【作者】 孔亮；

【导师】 刘宝林；

【作者基本信息】 第四军医大学 ， 颌面外科学， 2007， 博士

【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,而颌骨局部负荷过大引起的种植体周围骨吸收是造成种植修复失败的主要原因之一。这就要求种植体在设计和选择上,除了具备良好的生物相容性外,还应具备良好的生物力学传递特性,从而保障种植修复的远期成功率。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、种植体的宏观结构设计、修复体设计、颌骨的解剖形态、颌骨的生物力学特性和咬合力的加载方式等。相对于其它因素而言,种植体的宏观结构对咬合力传导的影响更为明显,并且在临床上更易选择和控制。目前,国内市场上主流的种植系统仍以进口产品为主,其价格高昂,在很大程度上限制了其应用。这就迫切要求国内研发单位开发生产出具有自主知识产权的高品质、低价位的种植系统。目前,种植系统的开发设计研究主要集中在种植体的材料、形状、宏观结构、表面微观结构和种植体与上部结构的连接等方面。国内外的学者在这些领域里进行了大量的研究,但关于种植体宏观结构生物力学传递特性的研究多为离散的或单因素的比较分析,这些研究结果对于开发设计带有详尽参数的种植体产品而言,并不具有充分的指导意义。本课题旨在借助Pro/E和Ansys Workbench的机械工程优化设计方法,从生物力学角度,模拟不同载荷条件下,对种植于B/2类骨质内的种植体的宏观结构(直径、长度、锥度、螺纹高度、螺纹宽度、螺纹螺距、颈部锥度、末端倒角、穿龈高度等)进行系统的优化设计分析。以期进一步认识种植体宏观结构参数在其生物力学传递中的作用,了解种植体宏观结构各个参数对其生物力学传递影响大小的排序。同时提供种植体开发生产所需的详细宏观结构参数,为临床优化设计开发和选择种植体提供理论参考。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设计提供了技术平台。实验二: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)加载时,皮、松质骨的EQV应力峰值分别降低77.4%和68.4%;颊舌向(Buccolingual,BL)加载时,皮、松质骨的EQV应力峰值分别降低了64.9%和82.8%;AX和BL加载时,种植体-基台复合体位移峰值分别降低了56.9%和78.2%。在各种加载下,当D大于3.9mm同时L大于9.5mm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比L对OBJ的影响更明显。结果提示,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3.9mm,种植体长度应不小于9.5mm。实验三:设定种植体锥度(T)为DV,T变化范围为0°-2.5°,OBJ设定同实验二,观察DV变化对OBJ的影响。结果发现,随着T的减小,AX加载时,皮、松质骨的EQV应力峰值分别降低11.1%和22.2%;BL加载时,皮、松质骨的EQV应力峰值分别降低了12.0%和16.6%;AX和BL加载时,种植体-基台复合体位移峰值分别降低了12.6%和12.4%。在各种加载下,当T小于1.2°时,DV的响应曲线切斜率位于-1和0之间。结果提示,种植体的锥度小于1.2°以内为种植体的最优设计。实验四:设定种植体颈部锥度(T)和末端倒角(R)为DV,T变化范围为45°-75°, R变化范围为0.5-1.5mm,OBJ设定同实验二,观察指标同实验二。结果发现,随着T和R的变化,AX加载时,皮、松质骨的EQV应力峰值分别降低71.6%和11.0%;BL加载时,皮、松质骨的EQV应力峰值分别降低了69.2%和14.8%;AX和BL加载时,种植体-基台复合体位移峰值分别降低了9.1%和22.8%。在各种加载下,当T介于64°至73°,同时R大于0.8mm时,单DV的响应曲线切斜率位于-1和1之间。通过OBJ对DV的敏感度分析发现,T比R对OBJ的影响更明显。结果提示,种植体颈部锥度介于64°至73°之间,同时末端倒角大于0.8mm时为圆柱状种植体的最优设计。实验五:设定种植体螺纹高度(H)和螺纹宽度(W)为DV,H变化范围为0.2-0.6mm,W变化范围为0.1-0.4mm,OBJ设定同实验二,观察指标同实验二。结果发现,随着H和W的变化,AX加载时,皮、松质骨的EQV应力峰值分别降低4.1%和38.7%;BL加载时,皮、松质骨的EQV应力峰值分别降低了16.4%和54.1%;AX和BL加载时,种植体-基台复合体位移峰值分别降低了46.0%和35.2%。在各种加载下,当H介于0.33mm至0.48mm之间,同时W介于0.18mm至0.30mm之间时,单DV的响应曲线切斜率位于-1和1之间。通过OBJ对DV的敏感度分析发现,H比W对OBJ的影响更明显。结果提示,种植体螺纹高度比螺纹宽度更易影响颌骨的应力大小和种植体的稳定性;螺纹高度介于0.33mm至0.48mm,同时螺纹宽度介于0.18mm至0.30mm时为螺纹种植体的最优选择。实验六:设定种植体螺纹螺距(P)为DV,P变化范围为0.5-1.6mm,OBJ设定同实验三,观察指标同实验三。结果发现,随着P的变化,AX加载时,皮、松质骨的EQV应力峰值分别降低6.7%和55.2%;BL加载时,皮、松质骨的EQV应力峰值分别降低了2.7%和22.4%;AX和BL加载时,种植体-基台复合体位移峰值分别降低了22.3%和13.0%。在各种加载下,当P大于0.8mm时,DV的响应曲线切斜率位于-1和1之间。结果提示,螺纹种植体螺距最优设计应不小于0.8mm。实验七:建立了12种包含不同螺纹形态种植体的颌骨骨块三维有限元模型,三种矩形(S)、三种V形(V)、三种支撑形(B)和三种反支撑形(R)螺纹形态。对所有模型进行颌骨应力分布和种植体-基台复合体位移峰值的比较。结果表明,AX加载下S-2、V-3、B-3、R-1、R-2和R-3螺纹形态表现出较好的应力分布状态, BL加载下S-1、S-2、V-3、B-3、R-2和R-3螺纹形态表现出较好的应力分布状态。结果提示S-2、V-3、B-3、R-2和R-3螺纹形态均适用于圆柱形种植体。实验八:建立了包含单、双、三螺纹种植体的颌骨骨块三维有限元模型,观察指标同实验七。结果表明,AX加载下,双螺纹皮、松质骨的EQV应力峰值比单螺纹分别增加了10.4%和9.2%;BL加载下,双螺纹皮质骨的EQV应力峰值比单螺纹增加了9.1%,三螺纹松质骨的EQV应力峰值比单螺纹减少了14.2%。结果提示,单螺纹为圆柱状种植体的最优螺纹设计。实验九:设定种植体穿龈高度(H)为DV,H变化范围为1.0-4.0mm,OBJ设定同实验三,观察指标同实验三。