Enhanced anticaries action from drinking water containing 5 ppm fluoride.

Dental examinations were conducted on 1,878 adolescent schoolchildren native to seven US cities in five states, where the water was fluoride-deficient, fluoridated, or contained approximately 5 ppm of naturally occurring fluoride. Dental caries experience was considerably lower in all the communities with fluoridated water than in Boston, which had water deficient in fluoride, and ranged from 38% to 83% fewer mean DMF for the children in the regions with fluoridated water than for the children in Boston. Moreover, dental caries experience was significantly lower in Midland, Tex (5 to 7 ppm fluoride) than in each of the four cities with fluoridated water, and approximately 50% of the children in Midland had no caries. This report provides strong evidence that a much greater protection against human dental caries can result from a higher concentration of fluoride than is customarily recommended as best for prevention of caries. Fluoridating community waters to concentrations higher than 1 to 2 ppm fluoride, however, is not suggested because of the high risk of producing unesthetic enamel fluorosis.