Protective factors for caries of a school-based oral health program in Bangkok, Thailand: a retrospective cohort study

The aim of the study was to assess protective factors of a school-based oral health preventive program on caries in permanent teeth in students and to identify other risk and protective factors associated with caries in this group. This is a retrospective cohort study. A total of 433 students were examined in the 1st grade and followed up until the 6th grade. Each student was annually assessed for caries as per the World Health Organization index. Binary simple and multiple logistic regressions were performed to assess risk or protective factors with a P-value ≤0.05. In 1st graders, the caries prevalence in deciduous teeth was 87.2%, and the mean decayed, missing and filled teeth (dmft) index was 6.44 (±4.4); in 6th graders, the caries prevalence in permanent teeth was 51.7%, and the mean DMFT was 1.37 (±1.84). Protective factors for caries in permanent teeth were complete participation in the program, receiving fluoride varnish >4 times, and sealant applications on all first molars. Risk factors were female sex and caries prevalence in deciduous teeth. After multiple logistic regression, sealant application only remained significant, with an odds ratio (OR) of 0.19 (95% confidence interval [CI] = 0.06–0.63, P = 0.007), and for risk factor, caries prevalence in deciduous teeth only remained significant, with an OR of 5.44 (95% CI = 2.23–13.27, P