Fluoride has been in the news recently with some people questioning the worth of adding this vital mineral to the water supplies in the United States. 

Fluoride repairs and prevents damage to teeth caused by bacteria in the mouth. Bacteria in the mouth produce acid when a person eats or drinks. The acid dissolves minerals in a tooth's surface, making the tooth weaker and open to cavities.1

Fluoride replaces the minerals lost from a tooth due to acid breakdown. Some fluoride can replace minerals in the tooth surface, making the outer enamel layer harder to dissolve. Fluoride also may reduce the amount of acid that cavity-causing bacteria produce, as well as making it harder for these bacteria to stick to the teeth.1

Protecting teeth requires consistent, low levels of fluoride in the mouth (in the saliva and on tooth surfaces). Fluoride can also be incorporated into developing dental enamel before a tooth erupts into the mouth, enhancing the tooth's resistance to acid breakdown and preventing cavities later in life. (credits)

Some public figures have made false claims that adding fluoride to drinking water poses health risks, such as reduced intelligence in children and cancer. When used at recommended levels, fluoride in drinking water is safe and effective for preventing tooth decay, which also provides benefits for people’s overall health. Extensive research has consistently demonstrated that optimal fluoridation does not pose a detectable risk of cancer or other serious health issues.  (credits)

The discovery of Fluoride as a preventative for tooth decay.