by which a
compression of the walls is caused. This supposition receives
support from the fact that a thickening of the dentine may also
be observed around the larger masses of bacteria in decayed
dentine. When examined under the microscope, the dentine
bordering such masses may often be seen to differ from the sur-
rounding tissue by its higher refractive power.
By the action of acids upon carious dentine I have succeeded
in producing appearances greatly similar to, if not identical with,
the thickening described above. The resisting dentinal sheaths
(tubules), especially such as are filled with bacteria, are loosened
from the basis-substance and then more or less bent at the
FIG. 90.
1115
C
a
d
APPEARANCE OF DENTINAL SHEATHS
produced by the action of strong
acid on decayed dentino.
1100: 1.
FIG. 91.

ví
Öö
ROD-SHAPED, NON-VEGETA-
BLE ELEMENTS in de-
cayed dentine.
loosened extremities (Fig. 90, a, b), or flattened out (Fig. 90, c),
or, lastly, torn from their beds altogether (Fig. 90, d). On the
whole, however, it will be seen that I am not able to throw much
light upon this question, and must leave it for further investiga-
tion to settle.
The appearance of rod-shaped elements or fragments in the tubuli
of decayed dentine was first noticed by J. Tomes, and is no
rare phenomenon either in natural or artificial decay. Fig. 91,
taken from a specimen of artificial caries, gives a fair idea of
it. J. Tomes 118 endeavored to explain this phenomenon by the
consolidation of the dentinal fibrils, while Wedl 91 regards this
view as not proved. Later Tomes 17 writes, "These rods may
be portions of consolidated fibrils, or they may be bits of the
MICROSCOPICAL PHENOMENA OF DECAY.
191
sheaths of Neumann, or they may be mere casts of the enlarged
tubules."
The fact, however, that these röds disappear often completely
as soon as they are brought into contact with dilute sulphuric
acid appears to me to render the view that they are bits of the
dentinal sheaths untenable. The rods are easily isolated by
crushing a section of dentine containing them in a drop of
water on an object-glass. If the specimen be now covered with
a cover-glass and dilute sulphuric acid allowed to flow through
it from the margin in the usual manner, we may clearly observe,
under a high power (1000 to 1500), how the pieces suddenly dis-
solve, leaving behind a hardly visible granular detritus, and in
FIG. 92.
FIG. 93.
FIG. 94.
:
O
ROD-SHAPED FORMATIONS IN
DECAYED DENTINE,
with a central black thread
(dentinal fibril ?).
1100: 1.
ROD-SHAPED FORMATIONS
(lime formations?) in a tubule,
surrounded by micrococci.
1100: 1.
some cases disappearing altogether. In one case I plainly saw
the form represented in Fig. 92 appear at the instant when the
acid came in contact with a larger fragment.
I do not regard it as improbable that the products in question
are lime formations; to me, however, they look more like cylin-
drical casts of the dentinal tubules than calcified fibrils. And
indeed these pieces, when greatly magnified, are sometimes seen
to contain filaments which may be regarded as the remains of
dentinal fibrils (Fig. 93). The tubular structure may sometimes
be directly ascertained under high power. I have never found
micro-organisms in these rod-like products, but have repeatedly
seen them mixed together with cocci, in much enlarged tubules
192
THE MICRO-ORGANISMS OF THE HUMAN MOUTH.
(Fig. 94). This would seem to justify the hypothesis that after the
formation of these lime-casts an invasion of the micro-organisms
and an enlargement of the tubules takes place, loosening the casts
from the walls of the tubules. At any rate, we have here not a
vital but a chemical process, since the fragments in question are
very common in artificial decay. The fact that I have never
noticed the characteristic crystals of sulphate of lime, after treat-
ing the separate rods with sulphuric acid, appears at first to tell
FIG. 95.

ROWS OF SHINING GRANULES IN THE TUBULES, in decay of a tooth worn on a plate.
against the hypothesis that these elements consist of lime-salts ;
the quantity of lime in one fragment may, however, be too small
to give the crystal test.
The rods do not dissolve in organic acids; they even become
more distinct after treatment with lactic and acetic acids. Three
tests with alcohol and chloroform had no effect.
The occurrence of rows of shining, irregular grains in the tubules
(Fig. 95) is frequently observed in the beginning of caries.
Sometimes this deposit is made in a zone just in front of the
advancing caries, so that many have regarded it as an attempt
1
193
MICROSCOPICAL PHENOMENA OF DECAY.
on the part of the living pulp to retard the progress of the dis-
ease. But we can easily prove that such is not the case, since the
process occurs in living as well as in dead
teeth. In accordance with the above
view, Tomes, Magitot, and others took
these granules for lime-granules; Wedl,
Black, and others regard them as fat.
By crushing the above-mentioned casts
(page 191), grains are also produced in
the tubules which bear considerable re-
semblance to those which occur naturally)
Fig. 96).
I regard it therefore as not improbable
that the granular bodies have the same
origin as the rod-shaped (pipe-stems).
FIG. 96.
ROD-SHAPED FORMATIONS IN
DECAYED DENTINE
SE VA A
breaking up into granules.
1100 : 1.
4. DECAY OF CEMENT.
Decay of cement is confined chiefly to a very thin layer at the
FIG. 97.

APPEARANCE OF DECAY IN CEMENT WITH PRONOUNCED DEVELOPMENT OF THE CEMENT-
CANALS. a, surface of cement covered with various bacterium-forms; b, border of the den-
tine; c, enlargement of the cement-canals and formation of liquefaction-foci; d, spreading of
the decay into the dentine. 1100: 1.
neck of the tooth.
The decalcification and dissolution of the
cement proceeds either from the surface inward, in the form of
Wa
13
194
THE MICRO-ORGANISMS OF THE HUMAN MOUTH.
#
a progressive superficial dissolution of the cement, or the cavities
of the cement become infiltrated with bacteria, giving rise to
a parenchymatous dissolution,
accompanied by phenomena
very similar to those of dentine-
decay. Its similarity to the lat-
ter is especially striking in
places where Sharpey's fibers
are well developed. Immedi-
ately following decalcification
these fibers, or rather canals, are
infiltrated and enlarged by bac-
teria which gradually liquefy
the intervening tissue (Fig. 97).
In this way the tissue is rarefied, and finally totally destroyed.
I possess several specimens in which this form of cement-caries
has been artificially produced.
FIG 98.

DECAY OF CEMENT.
Enlargement of the lacunæ and gradual
liquefaction of the basis-substance
by bacteria. 800: 1.
When cement-corpuscles are present, they or their offshoots
(as far as I have had opportunity to examine such cases) are infil-
trated with bacteria and swollen (Fig. 98). I was not able to
determine any such inflammatory reaction on the part of the
cement as occurs, say in bone or cartilage.
DECAY OF TEETH WORN ON PLATES.
Some authors state that decay of human teeth, worn as arti-
ficial teeth, just as decay of natural teeth devoid of living pulps,
is exactly identical with and shows all the phenomena of decay
of living teeth. Other eminent authors, on the other hand,
describe appearances (transparency, thickening of Neumann's
sheath, etc.) which, they claim, occur in living teeth only. My
observations lead me to believe that all the phenomena of decay,
with the exception of transparency, which, strictly speaking,
cannot be regarded as a phenomenon of decay, occur in dead as
well as in living teeth. In fact, I have reproduced all artificially.
ARTIFICIAL DECAY.
The attempt to procure artificial decay has been made by many
investigators. Magitot made extensive experiments in order to
MÍCROSCOPICAL PHENOMENA OF DECAY.
195
determine the action on the teeth of various acids and salts, as
well as of fermenting albuminous substances and carbohydrates.
The fermentative substances especially showed a pronounced
action in the course of two years; when a tooth was so protected
that the agent touched it at one point only, nothing but the
exposed place was softened and destroyed. In this way a cavity
was produced which could in no wise be distinguished from a
natural cavity of decay. Magitot ascribed this action to the acids
arising in the fermenting mixtures, overlooking the further work
of the bacteria; he also neglected, unfortunately, to determine by
microscopical examination whether the tissue showed phenomena
identical with natural decay.
Similar experiments were afterward made by a number of
investigators, among others by Milles and Underwood. The
latter 119 constructed a large incubator, in which a mixture of milk,
bread, meat, saliva, and carious teeth was kept for six months
at blood temperature. No changes resembling caries occurred,
and this is easily conceivable from their own statements: "The
putridity of the baths was, however, so offensive that it was with
some relief that we decided to abandon this particular experi-
My health and appetite suffered from constant
exposure to all these putrid smells."
ment.
Milles and Underwood say nothing about the reaction in these
baths, but this "putridity" leads us to conclude that it most.
probably was alkaline. It cannot have been acid, since we are
told that the dentine was "not a bit softened." Now I think
that we are all pretty well agreed that there can be no caries
without acid; hence the failure in the above experiment.
In a second experiment the same authors subjected fragments
of teeth to the action of a mixture of saliva and bread for three
months.
It is not stated whether they renewed the mixture in this
time. It would be a serious mistake not to have done so, because
many bacteria are very sensitive to the action of their own pro-
ducts, and would be devitalized long before the close of the ex-
periment. (See page 14.) Besides, a thick felt of yeast-fungi
formed on the surface of the flasks, which probably also mate-
rially interfered with the course of the experiment. In this ex-
•
196
THE MICRO-ORGANISMS OF THE HUMAN MOUTH.
periment they obtained softening, but no discoloration. A micro-
scopical examination does not appear to have been made.
They came finally to the conclusion that artificial decay is an
impossibility, because the bacteria of decay lose their specific
power when cultivated out of the mouth.
Nevertheless, I affirm that a destruction of the tooth-substance
may be brought about artificially which the most practiced
microscopist will not be able to distinguish from real decay as
it occurs in the human mouth. In fact, not one of the many
microscopists who have made the attempt has been able to
determine which of a given number of preparations were arti-
ficial and which natural.
The chief object of my experiments was to produce the micro-
scopic appearances of decay of the teeth, since it had already
been proved by Magitot beyond doubt that by various means
macroscopical appearances may be produced which are identical
with those found in decay.
I cut up a number of teeth which were perfectly sound, but
of different density, into pieces of different size, and placed them
in a mixture of saliva and bread. This mixture was kept for
three months at a temperature of 37° C., and during the course
of the experiment repeatedly renewed. At the end of this time
I showed a number of these pieces to a well-known dentist of
thirty-three years' standing, and asked him if these were not.
peculiar cases of decay. He replied by saying that he saw such
cases every day in his practice. In many pieces the dentine was
softened through and through, in all to a considerable depth.
When the softening had penetrated through the dentine to the
inner surface of the enamel, the latter was found covered with a
layer of white powder exactly as it is found in natural decay.
Cracks and fissures in the enamel had an opaque, whitish appear-
ance, and in many cases could be easily penetrated by a sharp
instrument. At the neck of the tooth the dentine was likewise
much softened, though not to so great a degree as on the
crown. The border of the enamel was rough, and so brittle that
in many places an instrument could be inserted between the
enamel and the dentine. On the grinding-surface, in such cases.
where the structure of the tooth was imperfect and full of fissures
MICROSCOPICAL PHENOMENA OF DECAY. ·
197
3..
or depressions, the whole tissue had been converted into a soft
mass such as is often found on the surface of third molars.
In two cases, apparently on account of a defect of structure,
On those points
the cusps of the teeth had been attacked.
where the acid had penetrated through the enamel, its action
upon the dentine could be followed in all directions; where the
enamel was hard and thick, without cracks or other defects, it
had not even lost its natural polish.
All of the phenomena observed in cases of so-called white
decay were present in these cases of artificial decay. If the
mixture was allowed to stand until the reaction became alkaline,
or if the pieces were exposed to the air or to the action of dif-
ferent articles of food, such as coffee, tea, tobacco, fruit, etc., all
possible shades of color were produced just as they are found in
the mouth.
These experiments show, among other things, to what an
extent the resistance which the tooth opposes to the destroying
factors depends upon the structure; further, it furnishes an
answer to the question why all teeth under the same conditions
do not become decayed in the same degree. A tooth of sound
structure, protected by sound enamel, will resist the action of an
acid many years, whereas a soft, imperfectly developed tooth
under the same conditions would show decay in the course of a
few weeks.
Sections of these pieces showed all the microscopic changes
which have been described as characteristic of decay of dentine.
(See Figs. 99 to 101.) The canaliculi were filled with bacteria,
and at many points were much distended; the thickening of
Neumann's sheaths and the swelling of the fibrils could also be
well observed. A well-known dentist and histologist, to whom
I showed one of the preparations, at once called my attention to
the varicose swelling of the fibrils and to the distended canaliculi,
not knowing that he had an artificial preparation before him.
Up to the present, not one who has made the attempt has been
able to distinguish a specimen of artificial from one of natural
decay at its side.
When Atkinson 120 says, "There is not one of these cases that
cannot be discovered in an instant as to which is natural and
198
THE MICRO-ORGANISMS OF THE HUMAN MOUTH.
which artificial," and bases this declaration on the ground that
"in every one that was artificial the micro-organisms followed
the line of the tubules without striking into the consolidated
intertubular substance," he makes a double mistake which I
Fio. 99.
ARTIFICIAL DECAY.
Tubules infiltrated with cocci, distended
and in parts running together through
the liquefaction of the intertubu-
lar substance. Circa 400: 1.
Compare Fig. 77.
a
FIG. 100


Sa
C
ARTIFICIAL DECAY.
a, tubules distended and melted together;
b, normal tubules; c, tubule under.
high power (1100:1). Cross-
section.
FIG. 101.


b
a
TWO TUBULES FROM ARTIFICIAL DECAY.
a, filled with rods; b, with cocci.
Only those branches lying in one plane are
represented. 1100: 1.
think he will correct himself when he shall have acquired a
thorough knowledge of the appearances of natural and artificial
decay under the microscope.
One does not require to examine a very large number of prep-
arations in order to discover that both in artificial as well as in
CARIES OF ANIMAL TEETH. ·
199
natural decay the micro-organisms in the deeper parts of the de-
caying tissue are confined strictly to the tubules, whereas those
nearer the surface, although they do not strike into the basis-sub-
stance, yet they gradually liquefy it, and thus produce caverns or
microscopic holes in it which they immediately fill up.
My experiments have been repeated and their results con-
firmed by Foerster. Since 1884 I myself have repeated the
experiments a number of times, and have somewhat changed the
conditions by adding meat to the mixture and changing it every
second or third day. Not unfrequently the course of the ex-
periment is interfered with by the appearance of yeast-fungi,
particularly of Saccharomyces mycoderma, in the mixture. This
fungus appears as a white, thick, dry, felty skin upon the surface
of the mixture, and uses up the acid. In the course of a few days
putrefaction sets in and the mixture shows an alkaline reaction,
by which the course of the experiment is interfered with. If no
such disturbance occurs, the pieces will be so far decalcified in a
week that they may be easily taken up with a needle; after five
weeks sections may be prepared, and by making sections each
successive week one will be enabled to observe how the micro-
organisms in the course of time penetrate deeper and deeper
into the tissue and gradually bring about its destruction.
I do not look upon discoloration as an essential phenomenon
of decay, and do not therefore trouble myself about the color of
the dentine in artificial decay. It has appeared to me that where
nitrogenous substances were present the discoloration appeared
sooner than if only carbohydrates were used. A decalcified
tooth placed in a mixture of saliva and meat will become discol-
ored in a few days or weeks.
៩
:
CARIES OF ANIMAL TEETH.
It is commonly believed that dental caries either does not
occur at all in animals, or at best so seldom that the few cases
which may have been observed are to be regarded as striking
exceptions. And indeed we must grant that the teeth of animals,
compared to those of modern civilized races, are relatively seldom
attacked by caries. But if we compare the teeth of certain
kinds of animals with those of uncivilized human races which
200
THE MICRO-ORGANISMS OF THE HUMAN MOUTH.
sions.
subsist principally on meat, we arrive at quite different conclu-
The animals referred to are such as live on the same food
as civilized human beings, especially dogs and other domesticated
animals that feed on substances which form acids by fermenta-
tion.
All writers on this subject are, I believe, unanimous in the
opinion that decay is exceedingly rare in the case of carni-
vora.
Bland Sutton, who has occupied himself with this study for
many years, found only a small number of decayed teeth in car-
nivora, and these almost invariably in animals living in captivity
for some length of time.
I have obtained information confirming these observations
from the directors of various zoological institutes and veterinary
colleges.
On the other hand, according to my experience, every consid
erable collection of dogs' skulls will be found to contain one or
more decayed teeth, nor is decay of very rare occurrence in
horses and apes.
In two hundred and ninety-five dogs' skulls, mostly of bull- and
lapdogs, I found eighteen cases of decay; in six, two teeth were
decayed; in each of the remaining twelve, one. In two other
cases probably incipient decay (I could not decide with cer-
tainty whether the teeth were really decayed or not); these two
are therefore not included in the above number. In all these
cases it was invariably the first upper molar that was decayed,
which is explained by the fact that this tooth possesses deep
retaining-points for food-particles on the grinding-surface. The
fourth bicuspid also frequently showed signs of decay, but no
cavity. Decay occurs in these skulls in the proportion of 6 : 100,
which signifies much higher percentage than has been found in
Esquimaux and various Indian tribes. I succeeded in obtaining
material from the dry, decayed tooth of a dog, which being
soaked for a few hours in water, and then cut on the freezing
microtome and stained with fuchsine, yielded very fair micro-
scopic specimens. Through these specimens I was enabled to
establish the interesting fact that decay of dog teeth is accom-
panied by exactly the same phenomena as that of human teeth
CARIES OF ANIMAL TEETH.
201
(Fig. 102). Here also, as far as my observations reach, micro-
cocci are the chief destructive agents. In twenty wild dogs,
forty foxes, and forty jackals I discovered no decay. Among
forty-four apes I found one having a molar tooth with a large
cavity extending to the pulp, and two molar teeth with small
cavities on the grinding-surface. Of a small number of porcu-
pines' skulls examined, one had
a molar completely broken down
by decay, nothing being left but
the thin walls.
In horses, decayed teeth are
frequently found. In the patho-
logical collection of the Berlin
veterinary school there are two
skulls in which nearly all the
molars show pronounced decay
on the grinding-surface. Other
skulls also had decayed teeth.
Out of about forty normal skulls
in the collection of the agricul-
tural school I found but one tooth
which I could with certainty
pronounce as decayed. But it
is exceedingly difficult to recog-
nize decay in old, dry teeth of
horses unless it be already far
advanced. Dr. Galbreath men-
tions three badly decayed teeth
which he saw in the collection
of Prof. Dr. Günther, of Han-
over.
SJA
W
{
FIG. 102.

GROUP OF TUBULES FROM DENTINE OF
THE DECAYED TOOTH OF A Dog. 400 : 1.
In the side figure, piece of a tubule in the
beginning of the infection. 1100: 1.
The microscopical examination of decayed dentine from the
horse also showed the phenomena characteristic of human caries,
-invasions of bacteria, enlargement of the tubules, etc. (Fig.
103).
I have found the searching for decay in dry teeth of sheep
skulls no easy matter. The many folds, islands, and spaces
which are filled with remnants of food, and always intensely dis-
202
THE MICRO-ORGANISMS OF THE HUMAN MOUTH.
colored, render it still more difficult to perceive small cavities
here than in horses' teeth.*
FIG. 103.
20
MAIS
@
DECAYED DENTINE FROM A HORSE'S
TOOTH, showing the destruction of the
tissue by bacteria. 800: 1.
I have examined a few pig
skulls and found but one small
point of decay. Since pigs eat
much fermentable food, we
should expect decay more fre-
quently, in spite of the alkalin-
ity of their saliva, if the teeth
were not so compact, and par-
ticularly if the animals were not
slaughtered at so early an age
(two to three years).

The conditions which explain
the comparatively rare appear-
ance of decay in animal teeth
are, in my opinion:
1. The firm structure of ani-
mal teeth..
2. The nature of their food
(but little fermentable).
3. The alkalinity of their saliva.
4. The comparatively short time during which the teeth are
exposed to the causes that produce decay.
SPOTANEOUS HEALING OF DENTAL DECAY.
The process of decay, if not retarded by the proper treatment,
usually results in the complete destruction of the crown. Cases,
however, occur (comparatively seldom) which strangely deviate
from the usual course, in that the destructive process ceases spon-
taneously, and the already softened dentine becomes hard again.
This process is most frequently observed in the permanent first
molars, but it also occurs in milk-teeth. Some years ago I ex-
amined the mouths of a boy and girl (twins, three years old)
C
* In more than one hundred skulls I could not establish with certainty the
presence of any trace of decay. I was, on the other hand, astonished at the fre-
quency of exostoses and destructive processes on the roots of sheep teeth.
SPONTANEOUS HEALING OF DENTAL DECAY.
203
whose teeth were in a very bad condition. All the front and
several, molar teeth were so much decayed that I entertained but
little hope of saving them.
I made temporary fillings in a number of the teeth, and
directed the little patients to be sent back again in two months.
At the end of this time they punctually returned, but as the
decay had apparently made no progress in the unfilled cavities,
nothing further was done. All of these unfilled cavities, eight
in the front teeth and three in the molars, healed completely,
the dentine became hard and smooth, and no further loss of
substance occurred.
The healed dentine retains the color of the carious dentine, is
almost as hard as the normal, and according to the determina-
tions of Dr. Cohn, of Berlin, contains a much greater percentage
of lime than decayed dentine. Microscopic examinations of
healed dentine have not, as far as I know, been made. In two
cases of healed decay I prepared some sections, but was not able
to note anything characteristic. The invasion of the bacteria in
the cases examined had been superficial, a fusion of the basis-
substance had not taken place, and the dilatation of the tubules
was confined to the external layer. Results obtained from the
examination of only two cases are, however, naturally not to be
relied upon too implicitly.
Opinions concerning the cause of this healing vary. Accord-
ing to some authors, it is to be explained by a renewed deposit
of lime-salts in the softened dentine. Such a deposit could of
course occur only in places not yet invaded by bacteria. Others
maintain that no vital process of any kind, as a redeposition
of lime-salts, can take place in the completely developed dentine.
They regard the healing as being due merely to the dehydration
(drying) of the dentine. As is well known, the decayed dentine
of extracted teeth becomes somewhat hard. Further experiments
are necessary to determine which of these views is correct.
If we accept the dehydration theory, we shall find it very diffi-
cult, I am afraid, to explain how the dentine, continually bathed
with liquid as it is, can at all dry out in the human mouth, par-
ticularly how it can dry out in one tooth and not in others
which may be decayed in the same mouth. We shall, further-
204
THE MICRO-ORGANISMS OF THE HUMAN MOUTH.
more, in case the experiments of Cohn should be confirmed, be
unable to account for the smooth, shining surface and the in-
creased percentage of lime-salts in the repaired dentine. If we,
on the other hand, accept the recalcification theory, we have to
choose between two possibilities,-(1) the possibility of a recalci-
fication of the dentine; more or less complete restoration of the
lime-salts of the decayed dentine through the medium of the
pulp (a virtual restitutio ad integrum), which would not be in
accordance with the conception of Hoppe-Seyler (page 149); (2)
the possibility that new dentine may be formed at the expense
of the fibrils in the manner described under transparency of the
dentine. Without pronouncing my adherence to the vitalistic
theory, I think I may say that I am not quite satisfied with the
dehydration theory. We have here another subject for experi-
ment.
CHAPTER VIII
ETIOLOGY OF DENTAL DECAY.
HAVING acquainted ourselves with the physiological proper-
ties of the chemical and organic ferments occurring in the oral
cavity, as well as with the nature of the fermentations excited
by them, and having furthermore examined the chemical and
microscopical changes of the dentine characteristic of decay, and
shown the possibility of producing decay artificially, we now
come to the question: What is the cause of dental decay?
Dental decay is a chemico-parasitical process consisting of
two distinctly marked stages: decalcification, or softening of the
tissue, and dissolution of the softened residue. In the case of
enamel, however, the second stage is practically wanting, the
decalcification of the enamel practically signifying its total de-
struction.
After having discussed the processes of fermentation in the
mouth, it is not difficult to determine the source of the acids
which effect the decalcification. They are derived chiefly from
particles of amylaceous and saccharine substances which lodge
in the retaining-centers and there undergo fermentation. The
presence of an acid reaction in cavities of decay and in caries-
centers may be easily determined by the simple test with blue
litmus-paper. The test should not be made at the surface, but
in the deeper layers, after the remains of food and outer layers
of carious dentine have been removed. I examined two hun-
dred and thirty cases in regard to this question, and found the
reaction acid in two hundred and twenty-five, neutral in four,
and alkaline in one case. The latter five cases may be explained
by the predominance of albuminous substances (meat, gangre-
nous pulp-tissue, etc.) in the cavity at the time of examination.
•
K
205
206
THE MICRO-ORGANISMS OF THE HUMAN MOUTH.
Inasmuch as the fermentation of carbohydrates gives rise to the
production chiefly of lactic acid, and since lactic acid even in
dilute form speedily acts upon tooth-tissue (decalcifies it), there
can be little doubt that the acid reaction and the decalcification
of the dentine are produced in a great part by this acid. The
accuracy of the supposition may be easily proved by the Ewald
test. If we place a large piece of decayed dentine in a test
tube containing the solution given on page 106, and allow the
tube to stand in the dark for some time, a yellowish zone like a
halo will be formed about the piece, indicating the presence of
lactic acid with tolerable certainty, since we know that the other
substances which give this test (page 107) are not formed except
in very minute quantities.
The acids formed in the mouth by fermentation of starch are
quite as injurious to the teeth as those formed from sugar. The
assertion that starch is not injurious to the teeth rests upon no
experimental basis. On the other hand, it has been irrefutably
established by experiment that saliva containing starch at blood
temperature shows an acid reaction as soon and develops as
much acid in a given space of time as saliva containing sugar.
If we divide a quantity of saliva into a number of equal por-
tions, and add to each an equal quantity of different carbohy-
drates (sugar, bread, potato, starch, etc.), we shall find that those
containing bread and potato not only show an acid reaction
sooner, but even develop more acid in a given time than the
portions to which sugar has been added. Starch-paste and
sugar, as far as my observations go, react about equally strong.
Some very interesting experiments were performed by Ellen-
berger and Hofmeister,121 which show that under certain circum-
stances starch-paste, too, is more rapidly transformed into lactic
acid than sugar. An alkalinized pancreas-extract containing
grape-sugar kept at a specified temperature did not develop an
acid reaction till after forty-eight hours or more, whereas on the
addition of starch-paste an acid reaction appeared in twenty-
four hours. "Sugar in statu nascendi seems to be transformed
into lactic acid more quickly than in its ordinary state. In all
experiments on digestion with starch-paste, lactic acid is rapidly
developed."
ETIOLOGY OF DENTAL DECAY.
207
}
In all cases the starch is first transformed into grape-sugar by
the ptyaline of the saliva or of the pancreatic juice, and is then
split into lactic acid by the lactic acid ferment of various bac-
teria. Now, it is well known that many chemical bodies possess
other affinities at the moment of their formation than at other
times. According to the experiments referred to, this appears
to be the case with sugar. For other reasons, also, I consider
starch and amylaceous substances more detrimental to the teeth
than sugar, particularly as sugar, being readily soluble, is soon
carried away or so diluted with the saliva as to be rendered
harmless, whereas amylaceous matter adheres to the teeth for a
greater length of time and consequently manifests a more con-
tinued action than sugar.
Hesse's 122 observations in respect to caries of bakers' teeth lend
support to this opinion. He writes, "In the Dental Institute of
this city [Leipzig] I have had the opportunity of seeing a great
number of patients among the industrial and working classes, and
have been particularly surprised at the bad condition of the teeth
of our bakers. They are affected by caries to such a degree that I
have been able in many cases, since my acquaintance with this phe-
nomenon, to determine the calling of a patient by the condition
of his teeth. There can be little doubt that we have here to do
with a disease which stands in causal connection with the calling,
and the theory of caries recently propounded by Miller gives a
satisfactory explanation of it. A few confectioners' children are
the only individuals I have seen who could bear comparison with
bakers, although their teeth were not in quite so bad a con-
dition. Probably the millers may be able to compete with the
bakers, and it would be desirable to be enlightened on this
point."
Busch, on the contrary, is of the opinion that "baker caries"
is due rather to the inhalation of sugar-dust than to that of flour-
dust.
Different sugars manifest but little difference in their capability
of being split up into acids. Those kinds belonging to the
grape-sugar group-grape-sugar (dextrose), fruit-sugar (levulose),
lactose (galactose), and maltose-are directly fermentable and de-
compose according to the equation: CH₁₂O, 2C,HO. Cane-
-12 6
3*
208
THE MICRO-ORGANISMS OF THE HUMAN MOUTH.
sugar (saccharose) and milk-sugar become fermentable only after
hydratization.
C12H22O11 + H2O = C6H12O6 + C6H12O6. C6H12O6 = 2C3H¸O3
Cune-sugar.
Dextrose.
Levulose.
Lactic acid.
There seems to be no considerable difference of time in respect
to the beginning of the fermentation of the grape-sugar and
cane-sugar groups: the one is apparently about as detrimental
to the teeth as the other.
Fermentable albuminous substances mixed with saliva de-
velop but small quantities of acid, which soon disappear. They
are not injurious to the teeth, even though retained for some
length of time; they may even retard the progress of decay by
neutralizing the acid through their alkaline products. The most
diverging opinions prevail in regard to the participation of differ-
ent substances in fermentations arising in the mouth, none of
which rest on solid foundations. Above all, the conception that
albuminous substances (meat) putrefying in the mouth produce
acids is totally erroneous.
The facts mentioned on pages 27 and 115 cannot leave us in
doubt on this point. It seemed to me desirable, however, to
refute the above views experimentally, and at the same time to
establish the relative significance of different carbohydrates as
acidifiers. For this purpose I made over two hundred experi
ments with human saliva, and also a few with the saliva of dogs
and rabbits. 4.0 c.cm. of fresh saliva were mixed with 0.5 g. of
the food to be tested, and the reaction as well as the quantity
of free acid determined after the lapse of a certain time.
The results obtained are given in the following table. The
"acid unit” signifies that quantity of acid which is necessary to
neutralize 0.1 c.cm. of a 0.5 per cent. solution of caustic potash.
Material.
Bread (dry)
Starch
Cane-sugar
Grape-sugar
Potato (boiled).
Corn (in milk).
Duration of experiment.
12 and 30 hours
66
66
64
66
66
66
66
66
66
66
66
6.6
66
66
(6
Acid formed in acid units.
22 and 72
20 “
42
17 66
37
19 "
40.
24"
75
24 "
77
ETIOLOGY OF DENTAL DECAY.
209
Material.
Bread (1.0 g.)
Sugar (2.0 g.)
Rice
Macaroni
Meat
Meat (raw)
Fish
Eggs
Cheese
Spinach (in water)
Potato (raw)
Salad (raw)
Fat.
Material.
Starch
Meat (cooked)
Meat (raw)
Sugar
Bread
Potato
Material.
NO
Grass
Turnips
(6
،،
•
66
66
،،
፡፡
66
46
،،
*The sign
Duration of experiment.
12 and 30 hours
66
66
66
66.
66
66
66
66
C
،،
،،
،،
66
،،
66
66
66
6.6
С،
66
66
66
66
66
،،
66
(C
6.6
،،
66
66
،،
In but one series of experiments with dog saliva I obtained
the following figures (reaction strongly alkaline at the beginning
of the test):
#
66
Duration of experiment.
Reaction.
41, 12, 20, and 35 hours. always alkaline.
66
66
66
66
6.6
66
66
66
،،
46.
66
46
66
6.6
"
66
،،
66
66
66
66
66
66
،،
46
66
66
Acid formed in acid units.
35 and 110
20 "
41
25
66
20 "
0 66
66
0 66
0
0 66
0 66
0 66
0
Styli
66
denotes an alkaline reaction.
66
0
.. 0
(?)
For rabbits' saliva.
Duration of experiment.
4 to 12 hours.
alkaline.
4호 ​" 35"
up to thirty
hours alkaline, then an acid reaction set in, but not so
strong as when the turnips were crushed in water.
72
76
-3*
-5
-5
(?)
alkaline, putrid smell.
،،
acid after 20 hours.
،، 12 (C
66
Reaction.
The fresh saliva of both animals showed a strong alkaline
reaction.
The few experiments made for the purpose of comparing the
acidifying power of raw and cooked food seem to indicate that
14
210
THE MICRO-ORGANISMS OF THE HUMAN MOUTH.
raw vegetable food is less fermentable than cooked. Should
further researches prove that this is indeed the case, the cooking
of food would have to be reckoned among those customs of
civilization which have a detrimental influence upon the teeth.
It is well enough known that acids, brought into the mouth
as medicines or with the foods, may have a deleterious action on
the teeth. An excess of sour fruit, grapes, lemons, etc., and the
continued use of acids or acid compounds doubtless has a decal-
cifying action on the teeth, attacking first not the concealed but
the exposed parts.
Schlenker72 calls attention to certain substances which, coming
into contact with the teeth, either as food or as medicine, are
generally injurious, some to such an extent that their decalcify-
ing action becomes visible to the naked eye in the short space
of five minutes. I do not attribute too great an importance to
the influence of such substances, nor do I underrate them, since
a slight injury of the enamel or dentine caused by such agents
may give rise to decay at points which otherwise would have
escaped.
An acid reaction of the saliva is equally detrimental. This
is said to occur in rheumatism, gout, gastro-enteritis, diabetes
mellitus, dyspepsia, and various disorders of the alimentary
tract, in fevers (typhus, intermittent fever, etc.), in diseases of
the lungs, etc., and during pregnancy. According to some
authors, the mucus also, under certain circumstances, has an
acid reaction, and the attempt has been made thereby to explain
pathological phenomena, particularly at the neck of the tooth
(wedge-shaped defect, neck decay). Our knowledge of the
properties of mucus is unfortunately too limited to determine
accurately the part it plays in decay of the teeth. (See page 42.)
With less reason, it appears to me, Tomes, Black, and others
ascribe a destructive (probably meaning a decalcifying) action.
on the neck of the tooth to the "acid secretion" of the irritated
gums. No conclusive facts have been adduced for this supposi-
tion. On the other hand, it is well known that decay very
seldom occurs in cases of pyorrhoea alveolaris, in which the
gums are in a state of irritation for months together. When-
ever decay does accompany inflamed gums, we invariably find
1
ETIOLOGY OF DENTAL DECAY.
211
1
124.
pockets or spaces which, by retaining food-particles, serve as
centers of fermentation and consequent decay.
According to Coleman,123 the acid reaction of decayed dentine
is caused by the formation of an acid phosphate of lime, arising
from the disintegration of the lime-salts.
Bridgman explains the acidification by an electrolytic de-
composition of the buccal juices.
The second stage of caries, the dissolution of the softened dentine,
is caused by bacteria. We have seen that many mouth-bacteria
have the faculty of dissolving coagulated albumen or albuminous
substances, of peptonizing or converting them into a soluble
modification. We have also seen that the basis-substance of
dentine consists of an albuminous substance. The explanation
of the second stage of decay is therefore very easy, the more so,
since the liquefaction of the softened dentine by bacteria is
directly detectable under the microscope and may be easily ac-
complished experimentally. The dissolution of dental cartilage
(in fact, decay in general) has been designated as putrefaction, on
the whole an ill-chosen term, inasmuch as the characteristics
of putrefaction (alkaline reaction and bad odor) are entirely
wanting in a cavity of real decay. The decaying dentine shows
an acid reaction and emits a sour smell.* This stage of caries,
therefore, is a digestive process. The dental cartilage is dissolved
by the bacterium-ferment, as albumen by the pepsine of the
gastric juice.
We must rid ourselves of the impression, which the applica-
tion of the very unscientific and unprofessional name of bugs
to bacteria has no doubt tended to spread, that the parasites
of the human mouth make holes in the dentine by boring
into it as a worm bores into wood or by gnawing at it as a dog
gnaws at a bone. Bacteria have no apparatus for boring, nor do
they have mouths or any provision for breaking off small por-
tions of solid substances which they then swallow whole or take
directly up at any point of their periphery after the manner of an
amoeba. They nourish themselves alone by substances in a state
*Of course the odor of a gangrenous pulp or of suppurating gums, etc., must
not be confounded with that of the dentine.
212 THE MICRO-ORGANISMS OF THE HUMAN MOUTH.
of solution, and if we present them solid substances they them-
selves must liquefy them before they can make any use of them
for their own nourishment.
Upon this power of bacteria to liquefy substances of an albu-
minous nature depends the destruction of the softened dentine,
-in other words, the second stage of dental decay.
The objection has been raised against the chemico-parasitical
theory of caries, that the reaction of the saliva in any mouth is
no criterion for the extent of decay in that mouth. When the
reaction of the saliva is alkaline, decay has been found to be
extensive; and, on the other hand, cases have been reported
where an acid reaction of the saliva was not accompanied by a
corresponding amount of decay. None but a very superficial
investigator, however, would draw conclusions from a simple
examination of saliva.
The rapidity with which the process of destruction of the
teeth in any mouth advances is evidently directly proportional
to the intensity of the fermentations going on in the retention-
centers, and inversely proportional to the density of the tooth-
substance. Now, both of these factors are virtually independent
of the reaction which the saliva may show on escaping from the
ducts. A prolonged strong acid reaction of the saliva would
indeed render the fluids of the mouth less adapted to the devel-
opment of bacteria, and in so far as the acid could penetrate the
centers of fermentation tend to decrease the intensity of such
fermentation. Such a decrease would, however, be compensated
for by the action of the acid itself.
The case becomes very different when we turn our attention
to the free surfaces of the teeth. A prolonged acid reaction of
the saliva would of necessity manifest its disastrous influences.
upon these surfaces sooner or later, according as the teeth are
soft or dense in structure. Consequently, if anyone can show
me a case in which an acid condition of the saliva has persisted
for some months (not one in which the saliva chanced to react
acid just at the moment of examination, or one in which the acid
reaction was caused by bad litmus-paper, or by handling the
paper with sweaty fingers, etc.), I shall have no difficulty in
pointing out places at which its action is plainly manifest.
ETIOLOGY OF DENTAL DECAY.
213
1
The total absence of decay in a closed root-canal which has
for years been harboring a putrid pulp and innumerable bacteria
is a still less warrantable objection to the above-mentioned theory.
It evinces an entire ignorance of the vital conditions and fer-
mentative action of bacteria. For, in the first place, the bacteria
in a closed root-canal either perish, or, what happens more
rarely, become inactive as soon as the nutriment in the pulp is
consumed,-i.e., in a few days. In the second place, even
though they could really vegetate for years in a root-canal, we
should still have no reason to expect decay, because the carbo-
hydrates, essential to the formation of acids, are wanting. The
reaction of a putrid pulp is invariably alkaline.
!
Leber and Rottenstein 8 discovered after boring into two
incisors, which had a peculiar blue color without exhibiting a
trace of decay externally, that the entire interior of the teeth
was brown, completely softened up to the enamel, and that even
the root was hollow. Such very exceptional cases "must not
be identified with common caries." They are of such rare
occurrence that no satisfactory explanation of them has yet been
offered, and every one who reads the report of them can only
shrug his shoulders and wait for the day when he may have an
opportunity to examine such a case personally, an opportunity
which but rarely comes even once in a lifetime.
The view that during the disintegration of the pulp the acid
necessary for the softening of the dentine was formed, is untena-
ble, first, because the reaction of putrid pulps is always alkaline;
secondly, because even in case an acid reaction should take place,
under peculiar circumstances, all bacteria of the pulp would be
destroyed long before even a fraction of the quantity of acid
requisite to decalcification would be formed. We cannot as-
cribe this occurrence to a process of nitrification, such as occurs.
in the soil, since this demands free access of air.
In support of the inflammation theory, a difference has been
assumed between decay of living and dead teeth. It has been
asserted that the softened layer of dentine is much thinner,
dryer, and blacker in dead than in living teeth. Every practi-
tioner has surely seen phenomena which seem to agree with this
assertion, but a satisfactory explanation may be found without
Gal
}
214
THE MICRO-ORGANISMS OF THE HUMAN MOUTH.
much trouble. The alkaline products of the putrefying pulp
and of the inflamed suppurating or disintegrating gums neu-
tralize the acids formed in the dental cavity by fermentation.
The process of decalcification ceases, partially at least, whereas
the dissolution of the already softened dentine proceeds. The
decalcified layer of dentine must gradually become thinner under
such circumstances. If a just extracted carious tooth be kept
in a putrefying albuminous solution for some length of time, the
softening of the dentine completely ceases, while the dentine
which has already been softened gradually disappears.
-
THE MICRO-ORGANISMS OF DENTAL DECAY.
Our knowledge of the micro-organisms most directly con-
cerned in the destruction of the substance of the tooth is as yet.
very deficient. We have been able to establish the fact that all
micro-organisms of the human mouth which possess the power
of exciting au acid fermentation of foods may and do take part
in producing the first stage of caries; also, that all possessing a
peptonizing or digestive action upon albuminous substances may
take part in the second stage; and, finally, that those possessing
both properties at the same time may take part in the produc-
tion of both stages. But whether there is any one bacterium
which may always be found in decayed dentine, and which
might therefore be entitled to the name of the bacterium of tooth-
decay, or whether there are various kinds which occur with
considerable constancy, we are not able to say.
During my experiments upon the bacteria of decay in the
year 1883, I isolated four different kinds of bacteria from decay-
ing dentine. These I described in the Independent Practitioner
for July, 1884.
F
I have frequently met with them in more recent investiga-
tions, and they have also been observed by others. I do not
consider the experiments I then made sufficiently extensive or
conclusive to be incorporated here, and experiments now in
progress, with new methods and larger material, are not yet
concluded, it being necessary to examine at least fifty to one
hundred different teeth in order to arrive at satisfactory results.
The researches recently made by Vignal and Galippe,125 and
THE MICRO-ORGANISMS OF DENTAL DECAY.
215
reported in L'Odontologie, although not yet concluded, appear
to be deserving of more notice.
The investigators named have examined eighteen decayed
teeth, in all which they found four different kinds of bacteria ;
a fifth kind they met with eight times, and a sixth five times.
1. The first kind met with is a short, thick bacillus, not
forming chains. It has a length of 1.5μ, and is almost as thick
as it is long. In puncture-cultures, in gelatine, it grows tolerably
rapidly, forming a white trail, and begins to liquefy the gelatine
at the end of the third or fourth day, turning it white and
opaque. In plate-cultures it forms small, slightly prominent
colonies, which having attained a diameter of two to three
millimeters spread out in the liquefied gelatine.
2. The second kind is a bacillus 3.0μ long and about one-half
as thick, slightly constricted in the middle. Its cultures are
similar to those of the preceding, except that its colonies spread
out more upon the surface of the gelatine before liquefying it.
3. The third kind is a bacillus quite similar to the preceding,
showing, however, no constriction. It is square at the ends, and
forms quite long chains, particularly in liquid media. It does
not liquefy the gelatine, but slightly softens it.
4. The fourth kind is a very small, thin bacillus, almost as
thick as long, so that it might at first be mistaken for a coccus.
It forms a white trail in the gelatine, which it speedily turns
yellow and then liquefies.
5. The fifth kind, found but eight times, is a bacillus with
rounded ends, which forms at first a white trail in the gelatine
and then liquefies and clouds it.
6. The sixth micro-organism, found but five times, is a very
large coccus. It was found only in advanced stages of decay,
where the canaliculi were already considerably dilated, it being
too large to enter the sound tubuli.
It forms trails in the gelatine, which it does not liquefy, and
to which it lends a whitish aspect.
In a memoir, soon to be published, Galippe and Vignal
promise to present in detail the characters of the cultures above
mentioned.
216
THE MICRO-ORGANISMS OF THE HUMAN MOUTH.
PREDISPOSING CAUSES OF DENTAL CARIES.
In contradistinction to the exciting causes of caries, we char-
acterize as predisposing such conditions of individual or of all
teeth which divest them of their normal power of resisting ex-
citing causes, or by which they offer them especial points of
attack.
Predisposing conditions are only found in the teeth them-
selves, in their development, position, etc., while, on the other
hand, all external agencies are to be considered as exciting
causes. It is therefore not logical to regard gout, e.g., as a pre-
disposing cause, because it is accompanied by an acid reaction
of the saliva. The action of an acid on the teeth will always be
the same, whether it is secreted by the mucus or salivary glands,
or formed in the mouth by fermentation, or introduced from
without; it is invariably an exciting, not a predisposing cause.
1. The structure of the teeth plays the most important part as
a predisposing cause of dental caries. Poorly developed, soft,
porous teeth, with many large interglobular spaces, are highly
predisposed to caries. As a lump of table-salt dissolves more
rapidly in water, on account of its porosity, than an equally
large piece of rock-salt, porous dentine is more rapidly decalci-
fied than well-developed, firm dentine, because the acid may the
more readily penetrate the tissue, and because less acid is
required to decalcify a porous than a hard tooth. It may easily
be proved by experiment that poorly developed dentine is much
more rapidly attacked by acids than sound dentine. (See page
196.) Not only does the decalcification, but also the destruction
of the cartilage, advance more rapidly in the former case, be-
cause the micro-organisms, in many cases at least, enter the
interglobular spaces and more readily pervade and destroy the
entire softened tissue.
t
2. As a second predisposing factor I designate abnormally
deep fissures or blind holes (foramina cœca) in molars and super-
ior lateral incisors, especially in cases where the enamel also is
poorly developed. By their continual retention of food-particles,
such points directly induce caries, and offer but little resistance
to it in consequence of the absence of an intact protecting cover
of enamel.
PREDISPOSING CAUSES OF DENTAL CARIES.
217
3. In the third place, fissures or cracks in the enamel are
regarded as a predisposing cause. I have not, however, been
able to convince myself that decay frequently starts from these
enamel-cracks, often found in senile teeth. They are usually
too narrow to permit the entrance of food-particles, and conse-
quently do not serve as points of retention.
4. In the fourth place, teeth are predisposed to decay by a
crowded, irregular position. An instructive example is furnished
in cases where the first bicuspid stands inside of the arch, so as
to form a triangle with the second bicuspid and the cuspid; or
the second bicuspid forms a triangle with the first bicuspid and
first molar. It is impossible to keep the space between these
three teeth clean, and fermentation and acid formation continu-
ally occur there and attack the teeth. Not only in such cases,
but wherever a crowded position of the teeth favors the reten-
tion of food-particles, or renders their removal difficult, a pre-
disposition to caries prevails. The form of a tooth is not without
influence; teeth with convex approximal surfaces touching each
other at one point only (Fig. 104) are, cæteris paribus, less subject
FIG. 104.
Fio. 105.
m m
가
​to caries than teeth with flat or slightly concave surfaces (Fig.
105), because the latter cannot be kept so clean, either sponta-
neously (by the tongue, etc.) or with the brush.
5. A recession or loosening of the gums from the neck of the
tooth not only lays bare the dentine, but also permits the entrance
of food-particles between the necks of the teeth or into the
pockets formed by the loosening of the gums, by which means a
further predisposing cause for caries is furnished.
6. Many consider pregnancy as a predisposing cause. It is not
to be denied that during pregnancy women are particularly sub-
ject to caries. The reason for this is, however, probably to be
sought in the fact that the patients generally neglect the care
of the mouth during that time, and that the buccal secretions
218
THE MICRO-ORGANISMS OF THE HUMAN MOUTH.
assume an acid reaction; these are both exciting causes of decay.
Pregnancy itself can only be regarded as a predisposing cause
in so far as it effects a loosening of the gums or a change in the
structure of the teeth by a withdrawal of the lime-salts to build
up the foetal skeleton. Whether such an extraction takes place
has not been definitely ascertained.
7. Many believe that a predisposition to caries may be inher-
ited. It cannot be denied that badly developed, irregular teeth
may be and are inherited, and in so far inheritance may be con-
sidered as a predisposing cause of caries.
8. Wedl, Tomes, and others mention as predisposing causes
various general diseases, as rheumatism, gout, diabetes, gastro-
enteritis, dyspepsia, cancer of the stomach, scrofula, rachitis, and
tuberculosis. These diseases may indeed furnish the exciting
causes of caries by imparting an acid reaction to the buccal
juices, but how they can predispose the teeth themselves to caries
is not readily apparent, unless they render them more easy of
access to the exciting causes by concomitant gum-diseases as
described under 5.
I doubt whether climatic or geological conditions have much
to do with the origin of caries. Esquimaux, Lapps, Icelanders,
Arabs in Nubia, Patagonians, etc., have the best teeth in spite
of unfavorable climatic conditions.
INFLUENCE OF CIVILIZATION ON DECAY.
That decay of the teeth is not a disease peculiar to civilization
is proved by the manifold observations which have been made
on the skulls of ancient and modern uncivilized races in Europe
and America. A visit to any anatomical or anthropological
museum and an examination of a large number of race-skulls
will convince every one of the correctness of this assertion. Such
examinations have been made by Broca, Magitot,126 Mummery, 12
Barrett,128 myself,129 and many others, and invariably led to the
same conclusion, that decay has occurred in all races, civilized
as well as uncivilized, and at all times.
Races subsisting solely on meat (Greenlanders, etc.) come near
forming an exception to the rule, yet they appear to be not abso-
lutely exempt from decay. (See page 221.)
INFLUENCE OF CIVILIZATION ON DECAY.
219
That the frequency of decay is greater in civilized races than
among savages has also been established by numerous observa-
tions. Mummery's interesting communications are especially
worthy of mention. He found decay among the old Britons of
the dolichocephalous type in 2.94 per cent., among the brachy-
cephalous Britons in 21.87 per cent., among the Anglo-Saxons in
15.78 per cent., among the Romano-Britons in 28.67 per cent.,
and among the ancient Egyptians in 41.66 per cent.
There is no doubt that a deterioration of the teeth accompanies
the progress of civilization. The reasons for this are many. The
mode of life of most uncivilized races not only conditions a
sound, well-developed body, but the osseous system, of course
including the teeth, shows the same vigorous development, and
above all a compact structure. An individual whose youth is
spent in the open air, unrestricted in his bodily freedom, is likely
to possess a body better developed in all its parts than one who
has been brought up in a modern school-room.
The quality of the food also exerts an influence on the teeth
not to be underrated. They form no exception to the rule that
an unused member will be less perfectly developed than one
constantly used.
The pressure brought to bear upon the teeth by mastication
causes a more lively circulation in the periosteum and in the
pulp, thereby inducing an increased deposit of lime-salts or a
more complete calcification. Practical experience also teaches
that children brought up on soft food (broths, paps, etc.) gener-
ally have bad teeth. If a race of human beings or of animals
were to make no use of their teeth for several generations, we
should expect to find a gradual deterioration of the dental struc-
ture. It is, to say the least, highly probable that the soft qual-
ity of many of our foods, as compared to those of uncivilized
races, conditions a soft, porous dental substance, as well as an
imperfect development of the jaw-bone, and a concomitant
crowded position of the teeth.
Then again, the chemical composition of the food is of great
influence upon the origin and extension of caries. Whoever
grants the truth of our proposition,-no caries without acid,-and
recognizes the fermentative processes in the mouth as the chief
220
■
THE MICRO-ORGANISMS OF THE HUMAN MOUTH.
source of the decalcifying acids, and has verified our table (pages
208, 209), will hardly deny the correctness of this statement.
A person living on such foods only as undergo no acid fer-
mentation in the mouth (meat, raw vegetables, roots, etc.) will,
I am convinced, be but comparatively little afflicted with caries.
If this supposition were well founded, a comparison of the fre-
quency of caries among races subsisting on meat alone with that
of races who consume vegetable or mixed foods would yield
higher figures for the latter. Caries should also then be more
frequent in phytophagous animals than in carnivora.
That such investigations are connected with enormous diffi-
culties is apparent. It is extremely difficult or altogether im-
possible to eliminate other simultaneously present, especially
predisposing causes. In the second place, the statements of cer-
tain authors concerning the food of savage tribes do not always
agree, and furthermore suitable material for these examinations.
is extremely scarce in most anatomical collections.
Very interesting and valuable figures have been gathered by
Mummery, which are meant to establish the relation of caries to
the healthy or unhealthy manner of life of a given race.
These figures, with a few changes which concern the nourish-
ment of the races specified, and with the addition of those which
I have deduced from various anatomical and anthropological
collections, are presented in the following table:
ANCIENT RACES.
Ancient Britons
(dolichocephalous.)
Ancient Britons
(brachycephalous.)
Ancient Britons
(exploration of Green-
well.)
Ancient Britons
(mixed.)
Romano-Britons
Anglo-Saxons
Ancient Egyptians
•
No. of
Skulls.
68
32
· 59
44
143
76
36
Carics.
2
7
24
9
41
12
15
Percentage
of
Caries.
2.94
21.87
40.68
20.45
2867
15.78
41.66
Food.
Meat (beef, wild boar).
Mixed food (meat, fish,
oats, wheat, beans,
roots, etc.).
•
Je Ne Sanda
INFLUENCE OF CIVILIZATION ON DECAY.
221

