Caries incidence in school-based oral health programs

Background: School-based caries prevention can increase access to critical dental services and reduce oral health inequities. However, little is known regarding the incidence of dental caries in children participating in school caries prevention, and caries diagnosis is often interval censored. Methods: In this paper, we used data from a longitudinal, school- based, randomized clinical trial of minimally invasive treatments for dental caries to estimate the per-visit incidence rate and compare the hazard of dental caries in children receiving either silver diamine fluoride or glass ionomer dental sealants. To account for interval censoring, we used semiparametric transformation models for univariate failure time data and imputed the caries incidence using G-imputation. Results: There were 3040 children that met inclusion criteria for analysis, 1516 (49.9%) of which were randomly assigned to receive silver diamine fluoride and 1524 (50.1%) assigned to receive glass ionomer dental sealants. There were no differences in the hazard of caries between treatments (HR = 0.98, 95% CI = 0.73, 1.24), while children with caries at baseline had a significant increase in the hazard of new caries (HR = 2.54, 95% CI = 2.26, 2.83) compared to those that were caries-free. The per-visit caries incidence ranged from 4.8 to 11.1 per 1000 person-years and increased with each successive study observation. Conclusions: School-based caries prevention can positively affect caries incidence, and results can be used to inform future program design and implementation.