A Comparison of enamel erosion repair by Leading Commercial Dentifrices

Objectives: The aim of this investigation was to measure the ability of two commercially available dentifrices (Crest Pro-Health Enamel Shield SnF2/HMP 0.16% w/v Fluoride ion and Sensodyne Pronamel NaF/KNO3 0.15% w/v Fluoride ion) to remineralise artificial erosive lesions in enamel, using a previously validated standard in vitro microindentation test. Methods: Human enamel specimens were mounted in resin and polished to a fine finish with 3um diamond paste. Artificial erosive lesions were prepared by exposure of the specimens to 1.0% w/v citric acid, pH 3.8 for 30 minutes. The baseline surface microhardness of the softened enamel specimens were measured using a Vickers indenter, with a mean of six indents per specimen. Six enamel specimens were then assigned to each treatment group, which comprised emersion into 1:3 aqueous slurries of the treatment pastes for two minutes, under agitation. The specimens were then incubated in artificial saliva for a total of 48 hours, with surface microhardness measurements at 24 and 48hrs. The saliva was modified by the addition of a small aliquot of the dentifrice slurries to mimic in vivo carryover of the formulations (to ca. 1.0 ppm fluoride) Results: The table shows statistical evaluation of indentation results for Crest® Pro-Health Enamel Shield USA (CPHES), Sensodyne® Pronamel USA (SP) and Fluoride free placebo groups. Conclusion: In this in-vitro model the SnF2 / HMP dentifrice failed to provide any rehardening benefit beyond normal salivary remineralisation. Sensodyne Pronamel, optimised to maximise fluoride availability, was shown to be statistically three times better than the SnF2/ HMP dentifrice at rehardening enamel. It can be speculated that the poor performance of the SnF2/ HMP dentifrice might be due to other constituent ingredients of the formulation such as HMP or SLS binding to the active mineralization sites on the enamel surface. Further research is required to confirm this hypothesis.