MODERN RACES.
Esquimaux.
North Americans
(coasters.)
North Americans
(interior.)
South Americans
Feejee Islanders
Polynesians.
Sandwich Islanders
New Zealanders
Australians
Tasmanians
Chinese
East Indians (north)
East Indians (south)
·
•
Africans (east)
Kaffirs
Africans (west)
Lapps
•
•
•
No. of
Skulls, Caries.
81
63
22
26
38
79
21
66
132
33
50
152
71
32
49
236
22
2 2
2
72
8
∞ ∞ ∞
3
2
27
9
21
9
10
8
7
66
1 (?)
Percentage
of
Caries.
2.46
3.17
9.09
27.00
5.26
10.12
14.28
3.30
Meat and fish.
Meat and fish, probably
not quite exclusively.
Mostly meat, some vegeta-
bles.
Principally meat.
Human flesh and mixed
food.
Mixed food.
،،
(L
Human flesh, pork, fish,
roots.
Mixed food.
..
((
..
20.45
27.27
40.20
5.92
14.84
25.00
14.28
27.96
4.54 (?) Meat or fish, milk, cheese.
،،
((
(
เ
(C
Food.
،،
"mostly vegetable
(C
((
((
((
.
The Gauchos, a cattle-breeding tribe, inhabiting the pampas of
La Plata, and subsisting on meat, are said to be free from caries,
while a related tribe in Chili, that subsists on bread, beans, meat,
etc., showed 19.3 per cent. of caries. Again, those Gauchos who
live in cities, and who eat mixed food and much sugar, also suffer
much from decay of the teeth.
A hasty examination of several skulls led Black 130 to the sup-
position that those races which consume much sour fruit are less
afflicted with caries than those living on meat and grain. But
when we remember how the teeth are destroyed by a grape
cure, we can only regard the result of Black's investigation as
accidental, particularly as it was but a "hasty" one.
In one point, however, all examinations coincide. All authors
call attention to the fact that the Esquimaux, certain meat-eating
tribes of North American Indians, Icelanders, and, as far as I
have observed, Lapps also, are almost entirely exempt from
caries.
222
THE MICRO-ORGANISMS OF THE HUMAN MOUTH.
The immunity of these races cannot, it seems to me, be ex-
plained by the favorable hygienic mode of life, climatic influ-
ences, etc., alone. They often suffer from famines; various dis-
eases are frequent, especially among the Lapps, and the latter,
as well as the Esquimaux, are becoming extinct. That the
number of inhabitants of Iceland has remained stationary for
the last few centuries is said to be due to "volcanic eruptions,
frequent epidemics, unhealthy mode of life, famines, etc."
I think therefore every one will agree with me that the con-
ditions prevailing in the countries named are not to be regarded
as conducive to a perfect development of the human body.
Those factors which contribute to restrict the occurrence of
decay of the teeth are, in my opinion, (1) a mode of life favor-
able to the development of the whole body, (2) the use of food
which is sufficiently hard to afford the teeth the exercise neces-
sary for their vigorous development, (3) the use of food which
does not undergo an acid fermentation in the mouth."
CHAPTER IX.
PROPHYLAXIS OF DENTAL DECAY.
To every one at all acquainted with the nature of that con-
dition of the teeth denominated as decay, caries, etc., and with
the causes by which it is produced, it must be apparent that
there are four ways by which we may counteract or limit the
ravages of this disease. We may endeavor (1) by hygienic
measures to secure the best possible development of the teeth; (2)
by repeated, thorough, systematic cleansing of the oral cavity and
the teeth, to so far reduce the amount of fermentable substances
as to materially diminish the production of acid, as well as to
rob the bacteria of the organic matter necessary to their rapid
development; (3) by prohibiting or limiting the consumption of
such foods or luxuries which readily undergo acid fermentation
to remove the chief source of the ferment-products injurious to
the teeth; (4) by the proper and intelligent use of antiseptics to
destroy the bacteria, or at least to limit their number and
activity.
That a great influence is exerted upon the process of fer-
mentation in the human mouth by the mechanical cleansing men-
tioned under 2 may be easily proved by the following experi-
ment: Take 10.0 c.cm. saliva from the mouth in the morning
before cleansing it, add 0.5 gr. starch, and place the mixture in
the incubator. Then cleanse the mouth and teeth most thor-
oughly with the brush, toothpick, floss silk, etc., after which
take 10.0 c.cm. again (easily obtained by chewing a quill tooth-
pick or in the manner described on page 40), add 0.5 gr. starch
as before, and place also in the incubator. The first mixture not
only shows signs of fermentation sooner than the second, but
also forms much more acid in a given time. That different
*
S
223
224
THE MICRO-ORGANISMS OF THE HUMAN MOUTH.
kinds of foods and luxuries play vastly different rôles in the
fermentations of the human mouth must be apparent to every
one from the table given on pages 208, 209.
The substances which give rise to fermentation in the mouth
accompanied by the development of acid, belong almost without
exception to the group of the carbohydrates. The general
opinion that putrefying meat gives rise to products which attack
the teeth is, I repeat it, entirely unfounded and erroneous. The
products of a putrefying mixture of saliva and meat (whether
cooked or raw) are always alkaline, and when meat has remained
for some time between the teeth it may even act as a preventive
to decay in so far as it tends to neutralize the acids produced
by the fermentations of carbohydrates. The latter, however,
are, as a rule, unless the albuminous substances preponderate to
a great degree, more than sufficient to satisfy the basic products
of the albuminous fermentation (putrefaction), so that in case of
mixed diet the reaction will still be acid, not so strongly, how-
ever, as in purely amylaceous diet.
Most authors give sugar the chief place among those foods
which exert an injurious action upon the teeth-again a concep-
tion which is not quite right. It is true that the constant breath-
ing in of sugar-dust exerts a very destructive effect upon the
front teeth in particular, known as sugar-decay (Zuckercaries).
In general, however, the chief rôle in the production of decay is
performed by bread, potatoes, etc., not only because they produce
more acid, but because they, on account of their insolubility,
may remain for a long time sticking to or between the teeth,
whereas the readily soluble sugar is soon diluted or carried
away. In my opinion, sugar can equal bread in its destructive
action upon the teeth only when it is consumed as an ingre-
dient of sticky, insoluble substances.
Naturally, we cannot think of making the attempt to banish
the carbohydrates from the list of the foods and luxuries of
civilized races; but we may accomplish a great deal for the
teeth if we prevent the constant and unnecessary consumption
of sweets, etc., indulged in by many young and not a few adult
persons.
"
:
•1
PROPHYLAXIS OF DENTAL DECAY.
225
THE USE OF ANTISEPTICS IN THE PROPHYLACTIC TREATMENT OF
DECAY.
When at the beginning of the present decade, through the
most exact methods of bacteriological investigation now in use,
the true (parasitic) cause of one disease after another was brought
to light, we had many reasons to hope that the helpless position
of medicine in the presence of the severest infectious diseases
was soon to be changed. As yet, however, our expectations
have not been realized. With the exception of the still some-
what doubtful triumphs of Pasteur over anthrax and hydro-
phobia, very little advantage whatever has resulted to therapeu-
ties from the eminent bacteriological discoveries of the last ten
years. Consumption, cholera, typhus, diphtheria, syphilis, have
not become less terrible through the discovery of the specific
micro-organisms of these disorders.
Diseases which come under the treatment of the dentist form
no exception to this statement. The fact that decay of the teeth
is of parasitic origin having been once established, the thought sug-
gests itself that we ought to be able by means of properly chosen
antiseptic materials not only to arrest decay, but to prevent its
appearance. This is, indeed, the avowed object of the very
many antiseptic mouth-washes now in the market. As a matter
of fact, however, there is no evidence that anything whatever
has as yet been accomplished in the prophylactic treatment of
the teeth through the use of antiseptic mouth-washes, and it is
evident that anyone who would discover some means by which
the often fatal ravages caused by decay of the teeth might be
held in check would thereby confer a great boon on humanity.
It would, however, be going too far if we were to adopt the
views of those who have expressed the opinion that by proper
care of the teeth and constant use of antiseptic washes from
childhood on, decay would be entirely banished from the human
mouth.
This view is too optimistic for various reasons: chiefly because
there are places in every denture which will remain completely
untouched even by the most thorough application of the anti-
septic, or the antiseptic will reach them in so diluted a con-
dition that it possesses little or no action. If a very thorough
15
226
THE MICRO-ORGANISMS OF THE HUMAN MOUTH.
mechanical cleansing has not preceded the antiseptic, its action
upon the centers of decay will be equal to little more than zero.
A great difficulty lies further, in the fact that nearly all mate-
rials which possess antiseptic action are either contraindicated
altogether in the mouth, or that they may be used only in very
dilute solutions, either because they are injurious to the general
health, or locally to the mucous membrane or to the teeth them-
selves. Finally, many otherwise useful antiseptics are excluded
because of their bad taste and smell.
For these reasons the preparation of a mouth-wash which pos-
sesses an antiseptic action of any importance is accompanied by
the greatest difficulties.
Determinations of the antiseptic power of different materials
have been made in great number. Some of them which refer
especially to those materials which are made use of in the human
mouth may find place here.
Koch 131 found for anthrax bacilli the following numbers:
Sublimate
Thymol
Oil of turpentine
Oil of peppermint
Chromic acid
Oil of cloves
Iodine
Salicylic acid
Oil of eucalyptus
•
Hydrochloric acid
Camphor.
Benzoic acid
Carbolic acid
Boric acid
Chinin
•
•
•
Permanganate of potash
•
•
•
Benzoate of sodium
Alcohol
Table-salt
•
•
Evident retardation
of the development
Complete prevention
of the development
was produced by a concentration of
1 : 300000
1 : 1000000
1: 80000
1: 75000
1: 33000
1 : 10000
1 : 5000
1: 5000
1: 3300
1: 2500
1 : 2500
1: 2500
1: 2000
1 : 1400
1 : 1250
1: 1250
1: 830
1:200
1 : 100
1: 64
1:5000
1: 1500
1: 1700
1:850
1 : 800
1 : 625
1:25
According to Miquel, the development of bacteria in bouillon
is prevented by the following antiseptics in the given concentra-
tion:
PROPHYLAXIS OF DENTAL DECAY.
227
Mercurous oxide
Peroxide of hydrogen
Bichloride of mercury
Nitrate of silver
Iodine
Salicylic acid
Mineral acids
1 : 4000
1: 1000
1: 500 to 1 : 333
Antiseptics.
Bichloride of mercury
Nitrate of silver
Peroxide of hydrogen
Iodine
Iodoform
Naphthaline
Salicylic acid
Benzoic acid
Permanganate of potash
Oil of eucalyptus
Carbolic acid
Hydrochloric acid
Biborate of sodium
Arsenious acid
Chloride of zinc
Lactic acid
•
1: 40000 Carbolic acid
1: 20000
1: 14300
1: 12500
In the Deutsche medicinische Wochenschrift for 1884 I gave in
the form of a table the results of a series of experiments which
I undertook for the purpose of determining the action of a
number of antiseptics upon the bacteria of the human mouth.
This table, to which a number of materials have recently been
added, follows here:
Carbonate of sodium
Listerine
Absolute alcohol
Chlorate of potash
·
Permanganate of potash
Arsenious acid
Boric acid
Borax
Alcohol
·
•
•
•
•
1: 313
1 : 286
1: 270
1 : 130
1 : 14
1: 10.5
Development of
Bacteria prevented by
1: 100000
1: 50000
1 : 8000
1 : 6000
1: 5000
1: 4000
1 : 2000
1: 1500
1 : 1000
1: 600
1 : 500
1 : 500
1 : 350
1: 250
1: 250
1: 125
1 : 100
1:20
1: 10
1:8
It is evident that it would not do to tax the value of these
materials for therapeutic purposes exactly according to the above
numbers. Whoever, for example, would consider bichloride of
mercury, particularly for dental purposes, two hundred times
as active as carbolic acid would make a great mistake, since the
former can as a rule be applied only in dilute solutions, whereas
the latter may usually be made use of in concentrated form.
In connection with the antiseptic materials used in the human
228
THE MICRO-ORGANISMS OF THE HUMAN MOUTH.
mouth, the question of their adaptability demands particular
consideration; and in regard to this point I have examined a
number of the materials used in the treatment of the human mouth
in the same form and concentration as they may be made use of
in the form of a mouth-wash. Usually in rinsing the mouth the
solution remains from a few seconds to at most a minute in con-
nection with the mucous membrane and the teeth; and we need
accordingly for the purpose of sterilizing the oral cavity a ma-
terial which in the adapted concentration is able to devitalize
bacteria inside of a minute. How far this is accomplished by
the means at our command may be seen from the following
table:
Antiseptic.
*Salicylic acid
*Benzoic acid
Listerine
Salicylic acid
Bichloride of mercury
Benzoic acid
Borobenzoic acid
Thymol
Bichloride of mercury
Peroxide of hydrogen
Carbolic acid
Oil of peppermint in agreeable strength
Permanganate of potash
Boric acid
Oil of wintergreen
Tincture of cinchona.
Lime-water
•
•
•
•
•
Concentra-
tion.
1: 100
1: 100
1: 200
1: 2500
1: 200
1: 175
1: 1500
1:5000
10 per cent.
1: 100
1 : 4000
1:50
1:18
Time necessary
for devitalization.
1 minute
14
،،
Valdy
to minute.
(6
½ to a
1 to 2 minutes
1 to 2
((
2 to 4
2 to 5
10 to 15
10 to 15
5 to 10
more than 15 minutes
15
"( 15
(( 15
"
*CC
(L
no action.
"
"L
(L
((
((
((
"L
(C
"L
((
The above experiments were made in the following manner:
A determined quantity of a pure culture of a ferment bacte-
rium of the mouth is brought into 0.5 c.cm. of the antiseptic to
be tested, and then in determined intervals single drops of this
mixture are brought into test tubes containing 5 c.cm. of a
nutritive solution. If a development of bacteria does not take
place in any tube or tubes, it may be taken as an indication that
the bacteria were devitalized in the corresponding time.
* Salicylic and benzoic acids may be applied in this concentration only on the
brush.
PROPHYLAXIS OF DENTAL DECAY.
229
Control experiments were naturally made at the same time.
A number of tests which I made with a coccus found in a case
of mycosis tonsillaris benigna led to the same result.
It appears from the above experiments that only few of these
substances are serviceable for the purpose of cleansing the
mouth. The bichloride of mercury is the most active, not only
because it has the highest antiseptic power, but because its action
continues for a longer time. Even after the solution has been
removed from the mouth, traces remaining retain their anti-
septic action, even when they have been diluted from one to two
hundred times by the fluids of the mouth. None of the other
materials possess this property in so high a degree. Further-
more, sublimate appears to penetrate particles of food, deposits,
etc., more rapidly than the other materials given. I have satis-
fied myself by many experiments that it is possible, after a com-
plete mechanical cleansing of the mouth, to obtain by means of
sublimate (1-2500) an almost perfect sterilization of the mouth.
Unfortunately, the application of the bichloride of mercury is
limited, on account of its very poisonous properties.
As for salicylic acid, many are of the opinion that it attacks
the teeth (decalcifies them), and that it consequently should
never be used in the mouth. On the other hand, others deny
this action. I myself have seen it used for years without any
evil consequences, and do not fear to use it now and then in the
strength of 1-200 or 1-300.
In all diseases of the human mouth in which antiseptics are
indicated, particularly in acute infectious diseases, salicylic acid
may be used for a short time without any danger to the teeth.
For continual use perhaps the milder, though somewhat weaker,
benzoic acid in the concentration of 1-200 is preferable, unless
it should turn out that this also may have an injurious effect
upon the teeth.
Listerine has proved to be a very useful and active antiseptic.
This is a preparation of Lambert & Co., in St. Louis, consisting
of oil of eucalyptus, borobenzoic acid, wintergreen oil, etc.; it
owes its antiseptic property probably more to the borobenzoic
acid than to the oil of eucalyptus. It is to be applied on the
brush in cleansing the teeth, or slightly diluted as a mouth-wash.
230
THE MICRO-ORGANISMS OF THE HUMAN MOUTH.
For cleansing root-canals, cavities, etc., the more powerful anti-
septics are of course preferable.
Wintergreen oil and similar aromatic substances, which usu-
ally form an important constituent of mouth-washes, have as far
as I have examined them, in an adaptable concentration, very
little antiseptic action, unless the oil of peppermint is an excep-
tion. This possesses considerable antiseptic action, and is conse-
quently as a constituent of mouth-washes to be preferred to the
other ethereal oils. According to Black,132 however, oil of cassia,
oil of cinnamon, and oil of cloves have a much higher antiseptic
action than the oil of peppermint. The results obtained by
Black, in so far as they refer to the oil of cloves and oil of pep-
permint, are in direct contradiction to those obtained by Koch,
who found that the oil of peppermint has an action nearly seven
times as strong as that of the oil of cloves. This difference is
no doubt to be accounted for in the difference of the bacteria
experimented upon.
If we compare the two tables last given, we find some appa-
rent contradictions. For example, listerine, which is, accord-
ing to one table, forty times weaker than a 10 per cent. solution
of the peroxide of hydrogen, devitalizes bacteria much more
quickly than the latter. I am able to explain this remarkable
difference only on the supposition that the rapidity with which
an antiseptic acts need by no means be proportional to its
strength. We must furthermore distinguish clearly between
those substances which only prevent development, as indicated in
the first three tables, and those which devitalize, as indicated in
the last table. It is possible that an agent may prevent the
development of bacteria in very dilute solutions, and yet not
devitalize them even in more concentrated condition.
G
In the third place, it may be readily conceived that a highly dif-
fusible substance may penetrate the cell-membrane more quickly
and therefore act more rapidly than a less diffusible one, even
though the latter may retard or prevent development in a much
more dilute condition.
Recently I have tested salol, aseptine, and the acetate of alu-
minium in a similar manner. Salol is a very agreeable antiseptic,
but in my experiments it showed very little action.
PROPHYLAXIS OF DENTAL DECAY.
231
(1) Water.
Alcohol
Aseptine compared with thymol, sublimate, carbolic acid, etc.,
is a very weak antiseptic, but it has the advantage that it may
be applied in concentrated solutions. Acetate of aluminium
is an old medicament still adhered to by many physicians; it
combines considerable antiseptic power with a strong astringent
action. The strongest solution which may be used in the human
mouth had in some cases a marked action, but on the whole not
strong enough to encourage me in its use.
I finally made a series of experiments with various mixtures,
my aim being to combine a number of antiseptics in such a
manner as to produce the greatest possible antiseptic action with
the least possible action upon the mucous membrane and the
teeth, etc.
My experiments were made on the following mixtures:
Tinct. eucalypt.
Benzoic acid
Thymol
(2) Listerine
Water
•
(3) Aseptin
Water
Alcohol
Tinct. eucalypt.
Benzoic acid
Thymol
•
•
50.00
5.00
0.75
0.15
0.0125
25.5
25.0
25.00
25.00
5.00
0.75
0.15
0.0125
(4) Water.
Alcohol
Tinct. eucalypt.
Benzoic acid
•
Thymol
Bichloride of mercury.
(5) Water.
Aseptin
Salol
Alcohol
Acetate of aluminium
Benzoic acid
Thymol
Tinct. eucalypt.
•
50.00
5.00
0.75
0.15
0.0125
0.025
25.00
25.00
5.00
5.00
1.50
0.15
0.0125
0.75
These mixtures are not mouth-washes, but they might serve as
bases for mouth-washes, as indicated below.
The alcohol was added only as a solvent, not because of its
antiseptic powers.
As a mouth-wash, we need above all a solution which acts
quickly, and which does not simply prevent the development of
micro-organisms while it is acting, but which devitalizes them.
There are agents which, even in very dilute form, if applied
constantly have a powerful antiseptic action, inasmuch as they
prevent the development of such micro-organisms as may be
232
THE MICRO-ORGANISMS OF THE HUMAN MOUTH.
present without, however, devitalizing them; such agents are of
no more value as antiseptics in the treatment of the oral cavity
than an equal amount of distilled water. It is seldom that any-
one in rinsing his mouth will retain the wash longer than one
minute, and an antiseptic mouth-wash, to be efficient, should be
able to devitalize the micro-organisms with which it comes in
contact within this short time.
Solution No. 4 accomplishes this for nearly, if not for all,
micro-organisms in the vegetative form. A solution which de-
vitalizes spores in one minute is out of the question, and, in fact,
is not at all necessary, since the conditions which lead to the
formation of spores do not exist in the mouth, where we find
almost exclusively the vegetative forms.
This solution (No. 4) has a decided action in one-fourth to one-
half of a minute; in one minute the sterilization is nearly or
quite complete.
D
Next to this came the solutions Nos. 5, 3, and 1, in close order;
the addition of aseptin and acetate of aluminium, both of which,
but particularly the former, are antiseptics of considerable
strength, did not produce the hoped-for increase in the action of
the solution. The addition of salol had, as I anticipated, no effect
whatever. These solutions produced a decided diminution in
the number of colonies in half a minute; a complete steriliza-
tion usually required two minutes, sometimes even longer.
Nearly as strong as these solutions was a 50 per cent. solution
of listerine, which also has the advantage of a very agreeable
taste and odor.
·
Now, it very often happens that the centers of decay about the
teeth are filled with particles of food, and we do not in such
cases have liquids to sterilize, but solid substances impregnated
with micro-organisms; what effect can we produce upon these
by the action of the solutions given above?
To determine this question, a second series of experiments
was made in the following manner :
Small porous bodies (bread, meat, paper, etc.), of as nearly the
same size as possible, were saturated with bouillon containing
certain micro-organisms, or with stale saliva, then subjected to
the action of the antiseptic solutions during a specified length
PROPHYLAXIS OF DENTAL DECAY.
233
of time, after which they were brought into culture-gelatine and
the number of colonies which developed determined. The
stronger the antiseptic and the longer the time of exposure, the
less will be the number of colonies which develop in the culture
tube. As control, the experiment was repeated, using sterilized
water instead of an antiseptic solution.
To avoid transferring too much of the antiseptic to the culture
tube, each piece was placed for an instant on sterilized blotting-
paper, to remove the excess of liquid. I give the results of one
of these experiments below. In this solution No. 4 was made
use of, and small pieces of bread charged with bacteria subjected
to the action of the solution 20, 35, 55, 70, 90, and 120 seconds
respectively. The control tube developed 4500 colonies:
Tube 1 (20 seconds action) developed 420 colonies.
66
66
66
66
66
2 (35
)
46
250
13
6.6
66
66
66
3 (55
4 (70
5 (90
6 (120
66
66
66
66
66
66
66
66
66
66
66
(6
) remained sterile.
،،
1 colony.
It may appear strange that tube 3 should develop more colonies
than tube 2, but such irregularities often occur, owing to the
fact that it is not possible to obtain pieces of bread or meat of
exactly the same size and consistency. The result of the experi-
ment is, however, very clear. When large compact pieces were
used (as large as a pea, for example), such as may sometimes be
found in cavities of decay, it required as much as ten to fifteen
minutes to effect a complete sterilization. The lesson is plain.
Even such a powerful wash as the one under consideration will
accomplish but little in sterilizing the human mouth when the
centers of decay are stuffed full of food. This is also the reason
why excessive smoking, notwithstanding the fact that tobacco-
smoke is a powerful antiseptic, does not insure the teeth against
decay; the smoke passes over the surface, but does not penetrate
to the point of action. It follows that the use of the mouth-
wash should always be preceded by the thorough use of the
brush or toothpick, removing at least all larger particles of food
and opening the spaces between the teeth, so that the wash may
234 THE MICRO-ORGANISMS OF THE HUMAN MOUTH.
penetrate to the vulnerable point. If this is conscientiously
done, I think that we have in solution No. 4, and, in a less
degree, in the other solutions specified, a powerful means of
preventing the excessive ravages of decay. The solutions 1 and
4 may be made use of in the following form :
No. 1. Thymol
Benzoic acid
Tincture of eucalyptus
Alcohol
Oil of wintergreen
(or oil of peppermint .
0.25 grams.
66
3.00
15.00
100.00
25 drops
. 20 66
Acid. thymic.
Acid. benzoic.
Hydrarg. bichlorid.
Tinct. eucalypt.
Alcohol absolut. .
Ol. gaultheriæ
(C
In use, enough of this mixture is added to a mouthful of
water to produce a decided cloudiness.
0.25
3.00
0.80
. 15.00
100.00
gtt. xxv.
66
The wash, no doubt, may be rendered softer and more palat-
able by the addition of glycerine, tincture of catechu, or some-
thing of the kind. Perhaps some one who is interested in
mouth-washes will kindly undertake the task.
No. 4 is prepared in the same way, with the addition of 0.8
bichloride of mercury:
)
{
One naturally hesitates to prescribe a mouth-wash which con-
tains bichloride of mercury, but I think a more thorough con-
sideration of the question will show that it is not so reprehensible
an act as may at first appear.
The strength in which the bichloride is used in the mouth is
about. Let us suppose that the patient swallows of the
solution two grams daily (as a matter of fact, one need not
swallow any at all); it would require one hundred days to have
swallowed 0.1 gram of the salt, which is the maximum dose for
one day. In this matter, however, reasoning is of little value;
PROPHYLAXIS OF DENTAL DECAY.
235
nowhere is the saying in medicine, experience is of greater value
than reasoning, truer than in questions dealing with the physi-
ological action of the salts of mercury. I, myself, have made
extensive use of the above formula without a trace of any physio-
logical or toxicological action, and if a sufficient number of
members of the profession would make a trial of this solution
upon themselves, and report the results, a great deal would be
done toward solving the question of the advisability of recom-
mending the wash in practice.
The taste of the bichloride is exceedingly disagreeable, even
in dilute solutions; it may to a certain extent be disguised by
the use of rose-water in place of aqua destillata as a solvent, as
suggested by Allan.
Unfortunately, our pharmacopoeia is not yet so rich that the
physician or dentist can restrict himself to the use of good-tast-
ing medicaments.
3
I have been informed by some who have used the bichloride
as a mouth-wash that whereas it has most excellent effect in all
suppurative diseases of the gums, it discolors the teeth. This
of course would be a serious disadvantage if it should prove
to be true. All the discoloration I have ever observed could
be readily removed with brush and powder.
On the whole, however, the fear of a possible toxic effect from
the bichloride, which, in consideration of the fact that certain
individuals are extremely sensitive to the action of this drug, we
shall scarcely be able to escape from, will probably prevent its
ever being extensively introduced except for occasional use in
acute infectious and putrid conditions of the mouth. I per-
sonally have never prescribed it for prolonged use, except for a
few friends who were in a position to control its action. From
such the only complaint I have heard has been of its bad taste.
Witzel is enthusiastic in his praise of sublimate in the treat-
ment of putrid and septic conditions of the mouth.
"A few
drops of a 2 per cent. ethereal solution of sublimate in a glass
of water suffice to remove for a short time the most offensive
smell from the mouth." "Syringing the alveoli with sublimate
1-1000 followed by the injection of six to eight drops of a 2 per
cent. solution into the septic parts
as most sover-
236
THE MICRO-ORGANISMS OF THE HUMAN MOUTH.
eign medicament in case of septic alveolitis." In septic wounds
following extractions, syringing with sublimate 1-1000 twice a
day was continued for eight days with most beneficial results,
etc.
In the last few years a large number of different materials
have been recommended as disinfectants for the mouth. The
most of them, however, have been as yet too little tested to
enable us to give an estimation of their value.
Von Kaczorowski 133 recommends iodine-chloride of sodium
solution (Natrium chloratum 1 per cent., Tr. Iodi 0.5 per cent.),
one-half to a whole teaspoonful every quarter to half hour.
Truman praises hydronaphthol, which he finds as efficient as
it is harmless.
Black 132 recommends a mixture of carbolic acid 1, oil of winter-
green 2, oil of sassafras 3. Others recommend iodol, sozoiodol,
betanaphthol, sanitas oil, etc.
Witzel 134 recommends his so-called 20 per cent. solution of sub-
limate, for root-treatments, which, however, is said to discolor the
teeth. Personally I use a 1 to 5 per cent. solution for the same
purpose, and a to 1 per cent. solution for syringing abscesses or
suppurating wounds after extraction, and for the latter purposes
in particular find it decidedly superior to either 2 per cent. carbolic
acid or 5 per cent. peroxide of hydrogen.
Busch 135 has obtained most beneficial results from the use of
peroxide of hydrogen, particularly in putrid and septic condi-
tions of the gums, and is of the opinion that no other antiseptic
at present in use is to be compared with this. He adds a suffi-
cient quantity of the so-called 10 per cent. solution to water to
produce about a 2 to 3 per cent. solution for rinsing the mouth.
Harlan has also enriched the dental materia medica with a
considerable number of new antiseptics.
C
I lay no particular value on tooth-powder as a means of clean-
ing the teeth. It is true that the external surfaces, particularly
of the front teeth, may be kept whiter by the use of tooth-pow-
der, but the centers of decay are more liable to become stopped
up than to be cleansed by tooth-powder, particularly when they
contain insoluble constituents.
Somewhat more recommendable I find the tooth-soaps, in so
THE ANTISEPTIC ACTION OF FILLING-MATERIALS.
237
1
4
far as they dissolve fatty substances without attacking the teeth,
and, furthermore, possibly make the penetration of the bristles
of the tooth-brush into the center of decay somewhat more easy.
They should be made of neutral soap, and have a neutral or
slight alkaline reaction. Under all conditions, however, the
chief thing is the thorough mechanical cleansing of the teeth.
THE ANTISEPTIC ACTION OF FILLING-MATERIALS.
It will scarcely be questioned by anyone acquainted with the
nature of those diseases of the teeth which we treat by filling,
that in a great many cases, if not in all, the probability of suc-
cess would be greatly heightened if the filling-material could be
made to exert a permanent antiseptic action upon the walls and
margin of the cavity. This is more particularly true of all cases
where, for some reason or other, carious dentine is left in the
cavity at the time of filling; and such cases constantly occur in
every dental practice. There are, I hope, very few practitioners
in dentistry who place so high an estimate upon their own skill
and thoroughness, or so far overlook the imperfection in the
structure of the dentine, as to imagine that they excavate every
cavity perfectly. Many even prefer leaving a thin layer of soft-
ened dentine in the cavity to removing it, if the pulp would
thereby be exposed. Others, no doubt, for very humane reasons,
sometimes excavate less thoroughly than they otherwise would
do, in order to spare their patient the excessive pain accompany-
ing the operation, or because the patient cannot or will not bear
the pain. Most of us, for the sake of our backs, toward the end
of a hard day's work, now and then decide that a difficult cavity
is ready to fill when a careful examination of it might still reveal
soft points. It is not necessary, however, to enumerate other
cases in which the preparation of the cavity is not quite fault-
less; most readers will no doubt be able to suggest many more.
Now, it may appear remarkable that, while so much attention
has of late years been bestowed upon the antiseptic treatment of
root-canals and the employment of antiseptic materials for fill-
ing them, very little attention has been given to the subject of
the antiseptic materials for filling cavities of decay; iodoform
ANN
238
THE MICRO-ORGANISMS OF THE HUMAN MOUTH.
cement being, as far as I know, the only material which was
introduced with this object in view. That it does not accom-
plish its object will, I think, be apparent from the experiments
recorded below.
METHODS.-I.
Various methods may be employed for determining the anti-
septic action of filling-materials. The two which I have made
use of are exceedingly simple, and at the same time very instruc-
tive. In applying the first of these methods we proceed as fol-
lows: A tube of ordinary nutritive gelatine is infected with a bac-
terium from the oral cavity, which grows rapidly at room tem-
perature without liquefying the gelatine. The gelatine is then
melted, slightly shaken, so as to distribute the fungi equally
throughout the solution, and poured upon a horizontal sterilized
glass plate, upon which we drop pieces of the filling-material or
other substances whose antiseptic action we wish to determine.
As soon as the gelatine becomes stiff we place the plate in a
damp chamber. A plate prepared in this way, without the addi-
tion of any material having an antiseptic action, will become
cloudy and opaque in the course of twenty-four to forty-eight
hours, through the development of innumerable colonies of bac-
teria. If, however, the pieces of filling-materials which we have
dropped upon the plate possess an antiseptic action, the devel-
opment of the fungi in their neighborhood will be retarded or
altogether prevented, and each piece will appear surrounded by
an area of transparent gelatine whose size will depend upon the
activity of the antiseptic employed. Most of the filling-materials
in use were tested by this method in respect to the antiseptic
action, with the result that the only one which possesses such
action and retains it for an indefinite time after it has been in-
serted is copper amalgam.* Not only freshly-mixed fillings, but
pieces of old, half-worn-out fillings, taken from teeth extracted
in the polyclinic of the Dental Institute, and even pieces of den-
tine from teeth which had been filled with copper amalgam, in-
Ca
pada
-*- Regarding an unexpected antiseptic action of certain preparations of gold
which might appear to furnish an exception to this rule, see the experiments.
described below.
!
THE ANTISEPTIC ACTION OF FILLING-MATERIALS.
239
variably manifested a retarding or preventing action upon the
growth of bacteria. (Fig. 106.)
Fa
These results accord exactly with those which I obtained by en-
tirely different methods in 1884 (Independent Practitioner, June),
and which have been called in question by Bogue and others.
Of course it must not be inferred from these remarks that a
little piece of copper amalgam dropped into a liter of bouillon
will keep it from spoiling. Nor would an experiment of this
nature be a just test of the antiseptic action of a material used
in filling.
Se
a
a
Db
FIG. 106.

