Fluoride is a compound of the element fluorine, which is found universally throughout nature in water, soil, air and food. Existing abundantly in living tissue as an ion, fluoride is absorbed easily into tooth enamel, especially in children's growing teeth. Once teeth are developed, fluoride makes the entire tooth structure more resistant to decay and promotes remineralization, which aids in repairing early decay before the damage is even visible. Two forms of fluoride protect the teeth: systemic fluoride and topical fluoride.

What is systemic fluoride?

Systemic fluoride is ingested into the body when added to public and private water supplies, soft drinks and teas and is available in dietary supplement form. Once systemic fluoride is absorbed via the gastrointestinal tract, the blood supply distributes it throughout the entire body. Most fluoride not excreted is deposited in bones and hard tissues like teeth.

What's topical fluoride, and when should I use it?

Topical fluoride is applied directly to the teeth. It is found in products containing strong concentrations of fluoride to fight tooth decay, such as toothpastes and mouth rinses. These products are then expectorated or rinsed from the mouth without swallowing. Dentists recommend brushing with a fluoride toothpaste at least twice a day or after every meal, combined with a regimen of flossing and regular dental checkups.

Professionally administered topical fluorides such as gels or varnishes are applied by a dentist and left on for about four minutes, usually during a cleaning treatment. For patients with a high risk of cavities, the dentist may prescribe a special gel for daily home use, to be applied with or without a mouth tray for up to six weeks.

Why is most of the water we drink fluoridated?

Fluoridated water protects against cavities and root caries – a progressive erosion of adult root surfaces caused by gum recession – and helps remineralize early carious lesions. Thanks to these preventive benefits, public water fluoridation is considered the most efficient and cost-effective cavity prevention measure available. More than 144 million United States residents in more than 10,000 communities drink fluoridated water, most from public water supplies with artificially added fluoride. A small percentage get water from private wells with naturally fluoridated water.

The Environmental Protection Agency (EPA) has determined that the accepted "optimal" range of fluoride in water lies between 0.7 and 1.2 parts per million (ppm) or milligram per liter. The limit allowed by the EPA in public water is 4 ppm. Backed by results from more than 140 documented studies undertaken in 20 different countries over the past several decades, fluoridated water adhering to these standards has been scientifically established as safe for drinking. Water fluoridation is endorsed by nearly every major health and safety-related organization. Fluoridation of community water supplies is the single most effective public-health measure to prevent tooth decay and to improve oral health for a lifetime.

Are children more sensitive to fluoride?

Developing teeth are sensitive to higher fluoride levels. In young children, excess fluoride intake can cause dental fluorosis, a harmless cosmetic discoloring or mottling of the enamel, visible as chalky white specks and lines or pitted and brown stained enamel ondeveloping teeth. They are at greater risk if they swallow or use too much toothpaste and fluoride supplements or regularly drink water containing excessive fluoride levels.

Parents should monitor the use of toothpaste, mouth rinses or other topical fluoride supplements in young children, checking with a dentist on proper dosage. If you are concerned about the fluoride levels in your drinking water, call the local public water department or your water supplier. If the source is a private well, request a fluoride content analysis taken via a water sample through your local or county health department.