Evaluation of carbonate apatite as a bone substitute in rat extraction sockets from the perspective of mesenchymal stem cells

Carbonate apatite (CO₃Ap) is a major inorganic bone component and an effective bone substitute. To clarify the function of CO₃Ap, we compared differences among CO₃Ap, hydroxyapatite (HAp), and β-tricalcium phosphate (β-TCP) by focusing on mesenchymal stem cells (MSCs) that have a role in wound healing. For in vivo experiments, maxillary molars were removed and the bone substitute was inserted. MSC accumulation around extraction sockets was significantly promoted in CO₃Ap and β-TCP groups. For in vitro experiments, MSCs were cultured with bone substitutes. The differentiation potential and amount of calcium deposition were significantly lower in CO₃Ap and HAp groups than in the β-TCP group. Increases in insulin-like growth factor-I and vascular endothelial growth factor were found only in the CO₃Ap group. CO₃Ap-filled extraction sockets accumulated MSCs, and MSCs cultured in the presence of CO₃Ap produced large amounts of growth factors. These results suggest that CO₃Ap promotes healing of tooth extraction sockets.