【作者】 苏爱军；

【导师】 邹敬才；

【作者基本信息】 第四军医大学 ， 口腔临床医学， 2008， 硕士

【摘要】 种植义齿因具有传统活动义齿、固定义齿无法比拟的优势,在近十几年中得到了长足的发展,越来越受到患者的青睐。虽然种植修复具有高达90%以上的远期成功率,但临床上仍不时有种植修复失败的病例报道,包括种植体的折断、松动,甚至于最后的脱落等,颌骨局部负荷过大引起的种植体周围骨吸收则是造成种植修复失败的主要原因之一。而种植修复的生物力学特性则在保障种植修复的远期成功率方面起着非常重要的作用。大量的研究结果表明,影响种植体生物力学传递的因素主要包括:种植体材料、种植体设计、修复体设计、颌骨的生物力学特性和咬合力的加载方式等。相对于其它影响因素而言,种植体直径、长度的优化选择和颌骨质量在影响种植修复的远期成功率方面起着更为重要的作用。在以往的关于种植体直径和长度的研究报道中,多为直径或长度的单因素、离散组合分析,其不能准确的反映种植体直径和长度同时、连续变化对颌骨应力和种植体稳定性的影响,同时目前尚未见种植体直径和长度在不同颌骨质量时相互关系的报道。本课题拟借助Pro/E和Ansys Workbench机械工程优化分析方法,对不同骨质条件下种植体的直径和长度进行系统的生物力学优化分析,为临床选择种植体提供生物力学理论参考。实验一:应用Pro/E参数化建模软件,绘制种植体、皮质骨、松质骨、冠修复体的三维实体模型,应用Pro/E的自适应装配功能,建立可随种植体宏观结构参数自适应改变的种植体骨块三维实体模型。应用Pro/E与Ansys Workbench软件的无缝双向参数传递功能,将实体模型导入Ansys Workbench软件中划分单元,建立可随种植体宏观结构参数自适应改变的种植体骨块三维有限元模型,力学加载后进行模型准确性的检测。该模型的建立为后期真正意义上的种植体优化选择提供了技术平台。实验二:I类骨质下,设定种植体直径(D)和长度(L)为设计变量(Design Variable,DV),D变化范围为3.0-5.0mm,L变化范围为6.0-16.0mm,设定颌骨平均主应力(Equivalent应力,EQV应力)峰值和种植体-基台复合体位移峰值为目标函数(Objective Function,OBJ),观察DV变化对OBJ的影响。同时进行OBJ对DV的敏感度分析。结果发现,随着D和L的增加,垂直向(Axial,AX)加载下,皮、松质骨的EQV应力峰值分别降低54.5%和70.2%;颊舌向(Buccolingual,BL)加载下,皮、松质骨的EQV应力峰值分别降低了73.5%和75.1%;AX和BL加载下,种植体-基台复合体位移峰值分别降低了51.4%和73.8%。在各种加载下,当D大于3.8mm同时L大于9.0mm时,单DV的响应曲线切斜率位于-1和0之间。通过OBJ对DV的敏感度分析发现, D比L对OBJ的影响更明显。结果提示I类骨质下,种植体直径比长度更易影响颌骨的应力大小和种植体的稳定性;在临床上选择种植体时,种植体直径应不小于3.8mm,种植体长度应不小于9.0mm。实验三:II类骨质下,DV、OBJ的设定及观察指标同实验二。结果发现,随着D和L的增加,AX加载下,皮、松质骨的EQV应力峰值分别降低67.9%和75.0%;BL加载下,皮、松质骨的EQV应力峰值分别降低了64.9%和65.4%;AX和BL加载下,种植体-基台复合体位移峰值分别降低了53.7%和73.7%。在各种加载下,当D大于3.85mm同时L大于9.0mm时,单DV的响应曲线切斜率位于-1和0之间。通过OBJ对DV的敏感度分析发现,D比L对OBJ的影响更明显。结果提示,II类骨质下,种植体直径比长度更易影响颌骨的应力大小和种植体的稳定性;在临床上选择种植体时,种植体直径应不小于3.85mm,种植体长度应不小于9.0mm。实验四:III类骨质下,DV、OBJ的设定及观察指标同实验二。结果发现,随着D和L的增加,AX加载下,皮、松质骨的EQV应力峰值分别降低65.3%和76.8%; BL加载下,皮、松质骨的EQV应力峰值分别降低了76.1%和78.0%;AX和BL加载下,种植体-基台复合体位移峰值分别降低了60.6%和77.0%。在各种加载下,当D大于3.95mm同时L大于10.5mm时,单DV的响应曲线切斜率位于-1和0之间。通过OBJ对DV的敏感度分析发现,D和L分别有利于BL和AX加载下的应力分布,并改善种植体的稳定性。结果提示,III类骨质下,种植体的直径和长度在保障种植体的远期成功率时都起着重要的作用;在临床上选择种植体时,种植体直径应不小于3.95mm,种植体长度应不小于10.5mm。实验五:IV类骨质下,DV、OBJ的设定及观察指标同实验二。结果发现,随着D和L的增加,AX加载下,皮、松质骨的EQV应力峰值分别降低63.9%和87.9%;BL加载下,皮、松质骨的EQV应力峰值分别降低了76.2%和92.7%;AX和BL加载下,种植体-基台复合体位移峰值分别降低了63.6%和74.7%。在各种加载下,当D大于4.0mm同时L大于11.0mm时,单DV的响应曲线切斜率位于-1和0之间。通过OBJ对DV的敏感度分析发现,D和L分别有利于BL和AX加载下的应力分布,并改善种植体的稳定性。结果提示,IV类骨质下,种植体的直径和长度在保障种植体的远期成功率时都起着重要的作用;在临床上选择种植体时,种植体直径应不小于4.0mm,种植体长度应不小于11.0mm。综上所述,从I类到IV类骨质,相同直径和长度的种植体传递至颌骨的应力和种植体的位移随之增加。从I类到IV类骨质,种植体直径变化造成的颌骨的应力和种植体的位移变化幅度逐渐减小;种植体长度变化造成的颌骨的应力和种植体的位移变化幅度逐渐增加。不同骨质情况下,种植体直径和长度的优化选择范围为:I类骨质,种植体直径大于3.80mm,长度大于9.0mm;II类骨质,种植体直径大于3.85mm,长度大于9.0mm;III类骨质,种植体直径大于3.95mm,长度大于10.5mm;IV类骨质,种植体直径大于4.00mm,长度大于11.0mm。更多还原

【Abstract】 With the outstanding advantages of the implant denture, the implant restoration has been improved dramatically in the recent decades. And more and more patients prefer to choose this new prosthodontics. Most of the studies have shown multiyear success rates of more than 90% for implants placed in patients. However implant failures were reported occasionally, including the implant fracture, loose, till the falling off. And one of main causes of implant failure is excessive load on the interface of implant and bone caused by stress