Effectiveness of water fluoridation.

The efficacy of communal water fluoridation in reducing dental caries has been reviewed based on surveys conducted in the last decade of caries prevalence in fluoridated and nonfluoridated communities in the United States as well as in Australia, Britain, Canada, Ireland, and New Zealand. The efficacy is greatest for the deciduous dentition, with a range of 30-60 percent less caries in fluoridated communities. In the mixed dentition (ages 8 to 12), the efficacy is more variable, about 20-40 percent less caries. In adolescents (ages 14-17), it is about 15-35 percent less caries. Current data on caries prevalence in adults and seniors are extremely limited and include several populations living in communities with higher than optimal fluoride levels. For these adults and seniors, a range of 15-35 percent less caries would also apply. Viewed in toto, the current data for children, adolescents, adults and seniors show a consistently and substantially lower caries prevalence in fluoridated communities. For an accurate measurement of the efficacy of water fluoridation in reducing dental caries, it is essential that only persons with a record of continuous or long-term residency in fluoridated versus nonfluoridated areas be included in such assessments. Because of the high geographic mobility in our society and the widespread use of fluoride dentifrices, supplements, and other topical fluoride agents, such comparisons are becoming more difficult to conduct. Accordingly, the effectiveness (rather than the efficacy) of water fluoridation has decreased as the benefits of other forms of fluoride have spread to communities lacking optimal water fluoridation.