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

小试样后压痕法可以测量羟基磷灰石（HAP）多晶的疲劳参数随酸性溶液pH值的变化规律，并可以测量微裂纹的扩展行为，该微裂纹的长度与陶瓷的断裂起源相似。虽然测量的疲劳参数与压痕载荷有关，但该参数的值与之前报道的相似。采用压痕后法测定了应力强度因子的最小值K_<Ith>。K_<Ith>值为HAP陶瓷断裂韧性的20% ~ 30%。热压被证明是一种成功的方法，可以获得无孔的70wt%HAP-30wt%聚乳酸（PLA）复合材料，其堆积密度与骨相似。对于30wt%PLA的HAP2复合材料，可以使HAP晶体垂直于加载方向排列，从而使复合材料具有各向异性微观结构。

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.