Comparison of calcite and vaterite as precursors for CO₃Ap artificial bone fabrication through a dissolution–precipitation reaction

Carbonate apatite (CO₃Ap) artificial bone is fabricated in an aqueous solution using calcium carbonate as a precursor. CO₃Ap has attracted attention because it demonstrates high osteoconductivity and can replace a damaged bone based on the bone remodeling process. This study aims to compare vaterite and calcite, which are metastable and stable polymorphs of calcium carbonate, respectively, as precursors. When the vaterite granules, which have higher solubility and consist of smaller crystals than calcite, prepared from calcium oxide granules were immersed in disodium hydrogen phosphate solution, the compositional transformation to CO₃Ap was quicker than that of calcite. Based on the investigations on rabbit femurs, it was observed that the remodeling of CO₃Ap to a new bone was faster when vaterite was used as a precursor compared to when calcite was used as a precursor. It is concluded that vaterite can be a better precursor than calcite for CO₃Ap artificial bone fabrication.