Ogiso M
Department of Fixed Prosthodontics, Faculty of Dentistry, Tokyo Medical and Dental University, Japan.
J Long Term Eff Med Implants. 1998;8(3-4):193-200.
The present paper reviews bone formation on dense hydroxyapatite (HA) implants. Calcification of bone matrix formed on HA is different in areas where collagen fibers are dense and scattered with matrix vesicles than in those interfacial layers containing few or no collagen fibers and matrix vesicles. Calcification of collagen-coated areas begins with crystallization within the matrix vesicles. In contrast, calcification of the interfacial layer is initiated by epitaxial crystal growth on the HA. Crystallization within the matrix vesicles near the HA and those on the HA start simultaneously. Calcification of the interfacial layer is the most important feature of HA as a biomaterial. Such calcification is never observed on titanium implants. The recent postulation that the rate of bone formation on calcium-phosphate (CP) ceramics correlates with the solubility of CP ceramics is improbable, as in vitro immersion tests have been unable to establish correlation between osteoblast differentiation and the solubility of the CP ceramics. With regard to HA-plasma spray-coated implants, future research should focus on the purity of HA and the structure of the ceramics in order to increase the in vivo chemical and mechanical durability of HA coating.
本文综述了致密羟基磷灰石（HA）植入物上的骨形成情况。在HA上形成的骨基质钙化，在胶原纤维密集且伴有基质小泡散布的区域，与在那些几乎没有或不含胶原纤维和基质小泡的界面层中有所不同。胶原包被区域的钙化始于基质小泡内的结晶。相比之下，界面层的钙化是由HA上的外延晶体生长引发的。靠近HA的基质小泡内以及HA上的结晶同时开始。界面层的钙化是HA作为生物材料的最重要特征。在钛植入物上从未观察到这种钙化。最近关于磷酸钙（CP）陶瓷上骨形成速率与CP陶瓷溶解度相关的假设不太可能成立，因为体外浸泡试验未能确定成骨细胞分化与CP陶瓷溶解度之间的相关性。对于HA等离子喷涂涂层植入物，未来的研究应集中在HA的纯度和陶瓷结构上，以提高HA涂层在体内的化学和机械耐久性。
