Fundamental Study of Bioactivity of Inorganic Materials

几种无机材料可以自发地与活骨结合。它们被称为生物活性材料，已经在临床上用作一些骨替代品。然而，它们的骨结合机制尚不完全清楚。本研究对影响其生物活性的因素进行了研究。体外和体内实验证实，Ceravital^<<0！>型含磷灰石玻璃陶瓷也通过其在体内表面形成的富Ca， p层与活骨结合，类似于生物玻璃和玻璃陶瓷a - w。x射线微衍射结果表明，在玻璃陶瓷a - w与羊骨交界面形成的富Ca， p层确实是体外实验预期的磷灰石层。对a - w玻璃陶瓷在模拟体液中的表面反应分析表明，玻璃陶瓷表面的磷灰石层是由溶解在玻璃陶瓷中的Ca （II）和Si （IV）离子与流体中的P (V)离子反应诱导磷灰石成核形成的，磷灰石的生长是通过消耗流体中的Ca （II）和P (V)离子实现的。对CaO- sio_2 - p_2o_5和CaO- sio_2 - al_2o_3玻璃在模拟体液中的表面反应分析表明，由于从玻璃中溶解的Ca （II）和Si （IV）离子对表面磷灰石的形成起协同重要作用，玻璃表面磷灰石的形成局限于CaO、sio_2基组分区。Ca （II）离子增加了周围流体相对于磷灰石的过饱和程度，而Si （IV）离子诱导磷灰石成核。

A few kind of inorganic materials spontaneously bond to living bone. They are called bioactive materials and already clinically used as some bone substitutes. Their bone-bonding mechanism is not, however, fully understood. In the present study, factors governing the bioactivity was studied. It was confirmed by in vitro as well as in vivo experiments that Ceravital^<<0!>>-type apatite-containing glass-ceramic also bond to living bone through a Ca, P-rich layer which is formed on its surface in the body, similar to Bioglass and glass-ceramic A-W. It was shown by X-ray microdiffraction that the Ca, P-rich layer formed at the interface between glass-ceramic A-W and the bone of a sheep is indeed an apatite layer as expected from in vitro experiments. Analysis of surface reaction of glass-ceramic A-W in a simulated body fluid showed that the apatite layer on the surface of the glass-ceramic is formed by a nucleation of the apatite which is induced by the reaction of Ca (II) and Si (IV) ions dissolved from the glass-ceramics with P (V) ion in the fluid, and growth of the apatite which is achieved by consuming Ca (II) and P (V) ions from the fluid. Analysis of surface reaction of CaO-SiO_2-P_2O_5 and CaO-SiO_2-Al_2O_3 glasses in a simulated body fluid showed that apatite formation on the surfaces of glasses is restricted to CaO, SiO_2-based compositional region, because the Ca (II) and Si (IV) ions dissolved from glasses play cooperative important role in forming the surface apatite. The Ca (II) ion increases the degree of the supersaturation of the surrounding fluid with respect to the apatite, whereas the Si (IV) ion induces apatite nucleation.