School-based caries prevention and longitudinal trends in untreated decay: an updated analysis with Markov chains.

Objective: Dental caries (tooth decay) is the most prevalent childhood disease in the world. A school-based program for the prevention of dental caries providing bi-annual sealants, interim therapeutic restorations, and fluoride varnish to children aged 5-12 years was previously associated with a significant reduction in the prevalence of untreated tooth decay over time. The objective of this study was to explore potential nonlinear change in the risk of untreated decay in children receiving caries prevention.

Results: Across all study participants, there was a significant increase in the odds of untreated tooth decay over time (OR = 1.90, 95% CI 1.51, 2.39), but the rate of this risk rapidly decreased with each observational visit (OR = 0.87, 95% CI 0.93, 0.91). Overall effects substantially depended on the oral health status of participants at baseline: for children with untreated decay at their first observation, the odds of untreated decay over time was 0.39 (95% CI 0.27, 0.55). A quadratic change for this subpopulation showed that the per-visit decrease in decay was attenuated with each subsequent observation (OR = 1.12, 95% CI 1.04, 1.20).