What Does Fluoride Do?

Fluoride prevents tooth decay and strengthens teeth. Tooth decay, or dental caries, is an infection caused by the acid formed when bacteria in the mouth combines with sugars. It causes demineralization and severe damage to the hard tissues of the teeth, which are the enamel, dentin and cementum.

Demineralization is when a tooth loses minerals, such as calcium from the tooth enamel, which leads to the erosion of the enamel. Fluoride prevents this by strengthening the damaged areas of the enamel, a process known as remineralization. This is commonly done by brushing teeth with fluoridated toothpastes. Remineralization can also be achieved by drinking fluoridated water.

Many regions in the United States and some countries in Europe add fluoride to drinking water sources as a measure for preventing tooth decay. Studies have shown that by doing this, the rates of tooth decay have lowered up to 50 percent.

However, high concentrations of fluoride can lead dental fluorosis, which is a dental condition characterized by discoloration and pitting of the teeth. In severe cases, too much fluoride can lead to skeletal fluorosis — a bone disease, which in the advanced stage, causes pain and damage to bones and joints. According to the World Health Organization, fluoride in excess of 1.5 milligrams per liter can lead to dental and skeletal fluorosis.