The Oral Healthcare System in Japan

Functional dentition and well-being among Chilean 80-year-olds

BACKGROUND

The Decade of Healthy Aging 2021-2030 calls for a strengthening of the policies for older people in Latin America. An example of successful oral aging is the Japanese "8020" campaign, which achieved 50% of people aged 80 years having ≥20 teeth by 2016.

OBJECTIVE

To evaluate the association between having a functional dentition (≥20 teeth) and cognitive health, social participation, and quality of life in people aged ≥80 years.

METHODS

Cross-sectional data from 299 complete observations (weighted N = 436 981) of individuals aged ≥80 years from Chile's National Health Survey 2016-2017 were included (3% of the population; total = 5520 clinical observations/weighted N = 14 518 969). Generalised structural equation models (GSEM) evaluated the association between having a functional dentition and cognitive health, measured with the Mini-mental score, between having a functional dentition and social participation, and between having a functional dentition and quality of life, measured with the EQ-5D-3L. Models included the effect of mediators (daily fruit and vegetable consumption; oral health-related quality of life score) and controlled for the exposure-induced mediator-outcome variables: sex, educational level, and location. Data were analysed using the STATA-17 survey module. Statistical significance was set at P < .05 (95% confidence interval [CI]).

RESULTS

The sample was mostly female, had <8 years of education, and lived in urban areas. The prevalence of a functional dentition was 9.2% (95% CI 3.6,21.3/n = 21). GSEM demonstrated that the association between functional dentition and cognitive health was mediated by daily fruits and vegetables consumption (β = 0.12/95% CI 0.02,0.21/P = .015), with moderate strength of evidence. Additionally, there was strong evidence of an association between functional dentition and social participation frequency (β = 2.76/95% CI 0.60,4.73/P = .009). Finally, the association between functional dentition and quality of life was mediated by cognitive health (β =0.05/95% CI 0.02,0.09/P = .002) and oral health-related quality of life (β = -0.04/95% CI -0.08 to -0.01/P = .025), with strong and moderate evidence, respectively.

CONCLUSION

Given the beneficial implications of functional dentition in social participation, nutritional benefits and quality of life and well-being of individuals aged ≥80 years.

Association among the number of teeth, dental prosthesis use, and subjective happiness: A cross-sectional study from the Japan Gerontological Evaluation study (JAGES)

STATEMENT OF PROBLEM

Little is known about the association between the number of teeth and self-rated happiness or the association between dental prosthesis use and self-rated happiness in an older population.

PURPOSE

The purpose of this cross-sectional study was to examine the association between the number remaining of teeth with and without dental prosthesis use and self-rated happiness in an older population.

MATERIAL AND METHODS

The survey data from the 2016 Japan Gerontological Evaluation Study (JAGES) on independent participants aged 65 years or older were assessed. The Poisson regression and multiple imputation methods were used for analyses. Covariates were age, sex, marital status, educational attainment, self-rated health, self-rated economic situation, and symptoms of depression.

RESULTS

The data from 178 090 participants, 81 489 men (45.8%) and 96 601 women (54.2%), were analyzed, with a mean ±standard deviation age of 73.6 ±6.1 years. Overall, 66.4% of the participants were happy, declining to 45.7% in those who had 0 to 9 teeth and no dental prosthesis (n=3102). It was 61.5% in those who had 0 to 9 teeth and used a dental prosthesis (n=41 424), 56.8% in those who had 10 to 19 teeth and no dental prosthesis (n=6719), 65% in those who had 10 to 19 teeth and used a dental prosthesis (n=31 592), 70.5% in those who had ≥20 teeth and no dental prosthesis (n=52 525), and 70.1% in those who had ≥20 teeth and used a dental prosthesis (n=42 728). The interaction analysis showed that the reduction in the probability of being happy among those with fewer teeth was smaller among those who used a dental prosthesis.

CONCLUSIONS

Having a higher number of teeth and using a dental prosthesis were independently associated with being happy. A significant interaction suggested that dental prosthesis use improves happiness among those with moderate to severe tooth loss (<20 remaining teeth).

Association of rotating night shift work with tooth loss and severe periodontitis among permanent employees in Japan: a cross-sectional study

Background

The modern 24/7 society demands night shift work, which is a possible risk factor for chronic diseases. This study aimed to examine the associations of rotating night shift work duration with tooth loss and severe periodontitis.

Methods

This cross-sectional study used data from a self-administered questionnaire survey conducted among 3,044 permanent employees aged 20-64 years through a Japanese web research company in 2023. The duration of rotating night shift work was assessed using a question from the Nurses' Health Study. Tooth loss was assessed based on self-reported remaining natural teeth count. Severe periodontitis was assessed using a validated screening questionnaire comprising four questions related to gum disease, loose tooth, bone loss, and bleeding gums. We employed linear regression models for tooth loss and Poisson regression models for severe periodontitis, adjusting for demographic, health and work-related variables and socioeconomic status.

Results

Among participants included, 10.9% worked in rotating night shifts for 1-5 years, while 11.0% worked in such shifts for ≥6 years. In fully adjusted models, rotating night shift work duration of 1-5 years was associated with tooth loss (beta -0.74, 95% confidence interval (CI) [-1.55 to 0.08]) and severe periodontitis (prevalence ratio 1.80, 95% CI [1.33-2.43]); however, the association with tooth loss was not statistically significant.

Conclusions

This study supports that employees who work short-term rotating night shifts may experience poor oral conditions. Further research is needed to determine whether long-term rotating night shift work is associated with deteriorated oral health.

Association between Short Stature at Grade 1 and Permanent Teeth Caries at Grade 6 in Elementary School Children in Japan: A Population-Based Cohort Study

Short stature in children is a marker of low nutritional status and has been suggested to be associated with dental caries. However, longitudinal studies on this topic are scarce. Data from a longitudinal study of elementary school children in Adachi City, Tokyo, Japan, were analyzed. In 2015, caregivers of children at grade 1 answered questionnaires, and information on dental caries and height measured at school health checkups was merged and followed to grade 6 (N = 3576; follow up rate = 83.3%). The association between short stature at grade 1 (-2.01 standard deviation (SD)--3.00 SD, or <-3.00 SD in height-for-age according to the World Health Organization criteria) and the number of decayed, missing, or filled permanent teeth (DMFT) at grade 6 was examined using multivariable Poisson regression with robust standard error. After adjusting for confounders, children with a short stature at grade 1 had a higher DMFT number at grade 6: the mean ratios (95% confidence interval) were 1.17 (0.89-1.54) and 2.18 (1.03-4.64) for children with a height-for-age -2.01 SD--3.00 SD, and those with a height-for-age < -3.00, respectively. Short stature at grade 1 could be a marker of future dental caries in the permanent teeth at grade 6.

