Prefecture-level factors associated with home-visit dental care utilization in Japan: focus on dentist workforce...

Population aging has increased demand for home-visit dental care in Japan, yet regional disparities persist, as in other aging societies. This study aimed to identify factors associated with regional variation in the utilization of home-visit dental care. As part of an exploratory approach, we also examined home-visit medical care data to consider possible contrasts with dental service provision.

This ecological cross-sectional study followed the STROBE guidelines and used prefecture-level aggregated data. We calculated the standardized claim ratio (SCR) for home-visit dental services using the 9th edition of the National Database of Health Insurance Claims and Specific Health Checkups of Japan (NDB) Open Data (April 2022 to March 2023). Spearman's correlation coefficient was computed to examine associations between SCR and relevant variables, including average age of dentists, number of dental clinics, and number of dentists in medical facilities. Then, multiple regression analyses were conducted using the SCR of the home-visit dental services, adjusting for the average age of dentists, the number of dental clinics, and the regional aging rate.

Prefectural SCRs for home-visit dental services varied widely (range 24.68-168.79, median 70.52). SCR was negatively correlated with the average age of dentists (R = - 0.65, p < 0.001). In addition, it was positively correlated with the number of dentists working in medical facilities per 100,000 population (R = 0.60, p < 0.001) and number of dental clinics per 100,000 population (R = 0.71, p < 0.001). Multiple regression analysis showed that the average age of dentists had a negative relationship with SCR; the standardized regression coefficient (β) was - 0.30 (p = 0.017), whereas the number of dental clinics had a positive relationship (β = 0.47, p < 0.001).

Regional variation in home-visit dental care utilization was associated with structural characteristics of the dental workforce. However, these findings should be interpreted as ecological associations influenced by both supply- and demand-side factors, rather than as indicators of individual provider behavior or capacity. The results suggest that workforce structure, including age composition and service infrastructure, may be related to regional disparities in home-visit dental care. Further studies incorporating individual-level and socioeconomic data are needed to clarify underlying mechanisms.