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Research attempting to measure the impact of fluoride upon tooth decay began in the early 1900's. By the mid-1900's, the benefits of adding fluoride to drinking water were well-documented. As a result of fluoridated drinking water, a 1945 study showed a reduction of 50%-70% in the number of caries in communities using fluoridated water as compared with communities using water without additional fluoride.
Fluoridation of drinking water "is the most cost-effective method for preventing dental caries (cavities)." Adding fluoride to public water ensures that the benefits are available to all persons, regardless of age, socio-economic status, or other variables. While many toothpastes and other commercial products may also contain fluoride, these products may not be used by all persons.