Dental caries and fluorosis in relation to water fluoride levels

Objectives: This study assessed the relationship between dental caries and fluorosis at varying fluoride levels in drinking water. Methods: Subjects were followed from birth with questionnaires every 3-4 months to gather information on fluoride intake. 420 study subjects received dental examinations at age 5 on primary teeth and at age 9 on early-erupting permanent teeth. Composite fluoride levels in drinking water at home and childcare were determined from public, private well, and/or bottled water sources at 24 months of age for individual participants. Permanent tooth fluorosis cases were defined as subjects having definitive/severe fluorosis on 2+ teeth. Caries prevalence rates were calculated at age ~5 and ~9 on primary teeth. The linear trends between fluorosis or caries and fluoride levels in drinking water were assessed by Cochran-Armitage tests. Results: Fluorosis prevalence rates on early-erupting permanent teeth were 21.0%, 41.1% and 46.3% for composite water fluoride levels of <0.7, 0.7-1.2, and >1.2 ppm (P<0.001). Caries prevalence rates on all primary teeth at ~age 5 were 23.8%, 22.9%, and 24.4% for water levels of <0.7, 0.7-1.2, and >1.2 ppm (p=0.970). Specifically on primary second molars, the corresponding caries prevalence rates were 18.2%, 15.3%, and 17.0% at ~age 5 (p=0.631) and 37.1%, 34.3%, and 34.1% at ~age 9 (p=0.612), respectively. Similar relationships were found between fluorosis/caries and water fluoride levels at 12 months and 36 months. Conclusions: Fluorosis prevalence increased significantly with higher water fluoride levels; however, caries prevalence did not decline significantly. Supported in part by R01-DE09551, R01-DE12101, and M01-RR00059.