https://www.sciencedaily.com/releases/2018/06/180614213654.htm

In this large study, county-level estimates of the percentage of population with community water fluoridation from the Centers for Disease Control and Prevention 's Water Fluoridation Reporting System were merged with dental examination data from 10 years of National Health and Nutrition Examination Surveys (1999-2004 and 2011-2014).

The analysis showed that U.S. children and adolescents with greater access to fluoridated drinking water were less likely to experience dental caries. Counties in which over 75% of the population had access to community water fluoridation saw a 30% reduction in dental caries experience in the primary dentition, and a 12% reduction in dental caries experience in the permanent dentition, compared to counties in which less than 75% had access to community water fluoridation.