Po
M
00%
•0
d
AFLAT
d
C
c
AN INOCULATED GELATINE PLATE containing: a, pieces of oxyphosphate cement one day
old; b, pieces of gold amalgam one day old; c, pieces of an old copper amalgam filling, age
unknown; d, pieces of stained dentine from a tooth which had been filled many years pre-
viously with copper amalgam.
1
If the filling prevents the progress of decay in softened den-
tine under it or in immediate contact with it, and if it retards.
the progress of fermentation in fine spaces (leakages) between it
and the marginal wall, then it is doing a great deal toward pre-
venting the recurrence of caries, which another filling not pos-
sessing antiseptic properties would not do.
That so much is accomplished by copper amalgam, I am, I
believe, justified in concluding from the experiments enumerated
above, and more particularly from those made under the second
method and described below. It is a view, moreover, pretty
generally accepted by all operators who have had opportunity
240
THE MICRO-ORGANISMS OF THE HUMAN MOUTH.
of observing the action of copper amalgam fillings, that they do
possess a preserving action upon tooth-substance. I, along with
most others, formerly accounted for this action upon the sup-
position that copper amalgam does not shrink while setting. I
meet almost daily with amalgam fillings, not containing copper,
which admit of the point of an excavator being inserted between
the filling and the margin of the cavity, whereas copper amal-
gam fillings appear to hug the walls of the cavity perfectly.
b
FIG. 107.

a
a
a
a
α
AN INOCULATED GELATINE PLATE containing pieces of freshly-mixed cement. a, oxychlo-
ride; b, oxyphosphate. A very marked hindrance in the development of the bacteria is noted
around the pieces of oxychloride: around the pieces of oxyphosphate it is scarcely percep-
tible. Plate twenty-four hours old.
*
Elliott, however, found by a very extended series of experiments
that copper amalgams do contract, and some of them to a sur-
prising degree. Elliott's results are corroborated by the evidence
of J. Boyd Wallis,† who claims that the slight contraction is a
distinct advantage in the case of soft and sensitive teeth, because
of the more speedy formation of the oxide or sulphide, which,
being absorbed by the surrounding dentine, protects it from
further progress of decay. "Pulps dying under copper amalgam
* Transactions of the Odontological Society of Great Britain, December, 1888.
+ Dental Record, February, 1889.
THE ANTISEPTIC ACTION OF FILLING-MATERIALS.
241
fillings do not so readily decompose, owing to their becoming
charged with antiseptic cupric salts."
Other materials experimented with by the first method were
gold amalgam, oxychloride of zinc (agate cement), oxyphosphate
of zinc (Caulk's cement), gutta-percha, gold, tin, and tin-gold.
Gold amalgam, freshly mixed, caused a slight retardation in the
development of bacteria; old pieces had no effect. Oxychloride
of zinc, fresh, had a very marked action. (See Fig. 107.) Pieces
which had lain twenty-four hours in saliva and bread lost their
antiseptic power. Oxyphosphate of zinc, fresh, had a slight, in-
e
1.
f
FIG. 108.

C
CL
INOCULATED GELATINE PLATE containing Pack's pellets and Abbey's foil No. 4, fulded to
make strips of No. 32. a, b, c, d, annealed; e, f, g, unannealed. The latter have retarded the
growth of the bacteria in their neighborhood, as is shown by the gelatine remaining clear. Plate
twenty-four hours old.
constant action (Fig. 107), sometimes none at all. After twenty-
four hours' exposure in a mixture of saliva and bread, it showed
no action whatever; gutta-percha and tin proved completely in-
active.
The results obtained with gold were very peculiar and perplex-
ing. Some preparations of gold manifest a decided restraining
effect upon the development of bacteria, so that if a pellet is
dropped upon the plate it will after twenty-four to forty-eight
hours appear surrounded by a perfectly round circle of trans-
parent gelatine, separated from the clouded gelatine by a sharp
Gal
16
242
THE MICRO-ORGANISMS OF THE HUMAN MOUTH.
V
border. Within this zone the bacteria develop very slowly, so
that the cloudiness appears much later than on other parts of the
plate. The antiseptic action of Pack's pellets was particularly
marked. Plugs of the unannealed pellets made in holes bored
in wood showed considerable action, even after they had lain for
forty-eight to seventy-two hours in a mixture of saliva and bread.
Also Abbey's soft foil and quarter-century foil showed similar
action, but in a somewhat less degree. Other preparations
showed varied effects; some were almost or quite indifferent.
The antiseptic action was completely destroyed by annealing the gold
beforehand (Fig. 108). Some preparations of sponge gold and
platinum gold acted in a similar manner, and even old gold fill-
ings now and then showed considerable antiseptic action.
S
I shall not attempt to give any explanation for these facts now.
Different explanations suggest themselves, none, however, with
which I have been quite satisfied. Nor will I at present en-
deavor to answer the question whether the action is strong
enough to be entitled to any consideration as a saving property
of unannealed gold. I am inclined to think that it would be
rather venturesome to assert that it is.
Tin-gold was less active than gold alone.
I applied this method of testing the antiseptic property of
filling-materials to a few other substances; among them to iodo-
form, which did not have the slightest action in checking the
growth of the micro-organisms tested.
II.
In order to make a direct test of the action of fillings upon
carious dentine or upon the micro-organisms contained in it, we
proceed as follows: A number of freshly-extracted teeth which
are extensively decayed, not, however, so as to expose the pulp,
are cleansed of the remains of food, and only partially excavated,
so as to leave a thick layer of carious dentine in each cavity.
The cavities are then filled with various substances whose
antiseptic action we wish to test, and the teeth placed in a mix-
ture of saliva and bread and kept for three days at a tempera-
ture of 30° C. to 40° C. At the end of this time they are taken
out, washed in pure water, placed for a moment in sublimate
THE ANTISEPTIC ACTION OF FILLING-MATERIALS.
243
1
1-1000, then in a larger quantity of sterilized water to remove
the sublimate, after which they are dried with sterilized bibulous
paper. We then take the teeth by the root or roots, rest the
side of the crown upon a small anvil, and strike a sharp blow
upon it with a hammer. The filling flies out, exposing the un-
touched surface of carious dentine. We now with a sterilized
spoon-shaped excavator remove a small piece of the carious den-
tine and place it upon a previously prepared plate of sterile
nutritive agar-agar. The plate is then put away in a moist
FIG. 109.

A STERILE AGAR-AGAR PLATE, containing in the left half pieces of dentine from a cavity
which had been filled with copper amalgam, in the right half pieces from a cavity which had
been filled with gold amalgam. The former have remained sterile, whereas an extensive
growth of bacteria has taken place around the latter. Plate three days old.
chamber at or near the temperature of the human body. If now
the bacteria in the carious dentine have been killed by the action
of the filling-material, or if the dentine has been so acted upon
by the material as itself to become antiseptic, no growth will
develop around it; otherwise we will find in the course of forty-
eight to sixty hours that the piece of dentine becomes surrounded
by a growth of varying extent.
In examining the plates, a low power of the microscope
should be used in cases where a growth is not visible to the
naked eye. Furthermore, a slight cloudiness or precipitate
which sometimes forms around pieces impregnated with copper
salts must not be mistaken for micro-organisms; and lastly, a
development of bud-fungi (yeast-fungi, Saccharomycetes), or
mould-fungi (Hyphomycetes), which is very frequently observed,
must not be mistaken for bacteria (Schizomycetes).
244
THE MICRO-ORGANISMS OF THE HUMAN MOUTH.
The following materials were examined by this method:
1. Copper amalgam (Lippoldt's). Fifteen teeth were treated
as described, and the carious dentine examined by culture. In
not a single case did a development of bacteria take place.
They had either been devitalized or the dentine itself had be-
come antiseptic. In two cases bud-fungi developed; in one
case mould-fungi.
2. Gold amalgam, ten teeth. In all cases a development of
bacteria took place around the dentine, to say nothing of bud-
and mould-fungi (Fig. 109).
3. Oxyphosphate, eight teeth. Result same as with gold
amalgam.
4. Oxychloride of zinc, eight teeth. In seven cases a growth
of bacteria formed, though very much retarded when compared
with the oxyphosphate or gold amalgam. In one case the piece
remained sterile.
GRA
5. Iodoform powder mixed with phosphate cement, one tooth.
Development of bacteria unchecked. In another case the floor
of the cavity was covered with powdered iodoform and oxyphos-
phate filled over. Pieces of dentine taken from the cavity after
three days and transferred to the culture plate were soon sur-
rounded by a growth of bacteria and bud-fungi.
6. Powdered sulphate of copper incorporated with cement or
with gutta-percha, or simply strewn upon the bottom of the
cavity before filling, nine teeth. No trace of bacterial growth
appeared in any case.
From these results we are forced to the conclusion that copper
amalgam fillings exert a marked antibacterial influence
upon the
walls of the cavities containing them, that oxychloride cements
have an appreciable though markedly less effect, and that oxy-
phosphate and gold amalgam are wanting in any such action.
We learn, furthermore, that by incorporating certain antiseptics
into the mass of the filling or covering the bottom of the cavity
before inserting the filling we may produce an effect analogous
to that of copper amalgam.
Can any application of these results be made in practice? I
think so, though I am certainly not in favor of being over-hasty
in drawing conclusions.
THE ANTISEPTIC ACTION OF FILLING-MATERIALS.
245
Personally, I have always had much faith in the preservative
properties of copper amalgam fillings, because I have had abun-
dant opportunity to observe the splendid results obtained by its
use even when very little care was taken in its insertion. The
experiments which I have made have naturally served to
strengthen my confidence in this material, in consequence of
which I have been using it to some extent in my practice.
At the cervical margin I often put a layer of copper amalgam,
and then fill the rest of the cavity with some other material.
In cases of complicated caries extending under the gum and very
near the pulp, where phosphate fillings are utterly unreliable,
and even combined with gutta-percha often very unsatisfactory,
and where it is not considered wise to risk a permanent filling
at once, I protect the neck of the tooth by copper amalgam,
allowing a very thin layer to extend over the floor of the cavity
in order to thoroughly sterilize the dentine and keep it sterile.
I then fill the remaining part of the cavity with cement or gutta-
percha, with the intention, in case all goes well, of replacing it in
some months by a permanent material.
I am inclined to believe that the use of antiseptic materials
may be accompanied by excellent results also for capping ex-
posed pulps, particularly when they are not in a healthy con-
dition, or contain germs of infection, as well as for covering the
floor of the cavity in all cases where the pulp is protected by
but a thin layer of dentine, which is very often more or less
softened, or even infected with bacteria. For this purpose sul-
phate of copper, incorporated with gutta-percha or with some
soft cement like oxysulphate, would, I am convinced, go far to
effectually sterilize the thin layer of dentine covering the pulp, and
thereby to prevent not only the decomposition of such softened
dentine as may have been left over the pulp, but also the infec-
tion of the latter, which is very often the cause of pulp-troubles
arising under fillings.
DO
The sulphate of copper, however, seriously stains dead teeth
in the course of three days, and would probably act with equal
rapidity upon living teeth, so that its use would be on that ac-
count very much restricted, if not altogether contraindicated.
Dr. Cunningham, of Cambridge, informs me, however, that he
246
THE MICRO-ORGANISMS OF THE HUMAN MOUTH.
has been using the sulphate of copper in this manner for some
time, without any discoloration resulting.
Various substances suggest themselves, which, being incor-
porated with cement or gutta-percha, might do good service as
antiseptic dressings over diseased pulps or over softened dentine;
first of all, naturally, the bichloride of mercury. Which of the
many available antiseptics, however, is best adapted to the pur-
pose must be determined by further experiments in the labora-
tory and in practice.
The practice of treating exposed pulps, whether healthy or
diseased, to a bath of concentrated carbolic acid has been sharply
criticised by various writers. There are nevertheless many
practitioners in high standing who treat all exposures of the
pulp in this manner, and claim to obtain better results than by
any other method. I will not venture to say that this may not
be so, because the ill effects of so severely cauterizing the pulp-
tissue may be balanced by the good effects of thorough antiseptic
treatment. If we, however, could attain the same object by the
use of less irritating agents, our probability of success would be
much greater..
Further experiments relating to this subject are now in pro-
gress, and will be reported in due time.
THE ACTION OF TOBACCO UPON THE TEETH.
Five grammes of old Virginia plug were boiled fifteen minutes
in 50 c.cm. of water, the loss by evaporation being constantly
replaced; the decoction was then filtered, and a portion added
to an equal volume of saliva with sugar. This produced a mix-
ture scarcely stronger than that which many veteran chewers
carry around in their mouths all day, and in it the bacteria led
only a miserable existence.
Much more remarkable, however, was the action of tobacco-
smoke upon the micro-organisms of the mouth; the smoke from
the first third or last quarter of a Colorado Claro cigar being
found amply sufficient to sterilize 10 c.cm. of a beef-extract-
sugar solution, previously richly infected with bacteria from de-
cayed dentine.
STERILIZATION OF TEETH FOR IMPLANTATION.
247
The apparatus used for this experiment (Fig. 110) explains
itself. A current of water passing through the part B in the
direction of the produces a current of air through the part
A, in the direction of the, which draws the smoke from a
lighted cigar through the solu-
tion. The rate at which the
cigar smokes may be regulated
at will by the cock of the hy-
drant. The results of my ex-
periments, which I 136 published
in 1884, have been completely
confirmed by an extended series
of experiments by Tassinari.137
In consideration of the strong
antiseptic power of tobacco-
smoke, we might be inclined
to infer that tobacco-smokers
should never suffer from decay
of the teeth; it is evident, how-
ever, that there are many points
in the dental arch, particularly
when the teeth are not kept
scrupulously clean, to which the
smoke never penetrates.
1
THE STERILIZATION OF
TEETH FOR THE PURPOSE OF.
IMPLANTATION.
Id"
FIG. 110.

2
d'
7.
TRELLBAUSTIN.
£4++ p
e
1
A
a
a, glass cylinder with infected solution;
b, c, glass tubes; d, d', d', rubber tubing;
e, cigar (Colorado Claro); B, water air-
pump; A, current of water passing through
B in the direction of the double arrow pro-
duces a partial vacuum in the bulb, and
'consequently a current of air in the direc-
tion of the arrow or through the cigar,
which if lighted will smoke at a rate de-
termined by the pressure under which the
water is flowing.
It is well known that opera-
tions designated as replantation,
in which a diseased tooth is extracted, cleansed, and returned to
its alveolus again, and transplantation, in which a tooth taken
from one individual is planted into the alveolus of another, which
has been emptied by extraction, have now and then been per-
formed by individual dentists for two and a half centuries.* Since
some few years, a similar but more serious operation is being
* Dupont, Remède contre le mal des dents, 1633, recommended for toothache
the extraction and replantation of the tooth.
248 THE MICRO-ORGANISMS OF THE HUMAN MOUTH.
performed, which consists in making an artificial alveolus at any
point of the dental arch, which may have been toothless for an
indefinite length of time, and consequently contains no alveolus,
and often but little alveolar process, and then implanting the
proper tooth in this artificial alveolus.
For this purpose teeth are often used concerning whose
origin, whether from healthy or diseased individuals, nothing is
known; and it becomes a question of great importance, for the
patient as well as for the operator, whether or not infectious dis-
eases may not be communicated in this way.
John Hunter 138 (1786), in whose time the operation of trans-
plantation seems to have been extensively performed, describes
seven cases in which it was followed by serious disturbances of
an infectious nature. Hunter, who combatted the tendency then
existing to ascribe all such disturbances to syphilitic inoculation,
was forced to admit the transmission of syphilis in two out of the
seven cases. He also readily admits the possibility of such inoc-
ulations through dental operations.
J. C. Lettsom 139 (1786) reports a number of cases which came
under his notice, some of which he pronounced undoubted syph-
ilis. He gives the following description of one case resembling
syphilis: Eight weeks after the transplantation of two teeth the
patient has a painful sensation between the roots, followed by
ulceration through the gums and by soreness of the glands of
the neck and throat. Within three or four days efflorescence of
the skin appears, advancing to an eruption resembling syphilis.
Inflammation and ulceration of the tonsils also occur, together
with fever in the evening and profuse sweats in the morning. The
teeth gradually loosen and almost fall out. Exophthalmia in one
Both attacks
eye. Eight weeks later a similar attack came on.
were successfully treated with mercurials.
Of all cases of transplanting one in twenty have this disease, and
one-fourth of these die.
In my judgment, the dentist who undertakes the above opera-
tion without having previously convinced himself that the tooth
to be implanted is in a perfectly aseptic condition, or most cer-
tainly contains no specific germs, commits a serious wrong.
But how can we thoroughly sterilize a tooth? We must, in
STERILIZATION OF TEETH FOR IMPLANTATION.
249
the first place, reconcile ourselves to the fact that a complete
sterilization of a suspected tooth with the conservation of the
periosteum is absolutely out of the question. It is not alone
necessary to sterilize the surface of the tooth, but the whole sub-
stance of the tooth; and since under certain circumstances the
cement-lacunæ, as well as the dentinal tubules, may contain
bacteria, it is not to be supposed for a moment that we can
reach and kill them in these portions without injuring the peri-
cementum. The transplantation or implantation of a tooth with
living pericementum is therefore practicable only in such cases
where the tooth is taken directly from a living, perfectly healthy
individual, and placed at once, under antiseptic precautions, into
the alveolus.
In all other cases it is better first to remove the pericementum,
since it must be devitalized in the process of sterilization, and
the dead pericementum can act only as an irritant, and delay
the healing process. For implantation, chiefly old dry teeth
have been made use of, and in such cases the pericementum is
naturally already dead before beginning the disinfection.
The usual method of disinfection, placing the teeth in dilute
solutions of bichloride of mercury for a few minutes or even
hours, gives no guarantee that the teeth are made absolutely
sterile. How are we to know whether the solution penetrates
into the microscopic spaces of the tooth, the cement-lacunæ,
channels of chance blood-vessels, dentinal tubuli, etc., which are
filled with air? Dry teeth placed for a number of hours in watery
solutions of coloring-matter show no penetration of the coloring-
matter worthy of mention.
Under high pressure the permeation of the external layers of
the tooth with the solution might probably be accomplished. A
certain sterilization, however, can be effected by heat alone,
either by boiling water or by steam at 100° C. In order to
devitalize such spores as may be present, it will be necessary to
repeat the sterilization process two or three times, at intervals
of about twelve hours. A large number of teeth might be
sterilized at one time in a flask closed with cotton, and in this
shape put away for later use.
1
PART II.
THE PATHOGENIC MOUTH-BACTERIA,
AND
THE DISEASES WHICH THEY PRODUCE.
CHAPTER X.
THE BUCCAL SECRETIONS AS CARRIERS OF TOXIC SUBSTANCES AND of
PARASITIC EXCITANTS OF DISEASES.
It is a well-known fact that the inflammatory processes in the
tooth-pulp, pericementum, and gums, brought about by a dis-
eased condition of the human teeth, lead not only to obstinate
neuralgias, but also to severe diseases of the eye and ear, to erup-
tions of the skin, spasm of the muscles, etc.
Cases of spasms of the facial muscles, lockjaw, convulsions,
spasm and paralysis, of the ciliary and other muscles of the eye, stra-
bismus, ptosis, lagophthalmus, epiphora, ectropium, asthenopy,
amaurosis and amblyopia, mydriasis, myosis, glaucoma, cataract,
keratitis, retinitis, conjunctivitis, panophthalmitis, etc., otitis,
thrombosis of the sinuses of the brain, eczema of the face, indiges-
tion consequent on imperfect mastication, nervousness, epileptic
attacks, paralysis, etc., proceeding from decayed teeth, come to
our notice, many of them repeatedly, in dental and medical
literature. These are secondary affections caused by reflex
action, in which the mouth-bacteria participate only in so far as
they are to be regarded as the excitants of the primary diseases
of the mouth. As is well known, similar phenomena very fre-
quently occur during dentition, in obstructed eruptions of wis-
dom-teeth, in exostosis of the cement, formation of pulp-stones,
;
etc.
The intimate connection of the quintus through the ganglia
ciliare, spheno-palatinum, oticum et submaxillare with other
cranial nerves and with the sympathicus, easily accounts for
them.
We have, however, at present to occupy ourselves with the
253
254 THE MICRO-ORGANISMS OF THE HUMAN MOUTH.
infectious diseases of the oral cavity itself, and with those that are
called forth by a migration of pathogenic micro-organisms from
the mouth to more remote parts of the body.
TOXIC PROPERTIES OF MIXED HUMAN SALIVA.
The belief that the human saliva may under certain circum-
stances have a poisonous effect upon the animal body is by no
means of recent origin. Habdarrhamus, Egyptus, Aëtius (De
re med. 2. 107), Elianus, and many others were aware that the
saliva of a person with an empty stomach is fatal to scorpions,
and the celebrated Galen himself saw a scorpion killed by saliva
without the use of magic. Aristotle observed a girl whose
bite was as poisonous as the most fatal snake-bite; an arrow
dipped in the saliva invariably killed anyone wounded by it
(Stricker). Various other celebrated authorities of olden times
who bear evidence to the poisonous character of the human saliva
will be found in the work of Stricker,140 from whom the above
notes are taken. In modern and in very recent times the saliva
has been the subject of repeated experiment on the part of both
physiologists and pathologists.
Eberle 14 maintained that the saliva of persons excited or en-
raged or suffering pain acquired poisonous properties, which he
accounted for by an increased formation of sulphocyanide of
potassium. Eberle was actually able, as he thought, to detect
an increase in the amount of this salt in his own saliva during
rage or anger.
Senator 142 made subcutaneous injections of purulent sputum
in dogs, and saw the animals soon sicken; they manifested high
temperatures, chills, diarrhoea, etc., and perished without excep-
tion.
Wright observed that the injection of his own saliva into the
stomach of dogs was invariably followed by sickness and vomit-
ing. Since, however, Wright and others who followed him
smoked tobacco in order to excite the flow of saliva, the toxic
action is in this case to be attributed to the tobacco alone.
When the experiments were repeated without the use of tobacco,
no vomiting occurred.
:
TOXIC PROPERTIES OF MIXED HUMAN SALIVA.
255
Moriggia and Marchiafava (1878) demonstrated that an injec-
tion with the saliva of children who had died of lissa proved fatal
to rabbits.
The first authors who referred the poisoning caused by the
injection of mixed saliva to the presence of micro-organisms
were, as I believe, Raynaud and Lannelongue.143 They vacci-
nated rabbits with the saliva of a child afflicted with hydro-
phobia, and saw the rabbits die within forty-eight hours. Injec-
tions with the blood as well as with the buccal mucus of the
dead child had negative results.
At the same time Pasteur 14 reported on experiments which he
had made together with Chamberland and Roux, with the saliva
of the same child. Two rabbits inoculated with it died after
thirty-six hours. The micro-organisms from the blood, cultivated
in bouillon, appeared as rods 1u in diameter, contracted in the
center, resembling the figure 8. They were surrounded by a
gelatinous capsule. At first Pasteur thought he had discovered
the cause of hydrophobia in this microbe, although Colin at once
expressed the opinion that the disease called forth in rabbits by
the experiments of Raynaud was not hydrophobia, but rather
showed much more similarity to septicemia. The rapid pro-
gress of the disease particularly spoke against the former suppo-
sition. Colin was accordingly the first to obtain an insight into
the true nature of the affection following the injection of human
saliva.
Vulpian 145 soon after reported that he had produced the same
disease by vaccinating animals with the saliva of healthy persons.
By subcutaneous injections of minute quantities of blood the
disease could be transmitted from one animal to another. In
the blood of these animals Bochefontaine and Arthaud found
microbes which morphologically coincided with Pasteur's.
Sternberg 146 and Claxton, quite independently of the foregoing,
corroborated Vulpian's statements, while Griffin 147 showed that
pure parotid saliva is altogether harmless. In his opinion, the
local and general phenomena which appeared after an injection
with mixed saliva were caused by soluble or insoluble substances
formed in it by putrefaction.
G. Gaglio and di Mattei 148 concluded that human saliva as such
256
THE MICRO-ORGANISMS OF THE HUMAN MOUTH.
exerts no toxic influence, but gains its poisonous property by
admixtures from the oral cavity. Boiled saliva exerts no, or but
a comparatively insignificant, action.
A. Fränkel 149 further substantiated Vulpian's observations, and
especially emphasized the remarkable fact that the microbes in
question may be present in the saliva of one and the same indi-
vidual at certain times and at others not.
Fränkel, as well as other observers, found rabbits best adapted
for these experiments; mice and guinea-pigs also proved suscep-
tible, whereas chickens, pigeons, and dogs were refractory. I 150
obtained the same results by inoculating mice and rabbits with
the saliva of a woman afflicted with mycosis tonsillaris benigna.
The saliva mixed with bouillon was allowed to stand for a num-
ber of hours at blood temperature, and then injected into the
lungs of two rabbits and two mice. The death of all the animals
resulted within thirty hours; in the blood I found numerous
cocci and diplococci, most of them enveloped in a gelatinous.
capsule.
1
I furthermore isolated a micrococcus from decayed dentine
which exhibited unquestionable pathogenic properties.
Klein 151 and others also call attention to the infectious properties
of human saliva, particularly under diseased conditions. It was
established by these numerous investigations, beyond doubt, that
a group of micro-organisms belonging to the coccus form occurs
almost invariably in the buccal juices, which, when brought into
the circulatory system in sufficient numbers, may provoke the
most dangerous diseases. Of late years, by the cultivation of
mouth-bacteria on artificial media and in the animal body, the
pronounced pathogenic properties of a large number of them
have been conclusively demonstrated. The most important of
these will be discussed below.
PATHOGENIC BACTERIA OF THE HUMAN MOUTH.
Not for the less dangerous ferment-bacteria alone, but for
micro-organisms of a pathogenic nature as well, the oral cavity
presents in point of temperature, moisture, nutritive materials,
etc., an almost perfect breeding-place.
From this reason it is to be expected that among the many
}
PATHOGENIC BACTERIA OF THE HUMAN MOUTH.
257
1
pathogenic micro-organisms entering the mouth from time to
time some may obtain at least a temporary foothold, or may
propagate themselves for a certain length of time, as long as the
conditions remain favorable, or finally may establish themselves
permanently.
The observations of many bacteriologists have led to the
unanimous conclusion that there is a large number of well-char-
acterized mouth-microbes which will not grow on any of the
artificial nutrient media now in use. The thought therefore
suggests itself that there may be other bacteria in the mouth,
which, possessing no striking morphological features and not
growing on artificial media, have thus far escaped detection, and
which, nevertheless, may possess pathogenic properties which
they may unfold under propitious circumstances.
For the present, therefore, we distinguish two groups of
pathogenic mouth-microbes, the non-cultivable and the culti-
vable.
1. NON-CULTIVABLE PATHOGENIC MOUTH-BACTERIA.
As has been stated above, there is a considerable number of spe-
cies of bacteria in the mouth which do not appear to grow on any
of the media at present in use; among others, Leptothrix innomi-
nata, Bacillus buccalis maximus, Jodococcus vaginatus, Spirillum
sputigenum, and Spirochete dentium. These occur in every
mouth, the last-mentioned sometimes even in almost pure culture.
Nevertheless, all attempts at cultivation, and thousands of them
have been made, proved futile. For some years I myself made
hundreds of experiments with diverse solid and liquid nutrient
media, in order to obtain a pure culture of Spirillum sputigenum
and Spirochete dentium, but in vain. Up to the present, no
one, as far as I know, has been more successful than I.
Since these well-known microbes will not grow outside of the
mouth, we may suspect that there are other organisms in the
mouth, less known or wholly unknown, pathogenic as well as
non-pathogenic, which are not cultivable. This, of course,
renders it difficult, if not impossible, to acquire a knowledge of
their properties.
An important contribution to the study of this group of mouth-
17
258
THE MICRO-ORGANISMS OF THE HUMAN MOUTH.
bacteria has been furnished by Kreibohm,152 in the hygienic insti-
tute of Göttingen. He found two pathogenic bacteria in the
mouth, which were characterized by the fact that they would
grow on none of the usual artificial media.
"The first kind was twice obtained by injecting mice with
scrapings from a coated tongue; the mice died after a few days,
and showed great quantities of uniform bacilli in the blood. The
rods are very like those of rabbit septicemia, perhaps somewhat
longer and more pointed; they are not contracted in the middle,
take up coloring-matter at the extremities only, consequently dis-
play a light central zone. In the blood they lie singly or in small
groups, seldom arranged in threads by twos or threes. Blood
containing these bacilli inoculated into mice in quantities of one
drop invariably gave rise to the same disease in thirty successive
generations. On the first day no change in the inoculated ani-
mals was perceptible, on the second day they became sluggish,
sat with their backs drawn up, the eyes glued together; usually
after two to three days, sometimes only after five days, death
ensued.
"The autopsy showed only a greatly enlarged spleen and less
enlarged liver. In sections of all the organs small heaps of bac-
teria were found within the capillaries, but they did not occur
in great numbers, except in the lungs. Rabbits were compara-
tively little susceptible. After inoculation with small quantities
of blood, they became only temporarily ill. After a subcutaneous
injection of larger quantities of blood, the animals died in the
course of two or three days, and showed the same distribution of
bacilli as mice. Field-mice were very susceptible. The inocu-
lation of a chicken had a negative result.
"Cultures on diverse solid and fluid media were tried at vari-
ous temperatures; all of them, however, remained sterile."
"The second species was isolated in the same manner, through
the animal body (mice) from the coating of the human tongue.
They presented short rods, rounded at the extremities and
slightly contracted in the middle. After coloration, which in
this case also is more intense at the extremities, they resemble
the figure 8, and are also surrounded by a light halo, on the
whole most like the bacilli of chicken-cholera. The rods were
Jala
PATHOGENIC BACTERIA OF THE HUMAN MOUTH.
259
contained in great numbers in the heart-blood of the dead mice.
In sections of the organs they were found within the capillaries,
but generally in isolated heaps, and not more plentifully in the
lungs than in other organs. By means of minute quantities of
blood it was possible to transfer the disease to forty to fifty gen-
erations of mice; death ensued more rapidly than from the bac-
terium described first, often after but eighteen, at most after
forty hours.
"Rabbits were completely refractory. Culture experiments
yielded an increase of bacteria only in the blood transferred to the
first medium; in further inoculations no increase ever occurred."
While experimenting with the bacteria of the gangrenous
pulp (Dental Cosmos, April, 1888) I discovered a microbe, which,
subcutaneously injected into mice, excited a gangrenous process.
Twenty-four hours after the infection a pea-sized swelling had
formed, which when lanced emitted a stinking pus mixed with
gas-bubbles. By inoculating small quantities of this matter
from one animal to another the infection was transferred through
several generations. The bacteria cultivated from such abscesses
did not possess this characteristic effect, from which fact I con-
cluded that the specific bacterium is uncultivable.
I do not doubt that continued study will discover other mem-
bers of this group of uncultivable pathogenic mouth-bacteria.
2. CULTIVABLE PATHOGENIC MOUTH-BACTERIA.
a. Micrococcus of Sputum Septicæmia.
Of the many pathogenic bacteria which have of late been ob-
tained in pure culture from the mouth, the micrococcus of sputum
septicemia is perhaps the most important. It is probably the
same micro-organism which Pasteur, Raynaud, Lannelongue,
Vulpian, Moriggia and Marchiafava, Sternberg, Klein, myself,
and many others had to do with in the experiments on the infec-
tious nature of healthy as well as diseased human saliva.
Klein 151
was, it
appears, the first who succeeded in obtaining a
pure culture of the coccus of sputum septicemia, using blood-
serum and agar-agar peptone at 38° C.
260
THE MICRO-ORGANISMS OF THE HUMAN MOUTH.
A. Fränkel 153 also obtained pure cultures of the same organism
from the blood of a rabbit which had just died. He used agar-
agar dissolved in calf's or beef broth, and added to 1 per cent.
grape-sugar or an equal quantity of the double tartrate of potas-
sium and sodium. A culture on coagulated beef-blood serum
proved still more successful. Optimum of temperature, 35° to
37° C.
"Within twenty-four hours, at 35° to 37° C., the culture grew
in the shape of a nearly transparent grayish-white, gelatinous
coating upon the surface. Viewed by reflected light, it resem-
bled a dew-drop.
"When scraped together with the needle, the coating pre-
sents a yellowish-brown appearance."
Flasks of bouillon exposed to a temperature of 30° to 35° C.
become equally clouded throughout twenty-four hours after the
infection; later the culture sinks to the bottorn as a peculiar,
granular, sandy precipitate, while the liquid above it becomes
clear.
The coccus of sputum septicæmia grows only between 22° and
42.5° C., no development taking place either below the former or
above the latter temperature.
Its cultivation is difficult un-
der all circumstances. Above
all, the nutrient medium must
not be too concentrated (ac-
cording to Weichselbaum, 13
per cent. of peptone, 1 per
cent. of grape-sugar, 1 per
cent. of common salt in 13
per cent. solution of agar-
agar), and must be exactly
neutralized.
This bacterium appears in
the form of oval cocci, some-
times single, oftener in pairs, as diplococci, or in short chains (Fig.
111). The separate cells, as well as the chains, are surrounded
by gelatinous capsules, which become visible even under 300
to 400 diameters, and may be stained by the method of Fried-
0
FIG. 111.

CAPSULE Cocer
from pneumonic exudation in man.
Baumgarten.) 1500: 1.
(After
PATHOGENIC BACTERIA OF THE HUMAN MOUTH.
261
länder. The specimens are placed for two minutes in a con-
centrated solution of gentian-violet in aniline water, then treated
with alcohol (from one-quarter to one-half minute), and rinsed
with water. They may be examined in water, or after being
mounted in Canada balsam.
Injections of pure cultures into the subcutaneous connective
tissue, or into the abdominal or thoracic cavities, or directly into
the lungs, provoke the same symptoms as injections with saliva.
Death ensues within twenty-four to thirty-six hours, under phe-.
nomena resembling septicemia. The autopsy reveals large
quantities of capsule-cocci in the blood and in the different
organs, large tumor of the spleen, often also peritonitis with
or without slight exudation. But little reaction occurs at the
point of infection. Mice and rabbits were highly susceptible;
pigeons, chickens, dogs, refractory; guinea-pigs variously dis-
posed.
The blood of the deceased animals is highly infectious. Ani-
mals which had survived one severe infection did not react a second
time.
·
An exposure of forty-eight hours in a liquid culture medium
to a temperature of 42° C. was sufficient to destroy the patho-
genic properties of the coccus of sputum septicemia. Cultivated
in milk, it is said to lose its virulence in a short time.
If the micrococcus of sputum septicemia has been repeatedly
found in the oral cavity of healthy persons, its occurrence in the
mouths of those suffering from pneumonia is almost constant.
In genuine croupous pneumonia Fränkel found it twelve times
out of fourteen, and Weichselbaum eighty-one times out of
eighty-eight.
When we take into consideration the fact that this coccus is
not easily cultivable, we may readily suppose that its absence in
the two and seven cases respectively may have been due to faults
in the method of cultivation.
If, now, the view held by Fränkel, Weichselbaum, etc., to
which also Baumgarten 154 adheres, that the coccus of sputum
septicemia is to be regarded as the most frequent, if not as the
sole, excitant of lobar pneumonia, be correct, then we may with
sufficient reason assume that the infection, at least in many cases,
262
THE MICRO-ORGANISMS OF THE HUMAN MOUTH.
most probably proceeded from the mouth. The oral cavity
serves as a gathering-point for this microbe, which from time to
time is carried into the lungs with the air until at last, at some
weak point, or as the result of some slight inflammatory action
in the lungs through which their power of resistance is impaired,
it obtains a foothold in the lungs themselves. For this reason,
therefore, among many others, the neglected oral cavity furnishes
a most dangerous source of infection, which has by no means.
received the attention which its importance demands.
b. Bacillus crassus sputigenus.
Kreibohm 155 found twice in sputum and once in the coating of
the tongue a cultivable bacterium which he termed Bacillus
va
30%
QIND
I O NE
FIG. 112.