结果发现,随着H的变化,AX加载时,皮质骨的EQV应力峰值降低了4.7%;BL加载时,皮、松质骨的EQV应力峰值分别降低了17.3%和18.5%;在AX和BL加载下,种植体-基台复合体位移峰值分别降低了4.1%和48.9%。在各种加载下,当H介于1.7mm和2.8mm之间时,DV的响应曲线切斜率位于-1和1之间。结果提示,种植体穿龈高度最优设计应介于1.7mm和2.8mm之间。综上所述,依照宏观结构参数对种植体生物力学传递影响的大小排序如下:种植体直径、长度、螺纹高度、颈部锥度、螺纹螺距、穿龈高度、锥度、螺纹宽度、末端倒角。从生物力学角度得出优化的种植体宏观结构参数范围如下:种植体直径大于3.9mm,长度大于9.5mm,螺纹高度介于0.33mm至0.48mm之间,颈部锥度介于64°至73°之间,螺纹螺距大于0.8mm,穿龈高度介于1.7mm和2.8mm之间,锥度小于1.2°,螺纹宽度介于0.18mm至0.30mm之间,同时末端倒角大于0.8mm。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 macrostructure plays a more important role in implant biomechanics transmission than other factor and it is more easily controlled and selected in clinical experience.At present, the mainstream implant systems are imported from abroad in the domestic market primarily and limit their application to a great extent for their high price. It is imperative that domestic researchers and manufacturers develop high quality implant products but with the lower price. Previous implant design and development researches mainly concentrated on implant materials, shape, macrostructure, surface microstructure, and implant-superstructure connection. Lots of domestic and foreign scholars have conducted massive studies in these domains. Nevertheless, many of the studies about biomechanics characteristic of implant macrostructure were discrete and independent. And these findings were insufficient to instruct us to develop and design implant with exhaustive parameters.The main aim of the present study, through the Pro/E and Ansys Workbench mechanical engineering optimum technology, was to systematically optimize implant macrostructure parameters (such as implant diameter, length, taper, thread height, thread width, thread pitch, neck taper, end filet, transgingival height) in type B/2 bone by biomechanics consideration. And this study was also to make us a better understanding about the role and effect order of each implant macrostructure parameter in biomechanics transmission. At the same time, present study was designed to provide us the detailed macrostructure parameters that were necessary to develop implant product and provided us the theoretical references for the clinical design and selection of dental implant.In 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 software. 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.In experiment 2, 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 77.4% and 68.4% respectively with D and L increasing. And under BL load, those decreased by 64.9% and 82.8% respectively. The Max displacement of implant-abutment complex decreased by 56.9% and 78.2% under AX and BL load respectively. When D exceeded 3.9mm and L exceeded 9.5mm, 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 more easily by implant diameter than implant length. Implant diameter exceeding 3.9mm and implant length exceeding 9.5mm are