Enamel uptake and patient exposure to fluoride: comparison of APF gel and foam

This crossover study with 46 child dental patients compared two topical APF products, a gel and a foam, with respect to the amounts of product and fluoride (F) applied, salivary F concentrations, and enamel F uptake. Half the subjects were treated for 4 min with the gel first and the other half with the foam. After approximately 16 days, each patient received a second treatment using the other product. An acid-etch enamel biopsy was performed and whole saliva samples were collected before and after each treatment. Significantly less F was applied to the teeth and retained by the subjects when the APF foam was used. Salivary F concentrations after treatment with the gel were higher than after treatment with the foam. The differences in enamel F uptake at both 15 min and 16 days after the APF applications, however, were not significant. We concluded that: 1) the two products are equivalent with respect to enamel F uptake; 2) only about one-fifth as much of the foam product is required for adequate coverage of the teeth, which significantly reduces F exposure and retention by the patient.