Black stains and dental caries in Brazilian schoolchildren: a cross-sectional study

The aim of this study was to assess the prevalence of black stains (BS) and factors associated with their occurrence and to investigate the association of BS with caries experience after adjusting for other risk indicators. A school-based, cross-sectional study using multistage sampling of children aged 10-12 years from 20 private and public schools in Pelotas/Southern Brazil was conducted (n = 706). Children were evaluated for BS and dental caries (DMFT/dmft index) and socioeconomic information was collected by questionnaire. Univariate and multivariate Poisson regressions were used to assess variables associated with the prevalence of BS and with caries experience. The prevalence of BS was 5.81%. The mean DMFT/dmft was 1.54 (+/- 1.91), with a maximum value of 10. Among the children with BS, mean dmft/DMFT was 1.22 (SD 1.68), with a maximum value of 6. After adjustments for demographics and socioeconomic variables, dental plaque and tooth brushing habits, prevalence of BS was associated with lower caries experience (RR 0.67; 95% CI 0.49-0.92). In conclusion, the presence of BS showed an association with lower dental caries experience in the evaluated population. Future studies should investigate the mechanisms behind this association.