Disasters in pediatric dentistry: a systematic review

BACKGROUND

Disasters can harm many people, especially children, in unpredictable and public ways. One of the neglected aspects of children's health in disasters is oral and dental hygiene, which can affect their physical and mental well-being. This systematic review explores how dentistry can help children in disasters, focusing on two aspects: providing oral health care and identifying disaster victims.

METHODS

A thorough search of databases, such as PubMed, Cochrane Library, Scopus, Embase, ProQuest, and Web of Science, was done to find English-language publications from 1930 to August 31, 2023. The screening, data collection, and quality assessment followed the PRISMA guidelines.

RESULTS

Out of 37,795 articles found in the databases, seven research articles were chosen. Five articles were retrospective, and two articles were prospective. The results showed that dentistry for children is very important in disasters by giving information about the oral and dental problems and identifying the victims. The results also showed some of the challenges and difficulties in giving dental care for children in disaster situations, such as changing control, referral systems, and parental fear of infection.

CONCLUSION

Dentistry for children can improve the health and well-being of children affected by disasters.

Lower socio-economic status in adolescence is associated with poor oral health at an older age: Mediation by social and behavioural factors

AIM

To examine the mediators between lower socio-economic status (SES) in adolescence and oral health at an older age to uncover the underlying mechanisms of the association.

METHODS

Participants (n = 21 536) aged ≥65 years from the Japan Gerontological Evaluation Study were evaluated. The dependent variables were self-rated chewing difficulty and having ≤19 remaining teeth. The main independent variable was self-perceived SES in adolescence. The Karlson-Holm-Breen method was used for mediation analysis.

RESULTS

Mean age of the participants was 74.8 years (standard deviation = 6.4), and 51.5% were female. Overall, 5598 (26.0%) participants reported chewing difficulty and 9404 (43.7%) had ≤19 remaining teeth. Lower SES in adolescence was associated with a higher prevalence of chewing difficulty (odds ratio [OR] = 1.38, 95%confidence interval [CI] = 1.29-1.48; total effect). After controlling for mediators, OR for lower SES in adolescence was 1.22 (95%CI = 1.13-1.30; direct effect) and 1.13 (95%CI = 1.11-1.16; indirect effect). Mediators, prominently the number of teeth and income, explained 39.3% of the associations. Lower SES in adolescence increased the odds of ≤19 remaining teeth by OR = 1.23 (95% CI = 1.16-1.31; total effect). After controlling for mediators, the OR for lower SES in adolescence was 1.03 (95%CI = 0.97-1.10; direct effect) and 1.19 (95%CI = 1.16-1.23; indirect effect). Mediators, prominently educational attainment, explained 85.0% of the associations.

CONCLUSIONS

Lower SES in adolescence was associated with poor oral health at an older age through mediators. Approaches that consider social determinants from the beginning of the life course are required.

A scoping review on the links between sustainable development goal 14 and early childhood caries

BACKGROUND

The Sustainable Development Goal (SDG) 14 addresses life below the waters, an important source of protein and contributor to global food security and economic development. Our aim was to explore possible evidence on the links between life below water and early childhood caries (ECC).

METHODS

This scoping review identified articles on the link between life below water and caries according to the PRISMA-ScR guidelines. Three electronic databases (PubMed, Web of Science, and Scopus) were systematically searched in January 2023, using specific search terms. Studies written in English, with full text available, addressing life under water, focusing on dental caries in humans, with results that can be extrapolated to control ECC in children less than 6 years of age were included in the review. Descriptive statistics were used to summarize the retrieved papers and graphical presentation was used for visualization.

RESULTS

There were 224 publications retrieved of which 13 studies, published between 1960 and 2022, were included in the analysis. The papers originated from Asia (7/13), North America (3/13), Europe (1/13), and 2/13 had multi-country authorship. Also, four laboratory studies extracted agents from marine products to determine their efficacy in preventing caries formation and preventing/slowing plaque formation; four letters discussed the caries prevention potential of sea salt as a source of fluoride; and two review articles about the positive effects of extracted marine products for caries prevention. Most (11/13) studies addressed target 14.1 concerned with enriching the marine environment with nutrients and minerals; two addressed target 14.4 focused on ensuring fish stocks are within biologically sustainable levels; two addressed target 14.7 aimed at increasing the economic benefits through sustainable use of marine resources such as fisheries; and one focused on target 14.5 aimed at conserving marine areas by increasing protected areas. In addition, one ecological study assessed the association between the ecosystem and ECC.

CONCLUSIONS

Currently, there is little known about the impact of protection of marine and coastal ecosystem from pollution and ocean acidification on the risk of ECC. Further evidence on possible associations between life below water and ECC management is needed.

Trends in dental expenditures in Japan with a universal health insurance system

BACKGROUND

The government of Japan has spent a significant amount on dental healthcare, but it remains unknown how the spending varies across age, type of service, and time. This study describes trends in dental expenditures in Japan.

METHODS

This descriptive study used two national data sources: Estimates of National Medical Care Expenditure and Survey on Economic Conditions in Health Care. We obtained annual total and average per capita dental expenditures by age in Japan from 1984 to 2020 and estimated the proportions of types of service from 1996 to 2021. All costs were adjusted for the 2020 Consumer Price Index (1 US dollar ≈ 100 yen in 2020).

RESULTS

Total dental expenditures increased from 1.96 trillion yen in 1984 to 3.00 trillion yen in 2020. In particular, total and average per capita dental spending for older persons showed a rapid increase (total: from 185 billion yen in 1984 to 1.18 trillion yen in 2020; average per capita: from 15,500 yen in 1984 to 32,800 yen in 2020), contributing to the total amount increase. The crown restoration and prosthesis category amounted to 50.3% of the total expenditure in 1996, and this proportion declined to 32.4% by 2021. In 0-14 years persons, expenses on the crown restoration and prosthesis category decreased while the medical management category (mainly including fees for a management plan for oral diseases or oral functions) increased. In persons aged 65 years or older, expenses on the crown restoration and prosthesis category decreased, with increasing expenses in the medical management and at-home treatment categories.

CONCLUSION

The amount of dental spending in Japan substantially increased from 1.96 trillion yen in 1984 to 3.00 trillion yen in 2020), a 1.53-fold increase. The observed changes in annual dental spending varied across age groups and types of service.