YO
・O・
O
O
O
70
ទន
BACILLUS CRASSUS SPUTIGENUS.
Cover-glass preparation from the heart-blood of a mouse. (After Flügge.) 700: 1.
crassus sputigenus, which possesses distinct pathogenic proper-
ties.
"Short, thick bacilli, representing oblongs with rounded
corners, often curved or twisted like a sausage. Immediately
after fissation the longitudinal diameter exceeds the transverse
only by about one-half; afterward the former becomes much
longer, so that before a second fissation the bacilli are three or
four times as long as they are thick (Fig. 112).
"We often see bacilli in a state of fissation, or still adhering to
PATHOGENIC BACTERIA OF THE HUMAN MOUTH. 263
each other after fissation; long pseudo-threads are, however, want-
ing. Specimens prepared from blood, as well as from cultures,
reveal bacilli with swollen extremities or irregular outlines (invo-
lution forms), here and there transformed into shapeless masses.
The bacilli are easily stained, and retain their color even after
the application of Gram's method. At a higher temperature
they appear to form spores.
"These bacilli may be cultivated on various nutrient media.
On gelatine-plates they form (after thirty-six hours) distinct
grayish-white dots, which soon rise above the surface and then
form large greenish-white, round, slimy drops, rising quite high
above the level of the gelatine. Under a weak power the
youngest colonies appear circular, of grayish-brown dark color,
and their entire surface covered with dark dots or with short,
dark lines and flourishes (Schnörkeln). The larger superficial
colonies appear much lighter, irregularly outlined; the surface
distinctly granular, especially at the margin.
"Puncture-cultures develop very quickly (in about twenty-
four hours), and show a typical nail-shaped growth. On potato
slices a thick, grayish-white, moist, shining coating is formed."
"Mice die about forty-eight hours after inoculation with small
quantities of the culture; numerous bacilli are found in the
heart-blood and in all the capillaries, most abundantly in the
liver. Rabbits are not perceptibly affected by small inocula-
tions; but after intravenous injections of small doses they perish
from blood-poisoning within forty-eight hours, and show great
masses of bacilli in the blood.
66
Large quantities of the culture injected into the veins caused
in rabbits, and in a more pronounced degree in dogs, diarrhea,
sometimes bloody stools, and death within three to ten hours;
the autopsy revealed also the characteristics of an acute gastro-
enteritis."
c. Staphylococcus pyogenes aureus and albus. Streptococcus
pyogenes.
It cannot for a moment be doubted that these typically pyo-
genic organisms, which are very widespread in nature, fre-
"
264
THE MICRO-ORGANISMS OF THE HUMAN MOUTH.
quently gain access into the mouth. It would also seem very
probable that the conditions existing in the oral cavity favor
their growth, although no attempt has as yet been made to
establish the accuracy of these two suppositions experimentally.
All results obtained from culture-experiments coincide in this,
that the two micro-organisms first named actually occur in the
mouth, whereas the statements concerning the frequency of their
occurrence greatly diverge.
Black 156 examined the buccal juices in regard to pyogenic
micro-organisms, and found them in many cases. In the saliva
of ten healthy persons he found Staphylococcus pyogenes aureus
seven times, Staphylococcus pyogenes albus four times, and
Streptococcus pyogenes three times. The material was obtained
by scraping the back of the tongue or any part of the mucous
membrane with a sterilized platinum wire. In some cases
Black found staphylococci in all parts of the mouth, in others he
did not succeed in finding them, but believes that they might
be discovered in almost all mouths if the latter were examined
with sufficient care. Black but seldom found other pyogenic
bacteria in the mouth.
"As dentists," he continues, "we must take into considera-
tion that the pyogenic bacteria are generally present in the oral
cavity and endanger every wound which we make in it.”
Other bacteriologists who have examined the buccal juices
have not succeeded in finding the above-named bacteria so con-
stantly. Vignal 59 found Staphylococcus aureus and albus but
rarely in the mouth; Streptococcus pyogenes never. Netter
found Staphylococcus pyogenes aureus seven times in one hun-
dred and twenty-seven cases. During the many years in which
I have occupied myself with the study of mouth-bacteria 1 have
met these species comparatively seldom; in suppurative pro-
cesses five times in twenty-two cases, in healthy mouths more
rarely. I have, however, made comparatively few experiments
for the sole purpose of determining the presence or non-presence .
of these organisms, and consequently do not attach very much.
importance to my own work on this point. The results of
Vignal and Netter are not so easily disposed of. Further ex-
periments must consequently determine whether pyogenic bac-
PATHOGENIC BACTERIA OF THE HUMAN MOUTH.
265
teria really occur in the saliva of healthy Iersons as often as
Black's observations would lead us to suppose.
d. Micrococcus tetragenus.
This micro-organism has been repeatedly mentioned as an in-
mate of the oral cavity. I myself have found it quite often, but
unfortunately took no notes concerning its frequency. Biondi
found it three times out of five.
It occurs in the form of cocci, about 1p in diameter, which
by fissation in two directions form groups of fours (Fig. 113).
The cells are inclosed and held together by a gela-
tinous disk.
FIG. 113.
It grows on gelatine-plates, without liquefying
the gelatine, in the shape of small, white, dot-like
colonies, which, under weak power, appear finely
granular and have a peculiar glass-like brilliancy
(Eisenberg).
White mice and guinea-pigs inoculated with
Micrococcus tetragenus perish in from three to ten days. Ac-
cording to Biondi, even the injection of saliva which contains
this microbe proves fatal in four to eight days. The cocci are
found in the blood as well as in all organs.
18
Micrococcus tetragenus (mentioned above).
Streptococcus septo-pyæmicus.
Staphylococcus salivarius pyogenes.
MICROCOCCUS
TETRAGENUS.
600: 1.
Micrococcus tetragenus was first found by Koch 157 and
Gaffky 158 in the lungs of a consumptive. It frequently occurs
in lung-tuberculosis, but the part it plays in this disease has not
yet been ascertained (Flügge).
BIONDI'S MOUTH-BACTERIA.
A valuable contribution to our knowledge of pathogenic bac-
teria of the mouth has been furnished by Biondi.159 He isolated
from human saliva five different pathogenic micro-organisms, to
which he gave the following names:
Bacillus salivarius septicus.
Coccus salivarius septicus.
266
THE MICRO-ORGANISMS OF THE HUMAN MOUTH.
e. Bacillus salivarius septicus.
Of these, Bacillus salivarius septicus is said to occur most fre-
quently in the saliva of healthy as well as of sick persons. It
forms very short elliptical rods with somewhat tapering extrem-
ities and comparatively thick bodies, and grows but poorly on
common neutral media.
"Mice and rabbits injected with one-half to one cubic centi-
meter of such saliva generally succumbed within twenty-four to
forty-eight or seventy-two hours. The autopsy revealed oedema,
hemorrhage, tumor of the spleen, and micro-organisms in the
blood. This bacillus acts most intensely at the point of infec-
tion, without showing a special predilection for any particular
organ. At first it proliferates at the point of entrance, is then
carried through the blood- and lymphatic vessels to the rest of the
body, and multiplies in these channels until death is caused."
Passage through the body of a refractive animal, high temper-
atures, etc., diminish the virulence of this micro-organism.
Animals infected with weakened material proved resistant to
virulent inoculations.
f. Coccus salivarius septicus.
Coccus salivarius septicus was found but once, and is there-
fore hardly to be regarded as a mouth-bacterium, but rather as
an accidental contamination of the saliva, particularly as the
patient in whose mouth it was found suffered from violent puer-
peral septicemia.
"Subcutaneous injections with this saliva in mice, guinea-pigs,
and rabbits proved fatal after four to six days. The only and
constant result of the autopsy was the presence of the cocci in the
blood and the tissues."
This microbe is easily isolated from the blood, and grows well
on the usual culture-media. The colonies within the gelatine
of plate-cultures are perfectly round, and of white-grayish color,
sometimes merging into black.
g. Streptococcus septo-pyæmicus.
"When subcutaneously injected in quantities of 1-1 c.cm.,
the saliva containing this streptococcus proved pathogenic for
PATHOGENIC BACTERIA OF THE HUMAN MOUTH.
26.7
guinea-pigs, rabbits, and mice, although not constantly. Often
also two different forms of disease are caused by it.
"Rabbits frequently perished after fifteen to twenty days,
showing symptoms of chronic septicemia,-increase of tempera-
ture, general debility, gradual emaciation, etc. At the point of
infection nothing characteristic was found, sometimes only a cir-
cumscribed infiltration with suppurating center; the internal
organs revealed intense anæmia; the blood and the organic juices
contained but few cocci, which were usually arranged in short
chains. Inoculations with the blood of the diseased animals were
without result.
"In guinea-pigs and mice which had been subcutaneously in-
jected with saliva, pus formed at the point of vaccination, and
had the tendency to spread into the subcutaneous connective and
muscular tissues. Guinea-pigs often survived this suppuration,
mice generally died.
"Infections with pure cultures of this bacterium also had the
same effect.
"This streptococcus cannot be distinguished from that of
erysipelas, phlegmon, and puerperal metritis. Their colonies
have the same appearances, their development is equally slow,
and the results of experiments made with them on animals are
identical."
Vaccination on the scarified ear of rabbits usually led to the
characteristic symptoms of erysipelas.
h. Staphylococcus salivarius pyogenes.
Staphylococcus salivarius pyogenes was likewise observed but
once, in the contents of an abscess of a guinea-pig which had
been inoculated with the saliva of an individual suffering from
angina scarlatina. It was cultivated in milk, bouillon, blood-
serum, agar-agar, potato, beef-water and wheat-infusion gela-
tine. The latter was liquefied. Milk was precipitated in large
flakes. In twenty-four hours bouillon at 37° C. became very
cloudy, afterward the growth was precipitated as a white,
dense deposit. This micro-organism is easily obtained in pure
culture from the contents of such abscesses, by making the usual
cultures from a drop of pus. Cultivated on gelatine at room
268
THE MICRO-ORGANISMS OF THE HUMAN MOUTH.
temperature, the growth does not become apparent until after
two or three days. The separate colonies, especially when lying
at some distance from each other, reach the maximum of their
development on the fourth to sixth day, and then slowly com-
mence to liquefy the surrounding gelatine. Colonies within, as
well as on the surface of the gelatine, observed at this time,
appear perfectly round, with clearly-defined margins, and of a
whitish opalescent color.
"It was immaterial whether the animal was inoculated subcu-
taneously with very minute quantities of material obtained from
old cultures, or with one-tenth of a drop of matter; all animals
infected with these micro-organisms reacted by abscess-forma-
tion at the point of inoculation."
In the pus these small cocci almost always appear singly,
neither united, as diplococci, nor in chains, nor in clusters.
Abundant quantities brought into the jugular vein caused gen-
eral infection and death. Injected into the abdominal cavity
they produced peritonitis.
G
ORIGINAL INVESTIGATIONS ON PATHOGENIC MOUTH-BACTERIA.
Although much attention has of late years been given to the
study of the pathogenic micro-organisms of the mouth, and our
knowledge concerning them has been essentially increased by
the investigations of Kreibohm, Biondi, and others, much yet
remains to be done before the subject will be but in some measure
exhausted.
I have occupied myself with the study of the pathogenic
mouth-bacteria for a number of years, and obtained some
results which may, perhaps, contribute somewhat to our knowl-
edge of them.
I have experimented with forty-two pure cultures, two mixed
cultures, and twenty-two gangrenous pulps, and have made
ninety-three subcutaneous inoculations of mice in pockets, using
pure cultures, ten subcutaneous injections of pure cultures, fifty-
eight pocket inoculations with pieces of gangrenous pulps, or
with pus arising from such inoculations, sixty injections of pure
culture into the abdominal cavity of mice, rabbits, and guinea-
PATHOGENIC BACTERIA of the HUMAN MOUTII.
THE
269
pigs, twenty-two injections into the thoracic cavity, besides a
number of mixed infections.
The pockets were made in the customary manner, at the root
of the tail, and the material for inoculation was usually taken
from an agar-agar culture one to two weeks old. Injections
were made with the sterilizable subcutaneous syringe, cultures
in beef-extract-peptone solutions from two to four days old being
used. For mice, 0.05 to 0.1 cc.; for rabbits and guinea-pigs, 0.25
to 0.5 cc. were injected. The mice were always etherized before
making the injection. The etherization renders the operation
much easier and surer; it may be accomplished in fifteen seconds
by taking the mouse by the tail and holding him in a wide-
mouthed ether-bottle.
+
-
In 18.8 per cent. of the pocket inoculations a severe local re-
action followed, resulting in the formation of a small abscess,
generally remaining superficial, but occasionally penetrating into
the subcutaneous tissue. In eight cases the inoculation was fol-
lowed by death, the mice showing, in three cases, symptoms of
blood-poisoning, the micro-organisms being also present in the
blood and different organs. In a number of cases necrosis of
the skin around the pocket occurred, a piece of skin one-fourth
to one-half inch in diameter being thrown off. In 50 per cent.
the reaction was light, nothing more than a slight local redness
and formation of a very minute quantity of pus being observed.
In 31.2 per cent. no reaction whatever could be detected, the
wound healing rapidly, without either suppuration or swelling.
Of the subcutaneous injections, 24 per cent. produced violent re-
actions, resulting either in the death of the animal from septi-
cæmia, peritonitis, pleuritis, etc., or in extensive suppuration and
abscess-formation. Slight reaction was produced in 32 per cent.:
temporary sickness, from which the animals soon recovered, or
slight swelling at the point of injection; in 44 per cent. no effect
could be detected.
Subcutaneous inoculation with portions of gangrenous pulps
produced comparatively severe symptoms in 36.8 per cent. of
the pulps experimented with, slight effects in 47.4 per cent.,
and no apparent reaction in 15.8 per cent.
It appears from these results that inoculation with portions of
270 THE MICRO-ORGANISMS OF THE HUMAN MOUTH.
gangrenous pulps is more dangerous than inoculation with pure
cultures from the same pulps, which is as we should naturally
expect it to be. I intend, however, later (Chapter XI) to discuss
the question of infection through foul pulps at length, and pass
the subject here with this brief mention.
The mixed infections invariably resulted in the death of the
animal.
During these studies I have found in the oral cavity a number
of bacteria which possess more or less pathogenic action, four of
which I have examined more in detail, and named as follows:
Micrococcus gingivæ pyo-
FIG. 114.
i. Micrococcus gingivæ pyogenes.
I found this organism in a case
of pyorrhoea alveolaris three
times in the same mouth, at
intervals of three months; also
in a very filthy mouth, in the
deposit around the teeth. It
appears as irregular cocci, or
very plump rods, singly or in
pairs (Fig. 114, u). In gelatine
plate-cultures it grows rapidly at room temperature, forming
round colonies, with a distinctly sharp margin. At first the
colonies appear very slightly colored under the microscope; as
they become older they grow very dark, especially where they
lie far apart. Line-cultures on agar-agar present a moderately
thick, grayish growth, having a tinge of purple by transmitted
light. Under the microscope they appear as a homogeneous,
nearly colorless matrix, interspersed with darker figures of vari-
ous irregular shapes.
Puncture- (stich) cultures in gelatine have, when eight days
old, the appearance seen in Fig. 114. The gelatine does not be-
come liquefied. Cultures in beef-extract-peptone-sugar solutions
a
genes.
Bacterium gingivæ pyogenes.
Bacillus dentalis viridans.
Bacillus pulpæ pyogenes.

MICROCOCCUS GINGIVE PYOGENES.
Culturo in gelatine, 8 days old. a, separate
cells. 1100 : 1.
PATHOGENIC BACTERIA OF THE HUMAN MOUTH.
271
show a strong acid reaction and develop considerable quantities
of gas. Subcutaneous inoculations of mice were followed by
abscess and necrosis of the skin, occasionally resulting in the
death of the animal. Injections in the abdominal cavity inva-
riably produced the death of the animal in twelve to twenty-four
hours, the autopsy revealing immense numbers of bacteria in the
abdominal cavity, a considerable quantity of a serous exudation,
peritonitis, etc. Only a very limited number of larger animals
-two rabbits and two guinea-pigs-were inoculated. The ani-
mals appeared sick for a time, sitting quietly in the corner of
the cage and refusing to eat. After two or three days, however,
all symptoms disappeared.
FIG. 115.
k. Bacterium gingivæ pyogenes.
This bacterium was found in
the same mouth with the micro-
organism just described, and also
in a suppurating tooth-pulp of
a second person. It appears in
form of thick, short bacteria with
rounded ends, one and a half to
four times as long as thick. (See
Fig. 115, a.) In plate-cultures
it grows very rapidly, even at
room temperature, the colonies
being clearly visible to the naked
eye in twenty-four hours. Under
the microscope they appear as beautiful, perfectly round, yellow-
ish colonies, with a sharp, dark border. The gelatine becomes
rapidly liquefied, so that in forty-eight hours the first dilution
is completely melted.

Ell
•
a
BACTERIUM GINGIVE PYOGENES.
Culture in golatine, 8 days old. a, single
cells under 1100 : 1.
Line-cultures on gelatine appear in fifteen hours as a trough
of melted gelatine 1 mm. broad, the side of the trough being
cloudy and the bottom marked by a line of white sediment.
Line-cultures in agar-agar present a thick, moist, slightly gray-
ish growth by transmitted light, having a slight greenish-yellow
tinge under the microscope, colorless at the margin, yellowish
brown toward the middle, and presenting a fibrillated structure.
272
THE MICRO-ORGANISMS OF THE HUMAN MOUTH.
Puncture-cultures in gelatine, eight days old, have the appear-
ance seen in Fig. 115. The gelatine rapidly melts in form of a
funnel, while the masses of bacteria sink to the bottom, the
melted gelatine, however, remaining cloudy.
Injections of this bacterium into the abdominal cavity of white
mice produced death in ten to twenty-five hours. During their
sickness the mice sat drawn up, with bent back and eyelids
glued together. The autopsy showed peritonitis, and in some
cases purulent exudation. Micro-organisms were found only in
very small numbers in the blood.
Injections of 0.25 into the ab-
dominal cavity of rabbits and
guinea-pigs produced identical
results. Injections into the lung
produced death in less than
twenty-four hours. Subcutane-
ous inoculation (injections) of
mice resulted in extensive ab-
scess-formation.
FIG. 116.

8
ос
8
ll
B
8
о
1. Bacillus dentalis viridans.
This organism was found in
the superficial layers of carious
dentine. It appears as slightly
curved, pointed rods, singly or
in pairs (Fig. 116, a). It grows well in plate-cultures at room
temperature; the colonies under the microscope are nearly
colorless, having but a slight yellow tinge; they are perfectly
round, with a sharp contour, and show, when they do not lie too
close together, two or three concentric rings. This bacterium is
characterized by the production of a beautiful opalescent green
coloring-matter, which it imparts to the gelatine; the cell itself
is not colored.
BACILLUS DENTALIS VIRIDANS.
Gelatine culture, 8 days old. a, single cells.
1100: 1.
Line-cultures on agar-agar produce a very thin growth, with
irregular margins, bluish by transmitted light, greenish gray by
reflected light, and colorless under the microscope.
Puncture-cultures on gelatine, eight days old, present the form
seen in Fig. 116.
PATHOGENIC BACTERIA OF THE HUMAN MOUTH.
273
Subcutaneous applications from pure cultures of this bacter-
ium produced severe local inflammation and suppuration, and
in one case death by blood-poisoning, the bacteria being found
in large numbers in the blood and tissues.
Injections into the abdominal cavity of white mice and guinea-
pigs produced death in 60 per cent. of the cases, in twenty-two
hours to six days, from peritonitis. Bacteria could not be found
in the blood microscopically, but cultures made from the blood
of the heart developed pure cul-
tures of the bacterium injected.
The fourth micro-organism
with pronounced pathogenic ac-
tion,
FIG. 117.

m. Bacillus pulpæ pyogenes,
was found in a gangrenous
tooth-pulp. It occurs as ba-
cilli, often slightly curved and
pointed, either singly, in pairs,
or in chains of four to eight
(Fig. 117, a). It grows moder-
ately well in gelatine plate-
cultures, the colonies appearing
large and round, dark, yellowish brown, with distinct margins.
Line-cultures on gelatine begin to melt in eighteen to twenty-
four hours, up to that time appearing as grayish, shining lines,
slightly elevated above the surface of the gelatine, and about
1 mm. wide.
a
BACILLUS PULPE PYOGENES.
Gelatine culture, 8 days old. a, single cells.
1100: 1.
Line-cultures on agar-agar produce a moderately extensive
growth, bluish white, glistening by transmitted light, gray by
reflected light; under the microscope granular, sometimes fibril-
lar in structure, gray, or in older colonies, yellowish.
Puncture-cultures in gelatine, eight days old, present the
appearance seen in Fig. 117, the gelatine melting with about
equal rapidity on the sides and in the middle of the tube. In-
jections of 0.05 into the abdominal cavity proved fatal to mice
in eighteen to thirty hours.
เ
18
CHAPTER XI.
ENTRANCE-PORTALS OF THE PATHOGENIC MOUTH-BACTERIA.
THE diseases caused by the pathogenic bacteria of the mouth
may be considered under six heads, according to the point of
entrance of the infection:
1. Infections caused by a breach in the continuity of the
mucous membrane, brought about by mechanical injuries
(wounds, extractions, etc.). These lead either to local or to gen-
eral disturbances.
2. Infections through the medium of gangrenous tooth-pulps.
These usually lead to the formation of abscesses at the point of
infection (abscessus apicalis), but also sometimes to secondary
septicæmia and pyæmia with fatal termination.
3. Disturbances conditioned by the resorption of poisonous
waste products formed by bacteria.
4. Pulmonary diseases caused by the inspiration of particles
of slime, small pieces of tartar, etc., containing bacteria.
5. Excessive fermentative processes, and other complaints of
the digestive tract, caused by the continual swallowing of
microbes and their poisonous products.
6. Infections of the intact soft tissue of the oral and pharyngeal
cavities, whose power of resistance has been impaired by debili-
tating diseases, mechanical irritations, etc.
In this connection the possibility of an infection by the accu-
mulation of the excitants of diphtheria, typhus, syphilis, etc., in
thé mouth must also be taken into consideration.
1. INVASION OF PATHOGENIC MOUTH-BACTERIA:FOLLOWING
MECHANICAL INJURIES.
Many facts favor the supposition that a considerable number
of pathogenic micro-organisms may thrive in the juices of the
274
¦
INVASION FOLLOWING MECHANICAL INJURIES.
275
mouth without showing in their vital manifestations any distinc-
tion 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 a point of entrance, and thus become able to manifest their
special actions.
Many of the fatal cases of infections following dental opera-
tions, which were formerly invariably, and are even now com-
monly, attributed to infected instruments, are most probably
to be accounted for by these auto-infections.
Every extraction not performed under antiseptic precautions
may be regarded as an inoculation which, unfortunately, often
proves very successful. The severe injuries of the soft tissues
and the bone caused by difficult extractions, as well as the open
wound left by every extraction, furnish a convenient point of
entrance for bacteria. Whoever has examined an unclean
mouth, with its broken-down teeth, inflamed gums, thick,
smeary deposits with which some of the teeth are wholly cov-
ered, will not wonder that inflammation, swelling, suppuration,
necrosis, caries of the bone, or even septicemia and pyæmia
may follow upon operations in the mouth, nor, in such cases,
without further consideration, accuse the dentist of having used
an infected instrument.
Tulpius,73 as early as 1674, mentions among the consequences
of toothache, "disfiguration of the face and certain death.” He
calls attention to the case of the Amsterdam physician, Gosvin
Hall, who died from the effects of gum-lancing, performed in a
case of impeded eruption of the wisdom-tooth. "Very soon
after the gums were lanced he suffered from insomnia, delirium,
and died."
•
Most probably this was a case of septic infection by means
of mouth-bacteria, for which the incision furnished an easy
entrance.
From this case we see that even as simple an operation as
lancing gums may not always be entirely free from danger, and
that not only the knife, but also the gums themselves should be
thoroughly disinfected before the incision is made. Subsequent
276
THE MICRO-ORGANISMS OF THE HUMAN MOUTH.
to the operation the mouth should be kept as free from micro-
organisms as possible by a frequent use of an antiseptic wash.
Leynseele (Bullet. de la société de Gand, 1885) describes a case
of meningo-encephalitis resulting from the attempted extraction
of a tooth. The lower jaw had been fractured at the point of
extraction; pus burrowed its way along the bone, laying it bare.
From this point it ascended the inner side of the ramus of the
jaw as far as the base of the skull, and entered the cranial cavity
through the foramen ovale, spinosum, and rotundum, where,
spreading along the base of the brain, it became the cause of
meningo-encephalitis (Wedl).
Of late years both dentists and physicians have paid particu-
lar attention to this fruitful source of most dangerous infections.
The cases of fatal infectious diseases proceeding from diseased
teeth are now no longer exceptional; not, I think, because they
occur more frequently at present, but because the great influ-
ence of the condition of the mouth upon the general health was
formerly not appreciated, and cases of this kind were not traced
back to their proper source.*
Not only has a large number of pathogenic micro-organisms
been discovered and described, but reports have also been made
concerning many different cases of general diseases proceeding
from the teeth. Zakharevitsch 160 relates the cases of two healthy,
vigorous physicians who died, the one on the sixth, the other on
the tenth day after the extraction of the left lower second
molar. In one case, osteomyelitis supervened; in the other,
periostitis and osteitis, with uncommonly severe symptoms.
The infection was from the beginning of a septic nature, which,
according to the reporter, was due to the use of infected instru-
ments.
G
Several similar cases have been cited by Baume.161 A physi-
cian had made an unsuccessful attempt to extract the decayed
left superior first molar of a student, twenty-four years of age.
On the following day a moderate swelling of the affected locality
set in; the pericementitis soon extended to the periosteum of
* A case illustrating this fact was brought to my notice some time since. In a
workman found dead, the autopsy revealed the cause of death to be a meningitis
directly traceable to an abscessed tooth.
INVASION FOLLOWING MECHANICAL INJURIES.
27.7
the jaw, causing necrosis; the necrotic alveolar process was
removed after two weeks. In the progress of the disease the
characteristic symptoms of pyæmia appeared,—chills, great
debility, and icteritous color of the skin. This was accompanied
by pleuro-pneumonia of the right lung. The patient died in
consequence of an eruption of pus into the lungs.
In another case, a young man died of pyæmia on the very next
day after having a tooth extracted. In this case the patient had
suffered from chronic parulis.
Delestre describes several cases "in which meningitis resulted
fatally in consequence of spreading inflammations and abscesses
after extraction." "A robust man, twenty-seven years old, had
a left superior molar drawn; an inflammation followed which
spread to the orbit and the brain; the patient died of menin-
gitis."
In a second case, a factory girl, twenty-six years old, died five
days after the extraction of the right inferior first molar. Swell-
ing, suppuration, and finally meningitis ensued, causing death.
Von Mosetig-Moorhof 162 noticed four cases of inflammation of
the jaw-bone with phlebitis suppurativa, leading to a fatal pyæ-
mia, which had been caused by diseased roots; moreover, many
cases of acute sepsis occurring after unsuccessful operations or
such performed without proper antiseptic precautions. He gives
the following account of one case of this kind as an example of
many others:
J
"M. Battista, a woman in the seventh month of pregnancy,
went on the 1st of February of the present year to the charitable
institute just mentioned in order to have the second right lower
molar extracted, which was badly decayed and whose crown was
partially wanting. The crown was completely broken off, and
the patient sent home without extracting the roots. The pain
increased, fever appeared, and on the next morning the face was
so much swollen that it was almost impossible to open the mouth;
the pain on swallowing was so great that she, in spite of her
intense thirst, was scarcely able to swallow a little water. The
swelling gradually increased, and finally became so extensive
that the totally disfigured patient even suffered from want of
breath. On the 3d of February she was transferred to the
278 THE MICRO-ORGANISMS OF THE HUMAN MOUTH.
Wiedener Hospital. We found particularly the right half of the
face terribly swollen, the skin reddened and tense, both eyelids
closed by cdema; the infiltration extended across the arch of the
jaw, occupied the entire floor of the oral cavity, and continued
upon the right side of the neck almost to the clavicle. The
whole part was tense and as hard as a board; a disagreeable
stench was emitted from the mouth; the jaws could hardly be.
opened to the breadth of a finger. The cheeks, gums, and base
of the tongue were all intensely swollen, and the gums corre-
sponding to the extracted tooth covered with a diphtheritic exu-
dation. Swallowing impossible; respiration somewhat difficult;
rattling on account of the inability to expectorate; evening tem-
perature 39.8°. The mouth is syringed with sublimate 1-1000;
externally ice-collars employed.
K
"On the morning of the fourth day we succeeded with com-
parative ease in removing the broken roots of the right inferior
second molar by means of the elevator. Iodoform gauze was
placed in the wound, permanganate of potassium used as a
mouth-wash and for syringing; evening temperature 40° C.
The respiration became more difficult; the patient spent the
night in a sitting posture, and gasped for breath.
"On the morning of the fifth day the patient is, if possible, still
more swollen; from the nose downward to far below the larynx
all outlines are erased; nothing is visible but a hard, stiff, even
surface, covered with the dark red skin; no trace of fluctuation.
We have here, therefore, an angina Ludovigi septica in optima
forma. Breathing is extremely difficult, the face somewhat
cyanotic. We bring her into the operating-room, and split the
soft tissues in the median line from the chin to below the hyoid
bone a distance of about 15 cm. The tissue is stiff from the
infiltration, bleeding very slight; a scanty, brown, thin ichor
flows from the incision. We make our way preparando to the
floor of the tongue, but discover no large center of infection, no
accumulation of fluid. Sublimate dressing 1-2000; improve-
ment in respiration; evening temperature 38.9°. On the 6th
of February we find fluctuation on the right side of the neck.
Another deep, longitudinal incision from the angle of the jaw
downward obliquely is followed by a discharge of ichor. The
7
INVASION FOLLOWING MECHANICAL INJURIES.
279
99
probing finger finds the jaw laid bare; sublimate dressing,
syringing with permanganate of potassium every two hours.
"Two more incisions into the cheek and in the region of the
ear were necessary. The fever gradually diminished, but up to
the present time some of the wounds are not yet closed, for
almost the entire cellular tissue in the region of the right side of
the neck and lower jaw became necrotic, and was gradually
thrown off. Fortunately, the periosteum formed again on the
lower jaw, and the case ended comparatively well. But the
patient had suffered terribly. Her life was in danger; she had
gone through an illness of five weeks' duration, and her face was
disfigured by scars. All this was the result of a really criminal
omission of all cleanliness and antisepsis, of unskillful operation,
and total ignorance of surgical principles."
The Zahnärztliches Wochenblatt of September 8, 1888, cites the
following case: "About six weeks ago, one Sunday afternoon, a
peasant girl, eighteen years of age, called on a dentist to have a
tooth extracted; not finding him at home, she sought the aid of
a barber. The latter succeeded in extracting the tooth, but was
not able, in spite of long-continued efforts, to stop the ensuing
hemorrhage, and dismissed the girl with the wound still bleed-
ing. At home the hemorrhage continued, and considerable
swelling set in, in consequence of which a physician was sent for,
who, however, came when it was too late, as the examination.
revealed blood-poisoning. A few hours later the girl was a
corpse.
A case of septico-pyæmia resulting from the extraction of a
tooth is related by Stanislaus Zawadzki.163 A locksmith, until
then in good health, forty-six years of age, whose left lower wis-
dom-tooth had been extracted fourteen days previously by a
barber, suffered on the following day from an exceedingly pain-
ful swelling of the corresponding part of the jaw, accompanied
by chills and sweats; later he was attacked by deafness of the
left ear, and continually increasing headaches. The chills
returned again and again, and finally the man lost conscious-
ness and was taken to the above-mentioned hospital, where high
stupor, grasping the head, groaning, slight icterus, contracted
pupils, high fever (39.9°), small, rapid pulse (ninety per minute),
280.
THE MICRO-ORGANISMS OF THE HUMAN MOUTH.
and a slight amount of albumen in the urine, were noted. The
region of the angle of the lower jaw on the left side was slightly
reddened, hard, swollen, painless, without fluctuation; on the
inner side greatly swollen, reddened, and hard. The wound was
filled with stinking, discolored matter, which discharged in mi-
nute quantities when the gums were pressed. The neighboring
lymphatic glands swollen, the spleen greatly enlarged. In the
left lower pulmonary region, marked exudation and increased.
respiratory murmur; cough with thin, stinking expectorations,
which contained many pus-corpuscles and streptococci. Inter-
mittent fever appeared, and finally death ensued under convul-
sions.
The autopsy revealed septic phlegmon of the entire left side
of the inferior maxilla and neck, with ichorous periostitis of the
affected jaw, cachectic pneumonia of the left lower pulmonary
lobe, and a great number of metastatic abscesses in both lungs,
further ichorous pachymeningitis of the dura mater, covering
the left sphenoid and temporal bone, with ichorous thrombi of
the corresponding sinus cavernosus, intercavernosus, and petro-
sus superior.
"In this case the infectious process, probably caused by an un-
clean instrument, had begun at the infected wound of the jaw
and then continued to spread from the roots of the vena submen-
talis, sublingualis, pharyngea to the plexus pterygoideus and
ophthalmicus, and through the superior sphenoidal fissure to
the sinus of the brain."
Another case which belongs to this group of infectious dis-
eases occurred in the surgical clinic of von Mosetig-Moorhof,
and has been reported by von Metnitz.164
A woman, forty-three years old, who had had several teeth
extracted a week previously, was brought to the Vienna Hos-
pital in an unconscious condition. A few days after the extrac-
tion she had fallen ill, suffering from continual pain and chills.
Three days before her admission delirium, psychical disturb-
ances, and one day before, total loss of consciousness had ensued.
Nothing could be ascertained as to any former complaint.
The scalp was considerably swollen, also the left cheek and the
malar and temporal regions. The skin of these parts was pale,
INVASION FOLLOWING MECHANICAL INJURIES.
281
shining, and tense, both bulbs very prominent, the conjunctiva
distinctly yellow and intensely chemotic, the pupils half dilated
without reaction. A terrible fœtor was emitted from the mouth;
lockjaw existed in the highest degree; the glands of the sub-
maxillary region on both sides were swollen, the neighboring
tissues infiltrated; the neck stiff. In the lungs there was noth-
ing especially remarkable. The heart was of normal size, with
a slight diastolic murmur at the apex; the abdomen was dis-
tended; the uterus could be felt above the symphysis; there was
deep stupor, delirium, restlessness, involuntary urination and
defecation.
"On the following day delirium, pulse very rapid; in the fol-
lowing night a hemorrhage of the uterus took place, and the
digital examination revealed a foetus, which was removed together
with the placenta; the fœtus was 17 cm. long. Death soon
followed, in a state of coma.
"On opening into the cavity of the skull the meninges are
found thickened, clouded, traversed by numerous densely filled
blood-vessels, and on the left hemisphere covered with a layer of
pus of considerable thickness. The right hemisphere likewise
plainly shows depots of pus along the course of the distended
vessels. The substance of the brain is soft, permeated with
moisture, and contains numerous ecchymoses. The chamber is
much dilated, and filled with a bloody serous liquid. The left
middle temporal convolution is yellowish and softened through-
out. The base of the brain is covered with a layer of pus, particu-
larly thick on the sella turcica, which may be traced as far as the
superior orbital fissure and the optic foramen. The meninges
here show the same character as on the convexity of the brain.
"The alveolus of the lower third molar is filled with fœtid pus,
the mucous membrane surrounding it is discolored and may be
pulled off in shreds. The probe discloses everywhere the rough
surface of the bone. All of the muscles inserted on the left side of
the lower jaw, as well as the whole of the articular aponeurosis,
are infiltrated with pus, at points destroyed, discolored, ichorous;
the temporo-maxillary articulation purulent. The submaxillary
glands are much enlarged, and also in the interior infiltrated
with pus. The bone of the lower jaw is completely divested of
282 THE MICRO-ORGANISMS OF THE HUMAN MOUTH.
periosteum, bicuspids and molars wanting, and the alveolar pro-
cess consequently much resorbed. The empty alveolus of the
third molar is 6 millimeters deep, and communicates through
wide openings directly with the marrow-spaces of the bone. The
marrow itself is discolored, fatty degenerated, and partly puru-
lently liquefied.
"The neglect of the wound caused by the extraction is without
doubt the source of this so violent inflammation in the bone."
According to the cases just cited, the most frequent cause of
death, next to blood-poisoning, seems to be secondary menin-
gitis, occasioned by the spreading of inflammation to the pia
mater. The inflammation, whether proceeding from the upper
or lower jaw, seems in most cases to make its way to the brain
through the fossa spheno-maxillaris, fissura orbitalis inferior,
orbita and fissura orbitalis superior, less frequently through the
foramen rotundum, ovale, spinosum.
Conrad 165 mentions a case of "death by tetanus, caused by the
extraction of two teeth." In dental literature, in fact, several
cases of tetanus following different dental operations have been
recorded.
In
It may be readily understood that not all infections proceed-
ing from the oral cavity result so seriously. Every gradation
may be noticed, from a slight inflammation of the gums to the
most severe suppurative periostitis and its consequences.
regard to this point, Ritter 166 writes as follows: "Not only the
fœtor often following a simple extraction, but even many accom-
panying suppurative inflammations, necrosis of the jaw, swell-
ings of the face, etc., are occasioned by the lack of proper anti-
septic precautions. I have been able in several hundred cases
of suppurative inflammations of the bone to trace clearly the
exciting cause of the affection. I have, indeed, seen one case of
this kind which terminated fatally, not, it is true, through the
local disturbance, but through a general sepsis occasioned by it.
I refer to the case of a young man in which the extraction of
the first and second inferior left molars was followed by a sup-
purative periostitis of the lower jaw. The patient died of
pyæmia a few days later, in spite of the most careful treatment.
I saw frequent cases of necrosis of the lower jaw arising after
Chu
INVASION FOLLOWING MECHANICAL INJURIES.
283
+
apparently simple tooth-extractions, some of which ran their
course under such septic symptoms as are usually noticed in in-
fected wounds in other parts of the body. In some of these
cases which I treated with the assistance of practicing physi-
cians, the sepsis did not remain local, but was accompanied by
symptoms of general infection."
Operations in unclean mouths are always attended with more
or less danger to the operator himself. Some months ago I saw
a case in which a scarcely perceptible injury of the finger by an
instrument used in excavating a tooth was followed by severe
swelling of the finger and back of the hand, resulting in the for-
mation of a large and stubborn abscess, which did not heal until
after several incisions had been made.
A still more serious case occurred some years ago in the clinic
of a dental college. A student of dentistry was unfortunate
enough to scratch his finger on the sharp point of a diseased
root. On the following day severe swelling, redness, and ten-
sion, accompanied by intense pain, ensued, which rapidly spread
under formation of numerous abscesses to the arm and shoulder;
high fever, delirium, and other symptoms of blood-poisoning
arose, and only by the most energetic treatment, and after a
long period of illness, was the danger of a fatal result completely
removed.
In late years the opinion has gradually gained ground that
operations in the oral cavity, extractions, lancing, etc., should
be performed under antiseptic precautions. Ritter recommends
that the tooth to be extracted, as well as the gums, be previously
disinfected by a suitable antiseptic, in order to avoid pressing
the masses of bacteria into the wound, by which means an infec-
tion is undoubtedly often brought about. Sachs regards it as
sufficient to dip the beak of the forceps in a five per cent. solu-
tion of carbolic acid, and relies upon the action of the antiseptic
adhering to the instrument to prevent an infection.
Parreidt 167 gives the following directions for antiseptic extrac-
tions: "Simple wounds after easy extractions in cases of pulpitis
or a beginning periostitis dentalis require no special treatment.
The danger of infecting such wounds is very slight; the tampon
of coagulated blood is a sufficient preventive against infection.
284
THE MICRO-ORGANISMS OF THE HUMAN MOUTH.
↓
Micro-organisms possibly adhering to the forceps, which might
be pressed against the gums or into the wound in performing the
extraction, are washed away by the flowing blood; moreover,
the gums are not especially liable to infections (wounds made
by files employed in operating upon decayed roots; Miller's and
Galippe's inoculation experiments)."
Parreidt opposes the treatment of the wound with so-called
antiseptic bandages, regarding them as more injurious than
beneficial. Only in case the wound should give pain a day after
extraction should an examination be made to determine whether
the thrombus in the alveolus is firm or possibly septical. The
latter will sometimes be found to be the case after difficult ex-
tractions, or in cases where osteo-periostitis alveolaris or maxil-
laris was present before the operation. The examination is made
by directing a stream of sublimate or carbolic acid solution upon
the thrombus, by which means it is readily washed out.
In cases where the protecting thrombus in the alveolus is
wanting, the latter should be syringed daily with an antiseptic
solution, at first morning and evening, later only once a day, in
order to prevent infectious matter from having too long or too
intense an action.
Parreidt recommends keeping the instruments as free as pos-
sible from germs by first thoroughly cleansing and drying them,
then dipping them into carbolic oil (1:2) and permitting them.
to remain moistened with this solution until the next operation.
Immediately before using the forceps they should be carefully
wiped, and then dipped into a five per cent. watery solution of
carbolic acid. Busch 168 recommends that the extraction itself be
performed under antiseptic precautions, but regards an antiseptic
after-treatment as unnecessary. Cold, clean water is best suited
for syringing the mouth until the bleeding stops; the addition
of antiseptics is not requisite, and only causes unnecessary com-
plication and expense.
Von Mosetig-Moorhof 162 most energetically demands a strictly
antiseptic proceeding in bloody operations in the mouth. "Op-
erative dentistry in its bloody interferences (Eingriffen) is a
specialty of surgery; those who practice it must consequently
be acquainted with at least the fundamental principles upon
GANGRENOUS TOOTH-PULPS AS CENTERS OF INFECTION. 285
•
which surgery is based. Now, the fundamental principle of the
modern science of surgery is antisepsis, and the dentist ought
not and dare not practice without it."
Witzel also recommends the cleansing of the mouth before
operations, and the requisite after-treatment of the wound or the
abscess-cavity.
Not only in tooth-extractions, however, but also in other less
serious operations in the oral cavity, removal of tartar, filling of
teeth, etc., must the greatest care be taken to keep the instru-
ments clean and aseptic. Years ago I observed a case of the
transmission of syphilis by means of dental instruments used in
the cleaning of the teeth, and only a few weeks since a severe
case of phlegmonous inflammation of the gums, following a
careless removal of the tartar. Lanceraux reports on two cases
of syphilis, one of which was caused by an infected instrument
used in the catheterization of the left tuba Eustachii, the other
by dental forceps used in extracting a number of decayed teeth.
In this connection I may say that to me it is always a source of
wonder that infections do not oftener occur through the repeated
use of the coffer-dam for different persons, particularly as it is
not always as carefully cleansed as it might be.
2. GANGRENOUS TOOTH-PULPS AS CENTERS OF
INFECTION.
Infections through gangrenous tooth-pulps are to be ranked
among the most frequent pyogenic infections of the human
body; they by no means always have the harmless character
commonly ascribed to them. The fact that the point of infec-
tion is so deep-seated, and is inclosed by hard, bony tissue, of
itself anticipates results of a serious nature. According to
Israel, the root-canal furnishes a point of entrance even for the
ray-fungus, Actinomyces, and in one case the microscopic exam-
ination revealed the elements of this organism in the canal of a
pulpless tooth.
If in any way or other (by tooth-decay, mechanical injuries,
attempted extraction, etc.) the tooth-pulp be deprived of its
natural covering, either totally or to such an extent that but a
thin layer of softened dentine remains, a number of different
286
THE MICRO-ORGANISMS OF THE HUMAN MOUTH.
processes may occur which will be discussed here only in as far
as is essential to an understanding of the subject under treat-
ment.
In regard to the faculty which the pulp possesses in taking
up germs of infection and transmitting them to the tissues sur-
rounding the apex of the root or even to the entire organism,
I distinguish the following possibilities:
1. The infection of the pulp begins either on the surface or
in the superficial layers; a progressive suppurative destruction
of the tissue takes place, gradually spreading towards the apex
of the root.
2. An infection of the entire pulp occurs, causing a total puru-
lent inflammation; or, a local septic infection becomes general:
for example, a case of pulpitis acuta partialis purulenta develops
into a case of pulpitis acuta totalis ulcerosa (Rothmann.)
In both 1 and 2 micro-organisms of a more or less pronounced
pathogenic character make their way to the apex of the root, or
may even encroach upon the periapical tissue.
3. Necrosis of the pulp occurs without any preceding infection
(in cases of total acute inflammation, destruction of the pulp by
arsenious acid, etc.). After the death of the pulp has occurred,
whether in the manner described in number 1, 2, or 3, an inva-
sion of various bacteria, strictly saprogenic as well as pathogenic,
usually takes place: the pulp, or its remains, becomes a stinking,
cheesy, or semi-fluid mass (gangrene).
4. We should take into consideration the possibility that
micro-organisms may be taken into the circulatory system from
a small focus of suppuration in the pulp, such as pulpitis acuta
partialis purulenta, etc., thereby leading to diseases of a more
serious nature. It is universally known that such a general in-
fection may proceed from alveolar abscesses, as shown by the
cases cited below. But, as far as I know, no communications
have been made as to the possibility of septicemia or pyæmia,
etc., arising directly from the pulp without the intervening stage
of an alveolar abscess, which acts as an accumulator of the poison.
A case which may belong under this head is that reported by
Schmid (page 291).
5. By way of the circulatory system microbes which acci-
GANGRENOUS TOOTH-PULPS AS CENTERS OF INFECTION. 287
dentally obtain entrance to the blood through slight wounds of
the skin, mucous membrane, etc., may enter a diseased pulp or
come in contact with a dead one. Finding here a suitable
medium, they proliferate, forming a focus of infection which
may bring about secondary disturbances at the point of the root.
This process may be illustrated by the following observation: A
mouse having a wound at the root of the tail was inoculated
subcutaneously near the foreleg with a pure culture of a mouth-
bacterium; twenty-four hours later this bacterium was found to
have established itself in large numbers in the old wound,
though it was not to be found in other parts of the body. If the
mouse had had a tooth with a dead pulp, I have reason to think
that the bacterium would there also have found a suitable nutri-
tive medium. The infection of the periapical tissue is usually
occasioned either by the micro-organisms working their way
into it independently from the pulp, or by the mechanical forc-
ing of infected material (remains of pulp, etc.) through the
foramen apicale. The latter may result from the pressure of
mastication when the open root is filled with soft contents, or
from the pressure of gases accumulating in the canal, or finally
from dental operations. The consequences of such an infection
depend upon the resistance offered to the advance of the bacteria
and upon the virulence and number of the latter. Putrid pro-
ducts, which may be forced through the foramen, intensify the
action of the bacteria by exerting a mechanical as well as a
toxical irritation upon the tissue. In case the decomposed pulp
contains no more living germs, particles of it may be forced
through the foramen without causing an infection. In such
cases a reaction takes places only in as far as it is produced by
mechanical or chemical irritation of the products of putrefaction,
which have been forced through the foramen.
Furthermore, apical infection with the harmless parasites of
the mouth will, cæteris paribus, be accompanied by comparatively
slight reaction.
If, on the other hand, living pathogenic bacteria are present
in the pulp, an infection will take place whose intensity depends
upon the number and virulence of the same.
Where the typically pyogenic micro-organisms, Staphylococcus
288
THE MICRO-ORGANISMS OF THE HUMAN MOUTH. ·
pyogenes aureus, etc., are present, we may expect severe suppu-
rative inflammation and formation of abscesses.
Parts of the pulp infected with the Bacillus pulpæ pyogenes
will also occasion suppurative inflammation.
Infections with various pathogenic micro-organisms (mixed
infections) will provoke divers phenomena. The progress of the
infection will in all cases materially depend upon the general pre-
disposition of the patient to infections, and upon his momentary
state of health. Consequently, apical infections exhibit all transi-
tions from a hardly perceptible reaction to the most dangerous
phlegmonous inflammations, accompanied by general symptoms,
such as high fever, chills, etc., which, as many instances show,
may lead to meningitis, as well as to pyæmic and septicemic
processes, with fatal termination.
The connection between affections of the teeth and severe dis-
eases of the jaw has already been pointed out by Hippocrates.
He wrote, "The jaw of the son of Metrodorus mortified in con-
sequence of toothache, and the gums became intensely swollen;
the suppuration was moderate. Not only the molar teeth, but
even the jaw-bone itself was thrown off."
The following in part fatal infections proceeding from the
pulp may also be mentioned. They are almost without excep-
tion to be regarded as indirect infections. In all cases, except-
ing that related by Schmid, a local affection first took place, and
only after a considerable quantity of poison had accumulated at
the point of infection did the general infection occur.
Mr. Pearce Gould (Journal of the British Dental Association,
April, 1886) has recorded a case of death from alveolar abscess,
resulting in thrombosis of the cavernous sinus. On admittance
the patient, aged fifty-seven, presented a sloughy opening in the
center of the right cheek. An incision was made from the out-
side, and six molar teeth were extracted. The trismus was
relieved, but ædema of the right temple appeared, and subse-
quently an abscess above the external angular process of the
orbit, and another in the posterior triangle of the neck, but the
internal jugular was not thrombosed. The respiration became
stertorous, pulse 126, small, temperature 103.8°, and crops of
herpes appeared about the lips. Great œdema of the orbit, and
GANGRENOUS TOOTH-PULPS AS CENTERS OF INFECTION. 289
1
chemosis with some proptosis followed, and slight rigors oc-
curred. Death ensued in a state of coma (Tomes).
Porre 169 (International Medical Congress, 1887) reported on
eleven cases of chronic pyæmia proceeding from the teeth, all of
which were healed by the extraction of the teeth. In one case
he mentions the following symptoms:
The patient, male, good constitution and habits, suffered for
the last thirty years from neuralgia, besides having constantly
recurring furuncles and eruptions in various parts of the body,
which would often for months become running abscesses. He
experienced burning and itching eruptions of hands and feet,
which finally changed to stubborn ulcerations. His bowels
were either stubbornly constipated or exhaustingly loose. He
suffered from frequent rigors and febrile attacks of varying
intensity, profuse night-sweats, retention of urine, serious con-
strictions of the bowels and urethra. Lancinating pains darted
from the maxilla of right side to bowels, bladder, limbs, hands,
and feet, or to whatever part was locally affected at the time.
This latter peculiarity, together with the discovery of a little pus
exuding from the locality of the wisdom-tooth, led to a final
correct diagnosis of his case. The tooth referred to was extracted,
and a speedy and complete recovery followed.
A case of chronic pyæmia following upon an alveolar abscess
has been observed by Mr. Howse. Suppuration occurred in
the inferior dental canal, and acute periostitis in the posterior
half of the lower jaw, which was denuded of its periosteum; the
inflammation extended thence through the pterygoid fossa into
the orbit, and thence backward. Ostitis of the vault of the
skull followed, and general pyæmia, resulting in the patient's
death on the ninth day after the supervention of the acute stage.
(Tomes.)
A similar case is described by Baker.170 Metastatic abscesses
formed in different parts of the body. The patient was healed
by antiseptic treatment and filling of the root-canal. Baker
also reports on a case of fatal pyæmia proceeding from an abscess
of a second molar; Poncet 171 on a case of osteitis which, pro-
ceeding from a carious tooth, led to a general septical infection,
and ended fatally in forty-eight hours. Fripp 172 saw a case of
19
290
THE MICRO-ORGANISMS OF THE HUMAN MOUTH.
inflammation of the brain proceeding from a dental abscess.
Ritter 173 also observed a case of septical blood-poisoning due to
a decayed tooth, which resulted fatally.
Coopman 174 noticed a fatal case of blood-poisoning in a boy
eight years old, caused by a delay in the extraction of an abscessed
tooth. An extensive periostitis accompanied by suppuration
supervened. In spite of the extraction of the tooth, which had
become quite loose, a metastatic abscess formed at the lower
margin of the orbital cavity. The condition of the child grew
worse from day to day, and death followed five days after the
extraction.
Marshall 175 describes a case of emphysematous gangrene pro-
ceeding from an abscessed lower wisdom-tooth, which ended
fatally in twelve days after a severe illness characterized by pro-
fuse suppuration, swelling, and throwing off of large necrotic
masses.
Ed. Pietrzikowski 176 observed in the clinic of Gussenbauer
a case of acute 'osteomyelitis accompanied by necrosis of the
articular process of the right lower jaw. The trouble originated
in an alveolar abscess.
Harrison Allen 177 reports the following case:
"A young man, in whom the roots of a lower wisdom-tooth
had been prematurely filled, was attacked with acute periodon-
titis, ostitis, and maxillary periostitis, as above described. This
was sufficiently severe to excite inflammation in the loose con-
nective tissue between the mylo-hyoid muscle and the jaw. An
•abscess followed here, and the pus gravitated to form a collection
about the hyoid bone, and from that point passed upward upon
the face, along the line of the facial artery. The abscess, in addi-
tion, 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.
M. Robert also relates a case in which necrosis supervened
in an abscess connected with a lower wisdom-tooth; what is
described as "purulent infiltration" of the side of the neck fol-
lowed, and the patient rapidly sank. (Tomes.)
A reference to a case of necrosis of the lower jaw in a boy
""
GANGRENOUS TOOTH-PULPS AS CENTERS OF INFECTION. 291
V
seven years old, following an abscess caused by a carious tooth,
will be found in the Dental Cosmos, vol. xvi, page 614. About
one-half of the ramus of the left side was removed through the
mouth, after enlarging the fistulous openings.
Schmid 178 gives a full report of a case of partial necrosis of the
left half of the lower jaw following upon traumatic septic (gan-
grenous) pulpitis. The patient had bitten a foreign body into
the cavity of an inferior left molar. The following morning the
left cheek was so swollen that he was not able to open his mouth.
After a long, severe illness, with varying symptoms (intense
swelling, recurring abscesses, temperature 40° C., pulse up to
120, insomnia, discoloration of the skin, diarrhoea, etc.), not less
than seventy pieces of necrotic bone were thrown off.
I am of the opinion that in this case a part of the septic tooth-
pulp was forced through the foramen apicale by the pressure of
the foreign body bitten into the pulp-cavity, and that the infec-
tion was brought about in this manner.
As is well known, diseased teeth very often occasion severe
diseases of the nasal cavity and maxillary sinus. Such cases are
too well known to every physician and dentist to necessitate the
enumeration of special cases here.
Ritter 179 has of late described sixteen such cases, and thereby
essentially strengthened the belief that by far the most cases of
diseases of the maxillary sinus and many of the troubles in the
nasal cavity are due to diseased teeth.
Galippe 180 also mentions the general disturbances that may arise
whenever a secretion of matter in the mouth becomes general and
profuse, as is the case in pyorrhoea alveolaris.
"We have seen
patients afflicted with fever, stiffness, loss of appetite, severe dis-
turbances of the alimentary canal, insomnia, subicteric discolor-
ation of the skin, etc."
Odenthal's 181 investigations have lent probability to the view
that the centers of infections formed by decayed teeth manifest
their deleterious influence in a manner hitherto but little sus-
pected.
Ungar 182 had previously communicated a case in which a
tubercular ulceration of the gums, followed by a swelling of the
ymphatic glands, had formed around a badly decayed cuspid.
•
292
THE MICRO-ORGANISMS OF THE HUMAN MOUTH.
The circumstances were such as to leave no room for doubt that
the tubercular infection of the lymphatic glands of the sub-
maxillary region, consequently the infection of the whole organ-
ism, stood in close relation to that observed around the decayed
tooth.
Von Bergmann 183 also regards lymphadenitis, the acute as
well as the chronic form, as a disease occasioned by infectious
germs which enter the lymph-passages from without, and are
thence carried into the glands.
Odenthal, prompted by these views and by the investigations
of Israel, discussed on page 341, undertook to determine whether
decayed teeth were actually often the cause of swellings of the
lymphatic glands of the neck. He examined in all 987 children,
and found decay of the teeth in 429; in 558 no decay was pres-
ent. Of the 558 children without decayed teeth, glandular swell-
ings were noticed in 275 cases, that is, in 49 per cent. of all. Of
the 429 children with decayed teeth, swellings were noticed in
424 cases, that is, in 99 per cent. Odenthal was also able to estab-
lish a constant relation between the extent of the glandular
swellings and that of the decay. In such cases where the pulp-
chamber was exposed, that is, where there was probably a gan-
grenous or highly-inflamed pulp, the swelling of the glands was
almost invariably more pronounced and extended. Further-
more, the presence of a number of decayed teeth was universally
accompanied by very marked glandular swellings. Where there
were decayed teeth on both sides of the jaw, there was a corre-
sponding glandular swelling on both sides.
The above by no means exhausts the number of cases reported
in the last few years, but what has been said may suffice to show
the importance of the subject under discussion, and the necessity
of thoroughly examining the oral cavity in all disturbances or
diseases the origin of which is not directly apparent. It also
shows that the custom of many physicians, to disregard dental
diseases altogether as a factor in pathology, is as unjust to their
patients as it is discreditable to their profession, and that no
physician can afford to be without a thorough knowledge of the
pathological processes occurring in the human mouth and their
relation to general diseases.
GANGRENOUS TOOTH-PULPS AS CENTERS OF INFECTION. 293
How often cases of this nature occur may be seen from the
fact that a pupil of mine, who is making a study of this ques-
tion, was able to secure the history of no less than twenty-one
cases which had come under the notice of two hospital directors
within the last five years.
Even leaving these extreme cases recorded above out of
account, we find often enough caries and necrosis of the alveolar
abscess or of the maxilla itself, chronic pyæmia, large abscesses
opening upon the outside, etc., as the consequences of an infected
tooth. The course of even the simplest form of alveolar abscess,
from the beginning of the pericementitis to the formation of the
abscess and the discharge of the pus, is often accompanied by
very disagreeable symptoms,-intense pain, swelling, high fever,
complete debility, etc. However, the symptoms of alveolar
abscesses are too well known to make a further explanation of
them necessary in this place.
As regards the etiology of alveolar abscess, we have adopted
the universally accepted view that it is caused by bacteria.
There can hardly be a doubt of this, particularly as the most
careful investigations have proved that suppuration can arise
without micro-organisms only in exceptional cases.
Black made the attempt to produce suppuration at the apex
of the root by mechanical irritation, and for this purpose several
times passed a sterilized steel wire through the foramen of a per-
fectly disinfected root-canal, but succeeded in causing only a
slight temporary inflammation.
According to Arkövy,184 Rothmann,185 and others, an infection
of the dental pulp may occur while it is still protected by a per-
fectly healthy layer of dentine, or, in other words, has not yet
been reached by the softening of the dentine. Under such cir-
cumstances Arkövy repeatedly observed the distinct phenomena
of pulpitis, and drew therefrom the conclusion that acute pulpitis
must be referred to a much earlier stage of dental decay and of
dental infections in general than heretofore supposed. The
microscopical examination revealed numerous micrococci in the
connective tissue at the base of the odontoblast layer, on the
nerves, etc. (Fig. 118). Comparative examinations of intact
pulps revealed no invasion of micro-organisms. On the strength
SA
•
294
THE MICRO-ORGANISMS OF THE HUMAN MOUTH.
of these facts Arkövy assumed that a pulpitis due to septical
causes is not only possible but actually occurs, and that the name
pulpitis acuta septica is appropriately applied.
I regard it as highly probable that bacteria from the decaying
dentine may pass through the tubules of a thin layer of sound
dentine and encroach upon the pulp; that they, however, pass
through thicker layers, unless in very exceptional cases, seems to
me doubtful; that they may pass through the entire thickness of
the solid dentine is quite out of the question.
A
Any doubts which might still be entertained concerning the
infectious nature of the germs contained in putrid pulps have
been completely removed by a series of culture and infection ex-
periments which I made during
the year 1888, and which prove
beyond doubt that purulent and
gangrenous tooth-pulps repre-
sent a very fertile source of in-
fection.
FIG. 118.

