Water Fluoridation Has a Pre-eruptive Effect in Preventing Caries in Children

Subjects School children age 6, 8, and 11 years attending two schools each in Cheongju (water fluoridation [WF]-ceased area) and Seongnam (non-WF area), both in South Korea, were examined in July 2011. The schools in each area were selected by using convenience sampling based on socioeconomic status. The study participants were examined after parental consent and had completed questionnaires covering sociodemographic features, frequency of daily tooth brushing, and consumption of cariogenic foods and beverages. As a result, the final sample sizes for children age 6, 8, and 11 years in Cheongju were 125, 106, and 104, respectively; in Seongnam these sizes were 192, 226, and 171, respectively. Boys accounted for 50.3% of the sample. In the Cheongju sample, only the children who had lived there since birth were included, accounting for its smaller final sample size compared to Seongnam. Key Exposure The cessation of water fluoridation in 2003 at Cheongju allowed for different levels of exposure from birth, at birth, and ages 1 and 4 years for the children of age groups 6, 8, and 11 years, respectively. On the other hand, Seongnam was never fluoridated. Thus the developing dentition of only the 8- and 11-year-olds of the study sample in Cheongju had early exposure to fluoridated water until age 1 and 4 years, respectively. Main Outcome Measure The effect of cessation was measured by dft and the DMFT ratios by using Poisson regression models adjusted for sex, monthly family income, frequency of consumption of cariogenic foods and cariogenic beverages a day, and frequency of tooth brushing. Main Results Bivariate analysis showed a lower caries experience among the 11-year-olds of Cheongju (WF-ceased). For example, there were significantly lower DMFS levels in Cheongju (1.54 +/- 2.73) compared to non-WE Seongnam (2.87 +/- 5.04). Multivariate models revealed significant dft (6-year-olds) and DMFT (11-year-olds) ratios of WF-ceased vs non-WF of 1.158 (95% confidence interval [CI]: 1.004-1.335) and of 0.581 (95% CI: 0.450-0.751), respectively. Conclusions The authors concluded that water fluoridation had an important systemic effect in the prevention of caries. Owing to the ingestion of fluoridated water in the first 4 years of life, the 11-year-olds from Cheongju (WF-ceased) showed a reduced caries level compared to their counterparts in Seongjam (non-WE).