钛种植体结构和弹性模量对骨界面应力分布的影响

Influence of structure and elastic modulus of titanium implanimplant on implant-bone interfacial stress distribution

采用CAD(Pro/E)软件建立颌骨和钛种植体的三维模型,设置3种不同结构钛种植体,即全致密型(1号样品)、穿皮质区致密而松质骨区外层多孔内芯致密型(2号样品)与整体低弹性模量型(3号样品),以致密钛弹性模量103.4GPa为基准,设置四种弹性模量:致密钛模量的20%、40%、60%、80%。在轴向加载150N和颊舌向45°加载25N应力下,采用Ansys Work bench10.0软件分析钛种植体骨界面应力分布状况。分析研究钛种植体结构和弹性模量对骨界面应力分布的影响,研究探讨能有效地转移应力至周围骨组织的新型种植体。研究结果表明:在相同载荷下,3种钛种植体颈部皮质骨均为高应力区,3号种植体的应力最高,为7.128MPa;在松质骨区2号种植体的应力比1号与3号种植体的低,且呈均匀递减趋势。在加载条件下,2号种植体随着弹性模量的降低,骨界面应力降低,且明显比1号种植体的低,当多孔层的弹性模量为致密钛的40%或以下时,骨界面应力明显降低;3号种植体随着弹性模量降低,皮质骨区骨界面应力增加,而松质骨区骨界面应力降低不明显。钛种植体的结构和弹性模量均影响骨界面应力分布;穿皮质区致密而松质骨区外层多孔内芯致密型钛种植体有利于界面应力转移到周围骨组织,降低多孔层的弹性模量,能有效地降低骨界面应力。

To investigate the effect of structure and elastic modulus of titanium implant on stress distribution in the implant-bone interface, and explore a new style of titanium implant which could effectively transfer stress to the surrounding bone, the 3-D finite element analysis models of a posterior mandible segment with an implant bone were constructed by the CAD （Pro/E Widefire 2.0） software. Three different structure implant models were created, including the whole dense structure style （No. 1）, porous structure style （No.2） and the overall low elastic modulus structure style （No.3）. The results show that the cervical cortical bones in threetitanium implants are all high stress region under the same load-bearing, and the maximum Von-Misese value is 7.128 MPa （No.3）. In the cancellous bone region, the Von-Misese value of No.2 implant is lower than those of No.1 and No.3 implants. Under load-beating, the implant-bone interface stress of No.2 implant decreases with the decrease of the elastic modulus, and the stress of No.2 implant is significantly lower than that of No.1 implant. When the elastic modulus of porous titanium layer of No.2 implant is 40% of dense titanium, the implant-bone interface stress decreases notably. In No.3 implant, with the elastic modulus decreasing, the stress on cortical bone interface increases, and the stress does not obviously decrease on cancellous bone region. It is proved that the structure and elastic modulus of titanium implant affect the distribution of stress on bone interface. The implant which has dense structure in the cortical bone area and porous-outer and dense-interior in the cancellous bone area contribute to transferring the stress to the surrounding bone. Furthermore, with the decrease of elastic modulus of porous layer, implant-bone interface stress will effectively reduce in the cancellous bone region.