Prevention of Dental Caries
Fluoride is used to reduce the incidence of dental caries and to slow or reverse the progression of existing dental lesions. Exposure to small amounts of oral and topical fluoride on a daily basis will reduce the risk for dental caries in all age groups. It was previously hypothesized that fluoride inhibited dental caries by a preeruptive effect (i.e., incorporation into developing dental enamel), but further laboratory and clinical research now indicates that the predominant effect is posteruptive, making consistent maintenance of a small amount of fluoride in saliva and dental plaque important.
Combined use of fluoridated dentifrices and fluoridated water has been found to provide greater protection against dental caries than either source alone. The US Centers for Disease Control and Prevention (CDC) recommends that adults and children at low risk for dental caries drink water with an optimal fluoride concentration and brush their teeth twice daily with a fluoridated dentifrice to prevent and control dental caries; those at higher risk for dental caries may require additional exposure to fluorides (e.g., mouth rinses, dietary supplements, preparations applied by dental personnel). The American Dental Association (ADA) and some clinicians recommend that, in patients without dental caries and with no apparent increased risk for dental caries, adequate water fluoridation or oral fluoride supplementation, combined with daily use of fluoridated dentrifice and semiannual topical applications of fluoride by dental professionals, may be appropriate. Individuals with, or at increased risk for, dental caries may require additional exposure to fluorides. Those with low rates of dental caries, or with a slightly increased risk, may require the addition of sodium fluoride 0.05% mouth rinse or 0.4% stannous fluoride gel. Those with moderate to high rates of dental caries, or with a moderately to greatly increased risk, also may require daily use of a neutral sodium fluoride 1.1% gel or an acidulated phosphate fluoride gel containing sodium fluoride 1.1%.
Patients at increased risk for dental caries include those with low socioeconomic status or low levels of parental education, those who do not seek regular dental care, and those without dental insurance or access to dental services. Additional risk factors include a high incidence of dental caries in older siblings or caregivers, root surfaces exposed by gingival recession, high levels of infection with cariogenic bacteria, impaired ability to maintain oral hygiene, malformed enamel or dentin, reduced salivary flow (because of medications, radiation, or disease), low salivary buffering capacity (i.e., decreased ability of saliva to neutralize acids), and wearing of space maintainers, orthodontic appliances, or dental prostheses. The risk of dental caries can increase if these risk factors are combined with dietary practices conducive to dental caries (i.e., frequent consumption of refined carbohydrates). The dental or health-care provider must periodically evaluate the individual's risk for dental caries, current fluoride sources, and potential for enamel fluorosis before recommending supplemental fluoride therapy.
Community Water Fluoridation
The most effective means of providing optimal levels of fluoride to large segments of the population is fluoridation of public water supplies. The CDC states that there is good evidence to support fluoridation of the public water supply to prevent and control dental caries. The optimal concentration of fluoride ion in drinking water to prevent dental caries is approximately 1 ppm (mg/L); however, optimal concentrations range from 0.7-1.2 ppm (mg/L) depending on the annual mean maximum daily temperature of the area, and concentrations should be at the lower end of the range in warm climates where more water is likely to be ingested. The National Academy of Sciences (NAS) states that the Adequate Intake (AI) of fluoride to prevent dental caries in children older than 6 months of age and in adults is 0.05 mg/kg daily, which coincides with the average dietary intake by US infants and children since 1980 in areas with optimally fluoridated water. Average dietary intakes for adults living in US communities with fluoridated water have ranged from 0.02-0.05 mg/kg daily. (For a definition of Adequate Intake and limitations on its use relative to Recommended Dietary Allowances [RDAs] and other reference values for dietary nutrient intakes, see Uses: Dietary Requirements, in Calcium Salts 40:12 and in the Vitamin D Analogs General Statement 88:16.)
