Systematic review of water fluoridation

Objective To review the safety and efficacy of fluoridation of drinking wat er. Design Search of 25 electronic databases and world wide web. Relevant journ als hand searched; further information requested from authors. Inclusion cr iteria were a predefined hierarchy of evidence and objectives. Study validi ty was assessed with checklists. Two reviewers independently screened sourc es, extracted data, and assessed validity. Main outcome measures Decayed, missing, and filled primary/permanent teeth. Proportion of children without caries. Measure of effect was the differenc e in change in prevalence of caries from baseline to final examination in f luoridated compared with control areas. For potential adverse effects, all outcomes reported were used. Results 214 studies were included. The quality of studies was low to modera te. Water fluoridation was associated with an increased proportion of child ren without caries and a reduction in the number of teeth affected by carie s. The range (median) of mean differences in the proportion of children wit hout caries was -5.0% to 64% (14.6%). The range (median) of mean change in decayed, missing, and filled primary/permanent teeth was 0.5 to 4.4 (2.25) teeth. A dose-dependent increase in dental fluorosis was found. At a fluori de level of 1 ppm an estimated 12.5% (95% confidence interval 7.0% to 21.5% ) of exposed people would have fluorosis that they would find aesthetically concerning. Conclusions The evidence of a beneficial reduction in caries should be cons idered together with the increased prevalence of dental fluorosis. There wa s no clear evidence of other potential adverse effects.