Fluoridation of drinking water reduces caries prevalence

Abstract

Objective To determine the effects of fluoridation of drinking water supplies on the incidence of caries. Data sources See page 37. Study selection See page 37. Data extraction and synthesis See page 37. Results Twenty-six studies met the criteria. There were no level ‘A’ studies. All but three were before and after studies, two used prospective cohort designs, and one a retrospective cohort. The most serious defect of these studies was the lack of appropriate analysis. The degree of caries reduction is not clear from the data available. It was estimated that a median of six people need to receive fluoridated water for one extra person to be caries-free [interquartile range of study number-needed-to-treat (NNT), 49]. Studies after withdrawal of water fluoridation (level ‘B’ and limited quantity) indicate that caries prevalence increased, approaching the level of the low fluoride group. The estimates of effect could be biased due to poor adjustment for the effects of potential confounding factors. Conclusions The best available evidence suggests that fluoridation of drinking-water supplies does reduce caries prevalence, both as measured by the proportion of children who are caries-free and by the mean change in dmft/DMFT score. The studies were of moderate quality (level B), but of limited quantity. McDonagh M, Whiting P, Bradley M, Cooper J, Sutton A, Chestnutt I, et al. A Systematic Review of Public Water Fluoridation, September 2000. York: University of York Publications Office, NHS Centre for Reviews and Dissemination. ISBN 1 900640 16 3