Co-Payments and Inequality in Gingival Bleeding and Dental Visits

OBJECTIVES

Japan's universal health insurance covers a wide range of dental treatments, and the co-payment rates differ by age. We investigated whether the inequality in gingival bleeding and dental visits was smaller amongst those with lower co-payment rates.

METHODS

This cross-sectional study used data from the 2019 Japan Gerontological Evaluation Study. The participants were functionally independent adults aged 65 years or older. The dependent variables were current gingival bleeding as a symptom of periodontal diseases and dental nonattendance for treatment in the past year. The independent variables were ridit scores of equivalent income and educational status. For covariates, we used age, sex, and the number of remaining teeth. To evaluate the inequalities, we used the slope index of inequality (SII) and the relative index of inequality (RII). We also conducted stratified analyses by co-payment rates (30%, 20%, and 10%) to clarify the difference in inequalities by co-payment rate.

RESULTS

A total of 15,389 participants were included in the analysis; their mean age was 71.8 (SD = 4.1) and 51.8% were women. There were significant absolute and relative inequalities in gingival bleeding and dental visits by equivalent income and education. With regards to educational status, inequalities were lower with a decrease in the co-payment rate. In particular, relative inequality by education in gingival bleeding was the largest amongst the 30% co-payment group (RII, 1.918; 95% confidence interval [CI], 1.386 to 2.656). For gingival bleeding, the absolute and relative inequality by equivalent income were not significant amongst the 10% co-payment group (SII, -0.003; 95% CI, -0.003 to 0.028; RII, 1.006; 95% CI = 0.676 to 1.498).

CONCLUSIONS

A low co-payment rate was associated with smaller inequalities in gingival bleeding and dental visits by equivalent income and educational status.

Is value-based healthcare a strategy to achieve universal health coverage that includes oral health? An Australian case study

The 2021 Resolution on Oral Health by the 74th World Health Assembly supports an important health policy direction: inclusion of oral health in universal health coverage. Many healthcare systems worldwide have not yet addressed oral diseases effectively. The adoption of value-based healthcare (VBHC) reorients health services towards outcomes. Evidence indicates that VBHC initiatives are improving health outcomes, client experiences of healthcare, and reducing costs to healthcare systems. No comprehensive VBHC approach has been applied to the oral health context. Dental Health Services Victoria (DHSV), an Australian state government entity, commenced a VBHC agenda in 2016 and is continuing its efforts in oral healthcare reform. This paper explores a VBHC case study showing promise for achieving universal health coverage that includes oral health. DHSV applied the VBHC due to its flexibility in scope, consideration of a health workforce with a mix of skills, and alternative funding models other than fee-for-service.

Education-related inequalities in oral health among older adults: Comparing Singapore and Japan

OBJECTIVES

Oral health inequalities exist worldwide, and cross-country comparisons can provide valuable insights into country-level characteristics contributing to such inequalities. However, comparative studies in Asian countries are limited. This study examined the magnitude of education-related oral health inequalities in older adults in Singapore and Japan.

METHODS

Longitudinal data for older adults, aged ≥65 years, from the Panel on Health and Ageing of Singaporean Elderly (PHASE; 2009, 2011-2012, and 2015) and Japan Gerontological Evaluation Study (JAGES; 2010, 2013, and 2016) were used. Dependent variables were being edentate and having a minimal functional dentition (MFD; i.e. ≥20 teeth). The absolute and relative inequalities were calculated using the slope index of inequality (SII) and relative index of inequality (RII) for educational level [low (<6 years); middle (6-12 years); high (>12 years)] in each country.

RESULTS

A total of 1032 PHASE participants and 35 717 JAGES participants were included. At baseline among PHASE participants, 35.9% were edentate and 24.4% had MFD, while among JAGES participants, 8.5% were edentate and 42.4% had MFD. The prevalence of low, middle and high educational levels for PHASE was 76.5%, 18.0% and 5.5%, and for JAGES were 0.9%, 78.1% and 19.7%, respectively. Older adults in Japan had lower education-related inequalities for being edentate [for both SII (-0.53, 95% CI = -0.55 to -0.50) and RII (0.40, 95% CI = 0.33-0.48)] and for not having MFD for both SII (-0.24, 95% CI = -0.27 to -0.20) and RII (0.83, 95% CI = 0.79-0.87) compared to Singapore.

CONCLUSIONS

Education-related inequalities for being edentate and not having MFD were higher among older adults in Singapore compared to Japan.

Cross-sectional associations between oral diseases and work productivity loss among regular employees in Japan

The association between oral diseases and work productivity loss remains unclear. This study examined whether dental caries, tooth loss, and poor periodontal status were associated with absenteeism and presenteeism. This cross-sectional study used two independent datasets: 184 employees at a medical university and 435 employees from among the registrants of an online research company. Absenteeism and presenteeism, according to the World Health Organization Health and Work Performance Questionnaire, were dependent variables. The independent variables were the number of decayed and filled teeth (DFT), missing teeth (MT), and self-reported periodontal status. Multivariable linear regression models were developed to estimate unstandardised coefficients with 95% confidence intervals (CIs) for absenteeism and presenteeism. After adjusting for covariates, among the 435 employees enrolled from among the registrants of an online research company, poor periodontal status was significantly associated with a 7.8% (95%CI = -14.5, -1.0) decline in presenteeism but not absenteeism. DFT and MT were not significantly associated with either absenteeism or presenteeism in both populations. Given that periodontal status was potentially associated with a 7.8% decline in work performance, occupational specialists, managers, and dental health professionals should be aware of the impact on work productivity.

Pneumonia incidence and oral health management by dental hygienists in long-term care facilities: A 1-year prospective multicentre cohort study

OBJECTIVE

To investigate the association between oral health management (OHM) by dental hygienists and the occurrence of pneumonia, and determine the effectiveness of OHM in pneumonia prevention.

BACKGROUND

In long-term care facilities in Japan, the need for professional OHM is increasing with an increase in the number of severely debilitated residents.

MATERIALS AND METHODS

A 1-year prospective multicentre cohort study was conducted using data from 504 residents (63 men; mean age: 87.4 ± 7.8 years) in Japanese long-term care facilities. Basic information, medical history, willingness to engage in oral hygiene behaviour, need for OHM and oral conditions were investigated at baseline. In addition, information on the occurrence of pneumonia was collected using a follow-up survey after one year. A Poisson regression analysis with robust standard errors was conducted, with pneumonia as the dependent variable, and factors associated with OHM and pneumonia occurrence as explanatory variables.

