Associations between school-based fluoride mouth-rinse program, medical-dental expense subsidy policy, and children's oral health in Japan: an ecological study

Abstract

Background Dental caries are a common non-communicable disease among children. As a public health measure at the prefectural level, school-based fluoride mouth-rinse (S-FMR) programs and medical/dental expense subsidy policies may reduce the incidence of dental caries and tooth loss. Prefectures focusing on promoting oral health policies may promote both, but the interaction effect of implementing both subsidy policies and S-FMR at the prefectural level on caries prevention has not yet been examined. Methods We conducted an ecological study using cross-sectional, prefecture-level aggregated data in Japan. Standardized beta (B) and 95% confidence intervals (CI) were calculated for the dependent variables for oral health using linear regression analyses adjusted for possible confounders such as dentist density and prefectural socioeconomic circumstances. Three dependent variables were used; the standardized claim ratio (SCR) of deciduous tooth extraction, the SCR of dental sealants, and 12-year-olds’ decayed, missing, or filled permanent teeth (DMFT). The independent variables were S-FMR and subsidy policy in three models: co-payment until children enter elementary school (n=23), no co-payment until children enter elementary school (n=7), and co-payment continuing beyond elementary school (n=17). Interaction terms were multiplied by the S-FMR and subsidy policy and entered into each model. Results S-FMR was not associated with the SCR of deciduous tooth extractions and dental sealants. High S-FMR utilization was associated with low DMFT (B = -0.26, 95% CI -0.46; -0.06). No co-payment until children enter elementary school was positively associated with the SCR of deciduous tooth extraction compared to co-payment until children enter elementary school (B = 0.37, 95% CI 0.05; 0.69). The subsidy policy was not associated with the SCR of dental sealants and DMFT. No interaction was found between S-FMR and the subsidy policy at all outcomes. Conclusion S-FMR, one of the universal approaches, was an effective strategy for maintaining oral health among children, and this association was independent of the subsidy policy on oral health.