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

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).