Topical fluoride for office use
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PRODUCT NAMES AND MANUFACTURERS
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Gel: Care 4—Sultan Chemists Inc., 85 W. Forest Ave., Englewood, N.J. 07631, 1-800-637-8582, "www.sultanintl.com"; Pro-Dentx—Pro-Dentec Inc., P.O. Box 3749, Batesville, Ark. 72501, 1-870-698-2300, "www.prodentec.com"; Fluorident—Premier Dental Products Co., 1710 Romano Drive, P.O. Box 4500, Ply-mouth Meeting, Pa. 19462, 1-888-773-6872, "www.premusa.com"; Protect—John O. Butler Co., 4635 W. Foster Ave., Chicago, Ill. 60630, 1-800-JBUTLER, "www.jbutler.com"; Perfect Choice—Challenge Products Inc., 650 S. Taylor Ave., Suite 20, Louisville, Colo. 80027-3068, 1-800-822-8550, "www.biotrol.com"
Foam: Topical Fluoride Foam—Laclede Professional Products Inc., 2030 E. University Drive, Rancho Dominguez, Calif. 90220, 1-800-922-5856, "www.laclede.com"
Topical fluoride is used to prevent and treat dental caries. Acidulated phosphate fluoride, or APF, preparations, which have been accepted by the American Dental Association since 1968, contain 1.23 percent fluoride ion (12,300 parts per million, or ppm). The fluoride ion is derived from sodium fluoride and hydrogen fluoride and is acidified by the addition of 0.1 molar phosphoric acid. The resulting pH is between 3 and 4. Some APF formulations are thixotropic, which means that they liquefy when the tray is pushed into place on the teeth and return to gel form once the tray is in place.
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CONSIDERATIONS FOR ACCEPTANCE
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The clinical effectiveness of 1.23 percent APF (described below) is widely recognized; therefore, the Council requires only evidence that these products maintain consistency in chemical composition and physical properties. Products are evaluated for pH, viscosity and fluoride content. Additionally, any claims, such as thixotropy, must be supported by appropriate studies.
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SAFETY AND EFFICACY DATA
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Several controlled clinical studies conducted in the 1960s and 1970s demonstrated the effectiveness of 1.23 percent APF solutions and gels in reducing caries. The following is a summary of these studies. A controlled study of 115 children (8 to 11 years old) who received a single yearly topical application of a 1.23 percent APF solution had approximately 70 percent fewer carious surfaces than did 113 children who did not receive treatment. This effect was observed after one and two years of treatment.1 Another controlled study of 195 children (8 to 11 years old) who received yearly topical applications of APF solution for two years found that those children had approximately 50 percent fewer carious surfaces than did 197 children who did not receive treatment.2 Furthermore, the caries-reducing effect of APF was found to be greater in children with poor oral hygiene than in children with good oral hygiene. In both of these studies, the water supply used by the children contained 0.1 ppm fluoride.
In 1968, a controlled, double-blinded study by Cartwright and colleagues3 examined the caries-inhibiting effect of 1.23 percent APF solution in 172 children (6 to 19 years old) who were residents of an orphanage in an area with nonfluoridated water. This study examined the difference between pre- and post-treatment decayed, missing or filled permanent teeth, or DMFT. The APF-treated group had an approximately 45 percent reduction in DMFT.
Bryan and Williams4 conducted a study in 287 children aged 8 to 11 years who lived in a nonfluoridated area and found a 45 percent reduction in DMFT one year after a single tray application of APF gel. A follow-up study in 208 of the original 287 children found that a second APF application the following year maintained the caries-inhibiting effect.5 This study found no correlation between effectiveness of the APF gel and the children’s oral hygiene status.
