Basic Biological Sciences Hydrolysis of Dicalcium Phosphate Dihydrate in the Presence or Absence of Calcium Fluoride

Abstract

Effects of temperature (25 and 37°C), pH (4.9-10.5), and CaF2 on CaHPO₄·2H₂O (DCPD) hydrolysis were studied in a pH-stat. Octacalcium phosphate (OCP) was the product at pH 6.2-6.8 and 25-37°C; thermodynamically stable apatitic compounds were formed at higher pH and/or higher temperature. In the presence of CaF2, apatite was the product, its crystallinity improved, and the fluoride content increased as pH of the reaction decreased. The results demonstrate the remarkable ability of fluoride to promote the hydrolysis of an acidic calcium phosphate, DCPD, to apatite.