Comparison of Erosion Prevention and Repair by Leading Commercial Dentifrices

Objectives: The aim of this in vitro investigation was to determine the ability of two commercially available dentifrices to inhibit enamel surface softening by a dietary acid, and to promote rehardening of erosive lesions. Methods: Human enamel specimens were treated with one of the two dentifrices or a placebo formulation lacking fluoride (1:3 aqueous slurries) for 2 minutes before exposure to 1.0% w/v citric acid, pH 3.8. Surface microhardness (SHM) was determined at baseline and at 10 minute intervals during acid exposure, up to 30 minutes total exposure. To assess the rehardening potential of the formulations, artificial erosive lesions were prepared by exposure of human enamel to citric acid for 30 minutes. Specimens were subsequently treated for 2 minutes with one of the three dentifrice slurries, and lesion rehardening monitored by SMH after 4, 24 and 48hrs incubation in artificial saliva. Results: In the erosion prevention study, all enamel specimens softened during the period in which they were exposed to citric acid. Specimens treated using Sensodyne Pronamel™ conferred statistically superior inhibition of enamel softening compared to specimens treated using Colgate Sensitive Enamel Protect (7% vs 18% softening after 10 mins, 18% vs 32% at 20mins and 27% vs 43% at 30 mins respectively) or the fluoride-free placebo. In the rehardening study, erosive lesions treated with Sensodyne Pronamel™ exhibited statistically superior rehardening compared to lesions treated using Colgate Sensitive Enamel Protect (47% greater rehardening at 24hrs and 39% greater rehardening at 48hrs) or the placebo dentifrice. Conclusion: This in vitro microhardness study has shown that fluoride dentifrices help protect sound enamel from dietary acid-mediated surface softening, and promote rehardening of erosive lesions. Sensodyne Pronamel™ exhibited statistically superior protection against enamel softening and enamel repair compared to Colgate Sensitive Enamel Protect.