A study by Horowitz and Doyle6 examined the caries-inhibiting effect of a topically applied APF solution and gel in 1,105 Hawaiian children who had minimal exposure to fluoridated water. This study found that after three years, overall reductions ranged from 24 percent fewer DMF surfaces for children treated annually to 41 percent fewer for children treated semi-annually. A follow-up study showed that the beneficial effect was maintained in these children three years after treatments ceased.7
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DOSING AND ADVERSE EFFECTS
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APF gels and foams have replaced solutions. The maximum recommended dose is 5 milliliters per tray. APF preparations should be applied for four minutes; the rationale behind this treatment time is that it was used in all the clinical studies that demonstrated an anti-caries effect associated with APF. The advantage of foam is that less fluoride is applied to the tray, thus decreasing the amount of fluoride that is swallowed. A study by Whitford and colleagues8 concluded that APF foam and gel are equivalent with respect to fluoride uptake; and that only one-fifth the volume of foam is required to adequately cover the teeth.
Acute oral exposure to sodium fluoride causes hypocalcemia (causing tetany and ventricular fibrillation), hyperkalemia and gastrointestinal disturbance. Fluorosis is the result of chronic exposure.9
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MECHANISM OF ACTION
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The mechanism of action of fluoride that results in the reduction of dental caries is not completely understood. There is evidence that fluoride inhibits the demineralization of enamel, enhances remineralization and inhibits bacterial enzymes. The bacteria that cause caries produce acid through the fermentation of carbohydrates, which can dissolve the carbonated hydroxyapatite mineral of teeth, a process called "demineralization." Incorporation of fluoride into apatite crystals reduces the dissolution of apatite during acid attacks.10,11
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FOOTNOTES
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"(Product Name) has been Accepted as an effective decay-preventive home-use fluoride agent when used in a conscientiously applied program of oral hygiene and regular professional care. Clinical effectiveness against hypersensitivity, plaque, gingivitis or other periodontal indications has not been proven." —Council on Scientific Affairs, American Dental Association.
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REFERENCES
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- Wellock WD, Brudevold F. A study of acidulated fluoride solutions, II: the caries inhibiting effect of single annual topical applications of an acidic fluoride and phosphate solution—a two-year experience. Arch Oral Biol 1963;8:179–82.[Medline]
- Wellock WD, Maitland A, Brudevold F. Caries increments, tooth discoloration, and state of oral hygiene in children given single annual applications of acid phosphate-fluoride and stannous fluoride. Arch Oral Biol 1965;10:453–60.[Medline]
- Cartwright HV, Lindahl RL, Bawden JW. Clinical findings on the effectiveness of stannous fluoride and acid phosphate fluoride as caries reducing agents in children. J Dent Child 1968;35(1):36–40.[Medline]
- Bryan ET, Williams JE. The cariostatic effectiveness of a phosphate-fluoride gel administered annually to school children, I: the results of the first year. J Public Health Dent 1968;28:182–5.[Medline]
- Bryan ET, Williams JE. The cariostatic effectiveness of a phosphate-fluoride gel administered annually to school children: final results. J Public Health Dent 1970;30:13–6.[Medline]
- Horowitz HS, Doyle J. The effect on dental caries of topically applied acidulated phosphate-fluoride: results after three years. JADA 1971;82:359–65.[Medline]
- Horowitz HS, Kau MC. Retained anticaries protection from topically applied acidulated phosphate-fluoride: 30- and 36-month post-treatment effects. J Prev Dent 1974;1:22–7.[Medline]
- Whitford GM, Adair SM, Hanes CM, Perdue EC, Russell CM. Enamel uptake and patient exposure to fluoride: comparison of APF gel and foam. Pediatr Dent 1995;17(3):199–203.[Medline]
- Agency for Toxic Substances and Disease Registry. Toxicological profile for fluorides: Draft for public comment. Atlanta: U.S. Department of Health and Human Services, Agency for Toxic Substances and Disease Registry; 2001.
- Burrell KH, Chan JT. Systemic and topical fluorides. In: Ciancio SG, ed. ADA guide to dental therapeutics. 2nd ed. Chicago: ADA Publishing; 2000:230–41.
