Community-Level Inequalities and Risk Factors for Incident Oral Frailty

INTRODUCTION: Oral frailty, characterized by tooth loss, chewing difficulty, and swallowing problems, has been associated with adverse health outcomes in older adults. However, longitudinal evidence on community-level inequalities and determinants of incident oral frailty remains limited. OBJECTIVES: This cohort study aimed to examine community-level inequalities in the incidence of oral frailty and identify individual- and municipality-level factors associated with its onset among older adults in Japan. METHODS: We analyzed data from 42,987 participants aged ≥65 y who completed the Japan Gerontological Evaluation Study surveys in 2019 and 2022. Oral frailty was determined using a validated prediction model including age, number of teeth, chewing difficulty, and choking. Individual-level variables included sociodemographic, health status, and social capital indicators. Municipality-level variables included population density, aggregated social capital, and the presence of prefectural or municipal dental health ordinances. Modified multilevel Poisson regression was used to estimate incidence rate ratios. RESULTS: < 0.05). At the municipality level, residing in urban, semi-urban, or rural-agricultural areas was associated with a lower risk of incident oral frailty compared with metropolitan area residency. Although not statistically significant in all models, higher municipality-level civic participation tended to be associated with a lower risk of incident oral frailty. CONCLUSION: Community-level inequalities in the incidence of oral frailty are driven by both individual vulnerabilities and municipality-level factors. Notably, higher municipality-level civic participation tended to be associated with a lower incidence of oral frailty. Effective prevention requires comprehensive strategies that address socioeconomic factors and promote community-level civic participation.Knowledge Transfer Statement:This nationwide cohort study demonstrates that community-level inequalities in the incidence of oral frailty are substantial. They are largely explained not only by modifiable individual socioeconomic factors but also by municipality-level civic participation. These findings highlight the importance of integrating individual risk-based prevention with community strategies that may contribute to reducing oral frailty and related oral health disparities in aging populations.