Association Between Caries Risk and Public Water Fluoridation in Balsas, Maranhão: A Cross-Sectional Study

Dental caries is a significant public health burden in Brazil, with regional disparities deeply affecting children in the North and Northeast. This study assessed the prevalence and severity of dental caries in preschool children from Balsas (MA) and investigated its association with fluoride concentrations in the public water supply.

A cross-sectional study was conducted with 256 children (aged 3-5 years) enrolled in municipal schools. Schools were selected using a stratified sampling strategy based on the water network, with exposure validated via chemical analysis. Calibrated dentists performed examinations using the FOA-UNESP risk scale, assessing biofilm and gingivitis as objective clinical proxies for hygiene. Fluoride levels were analyzed using an ion-selective electrode. Statistical analysis included Fisher's exact test, Kruskal-Wallis, and Multiple Correspondence Analysis (MCA).

Caries prevalence was 60.16%, with 41.8% of children in severe risk categories (F: 27.0%; G: 14.8%). Water analysis revealed universal hypofluoridation (0.02-0.34 µg F/mL). A significant association was found between residual fluoride (0.02 µg F/mL) and greater caries severity (p = 0.04). Poor hygiene markers (biofilm and gingivitis) were significantly associated with a higher number of decayed teeth (p < 0.05). MCA identified a cluster linking residual fluoridation to severe clinical conditions and social vulnerability.

High caries prevalence associated with inadequate fluoridation highlights critical regional health inequalities in Balsas. These findings underscore the urgent need for policies ensuring universal water fluoridation and strengthening school-based preventive strategies to mitigate the impact of social determinants on child development.