Trends in Denture Insurance Claims and Their Association With Socioeconomic Indicators and Population Aging in Japan

OBJECTIVES: To describe nationwide temporal trends in insurance-covered denture claims in Japan and examine their associations with prefectural socioeconomic indicators and population aging using the National Database of Health Insurance Claims and Specific Health Checkups (NDB). BACKGROUND: Japan is experiencing rapid population aging while tooth retention among older adults is improving. How these demographic and oral-health changes are reflected in the provision of insurance-covered complete dentures and removable partial dentures (RPDs) remains unclear. MATERIALS AND METHODS: A prefecture-level time-series analysis of NDB dental claims from 2013 to 2018 was conducted. The primary outcome was the annual number of total denture claims per dental clinic. Category-specific claims per clinic were also analysed for resin-base complete dentures and resin-base RPDs replacing 1-4, 5-8, 9-11 or 12-14 missing teeth. Prefectural income per capita, gross domestic product (GDP) per capita, and the proportion of residents aged ≥ 65 years were linked with annual claim data. Temporal trends, Pearson correlations, and category-specific multivariable linear regression models adjusted for calendar year were examined. RESULTS: Total denture claims per clinic declined nationwide during the study period, from an average of 177 to 159 claims per clinic; complete denture claims showed the largest decrease (16%). The proportional share of complete dentures decreased, whereas the share of RPDs replacing 1-4 missing teeth increased. Total denture claims per clinic showed moderate negative correlations with income per capita (r = -0.518) and GDP per capita (r = -0.411), and a weak positive correlation with the proportion of residents aged ≥ 65 years (r = 0.344). In category-specific multivariable models, the proportion of residents aged ≥ 65 years was positively associated with claims in all denture categories, and calendar year was negatively associated with claims. CONCLUSION: Total insurance-covered denture claims per clinic declined in Japan during 2013-2018, with regional variation and a larger relative contribution of small-span RPD claims. These findings suggest that geriatric denture service planning should account for both population aging and regional socioeconomic context.