Infection of the pulp with micrococci in
pulpitis acuta septica. (After Arkövy.)
Small particles of such pulps
brought under the skin of mice,
occasioned after twenty-four
hours in the majority of cases
inflammation and swelling sur-
rounding the point of infection.
At the end of the second or
third day a small abscess was
generally found, which, when
opened, discharged a drop or two of pus.
In all, fifty-eight subcutaneous infections were made in this
manner. In 36.8 per cent. the infections were accompanied by
severe symptoms, in 7 per cent. the disease resulted fatally, in
47.4 per cent. the infection was insignificant, and in 15.8 per
cent. no reaction was discernible.
As a rule, the reaction is not so violent following such inocu-
lations as when a human being is infected by forcing particles of
gangrenous pulps through the foramen apicale, for the reason
that in the latter case the point of infection is more deeply seated,
and at the same time surrounded by unyielding tissue. In
ACTION OF BACTERIA UPON THE MUCOUS Membrane. 295
one case especially, interesting and characteristic phenomena
appeared. In twelve to fifteen hours a blackish or bluish-black
spot had formed around the pocket; in twenty-four hours some
swelling was noted, and also a slight fluctuation, i.e., a slight
formation of pus. At the end of the second day a tumor about
the size of a pea had developed, which, on being punctured,
evacuated a considerable quantity of pus mixed with gas and
emitting an extremely strong and offensive odor. A second
mouse inoculated with a small quantity of this pus developed
exactly the same symptoms; likewise a third inoculated from
the second, and so on to the twelfth generation. At this time I
was obliged to leave Berlin for a few days, during which the
mouse last inoculated died, and with it this series of inocula-
tions. The specific bacterium of this strictly gangrenous pro-
cess I was unable to cultivate, for the reason that it, like many
others of the oral bacteria, does not grow upon artificial media.
Pure cultures from gangrenous, as well as from suppurating
pulps, revealed besides the pyogenic staphylococci other microbes
of considerable pathological action, one of which, Bacillus pulpæ
pyogenes, is described at length on page 273.
These few experiments suffice to show how dangerous a source
of infections the pulp represents. It is highly desirable that
this subject be investigated as thoroughly as its importance
demands.
3. COMPLAINTS CAUSED BY THE DIRECT ACTION OF
BACTERIA UPON THE MUCOUS MEMBRANE
OF THE MOUTH AND PHARYNX.
·
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 also
may occasionally obtain a foothold. The mucous membrane of
the mouth and pharynx is especially susceptible to the action
of certain germs of infection (those of diphtheria, syphilis, etc.),
and large portions of the mucous membrane and the submucous
tissue may be wholly destroyed by parasitical influences.
The question now arises: May not the constant contact with
296
THE MICRO-ORGANISMS OF THE HUMAN MOUTH.
bacteria and their fermentative products exert a deleterious influ-
ence even upon the normal mucous membrane and upon the
entire organism by impairing its condition, lowering the sensa-
tion of taste, spoiling the appetite,-in other words, by producing
a condition of the mouth which corresponds to that condition of
the stomach denominated as "disordered stomach"? May not
the "coated tongue," the "pappy taste," etc., which are concom-
itants of the disordered stomach, be conditioned, independently
of the stomach, by fermentative processes in the oral and
pharyngeal cavities? Indeed, the "spoiled mouth," as well as
the "spoiled stomach," deserves a place among the diseases of
the digestive tract, and many complaints of loss of appetite and
of bad smell, which are said to come from the stomach, no
doubt have their origin in the neglected condition of the oral
cavity.
86
As early as 1756 Pfaff 8 had recognized the importance of
putrefactive processes in the mouth. "It is necessary," he writes,
"to remove the tartaric matter, because it is a heavy body and
daily accumulates mucus, which alters the fine color of the teeth,
gradually putrefies, attacks the gums, or even destroys their con-
nection with the teeth. The teeth consequently become loose, a
very disagreeable odor is emitted from the mouth, which is often
falsely attributed to the innocent stomach."
+
B
The investigations of von Kaczorowski 133 have furnished a
satisfactory solution of the above question. He had long held
the belief that the nature of most inflammatory processes of the
gums consisted essentially in an infectious process brought about
by micro-organisms, and was strengthened in this belief by the
observation that a frequent disinfection of the inflamed gums or
oral cavity of teething children removed in a remarkably short
time not only the inflammation, but also the concomitant catarrh
of the mucous membrane of the respiratory and digestive tracts,
the feverish excitement, convulsions, conjunctivitis, eczema, etc.
Not in children alone, however, but also in patients of every
age has this fact been repeatedly observed. Von Kaczorowski
justly opposes the view that the tongue is an indicator of the
condition of the stomach, and that the latter is always responsi-
ble for the want of appetite. On the other hand, according to
ACTION OF BACTERIA UPON THE MUCOUS MEMBRANE. 297
him, the appetite is chiefly determined by the condition of the
mucous membrane of the tongue and of the oral and pharyngeal
cavities. When the tongue is clean, even fevering patients retain
their appetite, while, on the other hand, the digestive process may
go on perfectly while the appetite is impaired. This is proved
by the favorable results of stomach-feeding even of such patients
who are not able to take food on account of the retching produced
as soon as the attempt is made to swallow it.
The nausea is consequently not due to the stomach, but to the
diseased throat; and the antipathy to taking food, which is
caused by the condition of the throat, may be removed by fre-
quent disinfection of the oral and pharyngeal cavities.
What far-reaching disturbances of the general health may be
obviated by the simple sterilization of the mouth is shown by
the following case: "A lady, fifty years old, who was afflicted
with a long-standing insufficiency of the aorta, but otherwise in
good health and enjoying a vigorous digestion, began after a
heavy sorrow to lose her appetite, complained of cardialgia
(which set in after every meal), belching, and heartburn, until she
could take but slight liquid nourishment, and finally was com-
pelled to restrict herself to tea. Repeated courses of treatment
with Carlsbad water brought but temporary relief. A disagree-
able odor from the mouth, especially in the morning, led me to
an examination, which revealed swelling and slight ulceration of
the gums; besides this, the tongue was heavily coated and the
posterior wall of the pharynx somewhat inflamed. Frequent
syringing of the oral and pharyngeal cavities with the iodine-
myrrh tincture stopped the cardialgia in the course of a few
days, and restored the patient to her former appetite.
"As often as the patient, who has a great antipathy to medi-
cines, neglects the disinfection of her mouth for but a single
day, the always more or less hyperamic gums swell again and
the old digestive troubles recommence. I have been able now
for seven years to watch this play of stomach-complaints in the
wake of recrudescent inflammation of the gums."
The connection between bacterial growths in the mouth and
severe disturbances of general health is furthermore exemplified
by the following case, which occurred a short time ago in my
298
THE MICRO-ORGANISMS OF THE HUMAN MOUTH.
use.
own practice: The patient, forty-five years of age, had com-
plained for months of severe pains caused by eating or even
speaking, of loss of appetite, indigestion, disordered stomach, etc.
These troubles became so burdensome that the patient declared
that life had become insupportable. She showed me two
envelopes filled with prescriptions both for internal and external
One glance into her mouth, the odor emitted from it, and
the concomitant inflammation and suppuration of the gums, sug-
gested intense fermentative processes. The cleansing of the
oral cavity, as well as the use of antiseptic and astringent mouth-
washes, caused such a pronounced improvement in a fortnight
that the patient could not often enough, express her thanks. In
this case the source of the trouble was so apparent that I cannot
understand why it had not been discovered before.
We frequently meet with persons who, as von Kaczorowski
correctly says, carry such filth in their mouths as they would
never tolerate on the skin. The physician who must insert his
finger into such a mouth is sometimes well-nigh overcome with
disgust; the foetor ex ore is insufferable, the teeth are covered
with a thick deposit in a state of active fermentation, the gums
intensely reddened, inflamed, suppurating, and where decayed
roots are present, which is usually the case, chronic abscesses
produced by them continually discharge suppurative and putre-
factive products into the oral cavity; and with all this they still
expect to enjoy good health! Such patients travel from one
bathing-place to another, naturally without finding any relief,
whereas the only journey necessary would be to the next hydrant,
and the only remedy a strong tooth-brush and a disinfecting
tooth-wash, or, at most, a visit to the dentist.
That the relation existing between an unclean mouth and
other complaints has not been long ago and repeatedly empha-
sized is explained by the fact that the mouth as a source of dis-
eases has been very much underrated, as the case just cited most
clearly demonstrates.
PULMONARY DISEASES CAUSED BY MOUTH-BACTERIA. 299
4. PULMONARY DISEASES CAUSED BY THE INSPIRATION
OF GERMS FROM THE ORAL CAVITY.
Comparatively few investigations or observations have been
made with regard to diseases of the lungs which may be brought
about by the inspiration of mouth-germs. The cases communi-
cated by Leyden and Jaffé, as well as by James Israel, suffice,
however, to prove that an infection of the lungs by microbes
which have established themselves in the mouth is by no means
impossible.
In cases of gangrene of the lungs and of putrid bronchitis,
Leyden and Jaffé 186, 187 found elements in the sputum which mor-
phologically, as well as in their reaction upon iodine, were iden-
tical with those which occur in the mouth. They formed the
opinion that the germs always present in the mouth in such quan-
and
tities might be carried into the lungs with the inspired air,
there, under favorable circumstances, proliferate. On intro-
ducing shreds and larger casts into the lungs of rabbits, they
observed in some cases considerable inflammation with gradually
progressing contraction of the trachea, and in others severe
inflammation, followed by the formation of abscesses.
J. Israel 188 has also furnished striking proof of the correctness
of the supposition that pulmonary diseases may be brought
about by the inspiration of germs from the oral cavity. In a
case of primary actinomycotic infection of the lungs, Israel
found a small irregular body, resembling a piece of dentine,
which he sent me for examination. It was found to consist of
a small fragment of dentine, surrounded by a chalky mass, com-
posed of phosphate and carbonate of lime, presumably tartar.
The microscopic preparations of this fragment revealed numerous
threads of the ray-fungus, and there can be little doubt that the
fragment was the carrier of infection.
Baumgarten 189 also reports a case of primary actinomycosis of
the lungs with secondary propagation to the soft tissue of the
thoracic wall, caused by inspiration of the specific fungal ele-
ments accumulated in the lacunæ of the left tonsil.
1
On the whole, however, it may be taken for granted that in-
fections of the lungs proceeding from the oral cavity occur more
rarely than we might be led to expect, as a very strong inspira-
300
THE MICRO-ORGANISMS OF THE HUMAN MOUTH.
tion is requisite to detach infected particles from the surface of
the mouth and to carry them into the lungs. The very impor-
tant part probably played by the micrococcus of sputum septi- .
cæmia in this connection has been discussed on pages 261, 262.
5. COMPLAINTS OF THE DIGESTIVE TRACT CAUSED BY
MOUTH-BACTERIA.
More than thirty years ago the fact was commonly recognized
that various disorders of the stomach and intestines owe their
origin to local fermentative and putrefactive processes. Accord-
ing to Baginsky,190 Bednar 191 was the first to give clear expression
to this view, in 1854. Bednar expressed the view that indiges-
tion may be brought about directly by taking into the stomach any
substance already in the state of fermentation; indirectly, when
the food taken into the stomach undergoes subsequent fermen-
tation on account of its disproportion to the digestive juices.
Henoch 192 favored this conception; he emphasized the fact
that a large number of diarrhoeas, especially in the case of
infants brought up on the bottle or just weaned, depended solely
upon fermentative and decomposing processes of the contents of
the stomach and intestines, without a material alteration of the
mucous membrane of the alimentary canal.
Naunyn 193 and Leube 14 also regarded fermentative processes
in the stomach as important factors in the production of gastric
complaints: "the very pronounced chemical anomalies of gastric
digestion, recognizable through the fermentations in the stomach,
go hand in hand with the mechanical insufficiency.”
De Bary,195 on the contrary, concluded from his experiments
that the action of bacteria as a factor in the origin of dilatations
or other gastric complaints had been overrated.
Frerichs 196 also wrote, "They (the bacteria) neither interfere
with nor further the digestive processes, but are harmless in-
mates.'
""
1
Ewald,197 whose examinations of the process of digestion and
digestive troubles have met with universal recognition, assigns
to gastric fermentations a position corresponding to their im-
portance.
COMPLAINTS OF THE DIGESTIVE TRACT.
301
"In diseases of the stomach, which lead either to an insuffi-
cient acidification or an abnormally long retention of the food
in the stomach, fermentative decomposition of the ingesta readily
takes place. In such cases the carbohydrates are decomposed
partly into gaseous products, and, according to the ferments
present, sometimes the alcoholic or acetic acid fermentation and
sometimes the lactic or butyric acid fermentation will ensue.
"My colleague (Rupstein) and myself had opportunity to watch
a case in which, as the patient very drastically expressed himself,
the vinegar factory alternated with the gas factory. In one case
the alcoholic fermentation led to the formation of acetic acid,
then the butyric acid fermentation to the evolution of hydrogen
and carbonic acid. This case was especially remarkable for the
fact that the patient occasionally belched up higher compounds of
carbon and hydrogen, such as marsh-gas and possibly olefiant gas,
which, on holding a candle to his mouth, ignited and burned with
a weak flame."
-
Escherich,198 whose examinations into the diseases of the sto-
mach and intestines of infants are probably known to the reader,
also recognizes the important part played by bacteria in these
diseases, and recommends, besides the administration of antisep-
tics, as still more important than these, a strict regulation of diet.
It would, however, lead us too far to notice the different
views concerning the importance of gastric fermentation for the
origin of catarrhs of the stomach, dilatations, etc. The observa-
tions of thousands of physicians sufficiently prove the occurrence
of abnormal fermentative processes in the stomach; and no one
can deny that such processes may appear in stomachs whose
functions are otherwise normal as well as in diseased ones. The
greater the mechanical or chemical insufficiency, the more
violent will be the fermentative processes and the more injurious
their action on the digestion.
According to Minkowski,199 the disturbances which are directly
caused by the fermentative processes in the stomach may be
referred to the following factors:
1. Substances may be formed which irritate the mucous mem-
brane of the stomach and bring about a state of catarrhal inflam-
mation.
302
THE MICRO-ORGANISMS OF THE HUMAN MOUTH.
2. Considerable quantities of gas may be formed which cause
subjective complaints and heighten the already existing mechan-
ical insufficiency of the stomach.
3. The fermentations may lead to the production of sub-
stances possessing toxic properties.
4. In fermentations of albuminous substances alkaline pro-
ducts may arise which occasion neutralization of the gastric juice.
5. The gastric fermentations may further exert a great influ-
ence on the functions of the intestines.
We have now to consider the following question: What part
may be assigned to the oral cavity as a breeding-place or start-
ing-point for the infection of the digestive apparatus ?
There can be no question that microbes are carried from the
mouth into the stomach and intestines every time that food is
taken. The view formerly held, that the swallowed germs
perish in the stomach, is entirely erroneous, as I myself 200 have
shown, and as has since been corroborated by MacFadyan,201
Sucksdorf,202 and others. Baumgarten203 had previously estab-
lished the fact that in the case of the tubercle-bacillus the normal
gastric juice does not destroy its virulence. Sucksdorf under-
took to ascertain by experiments to what extent our food and
drink are responsible for the regular importation of bacteria into
the stomach and intestines, and in how far their quality and
composition and the manner of their preparation influence the
growth of germs found in the intestinal tract. As result of these
investigations, it was found that the number of bacteria in the
fæces was considerably diminished by partaking of sterilized
food only. In mixed food Sucksdorf found on an average
380,000 cultivable germs in one milligram of fresh fæces.
the food was sterilized before the meal, only 10,390 colonies on
an average developed. These results show very clearly that
the number of bacteria in the intestinal tract depends in a high
degree on the number continually reimported with the food.
If
Nothing is said in Sucksdorf's experiments as to the condition
of the oral cavity, and nothing concerning the manner in which
the food was preserved. Besides, the experiments were made at
a season which is most favorable to the development of bacteria
in foods.
COMPLAINTS OF THE DIGESTIVE TRACT.
303
When, therefore, Sucksdorf concludes that out of one hundred
bacteria found in the fæces ninety-seven must be considered as
derived from the food and drink and only three from the oral
cavity itself, this conclusion may possibly be correct in the case
of a healthy, well-cared-for mouth and badly preserved food; in
general, however, I do not think that it is so, as is shown by his
experiments on a second person, where 30 per cent. of the bacteria
present in the fæces must be regarded as derived from the mouth.
From neglected mouths, such as repeatedly come under the
notice of dentists, enormous quantities of bacteria must reach
the intestinal tract in spite of the sterilization of the food. In a
very unclean mouth examined for this purpose I estimated, by
culture methods, the number of cultivable bacteria at 1,140,-
000,000; many of these were doubtless carried to the stomach
during every meal, to be replaced by others developing between
meals and over night.
The following case, among many communicated by von Kac-
zorowski, proves clearly enough that the micro-organisms in an
unclean mouth, quite independently of those introduced with
food and drink, suffice to produce intense fermentative processes,
chronic dyspepsia, etc., in the stomach.
"A hale and hearty landed proprietor, fifty years of age, who,
according to his statement, had never been ill, nevertheless com-
plained for some years of a troublesome inflation of the stomach
after meals, which did not subside for hours. The examination
revealed an artificial plate of the upper jaw, which the patient
had not touched for two years. After removing it, I observed
an intense redness and sponginess of the gums and hard palate.
After the patient had become accustomed to removing his arti-
ficial teeth after every meal, and to disinfecting his mouth, the
digestive troubles ceased without the use of remedies, and after
four weeks, when I saw him again, a swelling of the liver with
which he had been affected for some time had also disappeared."
During 1885-86 I made some experiments in order to determine
the relation of mouth-, stomach-, and intestine-bacteria to each
other, and also concerning certain disturbances in the stomach and
intestines caused by them, the results of which I have communi-
cated in the Deutsche med. Wochenschr.,204 and here recapitulate:
304
THE MICRO-ORGANISMS OF THE HUMAN MOUTH.
"Of twenty-five different kinds of bacteria which I have isolated
from the secretions of the human mouth, twelve are cocci and
thirteen bacilli or bacteria. It was not possible in all cases to
make a distinction between bacilli and bacteria, since so many
kinds produce at the same time long rods (bacilli) and short
rods (bacteria).
"Twelve of the mouth-bacteria I found again in the fæces, and
eight in the contents of the stomach. In the latter case the
material for the investigations was furnished by a gentleman
who could evacuate his stomach at will an hour or two after
partaking of a small quantity of fruit, particularly strawberries.
Each time the oral cavity was carefully cleaned and sterilized
with sublimate (1-1000), in order to prevent the intermixture
of bacteria from the mouth. That the micro-organisms really
came from the stomach, and not from the mouth or esophagus,
could readily be seen by their large numbers. I have satisfied.
myself by repeated experiments that in plate-cultures from the
saliva of a mouth which has been treated as stated above, very
few, or no colonies at all, will be developed, while in the cultures
from the contents of the stomach a small drop in 5.0 cc. of gela-
tine would produce colonies so numerous that the separate ones
were indistinguishable. Again, all organisms which were repre-
sented by only a few colonies were excluded.
"It is, perhaps, allowable to take for granted that all the
stomach-bacteria enter the stomach along with the food; it is
much less probable that they find entrance from the duodenum,
although the possibility cannot be entirely excluded. It would
not be permissible to assume that the intestinal bacteria all came
from the stomach, since an entrance per anum is not to be over-
looked, and since the stomach is supposed to present an impas-
sable barrier for most micro-organisms. The results obtained
from the experiments to be described indicate, however, that
the latter is not the case, but that any bacterium, under a variety
of conditions, may readily pass the stomach without losing its
power of development. The resistance of many micro-organ-
isms to the action of the gastric juice may be seen from the fol-
lowing experiment:
"About three hours after a moderate meal, 70 cc. of the con-
3
COMPLAINTS OF THE DIGESTIVE TRACT.
305
tents of the stomach were evacuated and placed in the incubator
under exclusion of air-germs. Three hours later, by means of
plate-cultures, I found three kinds of bacteria, and ten hours
later one kind. Not till after the lapse of fourteen hours were
all bacteria missing. The fact that a bacterium in an artificial
gastric juice (containing 0.2 per cent. HCl) may lose its vitality in
a short time, is no proof that it may not safely pass through the
stomach, because-
"1. The microbes which are swallowed at the beginning of a
meal do not pass into a stomach filled with gastric juice, but
into an empty stomach having a neutral or alkaline reaction,
where free hydrochloric acid, in detectable quantities, does not
appear until after the lapse of one-half to one and one-half
hours.
"2. The micro-organisms are often imbedded in solid particles
of food, thus escaping for a while the action of the juice.
"3. Liquid substances do not remain long in the stomach, but
soon pass into the duodenum, and carry with them the bacteria
before any considerable quantity of gastric juice has been se-
creted. In a case of fistula in the upper part of the duodenum,
Busch saw the first portions of food appear fifteen or twenty
minutes after the beginning of the meal (vid. Hoppe-Seyler,
'Phys. Chem.,' page 326). In case of soft liquid food, the transit
may begin still sooner. The experiments of Watson Cheyne,
and others, in connection with this subject, do not appear to
me to be conclusive, because made under conditions too unlike
those actually present in the stomach. Cheyne added material
containing micro-organisms to a comparatively large quantity of
artificial gastric juice, and observed that they were destroyed
in a short time. Such experiments simply show that the normal
gastric juice has antiseptic properties sufficiently strong to
devitalize certain bacteria within a certain time. They give us,
however, very little information as to the real occurrences in the
stomach itself.
"In order to reproduce as nearly as possible the conditions
present in the normal stomach, I chewed up a quantity of bread
and meat, added a small quantity of liquid (milk), and divided
the mixture into portions of 26.0 cc. each. These portions were
20
306
THE MICRO-ORGANISMS OF THE HUMAN MOUTH.
4
brought into small flasks, sterilized, and then infected, some
with a very sensitive vibrio, the others with hardy ferment-bac-
teria from the stomach. To each portion was now added, every
ten minutes, 2.0 cc. of an artificial gastric juice containing 0.4
per cent. HCl (1.6 cc. HCl solution of sp. gr. 1.1233), so that,
at the end of the second hour, the mixtures contained each
0.2 per cent. HCl, corresponding to the most active point of
normal gastric digestion, which has been determined to be at
about the end of the second hour or a little later, when the
acidity of the stomach has reached its highest degree. Cultures
made from time to time, during the course of the experiments,
from the different flasks showed that the least resistant of the
micro-organisms experimented with retained their vitality till
the end of the third half-hour, sometimes even longer, and that
the less sensitive ferment-bacteria showed no diminution in
number at the end of the experiment, and in many cases some
of them were still found six to eight hours later. Inasmuch as
portions of food pass into the duodenum in less than half an hour
after entering the stomach, these experiments seem to indicate
that any micro-organism swallowed at the beginning of a meal
might readily pass through the stomach alive. The case is some-
what different, however, if the bacteria are swallowed when the
digestion is at its most active stage (second and third hour). Ex-
periments representing this stage of digestion showed that very
sensitive putrefactive bacteria may thus be destroyed within
ten minutes, while the hardiest ferment-bacteria may resist for
hours.
J
"From these experiments the conclusion appears warranted
that all bacteria which are swallowed at the beginning of a meal
may pass alive into the intestines, while of such as are swallowed
in the second or third hour, only those which are less sensitive to
the action of acids retain their vitality. If we furthermore, take
into consideration the various and numerous affections in which
the quantity of gastric juice or its percentage of HCl is abnor-
mally small, it will appear as though the stomach affords almost
no protection whatever against the entrance of pathogenic organ-
isms into the intestinal canal, and that the condition of the
intestines themselves must be looked upon as the factor which
Bad
COMPLAINTS OF THE DIGESTIVE TRACT.
307
determines whether a pathogenic micro-organism which has
entered the alimentary tract shall or shall not come to develop-
ment or manifest its characteristic action in the intestines. We
have an exact proof that such is the case with the cholera-
bacillus. Koch 205 found that in order to make guinea-pigs suscep--
tible to the cholera poison it did not suffice to secure the passage
of cholera-bacilli into the duodenum by neutralizing the con-
tents of the stomach, but that it was necessary first to induce an
atonicity of the intestines themselves, with cessation of the
peristaltic action.
"It is worthy of mention that, although particles of food take
up the acid with avidity, they nevertheless often appear to afford
a certain protection to the micro-organisms. I have repeatedly
observed in plate-cultures that muscular fibers in particular were
lined with colonies, while on other parts of the plate very few
were to be seen.'
""
Some further questions of interest in this connection are the
following: At what stage in the process of digestion, or at what
percentage of acid in the contents of the stomach, does fermen-
tation cease? How much of a given antiseptic-hydrochloric
acid, salicylic acid, etc.—must be administered in order to bring
about a cessation of an abnormal fermentation in the stomach? I
attempted to effect a solution of these questions through the fol-
lowing experiments:
I chewed up a portion of meat and bread, and added a small
quantity of sugar with sufficient milk to make a thick paste. I
then infected this mixture richly with three kinds of stomach-
bacteria which are characterized by the large quantities of gas that
they produce, and added to it an equal quantity of 4 per cent.
peptone-sugar gelatine. After it had stood for an hour in the
incubator, it was divided into a number of portions of 20 cc.
each. To each of these portions I added hydrochloric acid in
increasing quantities, so that the first received 4 parts of HCI
to 10,000, and the last 2 to 1000. After this they were poured
into test tubes, and the level of the mixture in each tube
accurately marked. The portions being kept at 20° C. soon
solidified, and after eight to twelve hours, in all the tubes where
•
S
308
THE MICRO-ORGANISMS OF THE HUMAN MOUTH.
fermentation took place an elevation of the surface of the gela-
tine was observed, due to the formation of bubbles of gas, and
in those tubes containing the smallest quantity of HCl the mix-
ture was in part driven quite out of the tube. I found that not
till the proportion of HCl reached 1.6 to 1000 did the surface
of the mixture remain at a constant level, or, in other words, did
the fermentation cease. Salicylic acid effected the same in the
proportion of 0.4 to 1000. If, therefore, in a food mixture we
wish to prevent fermentation, or to arrest it when once begun,
we must add 1.6 grams HCl or 0.4 gram salicylic acid to each
1000 grams of the mixture.
In the human stomach, however, we have to deal, not with a
total lack of HCl, but rather with a diminution in the quantity
of the same, so that we require only to supplement the acid
already present. When digestion is at its most active stage, the
proportion of HCl in the contents of the stomach under normal
conditions is about 2 to 1000, and since fermentation does not
take place till this proportion has been reduced to 1.6 to 1000,
we must, in cases of continued fermentation in the stomach,
suppose a lack of HCl equal to at least 0.4 gram per liter of
stomach contents, and this quantity must be administered in
order to restore the normal condition.
According to the determinations of Bidder and Schmidt, ten
to twenty liters of gastric juice are secreted daily. If we con-
sider this estimate as two to four times too high, and take
five liters as the real quantity, we still have ten grams HCl
(forty grams HCl solution of sp. gr. 1.1233) which are daily
poured into the human stomach. Under such circumstances we
can hardly expect to produce much impression by the three- to
ten-drop doses recommended in text-books. The quantity of
any given antiseptic which is necessary to suspend fermentation
in the human stomach depends upon the intensity of the fer-
mentation and the quantity of the stomach contents; in any
case we must calculate upon large and repeated doses of HCI
if we wish to produce a marked impression. In case of the
ordinary lactic-acid fermentation outside of the stomach the
process will, in a few hours, be retarded by the antiseptic action
of the acid which is produced. In the stomach this action loses
COMPLAINTS OF THE DIGESTIVE TRACT.
309
its significance, from the fact that the acid produced is speedily
absorbed, and the contents of the stomach are replaced a number
of times daily by neutral material. These experiments also show
how small a change in the quantity or quality of the gastric juice
may suffice to render a permanent fermentation (dyspepsia chronica)
in the human stomach possible.
The objection may be urged against these experiments that, in
the solidified condition of the mixture, the HCl could not have.
its full effect. The control experiments, however, made at the
temperature of the human body (at which the mixture of course
became liquid), confirmed the accuracy of the previous results.
It may be further said that a portion of the HCl disappeared in
combination with bases in the mixture, but I am satisfied, from
experiments not here described, that the loss from this source
must have been very small, and was compensated for by the acid
present in the mixture at the beginning of the experiment, the
reaction in each case being clearly acid.
I next attempted to determine the action of these micro-organ-
isms on carbohydrates, particularly their acid-producing power,
being anxious to find the source of the acids of the human
mouth. For this purpose I cultivated them in beef-extract-
sugar solutions, in peptone-sugar solutions, and in milk. Six-
teen of the mouth-bacteria produced an acid reaction, four an
alkaline, and five gave inconstant results. The corresponding
numbers for the stomach-bacteria were nine, two, and two; for
the bacteria of the intestines, six, five, and three. The propor-
tion of the acid-forming bacteria in the mouth and stomach is,
according to these results, much greater than in the intestines.
Whether this condition is constant or not, could be determined
only by a large number of series of experiments. The cultures
in sterilized milk gave results slightly different from the above.
It was, furthermore, not possible to draw a sharp line between
those bacteria which produced an acid and those which produced
an alkaline reaction, since in some cases the reaction was only
slight and changed with time, while in other cases it was
altered by a change in the amount of sugar present. One
bacillus which I tested in reference to this question, cultivated
in 3 per cent. beef-extract solution, left the reaction neutral
310
THE MICRO-ORGANISMS OF THE HUMAN MOUTH.
when one-tenth per cent. sugar was present; if the amount of
sugar was increased, the reaction became acid; if it was dimin-
ished, the reaction became alkaline.
It is equally difficult, I think, to draw a sharp line between
putrefactive and fermentative organisms, since many ferment-
organisms are capable of decomposing albuminous substances
with development of putrefactive products, while on the other
hand many organisms which pass as putrefactive, when brought
into saccharine solutions, give rise to fermentation without the
production of a trace of the characteristic products of putrefac-
tion. One of the mouth-bacteria which I examined in reference
to this question readily dissolved coagulated albumen with devel-
opment of bad-smelling gases, among which SH, (sulphuretted
hydrogen) and NH, (ammonia) could be easily detected.
also showed an inverting action, in that it converted cane-sugar
into dextrose and levulose. In the third place it split ferment-
able sugars into lactic acid, with production of CO₂ (carbon
dioxide). In the fourth place it gave rise to an acid reaction in
a solution of starch, while at the same time the solution acquired
the capacity of reducing the oxide of copper; in other words,
this bacterium showed also a diastatic action.
2
It
In these different fermentations there undoubtedly arise in the
later stages various secondary products, so that the changes
which may be brought about by this one micro-organism and
the products developed under its action make up a very large
number. This result affords an explanation of the fact that in
an open decomposing substance so many different products may
appear, and renders very doubtful the supposition that for every
new product in the process of decomposition a new organism
must be present. The twenty to thirty different compounds
which may be produced in an open decomposing solution are in
all probability not produced by one bacterium alone. It is, how-
ever, not in accordance with the facts to assume that for every
product, or indeed for every stage in the process, a new bac-
terium must be introduced.
Of the bacteria under consideration I would like to call atten-
tion to five which regularly form large gas-bubbles in the gela-
tine or tear it in pieces, as represented in Fig. 8. One of these,
COMPLAINTS OF THE DIGESTIVE TRACT.
311
which in albuminous substances also produces considerable quan-
tities of gas (SH, and NH,), was found in the fæces as well as in
a gangrenous tooth-pulp. Its possible agency in the causation of
dental abscesses has been referred to on page 36.
Three of the other four gas-forming bacteria I found in the
stomach, and one in the fæces. It is not difficult to see what
disturbances might be produced by an abnormal development
of these bacteria in the stomach or intestines.
A further question of interest regards the peptonizing action,
particularly of the bacteria of the intestines. By far the greater
number of the different species which I have examined grow
well on boiled white of egg, and can therefore be said to possess
a peptonizing action. In some cases the albumen became com-
pletely liquefied by the action of the organisms. Whether they
form more peptone than they need for their own nourishment,
and whether and to what extent they may thereby be of use to
the human body, is a question whose solution presents difficul-
ties not yet overcome. In a large quantity of sterilized white of
egg infected with a comma-bacillus, I found traces of peptone
at the end of the third day.
Very few of the organisms here treated of were found to pos-
sess any marked diastatic action. Of nine species which I ex-
amined specially with reference to this property, only one gave
a decidedly affirmative result. By the action of this bacterium
starch was converted into sugar, and this again into acid.
It is generally taken for granted that a bacterium which
grows on boiled potato must possess a diastatic action. Such
evidence is, however, of little value, because the bacterium is not
dependent upon the starch of the potato alone, but may derive
sufficient nourishment from the sugar and albumen of the potato
to maintain its existence for some time.
Not one, out of more than fifty species that I examined, be-
longed to that group of micro-organisms called anaërobian; i.e.,
no one of them grew better or exclusively under exclusion of
atmospheric air. On the other hand, I found every gradation,
from those which showed no development whatever under exclu-
sion of atmospheric air to those which grew equally well with or
without it.
312
THE MICRO-ORGANISMS OF THE HUMAN MOUTH.
vt
The following conclusions may be drawn from the experiments
described above:
1. A large number of the bacteria of the alimentary canal
are not restricted to one portion of it alone, but may develop
either in the mouth, stomach, or intestines.
2. In by far the greater number of cases, the gastric juice will
not prevent the entrance of bacteria into the intestines. All
bacteria which I have examined may pass the stomach without
losing the power of development, provided they are swallowed
at the beginning of a meal. If, on the other hand, digestion is
at its most active stage (two or three hours after the beginning
of a meal), then those bacteria more sensitive to the action of
acids will be destroyed before they reach the intestines.
3. Lactic-acid fermentation may continue in the stomach until
the percentage of HCl reaches 1.6 to 1000. If too little HCl
is secreted, or too much food taken at once, the fermentation
may become permanent. Diseases of the stomach, general dis-
orders of health, fever, etc., accelerate the fermentation by inter-
fering with the normal secretion of gastric juice.
4. Fermentation in the stomach may be more readily arrested
with salicylic than with hydrochloric acid.
5. A large number of the bacteria of the alimentary canal
cause lactic-acid fermentation in solutions of carbohydrates,
whereby the frequent appearance of lactic acid may be ac-
counted for. Other ferment-acids, acetic, butyric, etc., I have
observed less frequently and in smaller quantities.
6. Five of the species examined caused fermentation with
formation of large quantities of gas, chiefly CO₂ and H.
7. It is impossible to make an exact division between those
bacteria which produce an acid and those which produce an
alkaline reaction in a given solution; also between ferment and
putrefactive bacteria.
8. The majority of the bacteria which I have examined mani-
fested a peptonizing, very few a diastatic action.
1
COMPLAINTS OF THE DIGESTIVE TRACT.
313
ī
GAS-FORMING BACTERIA OF THE STOMACH.
Reference has been made above to five kinds of bacteria,
which are characterized by the very considerable quantities of
gas which they produce in starchy and saccharine substances,
and further by the marked resistance which they possess to the
action of the gastric juice.
In view of the great importance which a thorough knowledge
of the physiology of these micro-organisms has in the thera-
peutics of many disorders of the stomach, and especially in the
dietetic treatment of such troubles, the results of a series of ex-
periments made in connection with this subject may not be
without value.
Two questions in particular appear to me to require a solu-
tion: 1. Are the micro-organisms which are taken into the
stomach at any meal passed out or devitalized before the recur-
rence of meal-time, or does the stomach, of dyspeptics in par-
ticular, contain bacteria at all times? 2. In what manner is the
quantity of gas generated by these bacteria influenced by the
kind of food taken?
Respecting the first question, practical experience would incline
us to the belief that the diseased or impaired stomach contains
micro-organisms at all times, otherwise how are we to explain the
fact that many patients almost immediately after taking starchy or
saccharine foods are troubled with the distention of the stomach
from formation of gas? I have demonstrated by various ex-
periments that the bacteria which may be swallowed with a
piece of bread are alone certainly not capable of bringing about
this distention. Nevertheless, it appeared desirable to test the
correctness of this supposition experimentally; and since the
proper experiments could be performed on the human subject
only with great difficulty, I chose dogs as the subjects, as they
have a digestive process very similar to that of human beings.
Up to the present but six dogs have been experimented upon, but
as the results were the same in every case, they are entitled to
consideration.
Four of these dogs, all healthy, were fed for two days on a
mixed diet of meat, bread, milk, and sugar, richly infected with
[
314
THE MICRO-ORGANISMS OF THE HUMAN MOUTH.
the gas-producing bacteria referred to. In every case diarrhoea
made its appearance in from thirty to forty hours, and in two
cases distention of the stomach was very marked. After the
last feeding they were muzzled to prevent the possibility of
their taking anything into the stomach, and killed after two
and a half, six, eight, and nine hours respectively. In every
case, except the last, the four kinds of bacteria administered
were found in the stomach in great numbers, also in the large
intestines; but few were present in the duodenum. In two
cases the reaction of the contents of the intestines was strongly
sour throughout, in one case slightly sour, and in one only was
the reaction neutral or slightly alkaline. The remaining two
dogs were treated in the same manner, except that the bread and
sugar were omitted; the result was the same as above, only
more marked. One of the dogs had profuse diarrhoea in fifteen
hours, and the intestines, six hours after feeding, were distended
with gas, and the reaction strongly sour. In both cases the bac-
teria were found in large numbers in the stomach, as well as
in the intestines.
It appears from these experiments that these bacteria can
maintain their existence, even in the stomach of dogs, for eight
or ten hours, and can thereby give rise to disturbance in the
intestinal canal; and when we take into account the fact that
the gastric juice of the dog is one and one-half times as strong
as that of the healthy human subject, and from one and one-half
to many times as strong as that of the dyspeptic or stomach-
ailing, there is little room left for doubt that living bacteria are
constantly present in the stomach, and that many chronic
troubles of the stomach are due, not alone to the micro-organisms.
which are at each meal taken in along with the food, but more
particularly to those which are already in the stomach at the
beginning of a meal.
It is, consequently, of greater importance to sterilize the
stomach before eating than to sterilize the food itself. For
example: What is the use of repeatedly boiling milk to free it
from every single germ, and then taking it into a stomach con-
taining vastly more bacteria than were in the milk in the begin-
ning? It will furthermore be readily seen that the time for
COMPLAINTS OF THE DIGESTIVE TRACT.
315
administering antiseptics is not after a meal, or upon the full
stomach, but upon an empty stomach, about ten or fifteen minutes
before meal-time. In order to determine what action these
bacteria may have upon the digestive process when the conditions
present are such as to permit of their development, I swallowed
a full-grown test-tube culture of the Micrococcus aërogenes im-
mediately after a meal, consisting mainly of bread, potatoes, and
milk. A very disagreeable feeling of distention in the stomach
and bowels appeared after about one and one-quarter hours, and
annoyed me the whole of the next day; after thirty hours I was
attacked with diarrhoea, which I aborted by taking sixty drops
of hydrochloric acid in water after a light breakfast. The effects
of the bacteria did not entirely disappear for some days, and
even on the fifth day I still found them in large numbers in my
fæces.
I attempted to effect a solution of the second question by the
following experiment: I mixed 2.0 grams (30 grains) of the dif
ferent kinds of food with 3.0 of saliva, added 5.0 grams beef-
extract peptone-gelatine, which had been infected with Bacteria
aërogene (or, I simply chewed up the food to be tested and mixed
it with an equal quantity of the same gelatine). Each mixture
was then poured into a separate test tube, the level marked, and
placed at a temperature of 22° C. The amount of gas generated
in the different tubes would be measured by the rise in the sur-
face of the mixture. After a series of nineteen experiments I
succeeded in getting together a table of comparative values, in
which bread is used as the unit of comparison. (See Fig. 119.)
As expected, it was found that the carbohydrates are particu-
larly characterized by the production of large quantities of gas,
whereas from the albuminous substances only a trace, or no gas
at all, is produced. Among the ordinary articles of diet, bread
and potato occupy a prominent place as gas-producers, and
should be as much as possible avoided by the dyspeptic.
Of those foods which do not appear in the table, and which
produce large quantities of gas, I may mention all kinds of sweet
desserts, cakes, omelettes, pears, sweet apples, grapes, etc. Cran-
berries and prunes produce no gas, because they do not furnish
a favorable medium for the development of bacteria; if they are
316
THE MICRO-ORGANISMS OF THE HUMAN MOUTH.

