The process of adding fluoride to drinking water or another substance in order to reduce the occurrence of tooth decay.

Fluoridation was first introduced into the United States in the 1940s in an attempt to combat the serious problem of tooth decay. Today, more than half of the U.S. population drinks fluoridated water from public water supplies.

Tooth decay occurs when food acids dissolve the protective enamel surrounding each tooth and create a hole, or cavity, in the tooth. These acids are present in food, and can also be formed by acid-producing bacteria that convert sugars into acids. There is overwhelming evidence that fluoride can substantially reduce tooth decay. When ingested into the body, fluoride concentrates in bones and in dental enamel, which makes the tooth enamel more resistant to decay. It is also believed that fluoride may inhibit the bacteria that convert sugars into acidic substances...