Fabrication of carbonate apatite foam based on the setting reaction of α-tricalcium phosphate foam granules

Carbonate apatite (CO3Ap) foam has attracted attention as a bone substitute and scaffold for tissue regeneration. In this study, the feasibility of fabricating CO3Ap foam was evaluated on the basis of the setting reaction of α-tricalcium phosphate (α-TCP) foam granules. CO3Ap foam was formed when α-TCP foam granules were treated hydrothermally at 200 °C in the presence of NaHCO3 solution for 24 h. The precipitated CO3Ap crystals interlocked with each other to form the CO3Ap foam. The CO3Ap formed in high NaHCO3 containing solution was considered to be a B-type CO3Ap, which is the CO3Ap found in bones and contained 0.85 mass% CO3. When the α-TCP foam granules were treated at higher NaHCO3 solution, the content of the CO3 in the apatitic structure increased and changed the morphology of the CO3Ap from fiber-like to plate-like with a smaller aspect ratio; thus, the setting ability disappeared.