FIG. 119. Graphic representation of the quantities of gas evolved by different articles of diet.
No Formation|of| Gas.
A Matt Dam
mga m
Nuts.
Chicken stuffing.
Mush.
Green corn.
Carrots with white
sauce.
Carrots boiled in v
Raw cabbage.
Bread.
Cabbage.
Potatoos.
Milk.
Cauliflower.
Green beans.
Onions.
Tomatoes.
Macaroni.
Endives.
Spinach.
Meat.
Meat and sugar.
Meat hash.
Meat and plums.
Meat with sweet
cranberries.
Moat with sour cr
berries.
Meat with pick
spinach, & endiv
Meat with pickles
and spinach.
Meat and spinach.
Meat and pickles.
Butter.
Dried plums.
Cranberries.
Eggs.
Sour milk.
Salt pickles.
Fish.
Lettuce, undressed
Cheese.
COMPLAINTS OF THE DIGESTIVE TRACT.
317
mixed with meat, however, a very rapid development takes
place, accompanied by a production of gas.
According to these experiments, a diet for stomach-ailing
patients, which should be followed by no production of gas, dis-
tention of the stomach, sour eructation, etc., may consist of meat,
eggs, fish, spinach, fresh lettuce, and small quantities of endives
and sour cranberries.
The administration of an antiseptic before, and a digestive
during or immediately after the meal, will materially aid the
process of digestion.
I have had abundant opportunity to observe the happy action
of the above diet on one who has for years been troubled with
indigestion arising from abnormal fermentation in the stomach.
Morphology.
Bacterium aërogenes I. Short rods, single or in pairs, motile;
forms on gelatine-plates circular yellowish colonies with distinct
outlines. The colony is traversed by dark lines which often radiate
from the center and extend close to its margin; it grows rapidly
in line-cultures along the whole line with brown-yellow color,
and forms a flat grayish-white pappy button; it does not liquefy
the gelatine. On agar-agar it forms a grayish-white soft growth
with indented irregular margin; grows rather rapidly. In line-
cultures it grows as a cream-colored, moist deposit with smooth
outlines, and shows under the microscope dark lines, which
frequently run from the center to the margin. Growth without
access of air somewhat retarded, but numerous gas-bubbles
formed under the mica-plate.
J
Micrococcus aërogenes. Large oval cocci or plump rods, im-
motile; forms quick-growing, mostly round, but occasionally
somewhat indented colonies of dark color, with smooth contour.
It is characterized by leprous spots, which are dark or bright
according to the adjustment of the microscope; grows in line-
cultures like Bacterium aërogenes, but somewhat faster; in old
cultures slightly liquefying. Line-cultures are distinguishable
by the naked eye from Bacterium aërogenes I by the more undu-
lating course of the borders; under the microscope the dark rays
318
THE MICRO-ORGANISMS OF THE HUMAN MOUTH.
are wanting. Growth on agar-agar and on potato like that of
Bacterium aërogenes I, but somewhat more yellowish and less
moist; growth without oxygen but little retarded.
Helicobacterium aërogenes. Thin motile rods, single or in
chains; grows into long undulating threads which sometimes
form Spirulinæ; it develops transparent white or but slightly
colored colonies, whose composition of rods and threads is per-
ceptible even under 150 diameters. The colonies are round,
oval, snail-, spindle-, or spiral-shaped, in short, show almost every
possible form. In puncture-cultures the bacterium grows evenly
along the line of puncture with a light yellowish color, and
covers the surface after forty-eight hours (though not invariably)
with a thin, hardly visible, bluish, dry layer. In line-cultures it
also forms a thin, broad growth with very rugged margins; by
transmitted light the culture has a flaky or crystalline appear-
ance. Growth on agar-agar not characteristic; grows slowly on
potatoes; has an indented margin, dry surface, yellowish-brown
(mauve) color; growth without air restricted.
Bacillus aerogenes. Rather small, motile rods of various.
lengths; forms completely round, homogeneous, transparent,
white or slightly yellowish colonies. Older colonies occasionally
show a series of concentric rings. In line-cultures it grows
evenly along the line of inoculation; is of yellowish color; on
the surface it forms a thin, pearl-gray deposit with indented
margin; does not liquefy; in older cultures the line of inocu-
lation is dark brown, and surrounded by a peculiar light brown
halo; growth on agar-agar shows nothing remarkable; on potato
it grows very slowly, forming a dry deposit of bluish-yellow dirty
color and irregular margin; growth without air very limited.
Bacterium aërogenes II. Morphologically indistinguishable
from Bacterium aërogenes I; on agar-agar, potatoes, and in
line-cultures it shows a growth similar to the former. The
colonies, however, display essential differences: they are com-
pletely round, distinctly defined, yellowish, and, where they are
closely gathered, completely homogeneous; where far apart, they
show one or many black, irregular fissures on the surface;
growth without air very limited; but few air-bubbles form under
mica. A very slow liquefaction of the gelatine takes place,
forming a funnel (but only after a number of days).
M
-
POINTS OF ATTACK IN SOFT TISSUES OF THE MOUTH. 319
6. POINTS OF ATTACK FURNISHED BY A LACK OF RESIST-
ANCE IN THE SOFT TISSUES OF THE MOUTH.
It is well known that the mucous membrane of the mouth,
under certain conditions, loses its normal resistance to para-
sitical influences.
As a rule, only weakly children are afflicted with thrush; in
adults the thrush-fungus appears only after debilitating diseases.
Other parasitical diseases of the oral and pharyngeal cavities, as,
for example, stomatomycosis sarcinica (page 334), mycosis tonsil-
laris, etc., either accompany marantic processes, or are developed
in the course of local inflammations, but are seldom if ever ob-
served when the mucous membrane is intact. The gums are also
predisposed to infectious processes by local mechanical irrita-
tions.
In short, wherever, by any possible cause, mechanical, chemi-
cal, or thermal, local or general, external or internal, the nature
of the tissue is so changed as to furnish a suitable culture-me-
dium for certain microbes, a colonization of one or more of the
various species in the mouth will take place. The diseases
induced in this manner are:
a. Limited suppurative processes at the margin of the gums.
b. Formation of abscesses in consequence of impeded eruption
of wisdom-teeth.
c. The affection termed pyorrhoea alveolaris.
d. Stomatomycosis sarcinica.
e. Mycosis (pharyngomycosis) tonsillaris benigna.
f. Stomacace.
g. All inflammations of the gums accompanied by suppura-
tions and abscess-formations.
h. Thrush, occasioned by the yeast-fungus, Saccharomyces
albicans. (This disease will be mentioned in the chapter on
yeast-fungi.)
a. Limited Suppurative Processes at the Margin of the Gums.
The dentist daily meets with cases of the infections mentioned
under a. Accumulations of tartar, sharp edges of decayed or
filled teeth, pledgets of cotton, protruding fillings, etc., irritate
320
THE MICRO-ORGANISMS OF THE HUMAN MOUTH.
·
or inflame the gums, thus facilitating or making possible the
colonization of pyogenic bacteria. A small degree of suppura-
tion will always be found in such cases; it may, under certain
circumstances, extend to the pericementum and lead to abscess-
formation.
b. Abscess-Formation resulting from Impeded Eruption of Wisdom-
Teeth.
The affection which Arkövy calls abscessus alveolaris diffusus
must, in my opinion, as far as it is caused by those difficulties
accompanying the eruption of wisdom-teeth, also be assigned to
this group.
It is immaterial in these cases whether the disease be seated
in the gums,* or in the pericementum, or in the periosteum, or
finally in the bone itself. The invasion of the bacteria is in every
case made possible by the diminished power of resistance of the
soft tissues, caused by long and continued irritation.
The infection by pyogenic microbes, so often accompanying
impeded eruption, occasions not only profuse suppuration and
abscess-formation in the region of the lower jaw, which are ac-
companied by pronounced general symptoms, but also often leads
to general infection (septicemia, pyæmia), with fatal result.
Various fatal cases of blood-poisoning occasioned by the im-
peded eruption of lower wisdom-teeth have been cited on page
289 et seq.
The inflammation existing in the pericementum, or in the
gums, or in both simultaneously, manifests itself first by swell-
ing, redness, and accompanying soreness of the gums, which in
the mildest cases are circumscribed, in more pronounced cases
involving a large part of the mucous membrane of the corre-
sponding side of the mouth after inducing severe secondary
angina.
The appearance of suppuration is always a bad omen, in my
judgment calling for the immediate extraction of the tooth. I
have invariably found the formation of pus to begin on the
* The difficulties connected with the eruption of wisdom-teeth usually lead to
periosteal abscesses, while those arising from suppurative periostitis are generally
sub-periosteal. (Arkövy, page 281.)
POINTS OF ATTACK IN SOFT TISSUES OF THE MOUTH. 321
distal side of the tooth; a bent probe passed under the fold of
the gum enters a pocket filled with pus, from which more or
less pus exudes on pressure. If extraction is delayed, twenty-
four hours may suffice to bring about complete trismus, by
which the operation is extremely complicated, or for the time
being made impossible. Even in such cases, however, I have
seen all the swelling subside and the trismus and its accom-
panying symptoms disappear without any interference on the
part of the dentist. Very commonly, the suppuration not.
remaining confined to the pericementum causes secondary peri-
ostitis and osteitis, involving a large portion of the angle and as-
cending ramus of the jaw. The bone becomes infiltrated with
infectious sanious matter, which in this stage may readily be
absorbed in sufficient quantities to occasion general poisoning,
or it may make its way to the surface, usually at the outer angle
of the jaw (fistula), or the inflammatory process may extend
through the fossa pterygoidea, orbita, etc., to the brain, giving
rise to a fatal meningitis. The process is accompanied by ex-
tensive swelling of the submaxillary region, and sometimes
(seldom) by profuse suppuration or even gangrene of the gums.
The tooth itself finally becomes exceedingly loose through
destruction of the alveolus, and its extraction is accompanied by
the discharge of a large quantity of bloody, stinking pus. After
the extraction the wound should be thoroughly syringed with a
1-200 solution of sublimate.
c. Pyorrhoea alveolaris.
A disease of probably parasitic nature, which, next to decay of
the teeth, has attracted more attention among dental surgeons
than perhaps any other disease of the human mouth, and which
every dentist has abundant opportunity of observing in his
practice, is the so-called Riggs's disease, pyorrhoea alveolaris
(loculosis, blennorrhoea gingivæ, periostitis alveolo-dentalis, in-
fectious arthro-dental gingivitis, phagædenic pericementitis, ex-
pulsive gingivitis, symptomatic alveolar arthritis, etc.), a chronic
suppurative inflammation of the periosteum, with more or less
severe inflammation of the gums and necrosis of the alveolar
process of the diseased teeth.
21
322
THE MICRO-ORGANISMS OF THE HUMAN MOUTH.
The first stage of the disease presents but little characteristic;
it manifests itself only as a slight redness of the gums at the
neck of the tooth, which cannot be distinguished from a simple
gingivitis marginalis, such as is often caused by tartar. In the
majority of cases tartar is actually present. The disease at this
stage occasions but little or no inconvenience, and is therefore
generally overlooked.
Soon, however, distinct and characteristic symptoms appear;
the connection between the gums and the root is destroyed by
the suppuration of the pericementum, the gums appear more or
less swollen or puffed up, dark red or bluish red in color, and
but loosely surround the neck of the tooth. Pressure upon the
loose gums causes a slight discharge of pus. As the process ad-
vances, the margin of the alveolar process becomes involved and
gradually broken down.* The gums either become hypertro-
phied and puffy or gradually recede, exposing a large portion of
the root. A loosening of the teeth is now noticeable, which when
neglected generally increases until they drop out of their own
accord or become so troublesome as to make removal necessary.
The interval of time between the first appearance of the
disease and the falling out of the affected tooth varies. I
observed a case in which (according to the statement of the
patient) three weeks after the commencement of the loosening
of the teeth all the superior incisors were irrevocably lost; two
fell out spontaneously, the others had to be removed. In other
cases, however, the disease becomes chronic and many years
elapse before it comes to an end. After the loss of the teeth,
the phenomena completely disappear.
Pyorrhoea alveolaris usually attacks adults, by no means, how-
ever, exclusively, as many maintain. Some months ago I had
an opportunity of studying several pronounced cases of pyorrhœa
alveolaris in children of from four to twelve years of age.
By the kindness of Dr. Cass, director of the asylum for
rhachitic and scrofulous children at Middelkerk, Belgium, I
received permission to examine the mouths of over one hundred
patients, and discovered several typical cases of pyorrhoea alveo-
*By many the bone is regarded as the seat of the primary infection.
POINTS OF ATTACK IN SOFT TISSUES OF THE MOUTH. 323
*2
laris. In the case of a lame boy, nine and a half years old, with
remarkably advanced dentition, I found the left inferior first
bicuspid so loose that it could be pushed back and forth with the
fingers, the alveolus discharging pus profusely under pressure.
The superior incisors of a girl four years old were extremely
loose; the gums had receded, were very red, suppurating, in
short exhibited all symptoms of pyorrhoea alveolaris.
Its etiology is a very much debated question, and at present
the greatest differences of opinion prevail concerning it. Some
(including Riggs, who first accurately described the disease and
whose name it often bears) regard it as an altogether local affec-
tion, and consequently advise local treatment only. It cannot be
denied that a careful cleansing of the teeth, the removal of accu-
mulations of tartar, etc., may have a beneficial effect in the earlier
stages of the disease, although those doubtless go too far who
maintain that all cases may be permanently healed by this means.
We are never sure that a relapse will not occur; severe cases
may be kept within bounds, but not healed; a restoration of the
lost portion of the gums is, however, out of the question.
Others, on the contrary, define pyorrhoea alveolaris as a gen-
eral disorder.
Newland Pedley 206 writes, "The inferences that follow from the
points I have enumerated lead to the assumption that pyorrhoea
alveolaris is essentially of constitutional origin. In man and in
lower animals it is found connected with wasting diseases and
depressed conditions of the system. The local exciting cause
may be very trivial in nature.
"The weight of evidence tends to place pyorrhoea alveolaris
in the category of bone-diseases. The exposed position of the
alveolar margin and its intimate relation with organs of such
feeble vascularity as the teeth go far to explain why it is this
portion of the alveolus that is first affected, and also the usual
arrest of the disease by the removal of the teeth. It is not a
necessary concomitant of tabes dorsalis."
Bland Sutton 207 indorses the views of Pedley: "The disease
is undoubtedly of constitutional origin, but also requires local
treatment.' He has repeatedly observed the disease in rheuma-
toid arthritis, mollities ossium, etc.
""
:
324
THE MICRO-ORGANISMS OF THE HUMAN MOUTH.
Taft holds that pyorrhoea arises in consequence of a general
disorder of health, and that local treatment is useless unless the
general state of health be improved. Others, again, regard it
as a disease brought out by some local irritation, but for whose
causation a general bodily disorder (predisposition) is necessary.
Without both of these factors the disease seldom, perhaps never,
appears.
Reeve 208
accuses the use of spirituous liquors, which cause an
increased secretion of uric acid. The concrements in pyorrhoea
alveolaris, according to him, consist almost exclusively of uric
acids.
Patterson 209 examined twenty-four cases, and determined in all
the presence of catarrh of the mucous membrane of the nose or
pharynx; in many cases both affections. For the most part the
patients had the habit of breathing only through the mouth.
Patterson is of the opinion that pyorrhoea alveolaris and catarrh
are identical, a view to which F. J. Bennett 210 assents.
According to Witzel, pyorrhoea alveolaris is "a marginal
necrosis of the alveolus, caused by a septical irritation of the
bone-marrow," a view which Arkövy 211 seems to share, since he
terms the disease "caries alveolaris specifica." He regards the
"The
alveolar margins as the seat of the primary disturbance.
nature of the disease is a suppurative inflammation, which
spreads to all parts lying between the gums and the dentine of
the root."
Magitot, referring to the studies of Malassez and Galippe,
mentioned below, does not doubt the parasitical nature of the
disease; he concludes his remarks with the following proposi-
tions:
1. The affection characterized by alveolar suppuration and by
the loosening and falling out of the teeth should be designated
as a true symptomatic alveolar arthritis, septical and contagious.
2. It generally arises under the influence of certain unfavor-
able conditions of health and diathesis, also in exanthematic
fevers, etc., where it manifests itself either as a complication or
as a consequence.
3. The therapeutics should consist chiefly in the application
of antiseptics, local alteratives, astringents, or caustics.
$
POINTS OF ATTACK IN SOFT TISSUES OF THE MOUTH. 325
Malassez and Galippe have made very careful investigations
concerning the etiology of pyorrhoea alveolaris. Galippe con-
siders the disease as undoubtedly of a parasitical nature," which
may be proved by an examination of stained sections, by culti-
vation and isolation of the parasites contained in the dentinal
tubules, by the contagion spreading from tooth to tooth, as
well as from individual to individual, as we have observed more
than once in persons of different sex, who stand in intimate
relations to each other."
Galippe 180 found in the tubules of a tooth attacked by infectious
arthro-dental gingivitis a "parasite temporarily designated by the
letter 7, which shows the form of a very delicate double bubble
(Doppelbläschen), and is changed by cultivation into a bacillus,
the gelatine melting, and a characteristic rod appearing in the
tube of the gelatinous bubble.
Subcutaneously injected into guinea-pigs it produced, after
fifteen days, in the joints of all the paws a series of abscesses,
which made all motion impossible; the movements proceeding
from the pelvis were extremely painful. Some of the abscesses
opened spontaneously, the others were lanced with the necessary
precautions. The parasite y could again be isolated from the pus.
n
After several months the guinea-pig recovered from the infection,
but the awkwardness and stiffness in the joints remained.
"This parasite showed a preference for the osseous system in
a rabbit, into whose abdomen a pure culture of it was injected.
After fifteen days the emaciated rabbit manifested a sluggishness
of locomotion, and we discovered a considerable abscess in the
plane of the left thigh.
"This abscess was lanced; from the pus treated in the usual
manner the parasite 7 was again obtained in pure culture.
After a few days the abscess reappeared, and it was observed at
the same time that the animal breathed with difficulty. Emacia-
tion and depression increased, and the animal was killed about
a month after inoculation. The examination of the heart and
lungs revealed nothing particular; the kidneys were sound.
The injection had caused no inflammation, either in the diges-
tive organs or on the diaphragm. An enormous abscess occupied
the entire posterior surface of the liver. The lower portion of
326
THE MICRO-ORGANISMS OF THE HUMAN MOUTH.
the thigh showed numerous abscesses. On opening them, a
fracture of the lower extremity of the femur, about a centimeter
from the surface of the joint, was ascertained. Around the
fracture the bone was gangrenous, and the point of fracture
communicated with the adjacent abscesses. In the neighborhood
of the diseased spot we found a number of abscesses, varying from
the size of a hazel-nut to that of a walnut. The joint appeared
to be sound as far as could be judged from the preparation pre-
served in alcohol. On the plane of the ribs abscesses were dis-
covered, of which those facing the pleural cavity were especially
prominent. The subcutaneous abscesses were less developed;
longitudinal sections of the ribs, on a plane with the abscesses,
showed that the bone was swollen and much softened, as in
certain phases of osteitis. On other ribs, in the plane of the
abscesses, fractures were found which communicated with neigh-
boring abscesses.
66
According to the view of my teacher and friend Malassez,
who examined the lesions, we have here to deal with an osteitis,
which brought about the fracture of the bone and the surround-
ing abscesses. This is the only possible explanation of the
fracture of the femur, the care bestowed upon the animal ex-
cluding the possibility of a trauma. The same may be said of
the fractures of the ribs. The abscesses adjoining them vary in
size from a millet-seed to a hazel-nut.”
Besides this 7 parasite, Galippe found still others, on one of
which, called ẞ, he lays particular stress; injected under the
skin of the abdomen of a guinea-pig, it provoked the formation
of well-developed abscesses in the subcutaneous cellular tissue
and caused the death of the animal in twenty days.
Direct inoculation with the parasites 7 and ẞ between the
teeth and gums of animals yielded indefinite if not negative
results.
"The infectious arthro-dental gingivitis," says Galippe, "is in
reality only a local disease." But under certain circumstances
(abnormal nutrition, irregular mastication, neglected hygiene of
the oral cavity, conditions accompanying locomotor ataxia) "the
disease assumes a serious character, which is inversely propor-
tionate to the physical power of resistance of the individual."
POINTS OF ATTACK IN SOFT TISSUES OF THE MOUTH. 327
Galippe's experiments are doubtless the most extensive and
careful that have yet been made to prove the parasitical origin of
the disease in question; but notwithstanding the great progress
for which we have to thank this eminent investigator, I cannot yet
wholly give in my allegiance to the view held by the adherents
of the contagion theory.
Although the belief that the disease is hereditary is widely
circulated, and might be strengthened by the personal testimony
of many dentists (Morgan watched it through three generations),
we seldom hear (as far as I know, for the first time in this place)
of the transmission from one individual to another by contact.
Pedley energetically denies the possibility of such a trans-
mission. I have myself treated many patients suffering from
pyorrhoea alveolaris, but have very rarely met with a case in
which husband and wife were afflicted with it; this we should
often expect to find if the disease were contagious, inasmuch as
the diseased locality is favorably situated for the transmission of
the infectious matter. And even should the case be observed,
that a person living for a number of years with another afflicted
with pyorrhoea alveolaris was also attacked by it, it would be
necessary to prove that the sec-
ond person did not acquire the
disease independently before
such a case could be regarded
as evidence of its contagious
nature.
The fact also that micro-organ-
isms are found in the dentinal
tubules of teeth lost in conse-
quence of pyorrhoea alveolaris
hardly justifies the conclusion
that they are the excitants of the
'disease. The invasion of bac-
teria into the dentinal tubules
occurs also in abscessed teeth, particularly when the roots are
partially resorbed, so as to expose the open ends of the tubules
where there is no trace of the disease. (See Fig. 120.)
FIG. 120.

