Effect of two sodium fluoride dentifrices on fluoride uptake and remineralization in situ

Two dentifrices containing 1100 ppm F from sodium fluoride in silica bases were compared to a placebo dentifrice in an in situ remineralization and fluoride uptake study. Fifteen subjects brushed artificially-formed caries lesions in 60 thin enamel sections and 30 enamel blocks with each dentifrice in a double-blind, randomized, cross-over study design. Analysis of the thin sections by quantitative microradiography before and after exposure to toothbrushing showed that the fluoride dentifrices produced 18.3% and 7.1% remineralization whereas use of the placebo resulted in 10.3% demineralization. The differences between all three dentifrices were statistically significant. Fluoride concentrations at the surface of the lesion increased from approximately 700 ppm F in untreated specimens to approximately 1800 ppm F in specimens treated with either of the two fluoride dentifrices. These data suggest that formulation differences may affect the anticaries activity of a dentifrice without being reflected by fluoride deposition.