Topical fluorides in caries prevention and management: a North American perspective

A review of evidence-based literature indicates incomplete evidence for the efficacy of most measures currently used for caries prevention, with the exception of fluoride varnishes and the use of fluoride-based interventions for patients with hyposalivation. Not all fluoride agents and treatments are equal. Different fluoride compounds, different vehicles, and vastly different concentrations have been used with different frequencies and durations of application. These variables can influence the clinical outcome with respect to caries prevention and management. The efficacy of topical fluoride in caries prevention depends on a) the concentration of fluoride used, b) the frequency and duration of application, and to a certain extent, c) the specific fluoride compound used. The more concentrated the fluoride and the greater the frequency of application, the greater the caries reduction. Factors besides efficacy, such as practicality, cost, and compliance, influence the clinician's choice of preventive therapy. For noncavitated smooth surface carious lesions in a moderate caries-risk patient, the appropriate fluoride regimen would be semiannual professional topical application of a fluoride varnish containing 5 percent NaF (22,600 ppm of fluoride). In addition, the patient should use twice or thrice daily for at least one minute a fluoridated dentifrice containing NaF, MFP, or SnF2 (1,000-1,500 ppm of fluoride), and once daily for one minute a fluoride mouthrinse containing .05 percent NaF (230 ppm of fluoride). If the noncavitated carious lesion involves a pit or fissure, the application of an occlusal sealant would be the most appropriate preventive therapy. The management of the high caries-risk patient requires the use of several preventive interventions and behavioral modification, besides the use of topical fluorides. For children over six years of age and adults, both office and self-applied topical fluoride treatments are recommended. For office fluoride therapy at the initial visit, a high-concentration agent, either a 1.23 percent F APF gel (12,300 ppm of fluoride) for four minutes in a tray or a 5 percent NaF varnish (22,600 ppm of fluoride), should be applied directly to the teeth four times per year. Self-applied fluoride therapy should consist of the daily five-minute application of 1.1 percent NaF or APF gel (5,000 ppm of fluoride) in a custom-fitted tray. For those who cannot tolerate a tray delivery owing to gagging or nausea, a daily 0.05 percent NaF rinse (230 ppm of fluoride) for 1 minute is a less effective alternative. In addition, the patient should use twice or thrice daily for at least 1 minute a fluoridated dentifrice as described above for treatment of noncavitated carious lesions. In order to avoid unintentional ingestion and the risk of fluorosis in children under six years of age, fluoride rinses and gels should not be used at home. Furthermore, when using a fluoride dentifrice, such children should apply only a pea-size portion on the brush, should be instructed not to eat or swallow the paste, and should expectorate thoroughly after brushing. Toothbrushing should be done under parental supervision. To avoid etching of porcelain crowns and facings, neutral NaF is indicated in preference to APF gels for those patients who have such restorations and are applying the gel daily. The rationale for these recommendations is discussed. Important deficiencies in our knowledge that require further research on topical fluoride therapy in populations with specific needs are identified.