In some communities where fluoridation of the water supply was not possible (e.g., rural areas), fluoridation of the school's water supply (at a concentration of 4.5 times the optimal concentration to compensate for the more limited consumption of fluoridated water outside the school) was promoted to provide a source of fluoride for children in the community. Although studies evaluating the effects of school water fluoridation reported a 40% reduction in dental caries in school children, the trials were not blinded and lacked concurrent controls. Therefore, CDC states that the appropriateness of this practice is limited and alternative fluoride sources should be considered.
Because consumption of commercially available beverages (including bottled water) in the US and Canada is displacing the consumption of tap or well water, the relative importance of fluoridation of local community water on fluoride intake may be affected. Some evidence indicates that more than 50-75% of fluid intake in children and adolescents may be from commercially available beverages. Thus, the fluoride concentration of water used in the preparation of these commercial beverages is an important factor affecting fluoride intake in the US and Canada. Despite this, however, current recommendations for fluoride supplementation in children continue to be based on the fluoride concentrations in local drinking water.(See Prevention of Dental Caries: Oral Fluorides, in Uses.)
Some community water supplies naturally contain fluoride at concentrations exceeding 2 ppm, a concentration associated with an increased risk for development of enamel fluorosis in children 8 years of age or younger.(See Cautions: Effects on Teeth.)In communities where the concentration of fluoride in the water supply exceeds 2 ppm, an alternative source of drinking water should be used for children 8 years of age or younger.
In areas where naturally occurring concentrations of fluoride in drinking water are inadequate and community water fluoridation programs are not available or feasible, daily administration of individualized fluoride supplements is used in children to provide adequate levels of fluoride ion to protect against dental caries. Fluoride supplements can be administered orally or applied topically directly to the teeth. The route of administration depends partly on the age of the child. Oral administration of fluoride is the method of choice, especially for young children. Topical application or oral rinsing solutions may be preferred for children whose permanent teeth have already erupted. Children younger than 14 years of age who are highly susceptible to dental caries may benefit from receiving both oral and topical fluoride supplements.
Sodium fluoride oral solutions and oral tablets are used as dietary supplements for the prevention of dental caries in children in areas where the concentration of fluoride ion in drinking water is less than optimal. Dosage is based on the concentration of fluoride in the drinking water and the child's age. Consideration also should be given to sources of fluoride other than the child's primary drinking water (e.g., other water supplies in the home, childcare settings, school; bottled water or processed beverages; dentifrice or mouth rinse) before selecting the dosage of fluoride to be prescribed.Oral fluoride supplements should not be used in areas where the fluoride content of drinking water exceeds 0.6 ppm (mg/L). The CDC states that there is good evidence to support the use of oral fluoride supplements in children 6-16 years of age who are at increased risk for dental caries and whose primary drinking water has a low fluoride concentration; however, clinical trials conducted in children younger than 6 years of age have been flawed in design and conduct, and there are no clinical studies to confirm the effectiveness of oral fluoride supplements in controlling dental caries in adults and children older than 16 years of age. Beginning in 1979, infant formula manufacturers in the US began to uniformly manufacture ready-to-use and liquid concentrate formulas with defluoridated water so that these preparations contain low fluoride concentrations (less than 0.3 ppm [mg/L]); therefore, fluoride concentrations in infant formulas that require reconstitution depend on the amount of fluoride added locally as fluoridated water prior to use.
The ADA, American Academy of Pediatric Dentistry (AAPD), and American Academy of Pediatrics (AAP) currently state that in areas where oral fluoride supplements are necessary, children should receive fluoride supplements daily from 6 months of age until approximately 16 years of age to provide maximum benefit to both deciduous and permanent teeth. The ADA, AAPD, and AAP currently recommend that children 6 months to younger than 3 years of age receive 0.25 mg of oral fluoride daily in areas where the concentration of fluoride ion in drinking water is less than 0.3 ppm (mg/L); children 3 to younger than 6 years of age should receive 0.5 or 0.25 mg of oral fluoride in areas where the concentration of fluoride ion in drinking water is less than 0.3 or 0.3-0.6 ppm (mg/L), respectively. Children 6-16 years of age should receive 1 or 0.5 mg of oral fluoride in areas where the concentration of fluoride ion in drinking water is less than 0.3 or 0.3-0.6 ppm (mg/L), respectively.