F MICROCOCCI PENETRATING THE CANALS
OF SOLID DENTINE, in a partially absorbed
and abscessed but not decayed root. 700: 1.
328
THE MICRO-ORGANISMS of the HUMAN MOUTH.
ORIGINAL INVESTIGATIONS CONCERNING PYORRHŒA
ALVEOLARIS.
Since 1885 I have examined thirty-nine cases of pyorrhoea
alveolaris in human beings and six in dogs, in order to determine
the presence of bacteria in the pus and in the root. The material
for this purpose was obtained in the following manner:
When the disease is so far advanced as to necessitate the ex-
traction of teeth, we first cleanse the crown and neck of the tooth,
as well as the adjacent gums, with 5 per cent. carbolic acid, and
then, after removing the antiseptic with sterilized cotton, care-
fully extract the tooth so as not to graze the gums, cheek, or
lips with the apex of the root; a small quantity of pure, fresh
pus
will be found on the root at the border between the dead
and the living pericementum. I used this matter, as well as
part of the periosteum of the apex of the root, in my culture-
experiments. In order to obtain in pure culture the bacteria
possibly contained in the cement-corpuscles or dentinal tubules,
I placed the tooth for a short time in a sublimate solution of
1-5000 (so as to destroy the germs on the surface). Hereupon
it was rinsed in a large quantity of sterilized water, dried with
sterilized blotting-paper, and the outer layers removed with a
sterilized knife. Small particles from the deeper layers were
then scattered on a culture-plate. If extraction is not desirable,
we may proceed in the following manner: The neck of the tooth
is carefully cleansed and a slight pressure exerted on the gums;
by this means the desired pus is pressed out between the gums
and the neck of the tooth.
I made dilution- and line-cultures on beef-water peptone gela-
tine of twenty-seven teeth afflicted with pyorrhoea alveolaris. In
two cases no growth took place; in one it was but very stunted.
Of the remaining twenty-four cases, twelve grew very rapidly,
five but moderately, and seven slowly. The gelatine was lique-
fied in five cases only. Staphylococcus pyogenes aureus de-
veloped but once; likewise Staphylococcus pyogenes albus.
Two formed yellow, one green coloring-matter; the latter is
of interest from the fact that it forms no pigment when the
access of air is prevented; if, however, the liquefied colorless
gelatine is shaken with air, a beautiful deep-green color almost
POINTS OF ATTACK. IN Soft tissues OF THE MOUTH. 329
immediately forms. In most cases I obtained but one kind, or
one kind so predominated that the rest could be left out of
account. In cases 8 and 13, the bacteria cultivated were found
to be identical; also in cases 16 and 17. In all the rest they
were different; that is to say, twenty-seven cases yielded twenty-
two different kinds of bacteria.
From these experiments we might conclude that if there is a
specific bacterium of pyorrhoea alveolaris it does not readily
grow on gelatine, a result which is of value in so far as it indi-
cates that in further experiments on this subject media should be
employed which admit of being kept at the temperature of the
mouth. At the same time the thought suggests itself that possi-
bly the bacterium of pyorrhoea alveolaris, like so many mouth-
bacteria, is cultivable on none of the artificial nutrient media,
which would of course render all experimenting useless.
The few experiments which were made on animals resulted
negatively. The gums of healthy dogs (these animals often
suffer from pyorrhoea alveolaris) were slightly detached from the
neck of the tooth and inoculated with pus, as well as with the
deposit on teeth attacked by the disease. Slight inflammation
invariably ensued, in one case also a little suppuration, but inside
of a week all cases were completely healed. Further experiments
are necessary to determine whether positive results may be gained
in the case of old or emaciated and sick dogs.
I next made a series of culture-experiments on agar-agar, at
blood temperature. Twelve cases of pyorrhoea in human beings
and six in dogs were examined. I isolated twenty different
bacteria from human beings, and nine from dogs. Among the
twenty kinds, Staphylococcus pyogenes aureus was found twice,
Staphylococcus pyogenes albus once, Streptococcus pyogenes
once. Of the other sixteen, nine subcutaneously injected pro-
duced no particular reaction, four a slight, three a severe sup-
puration in the subcutaneous connective tissue. One of these
is more fully described on page 270.
Among the nine species in dogs, Staphylococcus pyogenes
albus occurred once. Of the other eight, two subcutaneously in-
jected caused no reaction, five but a slight, and one very profuse
suppuration, by which large portions of skin were thrown off.
330
THE MICRO-ORGANISMS OF THE HUMAN MOUTH.
I succeeded, consequently, in cultivating a large number of
bacteria of pyorrhoea alveolaris which possessed pyogenic prop-
erties, but was not able to determine the constant occurrence of
any particular one which might be defined as the specific micro-
organism of pyorrhoea alveolaris. Nor is it evident from Ga-
'lippe's communication whether he found the 7 or 8 bacterium
in all cases examined or but once.
The microscopical examination of stained sections revealed
masses of different bacteria, cocci and bacilli, more seldom
leptothrix, on the surface of the cement, and where there were
microscopic cavities in the cement, or the dentinal tubules were
exposed in consequence of resorption, the micro-organisms were
found to have penetrated for a short distance (Fig. 120).
In my opinion three factors are to be taken into consideration
in every case of pyorrhoea alveolaris: (1) predisposing circum-
stances, (2) local irritations, (3) bacteria.
Every factor must be regarded as predisposing which impairs
the power of resistance of the parts in question,-constitutional
or local complaints, abnormal composition of the blood, digestive
troubles, unfavorable hygienic conditions, etc. Different authors
have mentioned as such particularly rhachitis, rheumatism, gout,
tuberculosis, scorbutus, scrofula, chronic constipation, exanthe-
matic diseases, malaria, diabetes, tabes dorsalis, dyspepsia,
rheuma, syphilis, repeated pregnancy, anemia, chlorosis and
wasting diseases of any kind, bad lodgings, lack of exercise,
improper food.
G
Rhachitis seems to furnish an especial predisposition for
pyorrhoea alveolaris. It is well known that the milk-teeth of
rhachitic children are shed at an early age.
I have seen many
rhachitic children of the age of four to six years who had but a
few teeth left. When, therefore, authors designate the disease
as peculiar to mature age (thirty to fifty years), they are unques-
tionably mistaken.
During the years 1888-89 I examined twenty-six cases of
rhachitis in children under twelve years; seven manifested
pronounced symptoms of pyorrhoea alveolaris,-i.e., intensely
bluish-red gums, suppurating when pressed, teeth loose, a deep
pocket between root and gums, loss of pericementum and alve-
POINTS OF ATTACK IN SOFT TISSUES of the MOUTH. 331
olar margin, disagreeable odor from the mouth. No symptom
was present which would have justified me in designating these
cases as anything other than real pyorrhoea alveolaris.
Three other children had previously shown the same symp-
toms, but were at the time being not afflicted with the disease;
the rhachitic symptoms had likewise also considerably dimin-
ished in consequence of proper hygienic regulations (sea air,
good food, and care). Four children, eleven and twelve years
old, who had been cured of severe rhachitis, had perfectly normal
teeth and normal healthy gums.
In other diseases of the osseous system, caries, coxitis, osteo-
myelitis, as well as arthritis, tuberculous inflammation of the
joints, tuberculosis, lupus, malum Potti, etc., of which I exam-
ined sixty-five cases, I could discover no especial predisposition to
pyorrhoea alveolaris. The teeth were also comparatively better
than those of the higher classes.
I formerly regarded scrofula as an important predisposing
factor in pyorrhoea alveolaris. Its frequent appearance together
with rhachitis renders it difficult to distinguish between the effects
of these two diseases. After examining over twenty cases of
scrofula, not complicated by rhachitis, I concluded that I had
overrated its predisposing effect, at least in regard to children.
It is a fact known to every dentist that constitutional diseases
are often followed by local expressions on the gums, the perice-
mentum, and the alveolar margin. I need only mention scor-
butus, mercurialism, and the gingivitis and pericementitis which
accompany exanthematic diseases.
Particularly striking are those affections of the gums that
occur during pregnancy, and which lead to swelling, puffiness,
and suppuration of the gums at the neck of the tooth, especially
between the superior central incisors. These affections bear
considerable similarity to pyorrhoea alveolaris, and are asserted
by some to result in this disease after repeated pregnancies,
although as a rule the symptoms, while yielding to no treatment,
completely disappear of themselves after confinement.
As unfavorable hygienic conditions we designate poor quarters,
bad food, bad air, want of exercise, etc.
The etiological significance of these factors in the origination
GE
332
THE MICRO-ORGANISMS OF THE HUMAN MOUTH.
of pyorrhoea alveolaris is most easily studied in animals. Wild
animals kept in captivity, lap-dogs, especially pugs and other
lady's dogs, which have little exercise and eat all kinds of un-
healthy stuff, very often lose their teeth, exhibiting symptoms
characteristic of pyorrhoea alveolaris, while, as far as I could find
out, hunting dogs and such as live under natural conditions are
never or but rarely afflicted with it.
Dr. Fröhner, professor at the veterinary high school of Berlin,
informed me that particularly dogs that are fed on potatoes,
farinaceous food, and sugar are often afflicted with this disease.
It also appears in connection with eruptions on the skin, rheu-
matism, etc.
As regards the local excitation, it can be furnished either by
tartar, food-particles, or any other mechanical or chemical agent.
Perhaps no other part of the body is exposed to so manifold and
lasting excitations (mechanical, chemical, thermal, etc.) as the
gums,―accumulations of tartar, particles of food which are
wedged between the teeth, strongly-seasoned food and drink,
contact with food in a state of decomposition or fermentation,
sharp tooth-corners, etc.,-so that the power of resistance of the
gums must be very great to avoid being affected.
It is still a matter of debate whether a local irritation be at all
requisite to the origination of the disease. I am not able to
form any decision regarding this matter, but so much is unques-
tionably certain that the symptoms are greatly aggravated by
local irritations, and that a removal of all such irritations and
extreme cleanliness are imperatively necessary in contending
against this disease.
As regards the participation of bacteria in pyorrhoea alveolaris,
our present knowledge of suppurative inflammations compels
us to consider the former as the cause of the suppurations inci-
dent to this disease. Micro-organisms which possess pyogenic
properties temporarily or permanently inhabit every mouth.
If, therefore, the power of resistance of the peridental tissue
be impaired by any one of the above-mentioned local or con-
stitutional causes in such a manner as to furnish a suitable culture
medium for the bacteria, they will, of course, begin their ravages,
and the usual symptoms will follow.
齡
​POINTS OF ATTACK IN SOFT TISSUES OF THE MOUTH. 333
Analogous circumstances are noticed in other parasitic diseases
of the oral and pharyngeal cavities.
According to this conception, pyorrhoea alveolaris is not caused
by any specific bacterium, which occurs in every case (like the
tubercle-bacillus in tuberculosis), but various bacteria may par-
ticipate in it, just as in suppurative processes not only one but
generally various species have been found. Besides, as far as we
know, there is no bacterium which, inoculated under the gums,
is able to provoke the disease in healthy persons.
The pronounced tendency of pyorrhoea alveolaris to recur after
it has been apparently healed may be explained by the fact that
we are seldom able to determine with certainty the predisposing
cause, or, having found it, to remove it. New infections of the
wound continually take place from the mouth.
The prognosis is always unfavorable; in the front teeth, how-
ever, a marked improvement, if not a complete cure, may be
effected. Even in far-advanced cases I have seen the suppura-
tion totally subside after appropriate treatment, and only reappear
months after at circumscribed points. I have therefore generally
found an after-treatment necessary at intervals of from four to
six months, and have in very many cases succeeded in at least
retarding the progress of the disease for years, and in restoring
the affected teeth, which had been painful and loose, to their
former condition of usefulness.
The chance of preserving the molars is exceedingly small.
The local treatment consists in a thorough cleansing of the
roots of the teeth, which in all cases anyways advanced can be
performed only after making an incision in the gums over and
parallel to each root, and extending at least to the line of demar-
cation between the healthy and diseased tissue. If, then, a tampon
of cotton is placed in the incision, the flaps of gums will be pressed
apart, and in a few hours the root plainly exposed to view. The
mechanical cleansing may be followed by an application of nitric
acid (2 to 4 per cent. solution). Finally, astringents, and par-
ticularly antiseptics, are to be used. The patient must pay the
strictest attention to his mouth, and when there are pockets be-
tween gums and roots, syringe them with an antiseptic solution
after every meal.
334
THE MICRO-ORGANISMS OF THE HUMAN MOUTH.
The systemic treatment must be directed against the predis-
posing cause, and varies therefore according to the history of
each individual case.
d. Stomatomycosis sarcinica.
The mycosis of the oral and pharyngeal cavities, thus desig-
nated, is caused by the colonization and proliferation of sarcina
in the shape of "frost-like coatings and deposits on the mucous
membrane of the mouth," when its normal power of resistance
is impaired by protracted illness, especially in marantic pro-
cesses, typhus, phthisis, etc. The disease is rare, and is said to
occasion no particular annoyance.
e. Mycosis tonsillaris benigna
occurs much more frequently. According to my observation,
it appears mostly in women and children who suffer from
hypertrophy of the tonsils, and are predisposed to chronic
pharyngitis. It occurs as a dirty, yellowish deposit, varying in
size from the head of a pin to a pea, consisting of numerous
bacterial forms and extending deep into the lacunæ of the ton-
sils. Both or only one tonsil may be attacked, while the tongue
and soft palate are more rarely affected. According to Schech,212
the subjective symptoms consist in tickling, dryness, burning,
slight pains in swallowing, inclination to hawking and cough-
ing. In one case he noticed fever with general discomfort;
weakness and loss of appetite preceded the appearance of the
spots. I myself never observed such disturbances, though
many cases have come under my notice, but have seen several
in which the mycosis followed an already-existing affection of
the pharynx, and concluded that the colonization of bacteria.
was made possible by the preceding inflammation.
The artificial removal of these deposits is very difficult, and
the strongest antiseptics do not seem to exert the least influence
on the course of the disease. The deposits, however, usually
disappear of their own accord in a few weeks, or as soon as the
conditions which made their formation possible are removed.
RE
POINTS OF ATTACK IN SOFT TISSUES OF THE MOUTH. 335
f. Stomacace.
Stomacace is a disease of the oral cavity or gums, which is
usually of a purely local nature. Some authors consider it as
an infectious disease, especially since it is often epidemic, and
Bergeron was able to communicate it to himself by means of
inoculation.
?
As far as I know, no culture-experiments have been made,
nor do we possess any information whatever concerning the
supposed bacterium of stomacace.
g. Stomatitis phlegmonosa, ulcerosa, etc.
In all these severe affections of the mouth, accompanied by
suppuration, abscess-formation, gangrenous decomposition,
sloughing, etc., we designate as chief etiological factors: im-
proper nourishment, unhealthy quarters, severe diseases impair-
ing and weakening the composition of the blood, scorbutus,
scrofula, rhachitis, typhus, scarlet fever, etc. At the same time
there can be no doubt that parasitical influences must largely
affect the aforesaid diseases, if indeed they do not stand in direct
causal relation to them. Next to a nutritious diet, antiseptics
and disinfectants form the chief remedies in their treatment.
It is not improbable that, under predisposing conditions, the
masses of bacteria in an unclean mouth perform the part of a
direct etiological factor in these affections.
There are, however, neither clinical observations nor culture-
experiments which permit us definitely to conclude what bac-
teria we have to deal with in connection with these different
diseases, or whether possibly each form owes its specific char-
acter to the action of a certain bacterium. It is highly probable
that various species, pathogenic and non-pathogenic, are present
in the later stages of these affections and contribute considerably
to the terrible devastations which are frequently consequent upon
them.
Diseases of the various tissues of the mouth which are to be
classed under this category are very common in domesticated
animals; more particularly in sheep. A disease known as scor-
butus (Spinola), stomatitis perniciosa (Gips), etc., frequently
336
THE MICRO-ORGANISMS OF THE HUMAN MOUTH.
The symp-
works terrible havoc in flocks of fine-wooled races.
toms of the disease are, consecutively, weakness, loss of appetite,
foaming at the mouth, redness of the gums, swelling of the gums
and formation of pockets around the neck of the teeth, epithelial
defects, ulceration, loosening of the teeth, periodontitis, perios-
titis and concomitant caries (of the bone), falling out of the
teeth (Gips).
The disease appears in the autumn when the animals are put
in the stall, attacking chiefly lambs or older animals which are
in poor condition, badly fed, anæmic, etc.
Here apparently, as in the
human being, predisposing
causes play an important rôle.
In stomatitis ulcerosa in the
calf, A. Lingard and E. Batt
(London Lancet, May, 1883)
have described peculiar bacilli
occurring in the tongue and
buccal mucous membrane (Fig.
121). The typical ulcer in ad-
vanced cases consists of a sore
with free overhanging edges.
On section through the sore, the
tongue is found necrosed to a
considerable depth. "When-
ever the sore touches any other
part of the mouth or cheek, the
disease is communicated and
rapidly spreads. In some cases
similar necrotic changes had taken place in the lung. The line
of junction of the necrotic with the healthy tissues was found to
be occupied by a dense mass of bacilli having the appearance of
a dense phalanx advancing upon the healthy tissues. The
disease has been proved capable of transmission (to the rabbit
and mouse) by injection of the bacilli in question, which are
equally numerous and virulent after passing through several
generations by inoculation." The disease often ends fatally in
calves (Klein).
FIG. 121.

CANC
FROM A SECTION THROUGH TONGUE OF
CALF, ulcerative stomatitis.
700:1. (After Klein.)
INFECTIONS FROM THE EXCITANTS OF DIPHTHERIA, ETC. 337
7. INFECTIONS RESULTING FROM THE ACCUMULATION OF
THE EXCITANTS OF DIPHTHERIA, SYPHILIS,
TYPHUS, ETC., IN THE ORAL CAVITY.
The question naturally follows close upon the above con-
siderations: Does the mouth present favorable conditions for
the growth of the specific excitants of those devastating in-
fectious diseases, tuberculosis, cholera, syphilis, etc.? May it
serve as a breeding-place for the specific germs of these diseases
which may enter it from the air, and thus lead to auto-infec-
tions?
We have seen (pages 259-262) that a bacterium identical with
the pneumonia-coccus often grows in the mouth of healthy per-
sons, and expressed the view that under certain predisposing
circumstances the germs carried from the mouth into the lungs
may produce croupous pneumonia.
The occurrence of diphtheria-bacilli in the saliva of a healthy
child, as has been observed by Löffler,213 favors the view that
the secretions of the mouth are a suitable nutrient medium for
the germs of diphtheria also, and that possibly they appear in
the mouth oftener than has hitherto been supposed, reserving
their specific action until certain favorable conditions prevail.
In such a case the diphtheria-bacillus might also be classed
among the mouth-bacteria.
The occurrence of a primary tuberculosis of the oral cavity
would seem to justify the hypothesis that the juices of the
mouth also furnish the tubercle-bacillus with a suitable nutrient
medium. But it must not be forgotten that tuberculosis arises
primarily in other localities remote from the oral cavity (testicles,
etc.), and that the saliva of healthy persons has hitherto been
examined in vain for tubercle-bacilli.
For the syphilis-bacillus the oral cavity seems, as a matter of
fact, to be a favorite abode; it is not only particularly preferred
by syphilis, but the buccal juices serve also as carriers of the
poison, and, leaving copulation out of account, the great majority
of infections take place from the oral cavity.
The transmission of syphilitic poison by means of saliva or
instruments employed in the mouths of syphilitic patients is,
well known, an only too frequent occurrence.
as
Y
22
338
THE MICRO-ORGANISMS OF THE HUMAN MOUTH.
I have already cited cases of this nature resulting from trans-
plantation of the teeth, on page 248. For most of the follow-
ing cases I am indebted to the excellent communication of L.
Duncan Bulkley 214 on this subject. Dulles 215 reports a case in
which the patient, a female domestic of excellent character,
developed a chancre of the lip two weeks after the extraction
of a tooth by a dentist. Otis 216 saw chancre of the lip develop
about three weeks after a morning spent in a dentist's chair.
Lanceraux 217 and Giovanni 218 relate similar cases. Leloir 219 and
Lydston 220 observed chancre of the gum resulting from cleansing
the teeth. Roddick 221 a like affection due to extracting with
infected forceps. Parker 222 observed a case where man, wife, and
child were all infected with syphilis through a tooth-extraction.
Bulkley furthermore refers to some thirty cases in which
syphilis was communicated through tooth-wounds (bites, or
blows upon the teeth), as well as to a number of cases in which
the dentist had inoculated himself by scratching the finger upon
a patient's tooth. It is, moreover, a significant fact that in a
recent sitting of the "Conseil d'Hygiène et de la Salubrité de la
Seine," it was even suggested to recommend to the proper
authorities that measures be taken to prevent the communication
of disease in this manner.
Apart from these cases, in which a single individual has
become the victim of an often criminal neglect of proper clean-
liness on the part of the operator, veritable epidemics have been
occasioned by infection with the saliva of syphilitic persons.
I observed the first case in the year 1878, at Philadelphia. A
large number of boys had been tattooed by a man who was in
the habit of moistening the instrument which he used, with his
saliva. This man was syphilitic, as was afterward ascertained.
Every one of the tattooed boys became afflicted with syphilis.
I also refer to the recent syphilis epidemic in the Russian prov-
ince of Wiatka. The belief is said to prevail among the peas-
ants of that region that all affections of the eyes are caused by
the presence of foreign bodies. In every case of eye-disease the
attempt is consequently made to remove the suspected disturb-
ance by inserting the point of the tongue between the eyelids.
Some individuals acquire a certain dexterity with their tongues,
ACTINOMYCOSIS.
339
•
and are employed to perform the operation. In this manner
thirty-four persons, 6 per cent. of the entire population, were
infected by a single woman, and as many more by other indi-
viduals.
The present state of our knowledge of the biology of the
germs of these diseases unfortunately makes it impossible for us
to determine whether and to what extent the human mouth may
serve as a nursery for those which may enter it with the air,
and thereby bring about an infection without direct contact with
an infected body. The facts given above are, however, sufficient
to demand earnest consideration, and present another warning
to those who are inclined to underrate the importance of the
mouth as a factor in originating and spreading disease.
ACTINOMYCOSIS.
In conclusion, we may mention a parasitical disease occurring
frequently in cattle, pigs, etc., but more seldom in human beings.
This disease, actinomycosis, is caused by the ray-fungus, Actino-
myces, of Bollinger,223 and has been for years the subject of nu-
merous investigations. Formerly the ray-fungus was thought to
belong to the mould-fungi, Hyphomycetes, but the more recent
investigations of Boström,224 who first succeeded in cultivating
Actinomyces on artificial media, have made it probable that the
ray-fungus belongs to the most highly developed bacteria, and
must be regarded as a species of Cladothrix (perhaps identical
with Streptothrix Försteri). Actinomycosis may therefore be
properly considered under the bacteritic infections of the mouth.
The ray-fungus, or ray-bacterium, as it should now be called,
occurs in the form of spirally curved furcated threads, radiating
from a center and dilating into bulbs at the extremities (Fig. 122).
These dilations were formerly called gonoids, while Boström
pronounced them to be involution forms. It grows slowly on
gelatine, quicker on agar-agar and beef-blood serum. According
to Boström, the optimum of temperature lies between 33° and
37° C.
"On the lower jaw of cattle tumor-like neoplasms sometimes
340
THE MICRO-ORGANISMS OF THE HUMAN MOUTH.
occur, which proceed from the alveoli of the molars or from the
spongiosa of the bone, inflate the latter, corrode it, and finally,
after having loosened the molars and destroyed the normal tis-
sues which impeded their growth, break through the skin ex-
ternally or into the oral or pharyngeal cavities.
Cate
po
FIG. 122.
THE RAY-FUNGUS. (ACTINOMYCES.)
(After Ponfick.)
"The inflated bones have
a pumice-stone-like appear-
ance, caused by central osteo-
porosis and external hyper-
ostosis. Most of the bulbous
and conglomerated growths,
which, after some length of
time, often become puriform
or entirely break down, and
lead to the formation of ul-
cers, abscesses, and fistulous
canals, usually attain the size
of a child's head or even
beyond.

"Such tumors are com-
posed of a conglomeration of
soft consistency, pale yellow-
ish color, and juicy luster
(saftigem Glanze), united by
tense connective tissue. On
the surface of the cut we
find scattered, usually cloudy,
yellowish-white, abscess-like
centers, or the hard cores are
of spongious structure, show-
ing numerous hemp-seed-
sized spaces and caverns in
the fibrous stroma, which contain murky, yellow, thick, often
cheesy pap. The mass of the tumor is infiltrated with a puri-
form or cheesy substance which often shows a reticular arrange-
ment, and may be readily obtained by scraping the surface of the
cut with a knife.
"The microscopical examination reveals, among other things,
ACTINOMYCOSIS.
341
numerous opaque, slightly yellow, coarsely granulated or gland-
like bodies of different sizes, often resembling mulberries. These
are here and there incrusted with lime, and on closer examination
are found to be of fungous nature.
"This mycosis occurs not only in the jaw-bones, but also in
the tongue of cattle, where it leads to the formation of erosions,
ulcers, and scars, or to secondary interstitial glossitis." (Bol-
linger.)
Soon after Bollinger's discovery, J. Israel 225 published his ob-
servations and investigations concerning two cases of disease in
human beings which showed the symptoms of chronic pyæmia.
The very numerous abscesses, appearing on all parts of the body,
when lanced, discharged profuse, stinking matter, strewn with
yellowish millet-seed-sized grains. These corpuscles, when
crushed, revealed various morphological constituents, which, as
Ponfick afterward proved, were elements of the ray-fungus.
Von Langenbeck made a similar observation as early as 1845.
Pontick,226 basing his deductions on the essential identity of the
constituents of the tumors of the jaws in cattle and the neoplasms
lining the cavities in human beings, but above all on the identity
of the morphological elements characteristic of both, came to
the conclusion that the ray-fungus is not confined to cattle, but
is found in man also.
In the human mouth the ray-fungus, like many other patho-
genic bacteria, seems to be able to exist without producing any
signs of disease, for example in the lacunæ of the tonsils, until
by some means or other (mechanical injury, etc.) a point of
attack is created.
James Israel,227 who has paid much attention to actinomycosis,
and to whom we are particularly indebted for our knowledge
on this subject, classified the cases of actinomycosis hominum,
observed up to 1885, according to the point of entrance of the
infection, into four chief groups:
1. Cases of invasion through the oral and pharyngeal cavities.
a. Central formation of foci in the mandibula.
b. Localization on the margin of the lower jaw in the sub-
maxillary and sublingual region.
c. Localization on the neck.
342
THE MICRO-ORGANISMS OF THE HUMAN MOUTH.
d. On the periosteum of the upper jaw.
e. In the region of the cheek.
2. Cases of primary actinomycosis of the respiratory tract.
3. Cases of primary actinomycosis of the intestinal tract.
4. Cases with uncertain point of entrance.
In dental literature very few cases of actinomycosis hominis
have been published. I can recall only one, but unfortunately
am not able to give a full description of it.
In medical literature, on the other hand, we find quite a num-
ber of cases of actinomycosis hominis. With the assistance
of Baumgarten's Jahresberichte, 1885-87, I have been able to
collect seventy-five cases, in addition to the thirty-eight mentioned
by Israel, making a sum total of one hundred and thirteen. Of
the newly-added cases, forty-eight have been described by
Hochenegg, 228 Rotter,229 Partsch,230 Moosbrugger,231 Roser,232 and
Braun.233
Of the one hundred and thirteen, about fifty-three must be
placed under the first division of Israel's classification. The
region of the mouth is consequently particularly prone to this
infection.
Israel refers the infections of the lower jaw and neck region
chiefly to the colonization of the ray-fungus in carious teeth,
but minor injuries or defects of the mucous membrane may also
suffice to create an entrance-point. (Ponfick, Partsch.)
We consequently have here again another dangerous source
of infection in the human mouth, which the dentist and physi-
cian do well not to lose sight of.
CHAPTER XII.
SUPPLEMENTARY REMARKS ON BUD-, MOULD-, AND ANIMAL-FUNGI.
BUD-FUNGI.
BUD-FUNGI (yeast-fungi, yeast, Saccharomycetes, Blastomycetes,
etc.) are microscopically small, mostly spherical, oval or cylin-
drical vegetable cells, with membrane and protoplasm (Fig. 123).
The size of the cells varies considerably in the different kinds,
from 2.5μ in thickness and 5μ in length in Saccharomyces exig-
uus, to 5μ in thickness and 100μ in length in Saccharomyces
V
FIG. 123.
A
с
a
b
C

VARIOUS FORMS OF YEAST-FUNGI. a, colonies of round cells (Saccharomyces conglomer-
atus?); b, single cells of different forms partly forming daughter-cells; c, cylindrical cells of
the pellicle-fungus (Saccharomyces mycoderma).
albicans (Flügge). They proliferate in the following manner: at
or near one or both ends a dilatation appears; this immediately
fills with the contents of the cells, gradually grows into a new
cell, and finally separates itself from the old cell by means of a
transverse wall. The old cell is called the mother-, the new
one the daughter-cell. The latter then forms new cells in the
same way. The daughter-cells either separate themselves from
343
344
THE MICRO-ORGANISMS OF THE HUMAN MOUTH.
}
the mother-cell and lead an independent existence, or remain
connected with it to form colonies (Fig. 123 a). Under certain
conditions of growth, proliferation may also occur by means of
spore-formation; it would lead us beyond the design of this
chapter, however, to enter more in detail into the biology of the
yeast-fungi. Certain species of bud-fungi, particularly Saccharo-
myces cerevisiæ and Saccharomyces ellipsoideus, possess the
power of exciting fermentation in saccharine solution (dextrose,
levulose, lactose, etc.), resulting in the production of ethyl alco-
hol and large quantities of carbonic acid (C,H12O6= 2 C₂H,,HO
+2 CO₂). In the alcoholic fermentation many by-products are
formed, and the actual decomposition is much more complicated
than is represented by the simple equation given above.
Of the best-known and most important yeast-fungi I mention :
1. Saccharomyces cerevisiae (Cryptococcus cer.), round or
oval cells, 8 to 9μ long, either single or united to colonies;
used in beer breweries and bread bakeries. At the higher
temperature at which beer is brewed (18° to 20° C.) the fermen-
tation progresses rapidly, and the yeast forms large branching
colonies which are carried to the surface by the great quantities
of carbonic acid evolved (upper yeast, Oberhefe).
At the lower temperature (4° to 10° C.) the fermentation pro-
ceeds more slowly, and the cells appear isolated or form only
small complexes which fall to the bottom of the vessel (under
yeast, Unterhefe).
The upper yeast is extensively used in the manufacture of
bread and in the preparation of compressed yeast. Added to
the dough it makes it "rise," and gives it a light, spongy
character through the development of carbonic acid. Recently
the chief part in this action has been assigned to bacteria, and
Laurent 234 among others describes a Bacillus panificans which
is said to be present during the fermentation of dough and to
produce the necessary carbonic acid; others again claim that
bacteria first convert the starch into sugar, which is then further
decomposed by the yeast into alcohol and carbonic acid.
2. Saccharomyces ellipsoideus, wine-yeast: elliptical cells, 6µ.
long, single, or in small branched colonies, very widespread in
nature, chief cause of the spontaneous fermentations.
BUD-FUNGI.
345
3. Saccharomyces conglomeratus, on decaying grapes and at
the beginning of wine-fermentation.
4. Saccharomyces mycoderma (pellicle-fungus, Kahmpilz),
which forms a white, wrinkled coating on fermenting liquids,
fruit-juices, etc. Cells 2 to 3μ thick and 6 to 20μ long, forming
much-branched growths, which sometimes have been mistaken
for moulds. It very often appears in mixtures of bread and
saliva left standing for some time at 25° to 35° C., consumes
the acid, and imparts an etherous smell to the mixture, espe-
cially if brought under the surface by stirring.
Bud-fungi are almost constant inmates of the oral cavity. If
cultures from the acid food-particles present in dental cavities
be made on slightly acid or neutral gelatine, round, rapidly-
growing, opaque white colonies will usually develop, which
under a low power (70: 1) may readily be recognized as masses
of yeast-cells. These organisms being widely distributed in
nature, and finding their conditions of growth best fulfilled in
slightly acid or fermenting media, their occurrence in the
human mouth is not to be wondered at. Compared to bacteria,
the bud-fungi play an insig-
nificant part in the oral cavity.
I regard them as the most harm-
less of all mouth-parasites.
Frg. 124.

On examining a piece of
dentine which had been pre-
served in water for some time,
as well as two human teeth
which had been worn in the
mouth as pivot-teeth, I noticed
the interesting fact that the
dentine had been perforated by a bud-fungus (Saccharomyces
mycoderma) (Fig. 124). I described this case in 1882, at the
time expressing the opinion that the fungus in question pro-
duced at its extremity an acid, "by means of which it perforates
or corrodes the hardest dental tissue."
YEAST-FUNGI, probably Saccharomyces my-
coderma, penetrating solid dentine. 105: 1.
Galippe noted a similar (perhaps the same) occurrence in the
teeth of an exhumed skeleton. He also thought it probable that
"these microbes secrete an acid," etc.
346
THE MICRO-ORGANISMS OF THE HUMAN MOUTH.
(
I am not, however, convinced of the correctness of this ex-
planation, but am now rather inclined to believe that dentine is
dissolved and destroyed by this fungus, similarly as bone or
dentine by the osteoclasts. It is a disputed question whether
acids participate in this process or not.
The only species of bud-fungi which, according to all observa-
tions hitherto made, possesses pronounced pathogenic properties,
is Saccharomyces albicans, the thrush-fungus. It was formerly
classed among the mould-fungi, and called Oidium. Numerous
experiments recently made by Plaut,235 Klemperer,236 Baginsky,237
Grawitz,238 Rees, etc., point, however, to the conclusion that
the fungus of thrush is not a mould, but a bud-fungus, a view
FIG. 125.
b
d
暑
​.
THRUSH-FUNGUS forming only round
cells and cell-colonies. (After Plaut.).
FIG 126.

que of you
THRUSH-FUNGUS forming cylindrical cells.
(After Plaut.)
now adopted by most mycologists, while others (Baumgarten)
accord the thrush-fungus a place in the class of the Torulaces,
-i.e., a middle position between the typical yeast- and mould-
fungi.
Ge
The shape of the cells of the thrush-fungus depends in a high
degree upon the conditions of cultivation; on acid, strongly
saccharine media (plum-decoction agar), it generally appears in
the form of quite spherical and oval cells (Fig. 125). In media
containing but little sugar and no acid, common beef-water-
peptone gelatine, the cells bud out to long threads (Fig. 126).
(Compare Klemperer and Plaut.)
A question not yet definitely settled, is that concerning the
identity of the thrush-fungus with other species of fungi:
BUD-FUNGI.
347
Saccharomyces mycoderma, Mycoderma vini (Cienkowski),
Monilia candida, etc. Plaut's numerous experiments lead him
to conclude that Saccharomyces mycoderma and the thrush-
fungus are not identical. "The former produces but minute
fermentation, during which the cells die; it readily forms spores;
its cells are somewhat spindle-shaped or ellipsoidal; it cannot
produce thrush when inoculated into hens in pure culture. The
thrush-fungus, on the other hand, excites pronounced fermenta-
tion, during which it grows exuberantly, forms no spores, shows
somewhat spherical cells, and is able to call forth pronounced
cases of thrush when transmitted to the crops of chickens." My
own observations coincide with the above. Cultures of both
these fungi on the same nutrient medium invariably manifested
the same differences of growth, in that Saccharomyces myco-
derma showed a constant tendency to form cylindrical cells,
whereas the thrush-fungus in my cultures, made on exactly the
same medium and in exactly the same manner, formed only
round or oval cells.
Baginsky discovered that in test-tube cultures on the surface
of the gelatine, i.e., exposed to the air, thrush-fungi form only
round or slightly oval cells, whereas those lying deeper develop
into thick mycelial threads, and those still farther down into
delicate ones. This is a phenomenon which characterizes the
growth of the fungus occurring pathologically in the tissues.
Thrush is peculiarly a disease of children or sucklings. In
adults it occurs, with very rare exceptions, only after exhausting
diseases, when the mucous membrane has completely lost its
power of resistance, or on the vaginal mucous membrane of
pregnant women. The infection is caused by inhalation of germs
from the air (the fungus of thrush being rather widely distrib-
uted), or more commonly by contact with infected objects. In
children the infection is chiefly due to unclean sucking-bottles,
sucking-bags, sugar-teats, etc., which, particularly when the con-
tents are undergoing fermentation, furnish most excellent nutri-
ent media for bud-fungi. According to Hausmann, the transmis-
sion of the disease from the vagina of the mother may also occur
at the time of delivery.
The neglect to keep the mouth in a proper state of cleanliness
K
348
THE MICRO-ORGANISMS OF THE HUMAN MOUTH.
naturally favors the proliferation of the fungus. It grows best
on the juicy, porous plaster-epithelium, and its chief seat of vege-
tation is therefore the mucous membrane of the oral and pharyn-
geal cavities and of the esophagus as far as the cardia; further-
more, that of the vulva, vagina, and anal orifice. But it also
occurs in the nasal cavity, larynx, trachea, and bronchi, on the
male genitals, and the nipples of the breast. The growth of this
fungus is, as a rule, restricted to the mucous membrane, only
exceptionally penetrating into the connective tissue or blood-
vessels, so that the observation of Zenker, who found elements
of the thrush-fungus in the interior of multiple abscesses of the
brain of a child, still stands alone.
Klemperer, by bringing pure cultures of the thrush-fungus
into the circulation of rabbits, succeeded in producing a general
thrush infection, which, however, was no more accompanied by
suppuration and abscess-formation, than the natural infection in
the mouth, so that the observation of Zenker is probably to be
accounted for by a mix-infection (Baumgarten).
The proliferation on the usually more or less inflamed mucous
membrane of the mouth first appears in the form of millet-seed-
sized, isolated and scattered white dots.
By the development of other centers of growth, or by the en-
largement or junction of adjacent growths, a continuous thrush-
membrane is produced which may line the entire oral cavity
and firmly adhere to the mucous membrane. The fungal pro-
liferation spreads itself from the oral to the pharyngeal cavity,
and in rare cases also to the oesophagus; sometimes even to the
mucous membrane of the stomach, to the nasal cavity, and the
larynx.
The fungi may multiply to such an extent in the œsophagus
that its entire lumen becomes filled, making the introduction of
food impossible. If the growth extends to the larynx, hoarse-
ness ensues, sometimes even want of breath. According to
Bühl and Virchow, the aspiration of thrush-masses may lead to
bronchitis and pneumonia.
The treatment of thrush must be chiefly prophylactic,-good
air, good food, above all the removal of any fermentable sub-
stances from the nursery and proper cleaning of the mouth after
MOULD-FUNGI.
349
drinking. If the fungus has already colonized, it must be
combated by applying alkalies, as it, in common with other
bud-fungi, does not flourish on alkaline media (repeated wiping
out of the mouth with a cloth dipped into a 5 to 10 per cent. solu-
tion of bicarbonate of soda). In more serious cases hourly
painting with nitrate of silver (0.1: 20 to 50) are prescribed.
Internally chlorate of potassium (1: 100.0, every two hours a
teaspoonful), and where the oesophagus threatens to become
obstructed, emetics. One should guard against the inexcusable
mistake of confounding thrush with leucoplakia oris.
MOULD-FUNGI.
Mould- or thread-fungi (Hyphomycetes, moulds) differ morpho-
logically from bacteria and bud-fungi by the formation of long,
branching threads (hyphæ), which, where the growth is not.
impeded, generally radiate from a center (the spore) and in-
crease by peripheral growth. The hyphæ are usually divided
into joints by transverse walls or partitions.
The entire development proceeding from a spore, exclusive of
the fruit hyphæ, is called a mycelium. Sometimes it is compara-
tively simple, but slightly ramified, sometimes again innumerable
ramifications appear, so that the mycelium forms a densely-
meshed flocculent mass. Finally, when the hyphæ are very
closely woven, firm, fibrous chords or bulbous, fleshy bodies of
various shapes (sclerotia) are formed.
Mould-fungi reproduce chiefly by spores. Individual threads
springing up from the mycelium (Fig. 127) display certain
differences in form and growth in contradistinction to the
others. These are the so-called fruit-hyphæ above mentioned,
on which spores are produced in various ways. At this stage,
the growth taken as a whole, mycelium and fruit-hyphæ, is
called a thallus.
Mould-fungi are very common in nature. They grow on
almost all kinds of organic media, and are able to send the
extremities of their threads into the hardest vegetable and
animal tissues, and even to perforate bones and teeth. They
do not by any means excite those intense processes of decompo-
sition in animal substances characteristic of bacteria. They
350
THE MICRO-ORGANISMS OF THE HUMAN MOUTH.
have been found, on the other hand, to be the cause of a large
number of devastating diseases of plants, vegetables, and cereals,
as well as of various diseases of fishes and insects. Several species
of Aspergillus and Mucor have proved pathogenic to mammals,
a
«Nike /
Goss
OM INTERIO
¿
Fun
LOMIERZEMA (COSTIER
d
C
STRAUMELMIERAS
FIG. 127.

