EDTA enhancement of strontium uptake by intact human enamel

The aim of this research was to study the effect of EDTA on the strontium uptake by intact tooth enamel. EDTA did not significantly affect the strontium uptake in an acid medium of pH 4.5. However, it caused a sharp rise in strontium uptake at pH 6.0. At such a pH, the stability constants of the Ca-EDTA complex are approaching a maximal value, and as a result of it a significant dissolution of the surface enamel, accompanied by a highly effective increase of the contact area for strontium uptake, is taking place. In all the experiments, treatment with strontium solution resulted in a decrease of the solubility and dissolution rate of enamel in an acidic environment. The resistance of enamel to acid attack was proportional to the quantity of absorbed strontium, reaching maximal values after treatment with strontium solutions in 10(-2) M EDTA at pH 6.0.