Although fluoride is distributed into milk, concentrations generally are less than 0.05 ppm (mg/L) and infants who are solely breast-fed ingest considerably less fluoride than infants receiving formula diluted with fluoridated drinking water. In the past, the ADA, AAP, and most clinicians have stated that oral fluoride supplements should be considered for infants who are solely breast-fed (i.e., those not receiving water, juice, or solid foods), especially those breast-fed for more than 6 months. However, the ADA and AAP currently do not recommend oral fluoride supplements in infants younger than 6 months of age, since limited evidence (based on caries rates between solely breast-fed infants not receiving fluoride supplements and infants receiving formula diluted with fluoridated water) suggests that fluoride supplementation may not be necessary for solely breastfed infants living in areas with adequately fluoridated water.
Sodium fluoride is commercially available in multivitamin or multivitamin/iron preparations for use as oral fluoride supplements in infants and children. However, the ADA currently states that the fixed proportion of fluoride contained in these combination preparations makes it difficult to appropriately adjust the amount of fluoride needed in areas where drinking water contains substantial but inadequate concentrations of fluoride.
Sodium fluoride has been administered orally to pregnant women to prevent caries in the deciduous teeth of their children; however, the ADA states that well-designed studies demonstrating the safety and efficacy of prenatal fluoride supplementation are lacking and currently does not recommend use of fluoride supplements during pregnancy. The ADA also states that fluoride dietary supplements administered to pregnant women will not affect permanent dentition in their children because the permanent teeth do not begin to develop in utero. In addition, the CDC states that there is good evidence that fluoride supplements administered orally to pregnant women provide no benefit for their children.
Sodium fluoride, acidulated phosphate fluoride (sodium fluoride and phosphoric acid), and stannous fluoride are applied directly to the surfaces of teeth in the form of solutions, foams, creams, or gels for the prevention of dental caries in children and adults. Topical application of fluoride can be used as an alternative to oral administration to provide supplemental fluoride to children who live in areas with inadequate concentrations of fluoride ion in drinking water. Topical application of fluoride also can be used to provide additional anticaries benefits in areas where drinking water contains adequate concentrations of fluoride ion.
The effectiveness of topically applied fluoride varies according to the concentration of fluoride ion in the preparation and the method and frequency of application; efficacy also may depend on the duration of use. The CDC states that there is good evidence to support the use of topical fluorides (rinses, gels) in patients at increased risk for dental caries. The CDC also states that there is good evidence obtained from one or more properly conducted randomized clinical trials to support the use of fluoridated dentrifices in all individuals; in children younger than 2 years of age, other sources of fluoride should be considered when weighing the risks and benefits of using fluoridated dentrifice. Topical application of sodium fluoride solutions (usually a 2% solution) has been reported to result in a 30-40% reduction in the incidence of dental caries in children 6-12 years of age. In more recent studies, semiannual application of fluoride preparations by dental personnel reportedly resulted in an average reduction of 26% in the incidence of dental caries in the permanent teeth of children residing in areas without fluorodated water. The beneficial effects of topical fluorides (e.g., dentifrices, gels, rinses) have not been adequately studied in adults; however, teeth remain susceptible to caries throughout life, and administration of topical fluoride could be effective in preventing dental caries at any age. On the basis of available evidence from clinical studies, the CDC states that in patients at increased risk for dental caries, the recommended frequency for application of topical fluorides by dental personnel is semiannually.
