key: cord-0997985-t8z5k2aw
authors: Suzuki, Seitaro; Ohyama, Atsushi; Yoshino, Koichi; Eguchi, Takako; Kamijo, Hideyuki; Sugihara, Naoki
title: COVID-19-related factors delaying dental visits of workers in Japan
date: 2022-05-10
journal: Int Dent J
DOI: 10.1016/j.identj.2022.05.001
sha: b78e4a2373f3d13485664d83b86d921b72913064
doc_id: 997985
cord_uid: t8z5k2aw

BACKGROUND: To investigate the factors associated with postponing dental attendance among Japanese workers during the coronavirus disease 2019 (COVID-19) pandemic. METHODS: We conducted an internet survey in Japan, from November 24 to 29, 2021. The participants were selected from people registered with an online research company. The inclusion criteria for this study were full-time or part-time workers aged 20–69 years. Participants filled out a questionnaire about their oral health, behavior, and working conditions. RESULTS: A total of 1,840 participants were included in the analysis. Three-hundred-ninety-eight participants (21.5%) answered that they postponed dental attendance due to COVID-19. Multiple logistic regression showed that women were more likely to postpone dental attendance (odds ratio [OR], 1.74; 95% confidence interval 1.33–2.26). Moreover, employment status, household income, changes in income, working at home, interdental cleaning device use, regular dental attendance, awareness of untreated teeth, and dental pain were also associated with postponing dental attendance. The results of decision tree analysis showed that regular dental attenders with dental pain were the most likely to postpone dental attendance. CONCLUSIONS: The characteristics of postponed dental visits for Japanese workers differ depending on whether one is a regular dental attender or not. Among regular dental attenders, worsening oral health due to interruptions in dental attendance is concerning. Meanwhile, untreated teeth might be neglected among non-regular dental attenders. Preventing patients from refraining from dental attendance, regardless of whether or not they are regular dental attenders, would be important during the COVID-19 pandemic.

The coronavirus disease 2019 (COVID-19) pandemic has had a tremendous impact on the society around the world. In the United States, dentists were advised to halt elective dental services and treat only patients requiring emergency dental procedures 1 

August 3, 2020, the World Health Organization (WHO) released interim guidance for oral health services. In this interim guidance, it was advised that routine non-urgent oral health care be delayed until there was a sufficient reduction in COVID-19 transmission rates 2 . In response to this guidance, despite the World Dental Federation releasing a statement for oral health services to continue under official recommendations 3 , there is concern that the number of people who postponed dental attendance based on this information may have increased during the COVID-19 pandemic.

Dental attendance is an important factor in maintaining good oral health 4 .

Pre-COVID-19 pandemic conditions, several factors, including sex [5] [6] [7] [8] , socio-economic status (SES) [5] [6] [7] [8] , dental insurance 7, 8 , lifestyle-related factors 5 , and oral symptoms 9 , were reported to be associated with dental attendance. Especially, SES is one of the main factors determining dental attendance 10, 11 . Low SES has been reported to be associated with difficulties in dental attenance 10 . Moreover, a systematic review indicated that free dental check-ups might be an important factor to promote regular dental attendance 12 . Meanwhile, COVID-19 significantly affected SES around the world 13 . There are several studies investigating the impact of COVID-19 on health care use [14] [15] [16] . In Taiwan, medical and dental visits from January to March 2020 decreased by 6 .8% and 5.1% compared with the same period in 2019, respectively 16 . It has been reported that preventive care, including cancer screening, significantly decreased 14 . These results indicate that preventive care or non-emergency procedures might be postponed due to the COVID-19 pandemic. Several studies reported the status of dental attendance during the COVID-19 pandemic [17] [18] [19] . One of these studies indicated that low SES was related to disruption of regular dental attendance in Japan 19 .

It is reasonable to assume that workers have experienced significant changes in their working environments due to the COVID-19 pandemic. Investigating the relationships between the factors associated with postponing dental attendance can facilitate planning of a dental care approach during the COVID-19 pandemic. This study aimed to investigate the factors associated with postponing dental attendance and the interactive relationships among Japanese workers during the COVID-19 pandemic.

This cross-sectional study was conducted in Japan, from November 24 to 29, 2021.

The participants were selected from people registered with an online research company called Macromill (). Macromill has approximately 1.3 million registered people living in Japan and is used in several studies 19, 20 . We outsourced the survey to Macromill.

The inclusion criteria for this study were full-time or part-time workers aged 20-69 years. The number of participants was designed to be the same for each sex and age group. Moreover, the regional numbers of participants were based on statistics from the National Population Census of the Ministry of Internal Affairs and Communications 21 .