Con
e
Q
m
T49
CYCLUS OF DEVELOPMENT OF THE FUNGUS PENICILLIUM GLAUCUM.
a, spores; b, c, bud-
ding of the spores (b after 24, c after 36 hours). 500:1. d, appearance of the mycelium after
48 hours, low power (75: 1); m, a small piece of the mycelium after 3-5 days, carrying a branched
fruit-hypha e, on whose extremities the spores are being thrown off. 500: 1.
while mould-fungi have also been shown to be the cause of a
number of cutaneous diseases in man. Mould-fungi, especially
Oidium lactis (milk-mould), are frequently met with in the
human oral cavity. The latter fungus is almost always found
MYCETOZOA, ANIMAL-FUNGI OR FUNGOUS ANIMALS.
351
in milk and butter (C. Fränkel 239). Its frequent occurrence in the
mouth is therefore easily explicable.
Cultures made from various parts of the mouth frequently
develop one or more colonies of moulds. (See Fig. 15.)
The mould-fungi of the oral cavity are, however, to be con-
sidered simply as occasional intermixtures; they attain to no
marked development, with the single exception, possibly, of the
fungus designated by Dessois as Glossophyton, which is said to
occasion a disease of the mouth called "black tongue." "In-
tensely black, inky stains, with rough, furry surface, which
slowly spread and may disappear of their own accord, are found
mostly on the back of the tongue, sometimes on the middle,
sometimes in the margins, at the base, or the point. The
black discoloration is said to be communicated to the epithe-
lium by imbibition from the black fungus-spores." (Schech.)
This affection seems, at best, to occur exceeding rarely, no other
case to my knowledge having been observed.
MYCETOZOA, ANIMAL-FUNGI OR FUNGOUS ANIMALS.
(AFTER ZOPF 240 AND DE BARY.241)
•
By the name Mycetozoa, de Bary has designated a group of
lowest organisms, whose proper position in the natural world is
still a subject of dispute, and which, consequently, have at pres-
ent been assigned a place outside of, or between, the animal and
vegetable kingdoms. They are, according to de Bary's concep-
tion, more nearly related to the simplest animal organisms (the
Amabæ) than to the fungi.
The Myxomycetes (Schleimpilze, slime-fungi) form the chief
contingent of the Mycetozoa.
These may be frequently observed as naked, slimy, transparent,
amoeboidal, protoplasmic bodies, sometimes of considerable
size, mostly in moist places, on dead vegetable matter (leaves,
etc.), or on the trunks of trees. Their resemblance to fungi lies
partly in their mode of life and nourishment, and partly in the
fact that they form organs of reproduction which are structurally
and biologically closely analogous to the spores of fungi. The
spores of Myxomycetes, when isolated, are almost without ex-
352
THE MICRO-ORGANISMS OF THE HUMAN MOUTH.
ception of spherical shape, and present the structure of simple
fungus-spores. In the process of germinating, the spores swell
up in consequence of absorption of water, the spore-membrane
ruptures, "and a protoplasmic body exudes or crawls slowly
out of the orifice” (Fig. 128, a, b, c).
In this state the organism forms a naked protoplasmic body
of changeable shapes, and is called a "swarmer" (Schwärmer).
These "Schwärmer" (Fig. 128, d, e, f) are partly provided with
cilia, partly without them, and manifest, according as they are
with or without cilia, two kinds of
movement, a hopping (hüpfende) and a
crawling.
Zopf therefore distinguishes a
"Schwärmerstadium" and an "Ame-
bastadium." According to him, a
Schwärmer is a membraneless lump of
plasm (primordial cell) in which we
may distinguish plasma, nucleus, vacu-
oli, and cilia. The amoeba also repre-
sents a primordial cell, in which plasma,
nucleus, and vacuoli may be distin-
guished. As they further develop, the
"Schwärmer" unite, forming larger
motile protoplasmic bodies (Plasmodia).
By the fusion of these plasmodia larger
plasmodia are formed, which resemble
arboreally ramified bodies or nets.
The development of the plasmodium
ends in spore-formation, either in the interior of sporangia or on
the surface of spore-bearers, sporophores, or in the form of
free reproduction-cells.
All better-known Myxomycetes are adapted to a saprophytic
mode of life. They occur in moist places or dead vegetable
matter, on decayed wood, on parts of trees, etc., but manifest no
pathogenic properties.
I am not acquainted with any investigations concerning the
occurrence of Myxomycetes in the oral cavity.
The Acrasia, a small group of fungous organisms belonging to
FIG. 123.

b
BUDDING OF A SPORE OF A
MYXOMYCETES (Trichia varia).
a, the spore at rest; b, c, d, rup-
ture of the spore-membrane
and escape of the " swarmer;"
e. amoeboid swarmer with, f
without cilium.
390:1. (After de Bary.)
MYCETOZÓA, ANIMal-fungi or funGOUS ANIMALS. 353
the Mycetozoa, differ from the Myxomycetes in this, that they do
not form true plasmodia.
Zopf and others also class among the Mycetozoa in a wider
sense, the Monadines, lower Mycetozoa, which by many botanists
are referred to the animal kingdom. They show a course of
development in its principal features identical with that of the
Myxomycetes. These play an important part as parasites. They
attack not only all kinds of aquatic growths (algæ, fungi, etc.),
but even higher plants; they have also been found in animal.
bodies, in the muscles of pigs, in the digestive tract of mice, etc.
In the human digestive tract, especially in intestinal diseases,
ambæ (Amoeba coli) have been found in enormous numbers
(Lösch, Cunningham, and others); furthermore, in the urine and
vaginal secretion of a girl suffering from tuberculosis of the uro-
genital organs (Bälz.) Marchiafava and Colli found plasmodia
in the blood of malarial patients.. It has not been possible, how-
ever, to determine with certainty the pathogenic significance of
these organisms in the human body, although many (Woronin,
Koch,243 Eidam,244 and others) have expressed the opinion" that the
appearance and development of many pathological excrescences
and swellings occurring in the animal body are brought about
by small Myxamæbe which invade the living organism, develop
into plasmodia, and cause considerable irritation," etc.
242
Flügge 245 and Baumgarten 246 also assign a greater significance
to the lower Mycetozoa as carriers of infection.
As far as I know, no investigations have been made concern-
ing the occurrence of Monadines in the human mouth; but that
they are often introduced into the oral cavity with vegetable
food and water cannot be doubted.
23
&
INDEX OF AUTHORS.
(The figures in heavy-faced type refer to the table of Literature, pp. xiii-xx.)
ABBOTT, 121, 124, 125, 126, 185, 83.
Ælianus, 254.
Aëtius, 121, 254.
Allan, 135, 184, 235, 102.
Allen, 290, 177.
Angermann, 145.
Aristotle, 254.
Arkövy, 134, 293, 294, 320, 324, 97, 184, 211.
Arthaud, 255.
Atkinson, 197, 120.
BABES, 7, 5.
Baginsky, 113, 300, 346, 347, 69, 190, 237.
Baker, 289, 170.
Balz, 353.
Barrett, 218, 128.
de Bary, 2, 4, 15, 17, 300, 351, 352, 1, 15, 195, 241.
Bassi, 15.
Bastyr, 134, 98.
Batt, 336.
v. Bergmann, 29, 292, 183.
Bidder, 308.
Binz, 40.
Biondi, 17, 90, 265, 268, 12, 159.
Black, 22, 90, 135, 161, 163, 193, 210, 221, 230, 236,
264, 265, 293, 24, 64, 103, 112, 130, 132, 156.
Bochefontaine, 255.
Boedecker, 121, 122, 123, 124, 126, 81, 82.
Bollinger, 339, 341, 223.
Boström, 339, 224.
Bourdet, 120, 71.
Boutroux, 25, 28.
Brauell, 15.
↓
Braun, 342, 233.
Brefeld, 52.
Bridgman, 135, 136, 211, 104, 124.
Brieger, 25, 29, 30, 34, 36, 26, 31.
Broca, 218.
Bücking, 130.
Bühl, 348.
Bühlmann, 46, 47, 70, 71, 50.
Bulkley, 338, 214.
Busch, 207, 236, 284, 305, 135, 168.
Cienkowski, 317.
Clark, 76, 163, 113.
Claxton, 255.
Baume, 131, 276, 161.
Baumgarten, 260, 261, 299, 302, 346, 348, 353, 154, Cohn, 12, 203, 204, 9.
189, 203, 246.
¡Coleman, 211, 123.
¡Colin, 255.
Becker, 130.
Bednar, 300, 191.
Bell, 120, 121, 77.
Colli, 353.
·Conrad, 282, 165.
Coopman, 290, 174.
Bennett, 324, 210.
Berdmore, 130.
Cornil, 7, 5.
Bergeron, 335.
Cunningham, 101, 184, 245, 353.
Cuvier, 123.
CANTANI, 14.
Carabelli, 120, 130. 73.
Cass, 322.
Castlo, 101.
Chamberland, 255.
Chase, 136, 137, 142, 143, 105.
Cheyne, 305.
DEHÉRAIN, 33, 37.
Delestre, 277.
Denecke, 34, 58.
Desirabode, 145.
Dessois, 351.
Dulles, 338, 215.
Dupetit, 32, 36.
Dupont, 247.
EBERLE, 254, 141.
Ebn-Sina, 121, 128.
Ehrenberg, 9, 6.
355
356
INDEX OF AUTHORS.
Eidam, 353, 244.
Eisenberg, 265.
Ellenborger, 38, 40, 206, 43, 44, 121.
Elliott, 240.
Engelmann, 35.
Erdl, 46, 132, 52.
Escherich, 113, 301, 68, 198.
Eustachius, 121, 74.
Ewald, 106, 300, 197.
FASBENDER, 29.
Fauchard, 129, 145, 85.
Ficinus, 46, 47, 132, 53.
Foerster, 199.
Forest, 145.
Fox, 121, 76.
Frank, 3.
Fränkel, 256, 260, 261, 351, 149, 153, 239.
Frerichs, 300, 196.
Friedländer, 261.
Fripp, 289, 172.
Fröhner, 332.
GAFFKY, 265, 158.
Gaglio, 255, 148.
Galbreath, 201.
Galen, 120, 121, 254.
•
Finkler-Prior, 34, 69, 78, 79.
Fitz, 23, 25, 26, 27, 27.
Flügge, 2, 7, 14, 19, 21, 23, 27, 28, 35, 262, 265, 343, Kappis, 120, 121.
353, 2, 21, 29, 41, 245.
Kirk, 42, 47.
Klebs, 52, 99, 100.
Gayon, 32, 36.
Giovanni, 338, 218.
Gips, 335, 336.
Goodsir, 123.
Gould, 288.
Gram, 51, 67, 174, 263.
Grawitz, 17, 346, 15, 18, 238.
Greser, 32, 34.
Griffin, 255, 147.
Günther, 67, 174, 201.
Guttmann, 145.
Gysi, 90, 134, 157, 166, 99, 114.
HALLIER, 70, 57.
Hansen, 31, 33.
Harlan, 236.
Hofmeister, 38, 40, 206, 43, 44, 121.
Hollarius, 129.
Henle, 46, 51.
Henoch, 300, 192.
Heraeus, 33, 34, 38.
Hermann, 42, 46.
Hoppe-Seyler, 18, 39, 40,147, 149, 150, 204, 305, 19,
42.
Hertz, 121, 79.
IIesse, 207, 122.
Hippocrates, 120, 288.
Hochenegg, 342, 228.
Howse, 289.
Hueppe, 12, 21, 22, 62, 66, 112, 23, 67.
Hufeland, 15.
Hunter, 121, 248, 75, 138.
ISRAEL, 285, 292, 299, 341, 342, 188, 225, 227.
JACUBOWITSCH, 38.
Jaffé, 299, 186, 187.
Jeserich, 164.
V. KACZOROWSKI, 236, 296, 297, 298, 303. 133.
Klein, 75, 256, 259, 336, 151.
Klemperer, 17, 346, 348, 11, 236.
Galippe, 100, 214, 215, 284, 291, 324, 325, 326, 327, LANCERAUX, 285, 338, 217.
330, 345, 125, 180.
v. Langenbeck, 341.
Lannelongue, 255, 259, 143.
Laurent, 344, 234.
Lebeaume, 46, 99, 100.
Klencke, 47, 132, 133, 56.
Koch, 10, 15, 16, 50, 52, 69, 79, 171, 226, 230, 265,
307, 353, 10, 131, 157, 205, 243.
Koecker, 121, 80.
Kräutermann, 120, 128, 70.
Kreibohm, 17, 258, 262, 268, 14, 152, 155.
Kremler, 128.
Kronecker, 35.
Krüger, 40.
Kühn, 15.
Leber, 71, 133, 160, 189, 213, 58.
Leeuwenhoek, 9, 45, 46, 72, 7, 48.
Leloir, 338, 219.
Lettsom, 248, 139.
Leube, 32, 300, 34, 194.
Lewis, 75, 61.
Leyden, 299, 187.
Leynseele, 276.
Liborius, 35, 41.
Liebreich, 164.
Linderer, 130, 87.
Lingard, 336.
Hausmann, 347.
Heitzmann, 121, 122, 123, 124, 126, 127, 81, 82, 84. Lydston, 338, 220.
Löffler, 67, 337, 213.
Lösch, 353.
MACFADYAN, 302, 201.
Magitot, 130, 131, 160, 193, 195, 196, 218, 324, 90,
94, 108, 126.
Malassez, 324, 325, 326.
Mandl, 46, 99, 49.
Maquenne, 33, 37.
Marchiafava, 255, 259, 353.
1
INDEX OF AUTHORS.
357
Marshall, 290, 175.
di Mattei, 255, 148.
Mayr, 129.
Mendelsohn, 12, 9.
v. Metnitz, 280, 164.
Miller, 18, 34, 76, 77, 78, 85, 90, 106, 111, 123, 134,
142, 164, 180, 207, 214, 218, 227, 239, 247, 256,
|
259, 284, 302, 303, 328, 345, 20, 60, 62, 63,
106, 116, 129, 136, 150, 200, 204.
Milles, 133, 134, 160, 195, 95, 119.
Minkowski, 301, 199.
Miquel, 226.
Moosbrugger, 342, 231.
Morgan, 327.
Moriggia, 255, 259.
v. Mosetig-Moorhof, 277, 280, 284, 162.
Mummery, 177, 218, 219, 220, 127.
Müntz, 32, 34, 35.
Murie, 123.
Musitanus, 128.
NÄGILI, 10, 52.
Nasse, 40.
Nathan, 17, 17.
Naunyn, 300, 193.
Nencki, 10, 29, 8, 30.
Netter, 264.
Neumann, 121, 186, 188, 189, 191, 194, 78.
ODENTHAL, 31, 291, 292, 181.
Otis, 338, 216.
Ovelgrün, 145.
Owen, 123.
PANUM, 29.
Parker, 338, 222.
Parreidt, 283, 284, 167.
Partsch, 342, 230.
Pasch, 130.
Paschutin, 104.
Pasteur, 21, 34, 225, 255, 259, 22, 144.
Patterson, 324, 209.
Paul, 130.
Pedley, 323, 327, 206.
Peirce, 135, 101.
Pfaff, 129, 145, 296, 86.
Pietrzikowski, 290, 176.
Plaut, 346, 347, 235.
Pollender, 15.
Poncet, 289, 171.
Ponfick, 340, 341, 342, 226.
Porre, 289, 169.
Prazmowski, 8, 23, 25.
RAYER, 15.
Raynaud, 255, 259, 143.
Rees, 346.
Reeve, 324, 208.
Riggs, 321, 323.
Ringelmann, 128, 130.
Ritter, 282, 283, 290, 291, 166, 173, 179.
Robert, 290.
Robertson, 130, 88.
Robin, 47, 70, 71, 54, 55.
Robinson, 101.
Roddick, 338, 221.
Rognard, 130, 89.
Rörsch, 29.
Rosenbach, 17, 14..
Roser, 342, 232.
Rothmann, 286, 293, 185.
Rottenstein, 71, 133, 160, 189, 213, 58.
Rotter, 342, 229.
Roux, 40, 255, 45.
SACHS, 283.
Schech, 334, 351, 212.
Scheurlen, 17, 16.
Schlenker, 120, 131, 160, 210, 72.
Schlösing, 32, 34, 35.
Schmid, 286, 288, 291, 178.
Schmidt, 38, 308.
Schmiedeberg, 29.
Schwann, 102.
Scribonius, 128.
Selmi, 29.
Senator, 254, 142.
Serapion, 121.
Serre, 120.
Sonnenschein, 29.
Spinola, 335.
Sternberg, 255, 259, 146.
Stockwell, 129.
Stricker, 254, 140.
Sucksdorf, 302, 303, 202.
Sudduth, 134, 100.
Sutton, 200, 323, 207.
TAFT, 131, 324, 93.
Tappeiner, 19.
Tassinari, 247, 137.
van Tieghem, 35.
Tomes, C. S., 160, 109, 117, 118.
Tomes, J., 123, 130, 131, 160, 188, 189, 190, 193,
210, 218, 289, 290, 92, 107, 109, 117, 118.
Truman, 236.
Tulpius, 275.
UNDERWOOD, 133, 134, 160, 195, 95, 119.
Ungar, 291, 182.
VARRO, 15..
Vaughan, 30, 32.
Vignal, 70, 71, 89, 90, 112, 113, 214, 215, 264, 59,
66, 125.
Virchow, 348.
Vittadini, 52.
Vulpian, 255, 256, 259, 145.
WALKHOFF, 160, 111.
Wallis, 240.
INDEX OF AUTHORS.
358
Warrington, 34, 39,
Watson, 177.
Watt, 90, 117, 131, 163, 65.
Wedl, 123, 130, 158, 160, 165, 188; 190, 193, 218; 276,
91, 110.
Weichselbaum, 260, 261.
Weil, 134, 165, 171, 172, 96, 115.
Westcott, 145.
White, 167.
Wildt, 149.
Witzel, 236, 285, 324, 134.
Woronin, 353, 242,
Wright, 254.
ZAKHAREVITSCH, 276, 160...
Zawadzki, 279, 163,
Zenker, 348.
€
Zopf, 7, 31, 351, 352; 353; 4, 240..
Zuckermann, 17, 13...
Zuelzer, 29.
ABSCESS from impeded eruption of wisdom- | Bacillus acidi lactici, 21.
teeth, 320.
Abscessus alveolaris diffusus, 320.
Acetic acid fermentation, 31, 113.
Acids, action of on bacteria, 12.
action of on the teeth, 130, 195, 210, 216, 219.
production of by albuminous substances, 208.
secretion of by bud-fungi, 345.
Acrasia, 352.
GENERAL INDEX.
Actinomyces, 28, 339.
Actinomycosis, 339-342.
hominum, 341.
Agar-agar, definition of, 48.
preparation of, 62.
Air, presence of micro-organisms in, 99.
Albumen, action of mouth-bacteria on, 115.
Albuminous substances in the mouth, 105, 208.
Alcohol, oxidation of to acetic acid, 31.
Algæ, 2.
Alkalies, action of on bacteria, 12.
Alveolar abscess, etiology of, 293.
general infection from, 286, 288.
Ammoniacal fermentation, 32.
Amoeba coli, 353.
Amoebæ, 351.
Animal teeth, caries of, 199.
Animalcula (Leeuwenhoek's), 45, 47.
饔
​Animal-fungi, 351.
Anthrax bacilli, 16, 34, 226.
Antiseptics, prophylactic treatment of decay
by, 225.
proper time for administering in digestive
troubles, 315, 317.
use of in dental operations, 275, 283.`
use of in digestive troubles, 308.
Billrothii, 32.
.
Apparatus for bacteriological investigation, 49.
Artificial decay, 194.
microscopic appearances of, 197, 198.
Ascococcus, 8.
buccalis, 87.
Aspergillus, 350.
BACILLI,,5.
curved, 76.
aërogenes, 318.
b, 59.
buccalis maximus, 69, 73, 257.
butyricus, 23, 24, 26, 112.
c, 89.
crassus sputigenus, 262.
d, 89.
dentalis viridans, 270, 272.
e of Miller, 77.
e, 89.
f; 89.
fuscans, 93.
g, 89.
gelatogenes, 90.
h, 90.
i, 89.
j, 89.
panificans, 344.
pulpæ pyogenes, 270, 273, 288, 295.
pyogenes fœtidus, 36.
salivarius septicus, 265, 266.
saprogenes, 36.
subtilis, 89.
ureæ, 32.
virens, 35.
Bacteria, 3. (See also Mouth-Bacteria.)
action of upon lifeless matter, 18.
aerobic, 11.
aerogenic, 35, 111, 310, 313.
anaerobic, 12.
antagonism among, 13.
arthrospore, 9.
chromogenic, 34, 90.
cultivation of, 52, 257, 259.
cumulative forms of,.7.
endospore, 9.
facultatively saprogenic, 19.
flavescentia, 94.
forms of, 4.
influence of various conditions on growth of,
11.
life-conditions of, 10.
morphology and biology of, 4.
non-pathogenic, 15.
359
360
GENERAL INDEX.
Bacteria, nutrient media for in the oral cavity, | Caries, inflammation theory of, 121.
37.
obligatory saprogenic, 19.
influence of civilization on, 218.
micro-organisms of, 214.
origin of, 9.
microscopical phenomena of, 165.
nigra, 152.
parasitic, 16.
pathogenic, 15, 256, 274.
presence of in diseased pulps, 96.
presence of in intestinal tract, 302.
pyogenic, 17.
reproduction of, 8.
saprogenic, 36.
saprophytic, 16.
self-destruction of, 14, 195.
viridantia, 93.
zy mogonic, 18.
Bacteriological investigation, apparatus for, 49.
methods of, 48.
Bacterium aerogenes I, 317, 318.
aerogenes II, 318.
chlorinum, 35.
gingivæ pyogenes, 270, 271.
lactis aerogenes, 113.
of pyorrhoea alveolaris, 325, 329, 330, 333.
termo, 71, 89.
ureæ, 32.
Baker caries, 207.
Biondi's mouth-bacteria, 265.
Black tongue, 351.
Blastomycetes, 4, 343.
Blood-serum, proparation of, 57.
Bone, organic matter in, 149.
worn theory of, 128.
Catarrh, identity of with pyorrhoea alveolaris,-
324.
Caverns, formation of in dentine, 180.
Basis-substance, liquefaction of by bacteria, Cavities, formation of in dental caries, 154, 156.
181, 199.
preparation of for filling, 237.
Cement, decay of, 155, 193.
Beggiatoa, 6, 146.
Bichloride of mercury, use of as a mouth-wash,
structural properties of, 148.
231, 235.
Chemical theory of dental decay, 130.
Chinese dentistry, 128.
Cholera bacillus, 75.
Choline, 30.
Botrytis Bassiana, 15.
Buccal secretions as excitants of diseases, 253.
Bud-fungi, 3, 343.
Bühlmann's fibers, 46, 47, 71.
Butyric acid formentation, 23, 112.
CADAVERINE, 17, 30.
Capsule cocci, 260.
of animal tooth, 199.
of cement, 155, 193.
of dentine, 153, 171.
of enamel, 151, 166.
of enamel-cuticle, 156, 165.
of teeth worn on plates, 194.
original investigations on, 146.
parasitic theory of, 130.
physical phenomena of, 151.
pigmentation of the tissue in, 162.
prodisposing causes of, 216.
prophylaxis of, 223.
putrefaction as cause of, 129, 208, 224.
second stage of, 211.
secondary, 151, 152.
Caries, accompanying phenomena of, 156.
acutissima, 152.
alveolaris specifica, 324.
artificial, 194.
chemical changes attending, 163.
chemical theory of, 130.
chronica, 152.
diverse causes of, 144.
electrical theory of, 135.
etiology of, 205.
humida, 155.
spontanoous healing of, 202.
undermining, 152, 168, 175, 176.
butyricum, 23.
Cluster-forms of bacteria, 7.
Cocci, 4.
Coccus & of Miller, 89.
cumulus minor, 90.
Carbohydrates, action of bacteria on, 309.
formentation of, 19, 105, 224.
salivarius septicus, 265, 266.
Carbolic acid, treatment of exposed pulps by, Colony, definition of, 49.
246.
Civilization, influence of on dental decay, 219.
Cladothrix, 6, 8, 339.
Clathrocystis, 8.
Cleanliness, relation of to health, 298, 303.
Climate, influence of on caries, 218.
Clostridium, 5.
Comma bacilli of human mouth, 78.
Conductivity of tooth-tissue, 138.
Copper amalgam, antiseptic qualities of, 239,
244.
Cover-glass preparations, 66.
Cronothrix, 6, 146.
Cryptococcus cerevisiae, 344.
Cryptogams, 1.
Culture-medium for bacteria, 10, 57.
DAMP chamber, 49.
Decalcification of tooth-tissue, 161, 163, 176, 205.
GENERAL INDEX.
361
1
Decay. (See Caries.)
Denitrification, 32, 117.
-- Dental bacterium of Clark, 76.
Dental pulp as a nutrient medium for bacteria,
43.
Denticola, 47, 71, 132, 133.
Dentinal tubules, thickening of, 189.
Dentine, decay of, 153, 171, 211, 213.
dehydration of, 203.
discoloration of, 90, 154.
recalcification of, 204.
structural properties of, 146, 148.
Dentine cartilage, density of, 150.
Dextrane fermentation, 22.
Dextrose, 116.
Dietetic table, 316.
Digestion, disorders of from bacteria, 296, 300.
experiments on, 305, 313.
Dilution cultures, 54.
Diphtheria-bacilli, 337.
Diplococci, 4.
Discoloration of tooth-substance, significance
of, 152, 156, 162, 199.
Disease, general, as a predisposing cause of
caries, 218.
production of by micro-organisms, 15, 274.
Disinfectants for the mouth, 236.
Dogs, tooth-decay in, 200.
Double-staining, 175.
Drop-culture, 65.
Dyspepsia chronica, 309.
Dyspeptics, proper diet for, 317.
inflammation of, 122.
normal,' penetration of by bacteria, 179, 327, Fermentative products, action of on digestion,
345.
300.
action of on oral tissues, 119.
Filling-materials, antiseptic action of, 237.
electrical action of, 143.
EBURNITIS theory of inflammation, 124.
Eggs, preparation of as culture media, 58.
Electric currents in the mouth, 141, 142.
Electrical theory of decay, 135.
Enamel, decay of, 151, 166.
density of organic substance of, 150.
discoloration of, 162.
fissures in, 217.
structural properties of, 147.
Enamel-cuticle, decay of, 156.
Enamel-prisms, disruption of, 169.
Epithelial cells, dead, as nutrient media for
bacteria, 42.
1
Fermentation, butyric acid. 23.
dextrane, 22.
diverse, 25.
lactic acid, 20, 105, 206, 312.
mannite, 22.
of carbohydrates, 19.
of fats, fatty acids, and oxyacids, 26.
of polyvalent alcohols, 25.
Euchema spinosum, 48.
Extractions, septic dangers from, 275, 283, 338.
production of by micro-organisms. 18, 102,
307.
yeast, 344.
morphology of, 317.
Gastric fermentation, 301.
Gastric juice, action of on bacteria, 302, 304, 312.
daily secretion of, 308.
Gelatine, advantages of as a culture-medium,
61.
Gigartina speciosa, 48.
Electricity, action of on growth of bacteria. 12. | Glossophyton, 351.
Embryonic elements, Abbott's, 124, 185.
Fissation, reproduction by, 8.
Fissures as caries-centers, 187, 216, 217.
Food, influence of on dental decay, 219–222.
Foramina coeca, 216.
Fuchsine, method of staining with, 174.
Fungi, classification of, 1.
Fungous animals, 351.
GADININE, 30.
Galvanic action of tooth-fillings,' 136.
Gangrenous pulp as an infection-center, 285,
294.
pure culture from, 61.
Gas, formation of in lactic-acid fermentation,
110.
production of by articles of diet, 315, 316.
Gas-forming bacteria, 35, 111, 310, 313.
Glutine, 149, 150.
Gold, antiseptic qualities of, 241, 244.
galvanic action of on the teeth, 137, 142.
Gonoids, 339.
Gracilaria lichenoïdes, 48.
Granules, presence of in dentinal tubules, 192,
193.
Gums, "acid secretion" of, 210.
exudations of, 43.
recession of as a predisposing cause of caries,
217.
suppurative processes at margin of, 319.
HELICOBACTERIUM aërogenes, 318.
FATS, fermentation of, 26, 117.
Fermentation, abnormal, in the digestivo pro- Heredity of dental decay, 218.
cess, 307, 312.
acetic acid, 31.
Horses, tooth-decay in, 201.
Hyphæ of mould-fungi, 349.
Hyphomycetes, 2, 213, 339, 349.
ammoniacal, 32.
362
GENERAL INDEX.
IMPLANTATION of tooth, 247.
Infection following dental operations, 275.
through foul pulps, 269.
through gangrenous pulps, 285, 294.
Inflammation theory of dental caries, 121.
Instruments, disinfoctión of, 275, 284.
Interglobular spaces, 148, 177, 216.
Iodine, reaction of on certain bacteria, 24.
Iodoform, antiseptic qualities of, 244.
Iron, presence of in dental tissues, 95.
Ivory, inflammatory reaction in, 123.
distontion of tubules in, 189.
JoDococcus magnus, 82, 88.
vaginatus, 69, 73, 74, 257.
W
LACTIC ACID fermentation, 20, 105, 206, 312.
Leptothrix, 5, 7, 90, 182.
buccalis, 47, 70, 71, 133, 134, 165.
buccalis maxima, 69, 74.
gigantea, 80.
innominata, 69, 72, 257.
Leuconostoc mesenterioïdes, 22.
Leucoplakia oris, 349.
Leveling apparatus, 51.
Levulose, 116.
Line cultures, 52.
Liquefaction-foci, 179, 180, 186.
Liquid culture media, 59.
Lichens, 1.
Light, action of on growth of bacteria, 12.
Lime-casts in dentinal tubules, 192.
MACROCOCCI, 4, 85.
Mannito fermentation, 22.
Listerine, 229.
Lungs, affections of from mouth-bacteria, 299.
Lungsarcina, 32.
Lymphadenitis due to diseased tooth, 292.
Mastication, influence of on the teeth, 219.
Matrix of Leptothrix buccalis, 165.
Mechanical injuries, invasion of pathogenic
bacteria following, 274.
Modullary elements of Abbott, 126.
Merismopedia, 7.
Morulius lacrymans, 133.
Micrococci, 4.
Micrococcus acrogenes, 315, 317.
gingivæ pyogenes, 270, 271.
nexifer, 88.
порожни
prodigiosus, 34.
tetragonus, 68, 90, 265.
i
ureæ, 12, 32.
viscosus, 22.
methods of cultivating, 52.
Microscope, best form of, 50.
1
1
Microscopical examination of micro-organisms,
65.
phenomena of decay, 165.
Milk-mould, 350.
Mix-infection, 183, 185, 288, 348.
Monades, 7.
Monadina, 3, 353.
Monilia candida, 347.
Mould-fungi, 3, 349.
Mouth-bacteria, action of antiseptics on, 227,
228.
action of on albuminous substances, 115.
action of on carbohydrates, 105, 309.
biological studies on, 68.
diastatic action of, 113, 311.
direct action on mucous membrane, 295.
influence of on general health, 297.
inverting action of, 113, 310.
mode of nourishment, 211.
production of fermentation by, 102.
pulmonary diseases caused by, 299.
relation of to formation of tartar, 99.
uncultivable, 80.
various forms of, 84.
Vignal's, 90.
Mouth-washes, antiseptic, experiments with,
231, 234.
use of, 225, 228, 233.
Mucor, 350.
Mucous membrane, susceptibility of to bac-
torial infection, 295, 319.
Mucus, buccal, 42.
acid reaction of, 210.
Muscarine, 30.
Mycetozoa, 2, 351, 353.
Mycoderma aceti, 31, 68.
vini, 347.
Myconostoc, 8.
Mycosis tonsillaris benigna, 334.
Mydaleïne, 30.
Myxomycetes, 351.
NASAL cavity, affections of due to diseased
tooth, 291.
Nasmyth's membrane, 147.
Nausea, causation of, 297.
Neumann's sheath, thickening of, 188.
Neuridine, 30.
Neurine, 30.
Nitric acid, formation of in the mouth, 117.
Nitrification, 32, 117.
OIDIUM, 346.
luctis, 350.
Micro-organisms of dental decay, 214.
of the mouth, development of study of, 45, Over-staining, effects of, 188.
63.
Oils, ethereal, antiseptic qualities of, 230.
Oxyacids, fermentation of, 26.
Oxychloride of zinc, antiseptic qualities of,
244.
+
GENERAL INDEX.
1
*
Oxygen, action of on growth of bacteria, 11.
dependence of fermentation on, 114.
Oxyphosphates, antiseptic qualities of, 244.
PATHOGENIC bacteria, 16.
cultivable, 259.
entrance-portals of, 274.
non-cultivable, 257.
original investigations on, 268.
Pellicle-fungus, 343, 345.
Penicillium glaucum, 350.
Peptonizing action of stomach-bacteria, 311.
Peptotoxine, 30.
Periapical tissue, infection of, 287.
Pericementum, removal of for implantation of
teeth, 249.
Phanorogams, 1.
Pigmentation of carious tooth-tissue, 94.
Pigs, tooth-decay in, 202.
Platinum needle, 49.
Pneumonia-coccus, 259, 337.
Polyvalent alcohols, fermentation of, 25.
Potato bacillus, 89.
Potato, preparation of as a culture-medium,
58.
Pregnancy as a predisposing cause of caries, 217.
Pressure, action of on growth of bacteria, 12.
Protococcus dentalis, 132, 133.
Ptomaïnes, 29.
Ptyaline, 27, 40.
Pulmonary diseases caused by bacteria, 299.
Pulp, dental, 43.
diseased, bacteria of, 96, 213.
gangrenous, as an infection-center, 285, 294.
Pulp-capping, use of antiseptics in, 245.
Pulpitis acuta septica, 294.
Pure culture, definition of, 52.
method of obtaining, 60.
Putrefaction as cause of decay, 129, 221.
influence of on life of bacteria, 14.
process of, 27.
Putrescine, 30.
•
RAY-FUNGUS, 285, 299, 339, 340.
Replantation of teeth, 247.
Rhabdomonas, 7.
Rhachitis as a predisponent to pyorrhoea alveo-
laris, 330.
Riggs's disease, 321, 323.
Rod-forms of bacteria, 4.
Rod-shaped elements in dentine, 190, 191, 193.
SACCHAROMYCES albicans, 343, 346.
cerevisiæ, 344.
conglomeratus, 345.
ellipsoideus, 344.
exiguus, 343.
mycoderma, 199, 343, 345, 347.
Saccharomycetes, 243, 343.
Saliva, antiseptic properties of, 41.
chemical ingredients of, 38.
reaction of, 206, 209, 212.
toxic properties of, 254, 338.
Salivary calculus, 101.
Saprine, 30.
Sarcina. 5, 334.
Schizomycetes, 2, 243.
Screw-forms of bacteria, 4.
Scrofula as a predisponent to pyorrhoea alveo-
laris, 331.
Sepsine, 29.
Septicine, 29.
Sharpey's fibers, 148, 193.
Sheep, tooth-decay in, 201.
Slime-fungi, 351.
Specimens, preparation of for microscopical ox-
amination, 166, 171.
Spirilla, 6.
Spirillum sputigenum, 44, 45, 46, 60, 69, 75, 77,
80, 257.
Spirochete dentium, 44, 69, 75, 80, 257.
Spirochetes, 6, 76.
Spiromonas, 7.
Spirulina, 6.
363
Spores, reproduction by, 8, 63, 86, 352.
Sputum septicæmia, micrococcus of, 259, 300.
Staining, methods of, 173.
poculiar appearances from, 187.
reagents for, 51, 66, 67.
Pyæmia from dental irritation, 289.
Pyogenic bacteria, presence of in oral cavity, Staphylococci, 7.
261.
Pyorrhoea alveolaris, 321.
etiology, 323, 325.
heredity of, 327.
in animals, 332.
in children, 322.
local treatment, 333.
original investigations on, 328.
parasitical nature, 324.
prognosis, 333.
symptoms, 322.
Staphylococcus citrous, 34.
magnus, 90.
medius, 90.
pyogenes albus, 68, 89, 263, 264, 328, 329.
pyogenes aureus, 25, 30, 68, 89, 263, 264, 288,
328, 329.
salivarius pyogenes, 265, 267.
Starch, 27, 206.
Sterilization, effectual methods of, 249.
of the mouth, influence on general health,
297.
of the stomach, 314.
Stomacaco, 335.
Stomach-bacteria, chemical reaction of, 309.
peptonizing action of, 311.
364
GENERAL INDEX.
}
Stomatitis phlegmonosa, ulcerosa, etc., 335, 336. | Tooth-animalcula (Leeuwenhoek's), 47.
Stomatomycosis sarcinica, 334.
Streptococci, 7.
Tooth-cartilage, 43.
Streptococcus continuosus, 90.
pyogenes, 30, 263, 264, 329.
septo-pyæmicus, 265, 266.
Stroptothrix Försteri, 339.
Sugar, action of on the tooth, 131, 145, 207, 224.
Sulphate of copper, antiseptic qualities of, 244.
Suppuration, production of by bacteria, 17, 293.
Suppurative processes at margin of gums, 319.
Surface-forms of bacteria, 7.
Swarmers of the Myxomycetes, 352.
Syphilis, transmission of by dental instruments,
285, 337, 338.
transinission of by transplantation of teeth,
248.
TARTAR, 39, 46.
presence of in pyorrhoea alveolaris, 322.
rolation of mouth-bacteria to, 99.
storilization of for implantation, 247.
structure of, in relation to caries, 216.
Temperature, action of on growth of bacteria,
11.
Tost-tube cultures, 56.
Tetanin, 30.
Thallophytes, 1.
Thread-fungi, 349.
Tooth-decay, pure cultures from, 60.
Tooth powders and soaps, use of, 236.
Tooth-substance, chemical composition of, 148.
Tooth-worms, 129.
Thrush, 319, 347.
fungus, 346.
Torula, 7.
Torulaceæ. 346.
Transparency, significance of in dental décay,
159.
Teeth, decay of. (See Carics.)
histology and chemistry of, 146.
irregularity of as a predisposing cause of VIBRIO viridans, 85.
caries, 217.
Vibrion butyrique, 23.
Vibriones, 6.
Vinegar fungus, 31.
Transplantation of teeth, 247.
Trichia varia, 352.
Tubercle-bacillus, 337.
Tubulos, enlargement of in decayed dentine,
180.
invasion of by micro-organisms, 182, 183.
Typhotoxicon, 30.
Typhus bacilli, 25, 34.
Tyrotoxicon, 30.
ULCERATIVE stomatitis, 336.
Undermining decay, 154.
WINE-YEAST, 344.
Wisdom-teeth, abscess from impeded eruption
of, 320.
Worm theory of dental caries, 128.
XANTHINE, 30.
YEAST-FUNGI, 89, 199, 343, 344, 345.
Tissue preparations, 67.
Tobacco, influence of on the teeth, 163, 233, 246. ZooGLEA-FORMS of bacteria, 8.
糖
​}

PLATE III.
11 TU
Fig.1.
Fig. 5.
Fig. 2.
Fig. 3.
FIGS. 1-4.-Test-tube cultures of chromogenic mouth-bacteria.
Fig. 4.
Fig. 6.
FIG. 5.-A cross-section of decayed dentine, stained with picrocarmine.
FIG. 6.-Nasmyth's membrane from a decayed tooth, stained with fuchsine
1100 1.

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