Relation of pH to the Effectiveness of Sodium Fluoride and Stannous Fluoride in Decreasing Enamel Solubility

Abstract
The effectiveness of NaF and of stannous fluoride in decreasing the solubility of powdered enamel is substantially independent of the pH at which the fluoride is applied to the enamel, as judged from expts. in which the pH ranged from 2.5 to 7. This is contrary to certain reports in the literature. The reason for the conflicting conclusions is presented. In accord with other evidence cited, it is shown that stannous fluoride is much more effective than NaF in preventing powdered enamel from dissolving in acid.