Mechanisms of Enamel Dissolution in Acid Buffers

Abstract

A method of analyzing enamel dissolution data is based on the simultaneous diffusion and chemical reactions of the various ionic and molecular species involved. The method was applied to data on the initial rates of enamel dissolution in lactic-acid buffers. A solution diffusion controlled mechanism involving dissolution from a hydroxyapatite surface in equilibrium with the solution adjacent to the surface best explains the data. Both pH and buffer concentration effects are quantitatively in agreement. Common ion effects and rate determinations in other acid buffers also agree with this theory. The theory indicates that conversion to dicalcium phosphate may take place on the surface at very high initial rates.