The sample size was set to perform multiple logistic regression analysis for 15 independent variables. Events per variable of 10 is widely used as the lower limit for developing prediction models 22 . Therefore, we assumed that at least 150 events were required for the analysis. Moreover, we hypothesized that 20% of participants would have postponed dental attendance based on a previous study 23 . Considering these results and budget limitations, the sample size was set to approximately 2,000.

In the first screening process, 40,000 candidates were selected from the online research company database by the quota sampling method ( Postponing dental attendance Postponing dental attendance was defined by the following question: "Have there been any changes in your behavior regarding visits to dental clinics since the first declaration of a state of emergency (April 16, 2021) until now?" and the answers were as follows: changed clinics; less frequent dental attendance; more frequent dental attendance; I wanted to attend a dental clinic, but I held back; there was no change in behavior regarding dental attendance; and others. Participants who answered "less frequent dental attendance" or "I wanted to attend a dental clinic, but I held back" were defined as postponing dental attendance.

Participants were requested to answer the following demographic variables: sex, age, residential region, employment status, household income, and educational attainment.

We assessed changes in workload and income and working at home as labor-related factors affected by COVID-19. Changes in workload were assessed using the following question, "Has there been any change in your workload due to COVID-19?" The answer was categorized as unchanged, increased, or decreased. Changes in income were assessed using the following question, "Has there been any change in your income due to COVID-19?" The answer was categorized as unchanged, increased, or decreased. Working at home was assessed using the following question, "Did you have to work from home due to COVID-19?" The answer was categorized as yes or no. We assessed the frequency of tooth brushing, interdental cleaning device use, regular dental attendance, number of teeth, untreated teeth, and dental pain as factors associated with oral health.

The frequency of tooth brushing was assessed using the following question, "How many times do you brush your teeth" The answer was categorized as <2 or ≥2. Interdental cleaning device use was assessed using the following question, "Do you use an interdental brush or floss?" The answer was categorized as yes or no. Regular dental attendance was assessed using the following question, "How often do you visit your dentist for regular dental checkups?" The answers were once a month, once in 2-3 months, once in 6 months, once a year, once in 2 years, once in 3 years, interrupted, and never. Those answers were categorized as yes or no. The number of teeth was assessed using the following question, "How many teeth do you have?" The validity of a self-reported number of teeth has been shown 24 . The answer was categorized as <20 or ≥20. Awareness of untreated teeth was assessed using the following question, "Do you currently have a tooth that has a hole or a filling that has been left untreated?". This question was based on a question used in a previous study of untreated teeth 25 . Dental pain was assessed using the following question, "Do you have pain in your mouth?" The answer was categorized as yes or no.

A chi-squared or Fisher's exact test was used to compare the characteristics between participants who did or did not postpone dental attendance by each variable. Multiple logistic regression analysis was performed with postponing dental attendance as the dependent variable. We tested four models to evaluate the association between postponing dental attendance and each variable. Model 1 included sex, age, and residential region. Model 2 included employment status, household income, and educational attainment, in addition to Model 1. Model 3 included labor-related factors affected by COVID-19, in addition to model 2. Model 4 included factors associated with oral health, in addition to model 3. Moreover, it was reasonable to assume that the characteristics of postponing dental attendance would be different by regular dental attendance 19 . Subgroup analysis using multiple logistic regression analysis was performed to compare the differences in the factors associated with postponing dental attendance between regular and non-regular dental attenders.

Decision tree analysis was performed to identify the interaction between the factors associated with postponing dental attendance. This analysis was used to analyze interactions between variables 26 . The Chi-Squared Automatic Interaction Detection (CHAID) algorithm was used 27 . The significant level for splitting nodes was set at p <0.05 and the Bonferroni method was used to obtain the significant values of adjustment. The data were analyzed using the computerized statistical package SPSS, version 26.0 (IBM Corp, Armonk, NY, USA), and the significance level was set at 5%.

A total of 1840 participants responded to the questionnaire (men: 49.8%, women: 50.2%). The mean and standard deviation of the participants' ages were 44.9 and 13.81, respectively.

In total, 398 participants (21.5%) answered that they postponed dental attendance due to COVID-19 ( Table 1) . As for the COVID-19 impact, changes in workload, income and working at home were significantly associated with postponing dental attendance; 462 participants (24.6%) reported that their income was reduced due to COVID-19.

Several factors were significantly associated with postponing dental attendance during the COVID-19 pandemic ( In addition, participants with a household income of 4,000-9,999 JPY were more likely to postpone dental attendance compared to those with <3,999 JPY (OR, 1.54; 95% CI, 1.15-2.05). This association was also observed in Model 4. Moreover, participants with the educational attainment of college graduate or higher were more likely to postpone dental attendance compared to those with high school or lower (OR, 1.36; 95% CI, 1.01-1.84). However, this association was not observed in the other models.