RESULTS

Overall, 349 (69.2%) residents required OHM by dental hygienists during that year of follow-up. Of those, 238 (68.2%) were provided with OHM, and 18 (7.5%) developed pneumonia. Among the 111 patients (31.8%) who were not provided with OHM, 21 (18.9%) developed pneumonia. The OHM group had lower pneumonia rates than the non-OHM group (prevalence rate ratio: 0.374; 95% CI: 0.210-0.665).

CONCLUSION

Oral health management by dental hygienists was associated with a lower incidence of pneumonia among residents of long-term care facilities, underlining the importance of professional OHM for such individuals. It is recommended that OHM be practised routinely in long-term care facilities.

Communication Management Processes of Dentists Providing Healthcare for Migrants with Limited Japanese Proficiency

Low health literacy results in health inequity are linked with poor adherence to medical care. In the globalized Japanese context, the number of migrants with Japanese as a second language is increasing year after year. Since limited Japanese proficiency may pose a greater health risk, dentists are expected to manage cross-cultural communication and provide dental care to foreign patients. This study explored dentists' experiences of treating patients with limited Japanese proficiencies. Semi-structured interviews were conducted with 11 community dentists and the qualitative data were analyzed through a thematic analysis approach. Their major challenges were classified into three themes-linguistic aspect (e.g., complicated explanation regarding root canal treatment), sociolinguistic aspect (e.g., communication with foreign residents with limited dental knowledge), and sociocultural aspect (e.g., cultural differences in their dental aesthetics and insurance treatment system). Several management strategies were employed, including linguistic accommodation, avoidance of complexities, use of various communication tools, and getting help from others. However, they were unsatisfied with their practice because they could not understand the patients' psychosocial aspects due to incomplete communication. These findings provided insights into dentists' practice in the globalized context.

Adherence to the food-based Japanese dietary guidelines and prevalence of poor oral health-related quality of life among older Japanese adults in the Kyoto-Kameoka study

Although better diet quality is inversely related to the risk of geriatric disorders, the association of adherence to dietary guidelines with oral health-related quality of life (OHRQoL) is unclear. We aimed to investigate this association in older Japanese adults. This cross-sectional study included 7984 Japanese participants aged ≥ 65 years from the population-based Kyoto-Kameoka study. Dietary intake was estimated using a validated self-administered FFQ. The scores for adherence to the Japanese Food Guide Spinning Top (range: 0 (worst) to 80 (best)) were calculated. These scores were stratified into quartiles (Qs). Poor OHRQoL was defined as a score ≤ 50 using a 12-item Geriatric Oral Health Assessment Index. The OR and 95 % CI were calculated using multivariable logistic regression and the spline model. Higher adherence score was associated with a lower prevalence of poor OHRQoL (Q1-Q4:36·0 %, 32·1 %, 27·9 % and 25·1 %, respectively). An inverse association was found between the score for adherence to the food-based Japanese dietary guidelines and the OR of poor OHRQoL among all the participants (Q1: reference; Q2: OR, 0·87 (95 % CI: 0·75, 1·00); Q3: OR, 0·77 (95 % CI: 0·66, 0·90); Q4: OR, 0·72 (95 % CI: 0·62, 0·85); P_{for trend} < 0·001). These relationships were similar to the results in the spline model. Higher adherence to the food-based Japanese dietary guidelines is inversely associated with the prevalence of poor OHRQoL in older adults. Our results may provide useful insights to improve and maintain oral health.

Overview of dental assistants in Taiwan from 2009 to 2021

Background/purpose

Materials and methods

Results

Conclusion

Difference of income inequalities of denture use by co-payment rates: A JAGES cross-sectional study

OBJECTIVES

Studies suggest that wearing dentures to restore missing teeth can have a positive impact on health status. However, income inequalities in denture wearing exist. The aim of this study was to investigate how differing co-payment rates under the current Japanese Universal Health Insurance Coverage System affect income inequalities in denture non-use among older adults with severe tooth loss.

METHODS

This cross-sectional study used data from the 2019 Japan Gerontological Evaluation Study (JAGES). Self-administered questionnaires were mailed to 345 356 independent people who did not receive long-term care insurance benefits and were aged ≥65 years. The dependent variable was denture non-use, and the independent variable was the equivalent annual household income. The Slope Index of Inequality (SII) and Relative Index of Inequality (RII) were used with regression-based approaches to determine both absolute and relative inequalities in denture non-use by co-payment rates. The covariates were sex, age, years of education, number of teeth and comorbidities.

RESULTS

Of the 240 889 responses received (response rate =69.9%), we analysed 21 594 participants who fulfilled the inclusion criteria. The mean age was 72.8 years (standard deviation =4.1), and 57.6% were men. For 30 per cent, 20 per cent and 10 per cent co-payment rates, the percentages of people who did not use dentures and had severe tooth loss (≤9 teeth) were 18.3%, 13.3%, and 8.5%, respectively. All analyses confirmed significant inequalities in denture non-use. The lower the co-payment rate, the smaller the inequalities. SIIs for each co-payment rate were as follows: 30 per cent =13.35% (95% confidence interval [CI] = 9.61-17.09); 20 per cent =7.85% (95% CI = 4.88-10.81); and 10 per cent =4.85% (95% CI = 2.55-7.16). Inclusion of interaction term between income and co-payment rate significantly lowered the inequalities by co-payment rate in logistic regression analysis and SII. For RII, although the interaction was not statistically significant, a similar trend was observed.

CONCLUSIONS

Income inequalities in denture use existed among older adults with severe tooth loss in Japan, and the inequalities appeared to be greater when the co-payment rate was higher.

Factors Affecting Hospitalization and Death of Older Patients Who Need Long-Term Care—The Necessity of the Support for Dysphagia in Home Dental Care

The demand for home dental care is increasing, but how it should be involved in the continuation of life at home for elderly people who need care has not been examined. Therefore, we examined whether items examined by dentists can affect hospitalization and death. The study included 239 patients with oral intake. They were divided into regular and non-regular diet groups, and ages, nutritional statuses, activities of daily living (ADLs), Charlson Comorbidity Indexes (CCI) and swallowing functions were compared. The nutritional statuses and ADLs of the three groups at the first visit and after one year were compared. The groups included those with stable, declined and improved diet forms. Factors influencing hospitalization and death over three years were examined. Nutritional status, swallowing function, CCI and ADLs were worse in the non-regular diet group. The declined diet form group had lower ADL levels and nutritional statuses at the first visit. A proportional hazards analysis showed significant differences in the changes in diet form for the stable and declined groups related to hospitalization (hazard ratio (HR): 6.53) and death (HR: 3.76). Changes in diet form were thought to affect hospitalization and death, and it is worthwhile to assess swallowing function in home dental care.

