Fluoridation in rural-urban settings in the United States

A significant reduction in caries is attributed to water fluoridation. Many community water sources actively maintain a fluoride level at 1 ppm to reduce the prevalence of caries. Untreated domestic wells and springs, and public non-fluoridated water systems are more likely in rural areas. The purpose of this study was to determine if there is a difference between urban and rural counties in access of fluoridated water, and determine if inadequate fluoridation is associated with poorer adult dental health outcomes. We conducted a retrospective, cross-sectional study of U.S. counties utilizing the CDC's My Water's Fluoride database, 2006 Behavioral Risk Factor Surveillance System, and the U.S. Census Area Resource File. The percent of the population with fluoridated public drinking water was 67.17% (SD 33.29). In metropolitan areas it was 72.6% compared to 63.3% in nonmetropolitan areas (F=45.93, df=1, 3045, p<.001). The differences among metropolitan, micropolitan, and noncore areas were significant (F=30.41, df=2, 3044, p<.001). Differences among fluoridation rates across the 12 urban-influence codes were significant (F=9.06,df=11, 3035, p<.0001). In urban areas, greater levels of fluoridation were related to lower levels of adult tooth loss. In non-metropolitan or non-core areas, measures of adult tooth loss were not significantly related to fluoridation rates, after controlling for other risks. This outcome was unexpected and may result from data limitations, or the greater use of oral health precautions other than fluoridated water among non-metropolitan populations.