Do carious phenomenon affect on the lifetime of artificial root made of apatite.

采用小试样压入法测量了羟基磷灰石（HAP）多晶材料的疲劳参数随酸性溶液pH值的变化，并测量了与陶瓷断裂起始点长度相近的微裂纹的裂纹扩展行为，虽然测得的疲劳参数与加载载荷有关，该参数的值与先前报告的值相似。用压入后方法测得了应力强度因子K的最小值。<Ith>结果表明，热压法制备的70wt%HAP-30wt%聚乳酸（PLA）无孔复合材料的体积密度接近于骨的体积密度。<Ith>对于HAP 2与30wt%PLA的复合材料，可以使HAP晶体垂直于加载方向取向，从而使复合材料具有各向异性的微观结构。

The post-indentation method with a small specimen was to be a successful one to measure the fatigue parameter of the hydroxyapatite (HAP) polycrystals as a function of pH of acidic solutions, and to measure the crack extension behavior of a micro-cracks, which length was similar to that of fracture origin in ceramics.Although the measured fatigue parameter had dependence on the indent load, the value of the parameter was similar to those reported previously. The minimum of the stress intensity factor, K_<Ith>, was also measured by using the post-indentation method. The value of K_<Ith> ranged from 20% to 30% of the fracture toughness of the HAP ceramics.The hot-pressing was shown to be a successful method to obtain pore-free 70wt%HAP-30wt%poly-lactic acid (PLA) composites with the bulk density similar to that of bone. For the composites of HAP2 with 30wt%PLA,it was possible to align the HAP crystals perpendicular to the loading direction, and hence, to make the composites having the anisotropic microstructure.