Novel composite cement containing the anti-microbial compound CPC-Montmorillonite

OBJECTIVES

The aim of this study was to evaluate the mechanical properties, bonding performance and anti-microbial activity of a novel composite cement containing cetylpyridinium chloride (CPC) modified montmorillonite ('CPC-Mont'), and using these parameters to determine the optimal particle size and concentration of CPC-Mont the composite cement can be loaded with.

METHODS

CPC-Mont particles with a median diameter of 30 and 7 µm were prepared and added to a composite cement at a concentration of 2, 3, 4, 5 and 7.5 wt%. Mechanical properties and bonding performance of the experimental composite cements were evaluated by 3-point bending and micro-tensile bond-strength testing. The amount of CPC released from the cement disks was quantified using a UV-vis recording spectrophotometer. The anti-biofilm activity was studied using scanning electron microscopy (SEM).

RESULTS

Adding 30-μm CPC-Mont decreased the mechanical properties and bonding performance of the composite cement, while no reduction was observed for the 7-μm CPC-Mont loaded cement formulation. Although CPC release substantially decreased during the 7-day period assessed, 5- and 7.5-wt% CPC-Mont loaded composite cement inhibited biofilm formation for 30 days.

SIGNIFICANCE

Loading composite cement with CPC-Mont with a median diameter of 7 µm at concentrations of 5-7.5 wt% was effective in achieving continuous anti-biofilm activity, while maintaining mechanical strength and bonding performance.

Association between Dental Caries and Influenza Infection in Children: A Japanese Nationwide Population-Based Study

Dental caries is the most common chronic childhood disease. Recent studies have suggested that dental caries harbor respiratory infections in adults. We investigated the association between dental caries and influenza in children. In this study, 42,812 children aged 2.5 years, 38,540 children aged 5.5 years, and 34,124 children aged 10 years were included in the analysis from the Longitudinal Survey of Newborns in the 21st Century in Japan, which targeted all children born during a certain period in 2001. We used information on dental caries treated at hospitals and clinics in the past year as exposure and influenza as outcome during the observation periods (1.5–2.5, 4.5–5.5, and 9–10 years of age). We performed a log-binomial regression analysis, adjusting for potential confounders, and stratified analysis according to previous dental caries status. The presence of dental caries increased the incidence of influenza in all three target ages compared with the absence of dental caries. The incidence of influenza increased with the presence of current dental caries, regardless of the presence of past dental caries. These associations were observed irrespective of household income. Early detection and treatment of dental caries may reduce the risk of influenza in children.

Comparing dental student preclinical self-assessment in the United States and Japan

PURPOSE/OBJECTIVES

Self-assessment is an essential skill for dental professionals. Understanding global trends in self-assessment can highlight the learning needs of students across a diversity of cultural backgrounds. The aim of this study is to compare the self-assessment ability of dental students in the United States and Japan, where cultural backgrounds may differ.

METHODS

Students in the United States (n = 176) completed a typodont premolar and anterior Class II and Class III preparation and restoration. Students in Japan (n = 175) completed a typodont premolar crown preparation. Students and faculty then evaluated the student performance using rubrics for each respective procedure. The difference between the student's self-assessment score and the average faculty score (S-F gap) was calculated and the data were analyzed.

RESULTS

The mean S-F gap was 2.8% in Japan and 7.6% in the United States. This indicates that Japanese students tended to assess themselves closer to their faculty graders than students in the United States. On average, students in both countries scored themselves higher than their faculty graders. Students in the United States more frequently overestimated their performance and students in Japan more frequently underestimated their performance. For students in the lower quartile, the mean S-F gap was 5.1% in Japan and 14.6% in the United States, indicating a large cultural discrepancy in the lower quartile groups.

CONCLUSIONS

Although different preclinical procedures were compared, our findings demonstrated that Japanese students may score themselves more closely to their faculty assessors than students in the United States. Further investigation with more students completing the same preclinical activity will be needed.

Regional Inequality in Dental Care Utilization in Japan: An Ecological Study Using the National Database of Health Insurance Claims

BACKGROUND

This study examined regional inequalities in dental care utilization in Japan and the association of dental care utilization with socioeconomic factors.

METHODS

Using the Fourth National Database of Health Insurance Claims and Specific Health Checkups of Japan Open data, this ecological study analyzed 216 million pieces of aggregated data from April 2017 to March 2018. Nine indicators of dental care utilization were used: outpatient visits, outreach services, cavity fillings, pulpectomies, dental calculus removals, periodontal surgeries, tooth extractions, dental bridges, and dentures. Standardized claim ratios (SCRs) for these indicators were calculated for Japan's 47 prefectures, which were divided into three groups based on the number of dental clinics per population, average income per capita, and the proportion of university enrollments. Associations of the dental care utilization with dental supply and regional socioeconomic factors were examined.

FINDINGS

The ratios of maximum to minimum of SCRs were 1·4 for outpatient visits, 19·3 for outreach services, and 17·6 for periodontal surgeries. Dental supply was positively associated with outpatient visits, outreach services, dental calculus removal, and periodontal surgeries. Regional average income and educational level were positively associated with dental calculus removals, and negatively associated with pulpectomies, tooth extractions, dental bridges, and dentures.

INTERPRETATION

In Japan, regional inequalities in dental care utilization exist for periodontal care and outreach services but are smaller for urgent and substantial dental care. Regional income and educational levels appear to have influence on dental care utilization.

FUNDING

Ministry of Health, Labour and Welfare of Japan (H31-19FA1001).

Evaluation of occlusal status of Japanese adults based on functional tooth units

OBJECTIVES

Although extensive national oral health data on dental caries and periodontal diseases in Japan are available, few studies have assessed the occlusal status of the Japanese population, and none are based on national survey data. The presence and prosthodontic conditions of the molar region are important for masticatory function, and the functional tooth unit (FTU) approach can be used to evaluate the occlusal status. Thus, using the national oral health survey data, this study investigated the occlusal status of the Japanese population using FTU.

METHODS

Overall, 3,605 adults (aged ≥20 years) who participated in the 2011 Japanese national oral health survey were included. FTUs were used as indices for evaluating the occlusal status. FTUs were calculated according to sex, age group, and the number of teeth present, and their associations were further analysed.