In model 3, changes in workload and income and working at home were significantly associated with postponing dental attendance. However, income reduction (OR, 1.44; 95% CI, 1.06-1.95) and working at home (OR, 1.73; 95% CI, 1.31-2.26) were only associated in Model 4. In model 4, interdental cleaning device use, regular dental attendance, awareness of untreated teeth, and dental pain were significantly associated with postponing dental attendance.

Decision tree analysis for the factors associated with postponing dental attendance showed the difference between regular and non-regular dental attenders ( Figure 1 ).

Among participants with regular dental attendance, postponing dental attendance was greater among those with dental pain (41.1%). Among participants without regular dental attendance, women were more likely to postpone dental attendance than men (7.4% vs. 20.3%). Moreover, postponing dental attendance was greater among participants with interdental cleaning device use in both sexes.

Similar results were obtained from subgroup analysis (Table 3) . Although household income, changes in income, working at home, and dental pain were associated with postpponed dental attendance among regular dental attenders, while changes in workload, interdental cleaning device use, and awareness of untreated teeth were associated with postponed dental attendance among non-regular dental attenders.

Overall, 21.5% of the participants postponed dental attendance due to COVID-19.

Similar figures were reported in an online survey conducted in Germany (22%) 23 , Spain (24.5%) 28 , and Japan 19 (28.5%). Although dentists were advised to limit their dental practice to urgent care in some countries 1 , no strong recommendations were made to limit dental practice in Japan 29 .

Regular dental attendance was strongly associated with postponing dental attendance.

It was also reported that individuals with regular dental attendance were the most likely to postpone their dental visits during the COVID-19 pandemic 23 . We believe that the WHO interim guidance on the postponement of non-urgent regular dental visits might be one of the reasons for changed dental attendance behavior among regular dental attenders.

Employment status, household income, and changes in income were also associated with postponing dental attendance. SES has been reported to be associated with dental attendance [5] [6] [7] [8] . Moreover, it has been reported that worsened SES was associated with poor oral health, and postponing dental visits was related to household income reduction during the COVID-19 pandemic 30 . Therefore, changes in socioeconomic factors might affect dental attendance behavior.

Interestingly, working at home has been significantly associated with postponing dental attendance. In Japan, self-restraining behaviors, including working at home, were requested by the government 31 . Moreover, working at home has been reported to be associated with becoming inactive during the COVID-19 pandemic 32 . Changes in the work environment might have influenced dental attendance behavior.

The decision tree analysis and subgroup analysis showed that the factors associated with postponing dental attendance differed according to regular dental attendance.

Among participants with regular dental attendance, dental pain was associated with postponing dental attendance in the decision tree analysis results. Approximately 10% of individuals reported having postponed dental attendance even though they had dental pain 23 . The results of this study suggest that people who had regular dental attendance might be suffering from dental pain because they refrained from visiting a dentist. Among participants without dental pain, women were more likely to postpone dental attendance. Similar to this study, Hajek et al. reported that postponed dental attendance during the COVID-19 pandemic was more frequent among women compared to men (24.7% vs. 19.1%) 23 . In addition, it has been reported that fear of COVID-19 infection was greater among women 28 . There might be sex differences in postponing health care visits. Moreover, the results of subgroup analysis showed that SES was also associated with postponing dental attendance among regular dental attenders.

Although participants with a household income of 4,000-9,999 thousand JPY were more likely to postpone dental attendance compared with those with a household income of <3,999 thousand JPY, this association was not observed among non-regular dental attenders. It is reasonable to assume that people with a higher SES more likely had regular dental attendance before the COVID-19 pandemic. Therefore, they might be more likely to postpone regular dental attendance. However, we did not have information on dental attendance patterns before the COVID-19 pandemic due to the limitation of the number of questions.

Among participants without regular dental attendance, sex and interdental cleaning device use were associated with postponing dental attendance. The Japan Dental Association recommended practicing oral health care to prevent infection during the COVID-19 pandemic 33 . Moreover, it has been reported that fear of COVID-19 was significantly associated with not visiting a dentist 28 . We hypothesize that people using interdental cleaning devices might be more likely to have a fear of COVID-19

transmission. However, we had no data to prove this hypothesis in this study. Moreover, the results of subgroup analysis showed that changes in workload and awareness of untreated teeth were associated with postponing dental attendance. Although it is important to recognize that untreated teeth might be neglected among non-regular dental attenders, the reasons for this could not be determined from this study due to lack of information. However, it is meaningful to mention that changes in workload was also associated with postponing dental attendance. Therefore, changes in workload due to COVID-19 might affect dental attendance behavior among non-regular dental attenders.

