Ioku K, Yanagisawa K, Yamasaki N, Kurosawa H, Shibuya K, Yokozeki H
Research Laboratory of Hydrothermal Chemistry, Faculty of Science, Kochi University, Japan.
Biomed Mater Eng. 1993 Fall;3(3):137-45.
Hydroxyapatite (Ca10(PO4)6(OH)2; HA) is one of the most biocompatible materials with bones, and porous HA is promising bone substitute materials for clinical applications. While there are reports that beta-tricalcium phosphate (Ca3(PO4)2; TCP) has higher resorbability than HA when the material is implanted in a bone defect. In the present study, porous HA coated with beta-TCP was prepared by our unique method. The porous HA of about 60% porosity with interconnecting pore structure was soaked in diammonium hydrogen phosphate solution, and then the HA was sintered at 900 degrees C for 3 h. beta-TCP was revealed by X-ray diffractometry on the surface of porous HA. It was possible to control the content of surface-formed beta-TCP arbitrary by varying the concentration of the solution. The obtained HA coated with 33 wt% beta-TCP (33TCP) had about 60% open porosity with the pore size from 150 to 400 microns. The average compressive strength of this porous ceramics was 17.5 MPa. Surface coated HA with beta-TCP deprived of the brittleness in handling. The weight of HA implanted into muscles was increased obviously at 4 weeks because of formation of carbonate hydroxyapatite on the surface of HA. The weight of 33TCP was scarcely changed up to 12 weeks, but the weight tended to increase at 24 weeks. The carbonate hydroxyapatite was not formed on 33TCP at 4 weeks, but formed on it at 24 weeks. Therefore beta-TCP coated porous HA behaved like beta-TCP initially after implantation, and then behaved like HA.
羟基磷灰石（Ca10(PO4)6(OH)2；HA）是与骨骼生物相容性最佳的材料之一，多孔HA有望成为临床应用的骨替代材料。虽然有报道称，当将β-磷酸三钙（Ca3(PO4)2；TCP）植入骨缺损处时，其可吸收性比HA更高。在本研究中，采用我们独特的方法制备了涂覆有β-TCP的多孔HA。将孔隙率约为60%且具有相互连通孔隙结构的多孔HA浸泡在磷酸氢二铵溶液中，然后在900℃下烧结3小时。通过X射线衍射法在多孔HA表面检测到了β-TCP。通过改变溶液浓度可以任意控制表面形成的β-TCP的含量。所获得的涂覆有33 wt%β-TCP（33TCP）的HA具有约60%的开孔率，孔径为150至400微米。这种多孔陶瓷的平均抗压强度为17.5 MPa。表面涂覆有β-TCP的HA在处理时没有脆性。由于HA表面形成了碳酸羟基磷灰石，植入肌肉中的HA重量在4周时明显增加。33TCP的重量在12周内几乎没有变化，但在24周时趋于增加。在4周时33TCP上未形成碳酸羟基磷灰石，但在24周时形成了。因此，涂覆有β-TCP的多孔HA在植入后最初表现得像β-TCP，然后表现得像HA。