RESULTS

The number of teeth present, posterior teeth, and FTUs decreased with age in both men and women. In the age group of those ≥60 years, all only natural teeth-FTU (n-FTU) and natural teeth and artificial teeth from fixed prostheses or implant-supported FTU (nif-FTU) scores were <8. The total-FTU scores of all age groups, except the 60-69 and 70-79 years age groups, were >10.

CONCLUSION

This is the first study to use FTUs and national oral health survey data to investigate the occlusal status in the Japanese population. People aged ≥60 years who have low n-FTU or natural teeth and artificial teeth from fixed prostheses or implant-supported FTU scores or those aged 60-70 years who have the lowest total-FTU scores require careful evaluation of masticatory performance.

Comparison of attitudes, awareness, and perceptions regarding oral healthcare between dental and nursing students before and after oral healthcare education

Background

Oral healthcare education for health professional students is important to promote collaborative oral healthcare practice among health professionals. The purpose of this follow-up, cross-sectional study was to investigate attitudes, awareness, and perceptions regarding oral healthcare among dental and nursing students and to compare them both between baseline and the completion of the education programme and between dental and nursing students to identify problems with oral healthcare programmes in dental education.

Method

The subjects included 88 dental and 119 nursing students. The dental students participated in geriatric and preventive dentistry courses for oral healthcare education. The nursing students participated in independent oral healthcare courses comprising 45 h of training with case-based learning and were taught and instructed by multiple health professionals, including dentists. Questionnaires were distributed to the participants to compare attitudes, awareness, and perceptions regarding oral healthcare between baseline and the completion of the education programme and between dental and nursing students. A chi-square test, Wilcoxon signed-rank test, and Mann–Whitney U test were used to compare the data.

Result and Conclusion

The data of 48 (28 male and 20 female) dental students and 103 (9 male and 94 female) nursing students who completed the questionnaires both at baseline and after the education programme were used for the comparisons. After the education programme, more than 90% of the students were interested in oral healthcare practice; hoped to practise oral healthcare post-qualification; and perceived oral healthcare to be effective for preventing dental caries, periodontal diseases, and aspiration pneumonia. These attitudes and perceptions were statistically significantly improved after the education. However, the level of awareness of oral healthcare and the level of perception of the importance of collaboration with healthcare workers in oral healthcare practice after education were lower in the dental students than in the nursing students. Multi-professional oral healthcare education with case-based learning has the potential to improve awareness of oral healthcare and perceptions of the importance of collaborative oral healthcare practice.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12903-021-01554-8.

Preliminary investigation of family caregiver burden and oral care provided to homebound older patients

Objectives

Family caregivers play an important role in maintaining the oral health of homebound older adults. Thus, this preliminary study investigated family caregivers' burdens and the oral care they provide to homebound older patients.

Material and Methods

A cross‐sectional survey was conducted. A questionnaire was distributed to 230 family caregivers of homebound older patients. We used the Japanese version of the Zarit Burden Interview (J‐ZBI) to measure caregiver burden. The cut‐off score for the J‐ZBI was 21 points. Caregivers with a care burden score below 21 points formed the mild group, while those scoring 21 points or more were included in the moderate/severe group. The differences between the groups were examined. The implementation status of oral care was assessed by the amount of time caregivers spent providing oral care and related concerns. The degree of independence for homebound older patients was measured using the Barthel Index. Multiple logistic regression analyses were conducted to determine the factors associated with the severity of caregiver burden.

Results

A total of 114 caregivers returned the questionnaires by mail (response rate: 49.6%). The moderate/severe care burden group represented 80.7% of the caregivers. A multiple logistic regression analysis revealed that the level of patient independence and time spent performing oral care were significantly associated with the severity of caregiver burden.

Conclusions

The results show that family caregivers experiencing high caregiver burden spent less time providing oral care than caregivers who reported less caregiver burden. Thus, support for oral health management provided by oral health professionals is considered necessary for family with a high caregiver burden of homebound older patients.

Associations between vision, hearing and tooth loss and social interactions: the JAGES cross-sectional study

BACKGROUND

Difficulties in communication due to vision, hearing and tooth loss have a serious impact on health. We compared the association between and attribution of each of these factors on social interaction.

METHODS

This cross-sectional study examined data from the 2016 Japan Gerontological Evaluation Study (n=22 295) on community-dwelling people aged ≥65 years in Japan. The dependent variable was the frequency of meeting friends as a measure of social interaction, and less-than-monthly was defined as fewer social interactions. The independent variables were self-reported degrees of vision, hearing (5-point Likert scale) and tooth loss (five categories), with 'poor' or '0 teeth' defined as the worst category. Sex, age, educational attainment, comorbidity and residential area were used as covariates. Poisson regression analysis with multiple imputations was used to estimate the prevalence ratios (PRs) of fewer social interactions by each status. Subsequently, the population attributable fraction (PAF) was calculated to assess the public health impact.

RESULTS

The number of participants with fewer social interactions was 5622 (26.9%). Proportions of fewer social interactions among those with the worst vision, hearing and number of teeth categories were 48.7%, 40.1% and 32.0%, respectively. Their corresponding PRs of fewer social interactions were 1.72 (95% CI 0.97 to 3.05), 1.35 (95% CI 0.99 to 1.85) and 1.23 (95% CI 1.10 to 1.37), respectively. The total PAF for vision, hearing and number of teeth was 8.3%, 5.0% and 6.4%, respectively.

CONCLUSION

Self-reported vision, hearing and tooth loss were associated with fewer social interactions. The magnitude of these impairments was largest in vision, followed by tooth and hearing loss.

Effect of Copayment on Dental Visits: A Regression Discontinuity Analysis

Despite their prevalence and burdens, oral diseases are neglected in universal health coverage. In Japan, a 30% copayment (out of pocket) by the user and a 70% contribution by Japan’s universal health insurance (JUHI) are required for dental and medical services. From the age of 70 y, an additional 10% is offered by JUHI (copayment, 20%; JUHI, 80%). This study aimed to investigate the effect of cost on dental service use among older adults under the current JUHI system. A regression discontinuity quasi-experimental method was used to investigate the causal effect of the JUHI discount policy on dental visits based on cross-sectional data. Data were derived from the 2016 Japan Gerontological Evaluation Study. This analysis contained 7,161 participants who used JUHI, were aged 68 to 73 y, and responded to questions regarding past dental visits. Analyses were controlled for age, sex, number of teeth, and equalized household income. Mean ± SD age was 72.1 ± 0.79 y for the discount-eligible group and 68.9 ± 0.78 y for the noneligible group. During the past 12 mo, significantly more discount-eligible participants had visited dental services than noneligible participants (66.0% vs. 62.1% for treatment visits, 57.7% vs. 53.1% for checkups). After controlling for covariates, the effect of discount eligibility was significant on dental treatment visits (odds ratio [OR], 1.36; 95% CI, 1.32 to 1.40) and dental checkups (OR, 1.49; 95% CI, 1.44 to 1.54) in the regression discontinuity analysis. Similar findings were observed in triangular kernel-weighted models (OR, 1.38 [95% CI, 1.34 to 1.44]; OR, 1.52 [95% CI, 1.47 to 1.56], respectively). JUHI copayment discount policy increases oral health service utilization among older Japanese. The price elasticity for dental checkup visits appears to be higher than for dental treatment visits. Hence, reforming the universal health coverage system to improve the affordability of relatively inexpensive preventive care could increase dental service utilization in Japan.

