In 1945, Grand Rapids, Michigan, introduced fluoride into public water systems to help residents fight tooth decay. In the meantime, a group of Wisconsin dentists succeeded in adding fluoride to the state's water system. After extensive testing, fluoride was found to reduce two-thirds of the rate of tooth decay, and in 1951 the U.S. Department of Public Health urged the nation to fluorinate public drinking water.
The idea of water fluorination came from the observation of a dentist in Colorado, Colorado in the early twentieth century. Frederick McKay noticed brown stains on the teeth of locals. He called the stain "enamel mottled" due to drinking water containing high levels of fluoride. He reported a decline in the incidence of tooth decay in locals. In 1940 another dentist disclosed that a fluoride per million parts of water is an ideal ratio to reduce decay and prevent staining. Fluoride was soon accepted, and today more than 60% of Americans add fluoride water.
