Fabrication of Carbonate Apatite Block from Calcium Sulfate by Hydrothermal Treatment

摘要

Carbonate apatite (CO_3Ap) is expected to be an ideal bone substitute since it can harmonize with the bone remodeling cycle. The aim of this study is to fabricate a CO_3Ap bone substitute from gypsum (calcium sulfate, CaSO_4.2H_2O) hardening bodies based on dissolution-precipitation reaction. Calcium sulfate hemihydrate mixed with water at a water-to-powder ratio of 0.5 was packed in a split stainless mold and kept at room temperature for 24 hours to obtain set CaSO_4.2H_2O. The set CaSO_4-2H_2O was hydrothermally treated in the presence of disodium hydrogen phosphate (Na_2HPO_4) and sodium hydrogen carbonate (NaHCO_3). The results of powder X-ray diffraction and Fourier transform infrared spectroscopy indicated that CO_3Ap block could be fabricated from the set CaSO_4-2H_2O block by hydrothermal treatment with Na_2HPO_4 and NaHCO_3. When the treatment temperature was increased, the conversion rate to CO_3Ap increased. However, the carbonate content decreased with increasing treatment temperature.