Fabrication of carbonate apatite blocks from set gypsum based on dissolution-precipitation reaction in phosphate-carbonate mixed solution.

Carbonate apatite (CO₃AP), fabricated by dissolution-precipitation reaction based on an appropriate precursor, is expected to be replaced by bone according to bone remodeling cycle. One ofthe precursor candidates is gypsum because it shows self-setting ability, which then enables it to be shaped and molded. The aim of this study, therefore, was to fabricate CO₃AP blocks from set gypsum. Set gypsum was immersed in a mixed solution of 0.4 mol/L disodium hydrogen phosphate (Na₂HPO₄) and 0.4 mol/L sodium hydrogen carbonate (NaHCO₂) at 80-200°C for 6-48 h. Powder X-ray diffraction patterns and Fourier transform infrared spectra showed that CO₃AP block was fabricated by dissolution-precipitation reaction in Na₂HPO₄-NaHCO₃ solution using set gypsum in 48 b when the temperature was 100°C or higher. Conversion rate to CO₃AP increased with treatment temperature. CO₃AP block containing a larger amount of carbonate was obtained when treated at lower temperature. [ABSTRACT FROM AUTHOR]