centralizing, which induces the absorption of the bone around implant. To maximize the chance for long-term implant stability and function, the design and selection of dental implant should base on better biomechanics compatibility except better biocompatibility. Lots of researches have demonstrated that the factors influencing implant biomechanics transmission of occlusal forces include implant material, shape, macrostructure, anatomy shape of jaw bone, biomechanics characteristic of jaw bone and complex forces loading. And implant diameter, implant length, and jaw bone quality play a more important role in implant biomechanics transmission than other factors.Many of the previous studies examined the effect of implant diameter and length discretely and independently. So the information about the two implant parameters was not accurate and some important information was lost. The main aim of the present study, through the Pro/E and Ansys Workbench mechanical engineering optimum technology, was to systematically optimize implant diameter and length in different bone qualities by biomechanical consideration. And this study also provided us the theoretical references for the clinical optimum selection of dental implant.Experiment 1: 3D models of thread dental implant , cortical bone, cancellous bone and superstructure were constructed by Pro/E software. And the implant-bone complexes were assembled based on implant parameters by self-adapting assembled programme of Pro/E. Then the models were imported to Ansys Workbench software by bidirectional parameters transmitting of the two softwares. Self-adapting assembled 3D finite element analysis (FEA) models of dental implant-bone complexes were rebuild and the accuracy of the models was also evaluated. The self-adapting assembled models provide the technical platform for further implant optimum design and analysis.Experiment 2: In type I bone, implant diameter (D) and implant length (L) were set as DV. D ranged from 3.0mm to 5.0mm, and L ranged from 6.0mm to 16.0mm. The Max EQV stresses in jaw bone and Max displacements in implant-abutment complex were set as OBJ. The effect of DV to OBJ and the sensitivities of the OBJ to DV were evaluated. The results showed that, under AX load, the Max EQV stresses in cortical and cancellous bones decreased by 54.5% and 70.2% respectively with D and L increasing. And under BL load, those decreased by 73.5% and 75.1% respectively. The Max displacement of implant-abutment complex decreased by 51.4% and 73.8% under AX and BL load respectively. When D exceeded 3.8mm and L exceeded 9.0mm, the tangent slope rate of OBJ response curves ranged from -1 to 0. The OBJ were more sensitive to D than to L. The results imply that the stresses in jaw bone and stability of implant are affected more easily by implant diameter than implant length. Implant diameter exceeding 3.8mm and implant length exceeding 9.0mm are optimal selection for a cylinder implant in type I bone.Experiment 3: In type II bone, DV, OBJ settings and evaluation were same as experiment 2. The results showed that, under AX load, the Max