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In the early 1900's, researchers began to gather data regarding the effects of adding fluoride to water. By the mid-1900's, the evidence was strongly supporting the benefits to dental health of fluoridated water. A 1945 study compared selected towns using fluoridated water with selected communities not using fluoride in the public water supply and found a 50%-70% decrease in the number of cavities developed.
Fluoridation of the public water supply guarantees that the entire population will benefit from the treatment, regardless of age, socio-economic status, education, or other factors. While there are many other fluoridated products available for commercial purchase, not all persons use those items. The most universal method of delivering the protection of the fluoride to the largest percentage of the population is to add it to the water supply. "Adding fluoride to drinking water is the most cost-effective method for preventing dental caries."