THE USE OF TOPICAL FLUORIDE TREATMENTS FOR ADULTS
Statements from the American Dental Association
What is fluoride and how does it reduce tooth decay?
Fluoride is a naturally occurring element that prevents tooth decay systemically when ingested during tooth development and topically when applied to erupted teeth.
Fact.
The fluoride ion comes from the element fluorine. Fluorine, the 17th most abundant element in the earth’s crust, is a gas and never occurs in its free state in nature. Fluorine exists only in combination with other elements as a fluoride compound. Fluoride compounds are constituents of minerals in rocks and soil. Water passes over rock formations and dissolves the fluoride compounds that are present, creating fluoride ions. The result is that small amounts of soluble fluoride ions are present in all water sources, including the oceans. Fluoride is present to some extent in all foods and beverages, but the concentrations vary widely. Simply put, fluoride is obtained in two forms: topical and systemic. Topical fluorides strengthen teeth already present in the mouth. In this method of delivery, fluoride is incorporated into the surface of teeth making them more decay-resistant. Topically applied fluoride provides local protection on the tooth surface. Topical fluorides include toothpastes, mouth rinses and professionally applied fluoride gels and rinses.
Systemic fluorides are those that are ingested into the body and become incorporated into forming tooth structures. In contrast to topical fluorides, systemic fluorides ingested regularly during the time when teeth are developing are deposited throughout the entire surface and provide longer-lasting protection than those applied topically. Systemic fluorides can also give topical protection because ingested fluoride is present in saliva, which continually bathes the teeth providing a reservoir of fluoride that can be incorporated into the tooth surface to prevent decay. Fluoride also becomes incorporated into dental plaque and facilitates further remineralization. Sources of systemic fluorides include water, dietary fluoride supplements in the forms of tablets, drops or lozenges, and fluoride present in food and beverages.
Researchers have observed fluoride’s decay preventive effects through three specific mechanisms:
- it reduces the solubility of enamel in acid by converting hydroxyapatite into less soluble fluorapatite;
- it exerts an influence directly on dental plaque by reducing the ability of plaque organisms to produce acid; and
- it promotes the remineralization or repair of tooth enamel in areas that have been demineralized by acids.
The remineralization effect of fluoride is of prime importance. Fluoride ions in and at the enamel surface result in fortified enamel that is not only more resistant to decay, but enamel that can repair or remineralize early dental decay caused by acids from decay-causing bacteria. Fluoride ions necessary for remineralization are provided by fluoridated water as well as various fluoride products such as toothpaste.
Maximum decay reduction is produced when fluoride is available for incorporation during all stages of tooth formation (systemically) and by topical effect after eruption.
Do adults benefit from fluoridation?
Fluoridation plays a protective role against dental decay throughout life, benefiting both children and adults. In fact, inadequate exposure to fluoride places children and adults in the high risk category for dental decay.
Fact.
Fluoride has both a systemic and topical effect and is beneficial to adults in two ways. The first is through the remineralization process in enamel, in which early decay does not enlarge, and can even reverse, because of frequent exposure to small amounts of fluoride. Studies have clearly shown that the availability of topical fluoride in an adult’s mouth during the initial formation of decay can not only stop the decay process, but also make the enamel surface more resistant to future acid attacks. Additionally, the presence of systemic fluoride in saliva provides a reservoir of fluoride ions that can be incorporated into the tooth surface to prevent decay.Another protective benefit for adults is the prevention of root decay. Adults with gum line recession are at risk for root decay because the root surface becomes exposed to decay-causing bacteria in the mouth. Studies have demonstrated that fluoride is incorporated into the structure of the root surface, making it more resistant to decay. In Ontario, Canada, lifelong residents of the naturally fluoridated (1.6 ppm) community of Stratford had significantly lower root decay experience than those living in the matched, but nonfluoridated, community of Woodstock.
People in the United States are living longer and retaining more of their natural teeth than ever before. Because older adults experience more problems with gumline recession, the prevalence of root decay increases with age. A large number of exposed roots or a history of past root decay places an individual in the high risk category for decay. Data from the 1988-1991 National Health and Nutrition Examination Survey (NHANES III) showed that 22.5% of all adults with natural teeth experienced root decay.
This percentage increased markedly with age:
- in the 18- to 24-year-old age group, only 6.9% experienced root decay;
- in the 35- to 44-year-old age group, 20.8% experienced root decay;
- in the 55- to 64-year-old age group, 38.2% showed evidence of root decay; and
- in the over-75 age group, nearly 56% had root decay.
In addition to gumline recession, older adults tend to experience decreased salivary flow, or xerostomia, due to the use of medications or medical conditions. Inadequate saliva flow places an individual in the high risk category for decay. This decrease in salivary flow can increase the likelihood of dental decay because saliva contains many elements necessary for early decay repair - including fluoride.
There are data to indicate that individuals who have consumed fluoridated water continuously from birth receive the maximum protection against dental decay. However, teeth present in the mouth when exposure to water fluoridation begins also benefit from the topical effects of exposure to fluoride. In 1989, a small study in the state of Washington suggested adults exposed to fluoridated water only during childhood had similar decay rates as adults exposed to fluoridated water only after age 14. This study lends credence to the topical and systemic benefits of water fluoridation. The topical effects are reflected in the decay rates of adults exposed to water fluoridation only after age 14. The study also demonstrates that the pre-eruptive, systemic effects of fluoridation have lifetime benefits as reflected in the decay rates of adults exposed to fluoridation only during childhood. The same study also noted a 31% reduction of dental disease (based on the average number of decayed or filled tooth surfaces) in adults with a continuous lifetime exposure to fluoridated water as compared to adults with no exposure to water fluoridation. A Swedish study investigating decay activity among adults in optimal and low fluoride areas revealed that not only was decay experience significantly lower in the optimal fluoride area, but the difference could not be explained by differences in oral bacteria, buffer capacity of saliva or salivary flow. The fluoride concentration in the drinking water was solely responsible for decreased decay rates.
Water fluoridation contributes much more to overall health than simply reducing tooth decay: it prevents needless infection, pain, suffering and loss of teeth; improves the quality of life; and saves vast sums of money in dental treatment costs. Additionally, fluoridation conserves natural tooth structure by preventing the need for initial fillings and subsequent replacement fillings.