Oral rinsing solutions containing 0.05 or 0.2% sodium fluoride and oral rinsing solutions of acidulated phosphate fluoride containing 0.02% fluoride ion are used to provide additional anticaries benefits in children 6 years of age and older. Oral rinsing solutions containing 0.63% stannous fluoride are diluted and used as 0.1% solutions to provide additional anticaries benefits in children 12 years of age and older. When recommended by a clinician, some of these solutions (e.g., Phos-Flur) can be used as a rinsing solution and then swallowed to provide topical and systemic fluoride in children 3 years of age and older who live in areas where the fluoride content in drinking water is less than optimal.(See Oral Fluorides under Uses: Prevention of Dental Caries.)Daily use of oral rinsing solutions containing 0.05% sodium fluoride or once-weekly use of rinsing solutions containing 0.2% sodium fluoride reportedly results in a 30-40% reduction in the incidence of dental caries in children who live in areas without fluoridated drinking water and also has been shown to provide additional anticaries benefits in children who live in areas with optimally fluoridated drinking water. Preliminary data indicate that there is no substantial difference in effectiveness between daily and weekly use of sodium fluoride oral rinsing solutions.
Acidulated phosphate fluoride gels or solutions containing 0.5-1.23% fluoride ion have been effective when used topically to control dental decay that frequently follows xerostomia-producing radiation therapy of tumors of the head and neck; these preparations are often used in conjunction with a saliva substitute (e.g., Xero-Lube) in patients with this condition. Gels containing 0.4% stannous fluoride also have been used to prevent decalcification in orthodontic patients and to protect against postirradiation caries.
Certain dentifrices containing sodium fluoride (e.g., Crest Cavity Protection Gel, Colgate Total) or sodium monofluorophosphate (e.g., Aquafresh Extra Fresh Toothpaste, Colgate Cavity Protection Gel, Colgate Cavity Protection Toothpaste) have been shown to be effective in reducing the incidence of dental caries in children when used in association with a program of good oral hygiene.
Intake from fluoridated dental products such as dentifrices and mouth rinses adds considerable fluoride, often approaching or exceeding that from diet, particularly in young children who have poor control of the swallowing reflex. Although exposure from professionally applied products (e.g., rinses and gels with high fluoride concentrations) occurs less frequently, such products also contribute to fluoride intake.
Sodium fluoride and acidulated phosphate fluoride are used topically to desensitize exposed root surfaces of teeth. It has been suggested that the effectiveness of topical fluoride therapy for this condition may be increased by concomitant iontophoresis, but the efficacy of this procedure has not been established.
Sodium fluoride is used orally to increase bone density and relieve bone pain in the treatment of various metabolic and neoplastic bone diseases.
Oral administration of sodium fluoride (30-100 mg daily), in conjunction with calcium and vitamin D or calcium and estrogen, has been effective in reducing skeletal fracture rates in patients with osteoporosis. However, further study is needed to evaluate the efficacy of sodium fluoride for the treatment of osteoporosis compared with treatment with estrogens, calcium, and vitamin D and to determine which patients may respond to sodium fluoride treatment.
Although results of some studies are conflicting, oral sodium fluoride (100-200 mg daily), alone or in conjunction with calcium carbonate, has been used with some success as an adjunct in the management of bone lesions in multiple myeloma.
Although placebo-controlled studies are lacking, oral sodium fluoride (100 mg daily) reportedly reduces bone pain in patients with metastatic prostatic carcinoma. Oral sodium fluoride (25-60 mg daily) has been reported to stabilize the progression of hearing loss in a limited number of patients with otosclerosis.
There is some evidence that oral sodium fluoride (e.g., 20-30 mg daily as an extended-release preparation) can increase spinal but not femoral neck bone mineral density (BMD) in patients with corticosteroid-inducedosteoporosis. However, controlled studies are needed to elucidate further the potential efficacy of the drug in patients with this condition, and other therapies currently are preferred (e.g., calcium, vitamin D, gonadotrophic hormone replacement) for the prevention and treatment of this condition.