Wider Dental Care Coverage Associated with Lower Oral Health Inequalities: A Comparison Study between Japan and England

Countries with different oral health care systems may have different levels of oral health related inequalities. We compared the socioeconomic inequalities in oral health among older adults in Japan and England. We used the data for adults aged 65 years or over from Japan (N = 79,707) and England (N = 5115) and estimated absolute inequality (the Slope Index of Inequality, SII) and relative inequality (the Relative Index of Inequality, RII) for edentulism (the condition of having no natural teeth) by educational attainment and income. All analyses were adjusted for sex and age. Overall, 14% of the Japanese subjects and 21% of the English were edentulous. In both Japan and England, lower income and educational attainment were significantly associated with a higher risk of being edentulous. Education-based SII in Japan and England were 9.9% and 26.7%, respectively, and RII were 2.5 and 4.8, respectively. Income-based SII in Japan and England were 9.2% and 14.4%, respectively, and RII were 2.1 and 1.9, respectively. Social inequalities in edentulous individuals exist in both these high-income countries, but Japan, with wider coverage for dental care, had lower levels of inequality than England.

Comparison of perceptions, attitudes and performance regarding collaborative oral health care among health-care workers

OBJECTIVE

Collaborative oral health care among health-care workers (HCWs) is important to prevent oral and systemic diseases. The purpose of this study was to investigate the perceptions, attitudes and performance of HCWs regarding collaborative oral health care and to compare them among HCWs.

METHOD

The subjects were dentists (DTs), dental hygienists (DHs), hospital nurses (HNs), speech-language-hearing therapists (STs) and certified care workers (CCWs) in Fukuoka Prefecture, Japan. DTs were members of the Fukuoka Dental Association, and DHs worked in dental clinics. HNs worked in hospitals without dental departments. STs and CCWs were members of professional associations. Data were collected by a mail survey. The chi-square test and Kruskal-Wallis test were used to compare the data among HCWs.

RESULTS

A total of 119 DTs, 91 DHs, 229 HNs, 119 STs and 121 CCWs participated in this study. The total response rate was 20.6%. There were significant differences in perceptions of what should be performed as part of oral health care among HCWs. Only 20%-60% of HCWs performed collaborative oral health care, while more than 75% were willing to perform such care. Levels of collaborative oral health care with other types of professionals and positive willingness to perform such care were lower among HNs than among the other HCWs.

CONCLUSIONS

It is suggested that oral health professionals should recognise the presence of differences in the perceptions, attitudes and performance among other types of HCW and try to improve these to promote interprofessional collaboration of oral health care in hospitals.

Oral health policymaking challenges in Iran: a qualitative approach

BACKGROUND

As the strategies proposed for oral health improvement in developed countries are not adapted for developing ones, this study aimed to identify the challenges of oral health policy implementation in Iran as a low-income developing country.

METHODS

This qualitative study was conducted in 2019 in Iran as a middle-eastern developing country. The study population consisted of experts who had experience in oral health and were willing to participate in the study. Snowball sampling was used to select 12 participants for semi-structured interviews and saturation was achieved after 16 interviews. Guba and Lincoln criteria including credibility, transferability, confirmability and dependability were used to determine reliability and transparency, and finally a five-step framework analysis method was used to analyze the data.

RESULTS

The analysis of the interviews resulted in identification of 7 main themes that were categorized into 5 problems of policy implementation as proposed by the Matus framework. The main themes of executive and preventive challenges to implement oral health policies were categorized as organizational problems, the main themes of educational and resource challenges were situated as material problems, and the main themes of insurance, policy making and trusteeship challenges were considered as legal, policymaking and perspective.

CONCLUSION

The implementation of oral health policies has faced some challenges. It seems that the national coverage of oral health and integration of these services in prevention and serious attention to the private sector can be considered as the most important strategies for achieving improved oral health in Iran.

Dental expenditure, progressivity and horizontal inequality in Chinese adults: based on the 4th National Oral Health Epidemiology Survey

Background

The financial burden of oral diseases is a growing concern as the medical expenses rise worldwide. The aim of this study was to investigate the dental expenditure, analyze its progressivity and horizontal inequality under the general health finance and insurance system, and identify the key social determinants of the inequality for Chinese adults.

Methods

A secondary analysis used the data of 13,464 adults from the 4th National Oral Health Epidemiological Survey (NOHES) in China was undertaken. The dental expenditure was collected and divided into out-of-pocket and health insurance payments. Horizontal inequality index and Kakwani index were used to analyze the horizontal inequality and progressivity, respectively. The decomposition model of the concentration index was set up to explore the associated socioeconomic determinants.

Results

The results showed that a mean dental expenditure per capita of Chinese adults was $20.55 (95% Confidence Interval-CI: 18.83,22.26). Among those who actually used dental service, the cost was $100.95 (95%CI: 93.22,108.68). Over 90% of dental spending was due to out-of-pocket expenses. For self-reported oral health, the horizontal inequality index was − 0.1391 and for the decayed tooth (DT), it was − 0.2252. For out-of-pocket payment, the Kakwani index was − 0.3154 and for health insurance payment it was − 0.1598. Income, residential location, educational attainment, oral hygiene practice, self-reported oral health, age difference were the main contributors to the inequality of dental expenditure.

Conclusion

Dental expenditure for Chinese adults was at a lower level due to underutilization. The ratio of payments of dental expenditure and utilization was disproportional, whether it was out-of-pocket or insurance payment. Individuals who were more in need of oral care showed less demand for service or not required service in time. For future policy making on oral health, it is worth the effort to further promote the awareness of the importance of oral health and utilization of dental service.

