Oral health has previously shown associations with functional disability and mortality. We aimed to explore the associations of various aspects of oral health status with functional disability and mortality using survival analysis, as well as the relative magnitudes of the impact of these aspects on outcomes. We obtained data for individuals aged 75 years and older in Shimane, Japan, who had at least one oral health check-up between April 1, 2016, and March 31, 2022 under Japan's long-life medical care system insurance system. Those with missing data or with functional disability at baseline were excluded. 13 aspects of oral health status were assessed by dentists or dental hygienists as part of the check-up (using protocols provided by the Japan Dental Association and the Japanese Ministry of Health, Labour and Welfare): number of remaining teeth, subjective masticatory performance, objective masticatory performance, periodontal tissue status, functional dysphagia, tongue mobility, articulation, oral hygiene, number of decayed teeth, inadaptation of dentures of the upper jaw and lower jaw (considered separately), oral mucosal disease, and dry mouth. Multivariate Cox proportional hazards models were used to analyse the associations between each aspect of oral health and functional disability and mortality, with fully adjusted models adjusting for sex, age, BMI, medical history, or a propensity score derived from these covariates. Population-attributable fractions (PAFs) were calculated to assess the differential impacts of these oral health status aspects on outcome occurrence. Of the 24 619 individuals who had an oral health check-up during the study period, 21 881 individuals were included in the analysis of functional disability (9175 [41·93%] men, 12 706 [58·07%] women, mean age 78·31 years [SD 2·88], mean follow-up 41·43 months [20·80]), and 22 747 individuals in the analysis of mortality (9722 [42·74%] men, 13 025 [57·26%] women, mean age 78·34 years [2·89], mean follow-up 42·63 months [20·58]). All 13 aspects of oral health status showed significant associations with the occurrence of mortality, while functional disability was associated with 11 aspects (excluding oral mucosal disease and dry mouth) in the fully adjusted model. Based on PAFs, of all oral health aspects assessed, objective masticatory performance had the greatest impact on both functional disability (PAF 23·10% [95% CI 20·42-25·69] for the lowest and 10·62% [8·18-12·99] for the second-lowest quartile of performance) and mortality (16·47% [13·44-19·40] and 8·90% [5·87-11·82]). Various aspects of oral health are associated with mortality and functional disability. Maintaining good oral health in older adults might help to reduce these outcomes. None.

Given that public transportation networks are less developed in rural than in urban areas, a lack of accessibility to dental care facilities could be a barrier to routine dental checkups. Thus, we hypothesized that the distance to the dental care facilities is a risk factor for tooth loss. The aim of this study was to test whether there is an association between the distance to dental care facilities, estimated by geographic information systems, and number of teeth, assessed by an oral examination, among elderly residents of a rural area in Japan. Data were collected in 2016 from a cross-sectional study conducted in Shimane prefecture, Japan. After excluding participants with missing data (n = 21), we analyzed data from 710 participants. Of them, 40.6% were male and the mean (standard deviation) age was 67.4 (7.4) years. Further, 68.0% (n = 483) had at least 20 teeth. We found that the distance to dental care facilities was significantly associated with the number of teeth (less than 20) (odds ratio = 1.07, 95% confidence interval = 1.01–1.12) after adjustment for potential confounders. This result suggested that individuals without easy access to dental care facilities may be important targets for dental care.

Given that public transportation networks are often worse in rural areas than in urban areas, rural residents who do not drive can find it difficult to access health-promoting goods, services, and resources related to masticatory ability. Moreover, geographical location, assessed by elevation, could modify this association. The aim of this study was to test whether the association between access to transportation and masticatory ability varied by elevation. Data were collected from a cross-sectional study conducted in Mizuho and Iwami counties, Japan. Objective masticatory ability was evaluated using a test gummy jelly and elevation was estimated by the geographic information systems according to the participant’s address. After excluding subjects with missing data, 672 subjects (Mizuho = 401 and Iwami = 271) were analyzed. After adjustment for potential confounders, being a driver was not significantly associated with masticatory ability among elderly people living at low elevation (≤313 m) in Mizuho county. However, after the same adjustment, being a driver remained significantly associated with increased masticatory ability among elderly at high elevations. Similar findings were observed in Iwami county. Accessible transportation was significantly associated with increased mastication ability in elderly people living at high elevations, but not in those living at low elevations.

Background and Objectives: Pre-frailty is characterized by a lack of social interaction, mental instability, and decreased interest in health behaviors and oral health. Thus, this study aimed to explore the relationship between oral function and social participation among community-dwelling older adults. Methods: The study participants were community-dwelling older adults who underwent dental and oral health examinations and health checkups conducted by the Shimane Extended Union of the Medical Care System for Latter-Stage Elderly People between April 2020 and March 2022. General background data, oral health status, and social participation data were collected. Logistic regression analysis was performed as the primary analysis, with social participation as the objective variable. Results: The participants included 4196 cases, excluding 513 cases with missing data. Logistic regression analysis of the presence of going out at least once a week demonstrated significant correlations in age, lower leg circumference, masticatory function, and oral hygiene status (p < 0.05). Significant correlations were found in sex, lower leg circumference, masticatory function, swallowing function, and oral hygiene status for regular meetings with family or friends (p < 0.05). Conclusions: There may be an association between social participation and a decline in oral function and hygiene status among community-dwelling older adults.

The relationship between oral health status and bone mineral density has been poorly elucidated. We conducted a cross-sectional study to examine the relationship between oral health status and bone mineral density with data from healthy community-dwelling elderly individuals in Ohnan-cho, Shimane Japan who were recruited in 2019 for the Shimane Center for Community-Based Health Research and Education (CoHRE) study. The study included 702 participants (306 men and 396 women). The median age, bone mineral density, and number of remaining teeth were 69.0 years, 86.2%, and 26.0, respectively. The two groups (Low teeth group and High teeth group) showed significant differences in age, hemoglobin A1c (HbA1c) level, and masticatory function in men (p < 0.05). In women, age, number of untreated teeth, and masticatory function were significantly different (p < 0.05). The odds ratio of propensity score analysis for the association between the number of remaining teeth and bone mineral density was 27.7 (95% confidence interval: 1.86–414.9, p < 0.05). The number of remaining teeth could be associated with bone mineral density in the healthy elderly women, and no significant association was observed in men. Number of remaining teeth and bone mineral density may be interrelated, and oral care by dentists/dental hygienists may play an important role in maintaining bone mineral density in elderly women.

The relationship between masticatory function and bone mineral density (BMD) is unclear. This cross-sectional study examined this relationship after adjusting for confounding factors. The subjects were 702 community-dwelling elderly adults (306 men, 396 women) who had been recruited for the Community-Based Healthcare Research and Education study in 2019. Objective masticatory function was assessed using the gummy jelly method. The median for each descriptive statistic was 69.0 years for age, 86.2% for the young adult mean, and 18.0 for masticatory function. Comparisons of the groups with good and poor masticatory function by sex revealed a significant difference in muscle mass and the tooth number for both sexes (p < 0.05). Men showed significant differences in age (p < 0.05) and salivary occult blood findings (p < 0.05). Multivariate analysis using propensity scores showed a significant association between masticatory function and BMD in both sexes (men: odds ratio 163.0, 95% confidence interval 1.36–19,610.55, p = 0.04; women: odds ratio 48.65, 95% confidence interval 1.52–1561.15, p = 0.03 in women). Masticatory function and BMD in the community-dwelling elderly may be related. However, other factors, including frailty and sarcopenia, may also be involved. Regular oral health care by dentists and dental hygienists may benefit this population.