Fluoride is a mineral that occurs naturally in all water sources, including oceans, lakes and rivers. Research shows that fluoride helps prevent cavities in children and adults by making teeth more resistant to the acid attacks that cause cavities. Fluoride is nature’s cavity fighter, helping repair the early stages of tooth decay even before the decay can be seen.

There are two ways that you can benefit from fluoride:

Systemic fluoride therapy refers to the ingestion of fluoride, usually through dietary supplements or the public water supply, which in the United States applies to nearly 74 percent of the population. While teeth are forming under the gums, the ingested fluoride is used by the body to form enamel, typically resulting in stronger enamel that is more resistant to cavities. This provides what is called a “systemic” benefit.

Topical fluoride therapy refers to the use of systems containing relatively large concentrations of fluoride that are applied locally, or topically, to erupted (exposed) tooth surfaces to prevent the formation of dental caries. Thus this term encompasses the use of fluoride rinses, dentifrices, pastes, gels, and solutions that are applied in various manners. This procedure results in a significant increase in the resistance of the exposed tooth surfaces to the development of dental caries. In essence, two procedures are available for administering topical fluoride treatments. One procedure involves the painting the solution onto the tooth surfaces. The second involves the use of fluoride gels applied with a disposable tray.

The maximum reduction in tooth decay occurs when fluoride is available systemically and topically. Studies show that community water fluoridation, the addition of fluoride to water to a recommended level for preventing tooth decay, prevents at least 25 percent of tooth decay in children and adults. In fact, community water fluoridation is noted as the single most effective public health measure to prevent tooth decay and the Centers for Disease Control and Prevention has proclaimed community water fluoridation as “one of 10 great public health achievements.
The American Dental Association and more than 100 other national and international organizations recognize the public health benefits of fluoridated water in preventing tooth decay. Visit ADA.org for more information about fluoride and fluoridation.

Effects of Fluoride on Plaque and Bacterial Metabolism

Thus far, we have assumed that the anti-cavity effects of fluoride are accomplished through a chemical reaction between this ion and the outermost portion of the enamel surface. A growing body of information suggests, however, that the caries-preventive action of fluoride may also include an inhibitory effect on the oral flora involved in the initiation of caries (cavities). The ability of fluoride to inhibit glycolysis (breakdown of sugar) by interfering with the enzyme enolase has long been known; concentrations of fluoride as low as 50 ppm have been shown to interfere with bacterial metabolism. Moreover, fluoride may accumulate in dental plaque in concentrations above 100 ppm. Although the fluoride normally present in plaque is largely bound (and thus unavailable for antibacterial action), it dissociates to ionic fluoride when the pH of plaque decreases (i.e., when acids are formed). Thus, when the carious process starts and acids are formed, plaque fluoride in ionic form may serve to interfere with further acid production by plaque microorganisms.

In addition, it may react with the underlying layer of dissolving enamel, promoting its remineralization as fluorhydroxyapatite. The end result of this process is a “physiologic” restoration of the initial lesion (by remineralization of enamel) and the formation of a more resistant enamel surface. The ability of fluoride to promote the reprecipitation of calcium phosphate solutions in apatitic forms has been repeatedly demonstrated.

In addition to these possible effects of fluoride, several investigators have reported that the presence of tin, especially as provided by stannous fluoride, is associated with significant antibacterial activity, which has been reported to decrease both the amount of dental plaque and gingivitis in both animals and adult humans. Existing evidence suggests that these antibacterial effects of fluoride and tin may also contribute to the observed cariostatic activity of topically applied fluorides.