This study had some limitations. First, the target of this survey was limited to full-time or part-time workers aged 20-69 years. Therefore, people who had lost their jobs during the COVID-19 pandemic or who were unemployed were not included. Although the number of participants was designed to be the same for each sex and age group, the participants in this survey may not be representative of the Japanese population.

However, the distribution of the participants in this study by region was similar to that of the population census in Japan 21 . Therefore, we assumed that the participants in this study reflected the population of Japan to some extent. Moreover, response rates were not obtained because the responses were registered in order of arrival until the default number of responses was reached. Possible bias due to this effect could not be estimated. Second, self-reported information was used and may be biased;

we did not have information on changes in behavior during the COVID-19 pandemic. For example, regular dental attendance was obtained at the survey time. Therefore, we could not determine whether they had regular dental attendance before the COVID-19

pandemic. There was uncertainty in the accuracy of responses because this study used a self-administered survey. Moreover, we did not differentiate dental visits for curative care and preventive purposes. Therefore, it was not possible to clarify for what purpose dental visits were postponed. Third, the factors associated with postponing dental attendance in the decision tree analysis were determined in a hierarchical manner and were only assessed in certain subgroups. Therefore, caution should be taken when applying these results to the general population. Forth, Japan has universal health coverage for dentistry 34 ; therefore, the external validity of this study is limited to countries with universal health coverage. Finally, this study was a cross-sectional study; therefore, further research is required to demonstrate causal relationships between the factors.

The results of this study suggest that the characteristics of postponed dental visits differ depending on the presence or absence of regular dental attendance. Among regular dental attenders, worsening oral health due to interruptions in dental attendance is concerning and SES might affect dental attendance behavior. Meanwhile, untreated teeth might be neglected among non-regular dental attenders. It is necessary to take actions to prevent patients from refraining from dental attendance, regardless of whether or not they have regular dental attendance. The data that support the findings of this study are available from the corresponding author upon reasonable request.

☒ The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper. 

Dental care and Oral Health under the clouds of COVID-19

World Health Organization. Considerations for the provision of essential oral health services in the context of COVID-19: interim guidance; 2020. Geneva: World Health Organization

World Dental Federation. Provision of Oral Health services can continue during COVID-19 but must comply with official recommendations at a country's national, sub-national OR local level

Long-term dental visiting patterns and adult oral health

Barriers to dental visits in Belgium: a secondary analysis of the 2004 National Health Interview Survey

A multi-country comparison of reasons for dental non-attendance

Predictors of dental care utilization in north-central Appalachia in the USA

Use of dental services among Australian adults in the National Study of Adult Oral Health (NSAOH) 2017-18

What influences the use of dental services by adults in the UK?

The effects of social class and dental attendance on oral health

Income-related inequalities in dental service utilization by Europeans aged 50+

Promoting regular dental attendance in problem-orientated dental attenders: A systematic review of potential interventions

The socio-economic implications of the coronavirus pandemic (COVID-19): a review

Disruption in essential health services in Mexico during COVID-19: an interrupted time series analysis of health information system data

Impact of the COVID-19 pandemic and response on the utilisation of health services in public facilities during the first wave in Kinshasa, the Democratic Republic of the Congo

Impact of the COVID-19 pandemic on the utilization of medical and dental services in Taiwan: A cohort study

2020 trends in dental office visits during the COVID-19 pandemic

Characteristics of US adults delaying dental care due to the COVID-19 pandemic

Factors associated with regular dental checkups' discontinuation during the COVID-19 pandemic: A nationwide cross-sectional web-based survey in Japan

Comparison of risk factors for tooth loss between professional drivers and white-collar workers: an internet survey

Ministry of Internal affairs and communications. Population census

Review and evaluation of penalised regression methods for risk prediction in low-dimensional data with few events

Postponed dental visits during the COVID-19 pandemic and their correlates. Evidence from the nationally representative COVID-19 snapshot monitoring in Germany (COSMO)

Validity of the self-reported number of natural teeth in Japanese adults

Relationship between amount of overtime work and untreated decayed teeth in male financial workers in Japan

Decision tree methods: applications for classification and prediction

An exploratory technique for investigating large quantities of categorical data

Fear of COVID-19 in Madrid. Will patients avoid dental care?

Ministry of Health, Labour and Welfare, Health Policy Bureau, Dental Health Division

Nosocomial infection control measures to prevent the spread of novel coronavirus in dental institutions

Dental pain and worsened socioeconomic conditions due to the COVID-19 pandemic

Office for Novel Coronavirus Disease Control, Cabinet Secretariat, Government of Japan. COVID-19 information and resources: declaration of the state of emergency

Relationships among changes in walking and sedentary behaviors, individual attributes, changes in work situation, and anxiety during the COVID-19 pandemic in Japan

Future of

Japan's system of good health at low cost with equity: beyond universal coverage