Oral cavity cancer incidence rates in Osaka, Japan between 2000 and 2014

BACKGROUND

We investigated trends in oral cavity cancer incidence from 2000 to 2014 in Osaka, Japan.

METHODS

Using Osaka Cancer Registry (OCR) data, oral cavity cancer incidence number and age-standardized incidence rates were calculated according to three 5-year-time-periods: 2000-2004, 2005-2009 and 2010-2014. We calculated the distribution of clinical stage for each 5-year period and the proportion of oral cavity cancer among all cancers.

RESULTS

A total of 6,086 oral cavity cancers were registered in OCR in 2000-2014. Across the period, between 55.6% and 65.0% were 65 years+ and approximately 60% were men. Tongue cancer accounted for 30.4% to 43.8% of the registrations, while gum accounted for 30.7% to 34.7%. 36.3% to 37.3% were regional, while 1.8% to 2.8% were distant. The age-standardized incidence rate of oral cavity cancer increased from 2.1/100,000 in 2000 to 3.8/100,000 in 2014, although the proportion of oral cavity cancer among all cancers only increased slightly from 0.71% in 2000 to 0.92% in 2014. Proportion of localized stage cancer was 60.8%-67.5% for tongue and 31.0%-49.5% for gum or floor of mouth. Proportion of distant stage cancer was 0.3%-1.0% for tongue and 2.5%-4.2% for gum or floor of mouth.

CONCLUSIONS

Age-standardized incidence rate of oral cavity cancer increased, but was not higher than other countries. The proportion of localized stage tongue cancer was higher, while that of distant stage cancer was lower than other sites. Tongue cancer might be easier to detect in its earlier stages than other sites.

An analysis of the current condition of the medical insurance system in Japan

The social security system, including the national health insurance system, in Japan has been maintained at a world-class level since 1974. However, an increase in the number of elderly people, and a decrease in the working generation, caused by a declining birthrate, represents a serious issue for the system both in the present and future. This report analyzes the key problems in the current insurance system and also considers how they can be handled in the future.

Relationship between oral environment and development of pneumonia and acute viral respiratory infection in dependent older individuals

AIM

The importance of oral care has been recognized for the prevention of airway infections in older individuals who require long-term care. The present prospective cohort study was carried out a decade ago to identify risk factors with numerous intraoral conditions as possible predictors involved in the onset of pneumonia and acute viral respiratory infection (AVRI) in older people requiring long-term care during a 6-month follow-up period (including winter).

METHODS

This study included 1785 older individuals residing in 31 long-term care facilities in which dental hygienists were involved in instruction on daily oral care. Primary end-points were development of pneumonia and AVRI during the 6-month follow-up period. Several factors related to each participant's general condition, oral environment, swallowing function and vaccinations (or lack thereof) were evaluated by calibrated dentists and dental hygienists before the study onset.

RESULTS

During the 6-month follow-up period, 74 participants (4.1%) developed pneumonia, and 28 participants (1.6%) developed AVRI. Cox proportional hazard analysis showed that poor nutritional status and the presence of dysphagia were significant risk factors for pneumonia onset. The presence of dry mouth and halitosis were significant risk factors for AVRI.

CONCLUSIONS

This prospective multicenter cohort study identified poor nutritional status and dysphagia as independent risk factors for the development of pneumonia, and dry mouth and halitosis as independent risk factors for the development of AVRI in older people who require long-term care and who routinely receive professional oral care. Geriatr Gerontol Int 2019; 19: 1136-1140.

Does the national dental scaling policy reduce inequalities in dental scaling usage? A population-based quasi-experimental study

Background

In 2013, the national dental scaling insurance policy was introduced in South Korea. The purpose of this study is to determine the impact of the policy on inequalities in dental scaling usage.

Methods

Data of a nationally representative sample of 1,517,097 people over the age of 20 were obtained from the 2010–2016 Community Health Survey. Respondents who reported that they had not received dental scaling in the past year were defined as dental scaling non-users. The excess prevalence and relative prevalence ratio of dental scaling non-users were calculated for the pre-policy (2010–2012) and post-policy periods (2014–2016) using monthly household income levels. Additionally, trends of dental scaling inequalities were shown as concentration indexes.

Results

The prevalence of dental scaling non-users declined from 58.0 to 48.7% in the highest income group and from 86.3 to 78.8% in the lowest income group. However, the adjusted excess prevalence for the lowest income group compared with the highest had increased from 11.9 (95% CI: 11.9–11.9) to 15.5 (95% CI: 15.5–15.5)%, and the adjusted prevalence ratio increased from 1.19 (95% CI: 1.19–1.20) to 1.29 (95% CI: 1.29–1.30). Absolute and relative concentration indexes of dental scaling non-users increased after policy implementation.

Conclusions

The national dental scaling insurance policy has increased socioeconomic inequalities in dental scaling usage. Because dental care access generally requires high individual agency, expanded dental coverage may have had limited effects in attenuating inequalities and inadvertently widened the gap. To reduce dental care inequalities, universal access with universal dental coverage should be considered.

Electronic supplementary material

The online version of this article (10.1186/s12903-019-0881-7) contains supplementary material, which is available to authorized users.

Income or education, which has a stronger association with dental implant use in elderly people in Japan?

OBJECTIVES

Although inequalities in dental implant use based on educational level have been reported, no study has used income as a proxy for the socioeconomic status. We examined: (i) income inequalities in implant use; and (ii) whether income or education has a stronger association with implant use in elder Japanese.

METHODS

In 2016, a self-reported questionnaire was mailed to participants aged 65 years or older living across Japan as part of the ongoing Japan Gerontological Evaluation Study. We used data from 84,718 respondents having 19 or fewer teeth. After multiple imputation, multi-level logistic regression estimated the association of dental implant use with equivalised income level and years of formal education. Confounders were age, sex, and density of dental clinics in the residential area.

RESULTS

3.1% of respondents had dental implants. Percentages of dental implant use among the lowest (≤ 9 years) and highest (≥ 13 years) educational groups were 1.8 and 5.1, respectively, and among the lowest (0 < 12.2 '1,000 USD/year') and highest (≥ 59.4 '1,000 USD/year') income groups were 1.7 and 10.4, respectively. A fully adjusted model revealed that both income and education were independently associated with dental implant use. Odds ratios for implant use in the highest education and income groups were 2.13 [95% CI = 1.94-2.35] and 4.85 [95% CI = 3.78-6.22] compared with the lowest education and income groups, respectively. From a model with standardised variables, income showed slightly stronger association than education.

CONCLUSION

This study reveals a public health problem that even those with the highest education but low income might have limited accessibility to dental implant services.