Fluoridated water impact on tooth decay and fluorosis in 17-20-year-olds exposed to fluoride toothpaste

Objective To determine the impact of water fluoridation on the prevalence and severity of dental caries and fluorosis in individuals aged 17-20 years exposed to fluoride toothpaste. Methods The study population consisted of 660 students from public schools, residents of areas supplied with fluoridated water (exposed group) or not (not exposed group). Students from both groups had access to fluoride toothpaste throughout life. A questionnaire about socioeconomic demographic aspects, conditions related to access and exposure to fluoridated water, and habits related to oral health was applied. Dental caries was measured by the DMFT index and dental fluorosis by the TF index. The chi-square test, t test, and subsequently logistic regression were applied for data analysis. Results Caries experience (DMFT not equal 0) was significantly higher in students from areas not exposed to fluoridated water, after adjustments to clinical conditions, demographic socioeconomic profile, and hygiene habits. The DMFT mean (+/- SD) was significantly higher in students from areas not exposed to fluoridated water than exposed (3.83 [+/- 3.28] and 2.48 [+/- 2.71] respectively). The prevalence of very mild/mild and moderate fluorosis was 41.1% and 21% for students either exposed to fluoridated water or not, respectively. Conclusion Exposure to fluoridated water was associated with a lower prevalence and severity of tooth decay, in spite of the use of fluoridated toothpaste. The prevalence of dental fluorosis at all levels was higher in fluoridated areas, however, in both groups, there were few cases with esthetic implications.