Preparation and Evaluation of Octacalcium Phosphate Bone Precursor Transformable to Apatite

Abstract

Reaction of an aqueous suspension of dicalcium phosphate dihydrate (DCPD) and calcium carbonate at 30 - 80°C was applied to prepare octacalcium phosphate (OCP) powder expected to be a bone precursor in accord with bone remodeling process. XRD analysis confirmed that the reaction temperature and reaction time strongly exert an influence on a crystalline form of prepared OCP. OCP synthesized at 60°C showed a characteristic stability to time changes. Increasing reaction temperature however resulted in the rapid decomposition of OCP to hydroxyapatite (HAp) because of the consecutive reaction DCPD→OCP→HAp. OCP powders were immersed in simulated body fluid (SBF) to evaluate its transformation ability to HAp. SEM micrographs and EDS analysis demonstrated that calcium-deficient HAp should be crystallized after the dissolution of OCP into SBF. OCP synthesized at 60°C was transformed to HAp rapidly after the immersion time of 21 days.