Fluoridation consists of adding fluoride to a substance (often drinking water) to reduce tooth decay. Fluoridation was first introduced into the United States in the 1940s in an attempt to study its effect on the reduction of tooth decay. Since then many cities have added fluoride to their water supply systems. Proponents of fluoridation have claimed that it dramatically reduced tooth decay, which was a serious and widespread problem in the early twentieth century. Opponents of fluoridation have not been entirely convinced of its effectiveness, are concerned by possible side effects, and are disturbed by the moral issues of personal rights that are raised by the addition of a chemical substance to an entire city's water supply. The decision to fluoridate drinking water has generally rested with local governments and communities and has always been a controversial issue.

Tooth decay occurs when food acids dissolve the protective enamel...