Effects of Heat Treatment of Hydroxyapatite on Osteoblast Differentiation

Abstract

To develop hydroxyapatite that promotes early cure of postoperative tissue, we heat-treated hydroxyapatite and evaluated its pH-increasing effect and Ca release. We also evaluated the effect of heat-treated hydroxyapatite on osteoblast differentiation. (1) No marked change was observed regarding the surface morphology or structure of heat-treated hydroxyapatite on SEM. (2) When hydroxyapatite was immersed in physiologic saline, the saline was made more alkaline by heat-treated than non-heat-treated hydroxyapatite. (3) When hydroxyapatite was immersed in physiologic saline, more Ca ions were released from heat-treated than non-heat-treated hydroxyapatite. (4) X-ray diffraction analysis showed a peak of CaO, which is considered to explain the Ca ion release, in heat-treated hydroxyapatite. (5) When osteoblasts were cultured with hydroxyapatite, heat-treated hydroxyapatite prevented the decrease in the number of alkaline phosphatase-positive osteoblasts in the presence of non-heat-treated hydroxyapatite. Thus, heat-treated hydroxyapatite was suggested to promote early cure of postoperative tissue. Detailed analysis of in vivo effects of heat-treated hydroxyapatite is anticipated to make its clinical application possible.