Fluoride is a component of the mineral fluorine that is naturally present in soil, water, air and certain foods (e.g., meat, fish, eggs, tea leaves). It is commonly added to community drinking water, and may be added to various foods and beverages during processing. Most people absorb fluoride through drinking water and the use of dental hygiene products that contain fluoride.

Fluoride is used to protect against tooth decay, cavities and the complications that can result. Tooth decay begins with demineralization. This occurs when bacteria naturally present in the mouth combine with sugar (remaining in the mouth from foods or beverages consumed) to produce acid that erodes tooth enamel. When demineralization is allowed to continue by not cleaning the teeth, it can lead to the formation of holes in the enamel. All cavities occur in this way.

Minerals such as fluoride, calcium and phosphate help to correct demineralization by strengthening weakened areas of tooth enamel. Fluoride accumulates in teeth and bones, adhering to areas where demineralization has occurred and making the enamel harder than it was before. The rebuilding of tooth enamel is called remineralization. It strengthens teeth and helps to prevent cavities, but cannot restore an area once a cavity has formed. Fluoride is also absorbed into plaque, and inhibits its growth by disrupting the acid-producing activity of bacteria in the mouth.

When fluoride is ingested, it enters the bloodstream and is absorbed into the teeth and bones. Fluoride may also be directly applied to teeth, where it is absorbed into tooth enamel. Fluoride levels in the mouth remain high for several hours after a topical application.

Daily use of fluoride is considered an important component of dental health care for all age groups. The Centers for Disease Control and Prevention (CDC) recommends that children and adults use small amounts of fluoride on a regular basis to help reduce tooth decay.

Fluoride is especially helpful for children whose permanent teeth are still developing. Teeth can be fortified with fluoride while they are still forming and before they have erupted. This way, a child’s permanent teeth are more resistant to decay the moment they appear in the mouth.

Fluoride is important for adults, too. According to the CDC, fluoride reduces tooth decay in adults by 20 to 40 percent. Older adults are particularly susceptible to root exposure (which can occur due to receding gums or gum disease, both of which are more likely to occur as a person ages) and dry mouth. These conditions can increase the risk of tooth decay, and the newly exposed surfaces require fluoride for strengthening and remineralization.

The use of fluoride is important because tooth decay remains a significant problem in the United States. More than two-thirds of American children and adolescents experience tooth decay, according to the CDC. The risk of decay increases as people age. Ninety-one percent of American adults (and 93 percent of those over 60 years old) have experienced tooth decay, according to the CDC.

People with a high risk of tooth decay may find the use of fluoride especially beneficial. This includes people with the following risk factors for tooth decay:

• History of cavities. People with a history of tooth decay may be more susceptible to tooth decay in the future.
  
  
• Infrequent dental visits. Regular dental examinations can identify problems while they are easy to fix (e.g., small cavities, buildup of plaque). Failure to visit the dentist regularly can lead to larger problems as the result of tooth decay.
  
  
• Poor dental hygiene. Failing to brush and floss the teeth daily can lead to the buildup of plaque and tartar, resulting in tooth decay.
  
  
• Diet high in sugar/carbohydrates. High levels of carbohydrates in the diet may leave sugar in the mouth, which acts as fuel for the bacteria that cause demineralization.
  
  
• Frequent snacking. People who frequently snack expose their teeth to a continual process of demineralization that can lead to decay.
  
  
• Braces. Braces can trap bacteria and food particles on the teeth, which may be difficult to remove with brushing and flossing.
  
  
• Crowns, bridges. Teeth with dental restorations such as crowns or bridges are still susceptible to decay where the restoration meets the tooth.
  
  
• Dry mouth. A lack of saliva in the mouth may be caused by a number of medical conditions (e.g., diabetes, Sjogren’s syndrome) and many different medications (e.g., drugs for allergies, high blood pressure, anxiety, depression, and radiation therapy).