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.