- Featherstone JD. The science and practice of caries prevention. JADA 2000;131:887–99.[Abstract/Free Full Text]
Topical fluoride
Fluoride concentrated in plaque and saliva interrupts the caries process by inhibiting the demineralization and enhancing the remineralization of enamel. Caries result from the bacterial metabolism of carbohydrates, which produce acids that solubilize the carbonated hydroxyapatite of teeth. When fluoride is present in sufficient concentrations, it adsorbs to the crystal surface, attracting calcium and phosphate ions to form a remineralized acid-resistant fluorapatite structure.1,2 The fluoride incorporated into teeth during development is not thought to be a major factor in preventing caries; rather, it is the daily presence of fluoride in plaque and saliva that plays a significant role.2 Therefore, regular exposure to fluoride in drinking water, toothpastes and topical preparations is important for caries prevention.
Topical fluoride in various forms has been used for decades to prevent caries. Topical fluoride gels and foams are sodium fluoride preparations that are either acidified or neutral. The 1.23 percent acidulated phosphate fluoride, or APF, gels and foams contain 12,300 parts per million, or ppm, fluoride; 2 percent neutral sodium fluoride gels and foams contain 9,040 ppm fluoride. Fluoride preparations are made acidic because of the rationale that low pH facilitates fluoride uptake in the enamel.3
Originally, 1.23 percent APF was a solution that was applied to teeth using repeated swabbings. Eventually, gels were formulated and trays were used for convenience and to minimize ingestion of the fluoride. This is important because topical fluoride treatments are used in children, and nausea and vomiting are not uncommon side effects of the treatment.4 Enamel fluorosis is not considered a risk with ingestion of professionally applied topical fluoride, because of the infrequent exposure (from one to four applications per year).5
Foam 1.23 percent APF formulations also were developed to minimize the amount of fluoride ingested. The foam’s low density means that a smaller amount is required to fill a tray compared with gel. The amount of fluoride retained in the oral cavity after treatment with a 1.23 percent APF foam was reported to be approximately one-half that retained with a gel (1.26 milligrams vs. 2.53 mg)6; however, the in vitro fluoride uptake was not significantly different.7 Foams may be particularly useful for patients who have a limited ability to rinse and expectorate.
Treatment times with 1.23 percent APF preparations vary from one to four minutes. However, the clinical studies that demonstrated an anticaries effect all used four-minute treatments; therefore, four-minute treatments are recommended (see the preceding Dental Product Spotlight for a summary of the clinical studies using a four-minute treatment time). There are no clinical studies evaluating the effect of 2 percent neutral sodium fluoride gels, applied for one to four minutes semiannually, for the prevention of caries. The frequency of fluoride application normally recommended is semiannual, although the optimal frequency has not been well-studied.5
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REFERENCES
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- ten Cate JM, Duijsters PP. Influence of fluoride in solution on tooth demineralization, II: microradiographic data. Caries Res 1983; 17:513–9.[Medline]
- Featherstone JD. The science and practice of caries prevention. JADA 2000;131:887–99.[Abstract/Free Full Text]
- Brudevold F, Savory A, Gardner DE, Spinelli M, Speirs R. A study of acidulated fluoride solutions, I: in vitro effects on enamel. Arch Oral Biol 1963;8:161–77.
- Whitford GM. Fluoride in dental products: safety considerations. J Dent Res 1987;66:1056–60.[Abstract/Free Full Text]
- Centers for Disease Control and Prevention. Recommendations for using fluoride to prevent and control dental caries in the United States. MMWR Recomm Rep 2001;50(RR-14):1–42.[Medline]
- Wei SH, Chik FF. Fluoride retention following topical fluoride foam and gel application. Pediatr Dent 1990;12(6):368–74.[Medline]
- Whitford GM, Adair SM, Hanes CM, Perdue EC, Russell CM. Enamel uptake and patient exposure to fluoride: comparison of APF gel and foam. Pediatr Dent 1995;17(3):199–203.[Medline]
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PRODUCT NAMES AND MANUFACTURERS
CONSIDERATIONS FOR ACCEPTANCE
