Quantitation of enamel demineralization mechanisms. 3. A critical examination of the hydroxyapatite model.

A physical model which assumes that hydroxyapatite is the thermodynamic governing phase for the acid dissolution-rate behavior of enamel has been critically examined theoretically and experimentally. Both enamel powder and synthetic hydroxyapatite initial dissolution-rate experiments were conducted under various conditions of acid-butler type and concentration, pH, and common ion concentrations.