Reinforcement of carbonate apatite bone substitutes with carbonate apatite by Ca salt introduction

Abstract

Reinforcement of carbonate apatite (CO3Ap) block with CO3Ap was studied to increase the mechanical strength of CO3Ap block and widen applicable clinical fields. First, calcium salt was introduced to the micropores of CO3Ap block. Then, calcium salt was carbonated to form calcite inside the micropores of CO3Ap block by exposing CO3Ap block to carbon dioxide at the second step. On the third step, the CO3Ap block was immersed in Na2HPO4 aqueous solution. In this process, calcite inside the micropores of CO3Ap block transformed to CO3Ap based on the dissolution–precipitation reaction, and the newly formed CO3Ap crystals entangled not only along the newly formed CO3Ap but also on CO3Ap crystals of the existing CO3Ap block. As a result of bonding between newly formed CO3Ap and the existing CO3Ap block, mechanical strength of the CO3Ap block increased approximately 1.5 times higher when compared to that before the treatment.