Prevalence and risk indicators for underlying dentin shadows among 12-year-old southern Brazilian schoolchildren

This study aimed to assess the prevalence, extent, and associated factors of underlying dentin shadows (UDS) in the occlusal surfaces of permanent posterior teeth among 12-year-old schoolchildren from southern Brazil. A population-based cross-sectional study that included a representative sample of 1,528 schoolchildren was conducted in Porto Alegre, southern Brazil (participation rate: 83.2%). A questionnaire on sociodemographic characteristics, behavioral habits, and access to dental services was sent to parents/legal guardians of each student selected. Caries examination included the recording of non-cavitated and cavitated lesions, including the presence of UDS, as defined by the ICDAS Group (i.e., a shadow of discolored dentin visible through an apparently intact enamel surface that may or may not show signs of localized breakdown - ICDAS Code 4). The association between predictor variables and UDS prevalence was assessed using survey Poisson regression models. The prevalence of UDS was 6.3% (95%CI = 1.2 -11.3). The mean number of affected teeth among the schoolchildren presenting UDS was 1.51 (95%CI = 1.40 -1.61), ranging from 1 to 6. Type of school (public, PR = 2.23, 95%CI = 1.22 -4.07) and caries experience (DMFT 1-2, PR = 2.41, 95%CI = 1.15 -5.04; DMFT ≥ 3, PR = 3.09, 95%CI = 1.52 -6.27) were significantly associated with UDS prevalence. In conclusion, this population-based cross-sectional study found a low prevalence of UDS in the occlusal surfaces of the permanent posterior teeth of 12-year-old southern Brazilian schoolchildren. Overall caries experience and type of school were associated with UDS in this population.