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

Carbonate apatite (CO(3)Ap) is a major inorganic bone component and an effective bone substitute. To clarify the function of CO3Ap, we compared differences among CO(3)Ap, hydroxyapatite (HAp), and beta-tricalcium phosphate (beta-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 CO(3)Ap and beta-TCP groups. For in vitro experiments, MSCs were cultured with bone substitutes. The differentiation potential and amount of calcium deposition were significantly lower in CO(3)Ap and HAp groups than in the beta-TCP group. Increases in insulin-like growth factor-I and vascular endothelial growth factor were found only in the CO(3)Ap group. CO(3)Ap-filled extraction sockets accumulated MSCs, and MSCs cultured in the presence of CO(3)Ap produced large amounts of growth factors. These results suggest that CO(3)Ap promotes healing of tooth extraction sockets.