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

Reinforcement of carbonate apatite (CO₃Ap) block with CO ₃Ap was studied to increase the mechanical strength of CO ₃Ap 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 Na₂HPO ₄ aqueous solution. In this process, calcite inside the micropores of CO₃Ap block transformed to CO₃Ap based on the dissolutionprecipitation 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.