A clear increase in fluorosis among populations drinking community water that contains less than 0.3 ppm fluoride was found. Results of the comparisons using studies with Dean’s Index pooled at different time points, comparisons in the same communities over time, and comparisons of prevalence found in selected communities before fluoride was widely available with the National Fluorosis Survey all support this conclusion. An increase in the prevalence of fluorosis in those drinking optimally fluoridated water likely has occurred as well; however, evidence for such a trend is not as clear as for fluoride deficient communities because of mixed results depending on the type of comparison. The majority of fluorosis cases continue to be mild and seem of little esthetic consequence for most of the public or dental profession. But a few cases of more severe fluorosis can be found now in some communities. Because the prevalence of fluorosis is now higher than 50 years ago, we can conclude that fluoride availability to the developing enamel during critical periods when enamel is at risk of fluorosis has increased in North American children.
J Public Health Dent. 1999 Fall;59(4):239-46.
The prevalence and severity of enamel fluorosis in North American children.
Rozier RG .