Development of calcium phosphate cement for rapid crystallization to apatite.

The purpose of this study was to develop an alpha-tricalcium phosphate (alpha-TCP) cement which transforms to hydroxyapatite (HAP) in a relatively short period. We used calcium and phosphate solutions as the liquid phase for the alpha-TCP cement. The alpha-TCP powder was first mixed with CaCl2 solution, and then mixed with NaH2PO4 or Na2HPO3 solution for a total powder/liquid ratio of 1.8. The setting time became shorter with the increase in the concentration of calcium and phosphate solutions, reaching 5 min, whereas the setting time was longer than 30 min when distilled water was used as the liquid phase. X-ray diffraction analysis revealed that the cement was mostly transformed to HAP within 24 h when kept in an incubator. We concluded that alpha-TCP should be mixed with calcium and phosphate solutions since this results in a moderate setting time and fast transformation to HAP even if the method of mixing becomes a little complex.