EQV stresses in cortical and cancellous bones decreased by 67.9% and 75.0% respectively with D and L increasing. And under BL load, those decreased by 64.9% and 65.4% respectively. The Max displacement of implant-abutment complex decreased by 53.7% and 73.7% under AX and BL load respectively. When D exceeded 3.85mm and L exceeded 9.0mm, the tangent slope rate of OBJ response curves ranged from -1 to 0. The OBJ were more sensitive to D than to L. The results imply that the stresses in jaw bone and stability of implant are affected more easily by implant diameter than implant length. Implant diameter exceeding 3.85mm and implant length exceeding 9.0mm are optimal selection for a cylinder implant in type II bone.Experiment 4: In type III bone, DV, OBJ settings and evaluation were same as experiment 2. The results showed that, under AX load, the Max EQV stresses in cortical and cancellous bones decreased by 65.3% and 76.8% respectively with D and L increasing. And under BL load, those decreased by 76.1% and 78.0% respectively. The Max displacement of implant-abutment complex decreased by 60.6% and 77.0% under AX and BL load respectively. When D exceeded 3.95mm and L exceeded 10.5mm, the tangent slope rate of OBJ response curves ranged from -1 to 0. The OBJ were more sensitive to D than to L. The results imply that the stresses in jaw bone and stability of implant are affected by implant diameter than implant length similarly. Implant diameter exceeding 3.95mm and implant length exceeding 10.5mm are optimal selection for a cylinder implant in type III bone.Experiment 5: In type IV bone, DV, OBJ settings and evaluation were same as experiment 2. The results showed that, under AX load, the Max EQV stresses in cortical and cancellous bones decreased by 63.9% and 87.9% respectively with D and L increasing. And under BL load, those decreased by 76.2% and 92.7% respectively. The Max displacement of implant-abutment complex decreased by 63.6% and 74.7% under AX and BL load respectively. When D exceeded 4.0mm and L exceeded 11.0mm, the tangent slope rate of OBJ response curves ranged from -1 to 0. The OBJ were more sensitive to D than to L. The results imply that the stresses in jaw bone and stability of implant are affected by implant diameter than implant length similarly. Implant diameter exceeding 4.0mm and implant length exceeding 11.0mm are optimal selection for a cylinder implant in type IV bone.To conclude, stresses of jaw bone and displacement of implant increased with the changing of jaw bone qualities from type I to type IV. The influence of the implant diameter to decrease bone stress and improve implant stablity decreased, and the influence of the implant length increased. The ranges of optimum selection of implant diameter and length in different bone qualities are: in type I bone, implant diameter exceeding 3.80mm, length exceeding 9.0mm; in type II bone, implant diameter exceeding 3.85mm, length exceeding 9.0mm; in type III bone, implant diameter exceeding 3.95mm, length exceeding 10.5mm; in type IV bone, implant diameter exceeding 4.0mm, length exceeding 11.0mm.更多还原