optimal selection for a cylinder implant.In experiment 3, implant taper (T) was set as DV. T ranged from 0°to 2.5°. OBJ setting 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 11.1% and 22.2% respectively with T decreasing. And under BL load, those decreased by 12.0% and 16.6% respectively. The Max displacement of implant-abutment complex decreased by 12.6% and 12.4% under AX and BL load respectively. When T was less than 1.2°, the tangent slope rate of OBJ response curves ranged from -1 to 0. The results imply that implant taper less than 1.2°is optimal selection for dental implant.In experiment 4, implant neck taper (T) and end fillet (R) were set as DV. T ranged from 45°to 75°, and R ranged from 0.5mm to 1.5mm. OBJ setting 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 71.6% and 11.0% respectively with T and R variation. And under BL load, those decreased by 69.2% and 14.8% respectively. The Max displacement of implant-abutment complex decreased by 9.1% and 22.8% under AX and BL load respectively. When T ranged from 64°to 73°and R exceeded 0.8mm, the tangent slope rate of OBJ response curves ranged from -1 to 1. The OBJ were more sensitive to T than to R. The results imply that implant neck taper ranging from 64°to 73°and end fillet exceeding 0.8mm are optimal selection for a cylinder implant.In experiment 5, implant thread height (H) and thread width (W) of implant were set as DV. H ranged from 0.2mm to 0.6mm, and W ranged from 0.1mm to 0.4mm. OBJ setting 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 4.1% and 38.7% respectively with H and W variation. And under BL load, those decreased by 16.4% and 54.1% respectively. The Max displacement of implant-abutment complex decreased by 46.0% and 35.2% under AX and BL load respectively. When H ranged from 0.33mm to 0.48mm and W ranged from 0.18mm to 0.30mm, the tangent slope rate of OBJ response curves ranged from -1 to 1. The OBJ were more sensitive to H than to W. The results imply that the stresses in jaw bone and stability of implant are affected more easily by thread height than thread width. Thread height ranging from 0.33mm to 0.48mm and thread width ranging from 0.18mm to 0.30mm are optimal selection for a screwed implant.In experiment 6, thread pitch (P) was set as DV. P ranged from 0.5mm to 1.6mm. OBJ setting and evaluation were same as experiment 3. The results showed that, under AX load, the Max EQV stresses in cortical and cancellous bones decreased by 6.7% and 55.2% respectively with P variation. And under BL load, those decreased by 2.7% and 22.4% respectively. The Max displacement of implant-abutment complex decreased by 22.3% and 13.0% under AX and BL load respectively. When P exceeded 0.8mm, the tangent slope rate of OBJ response curves ranged from -1 to 1. The results imply that thread pitch exceeding 0.8mm is optimal selection for a screwed implant.In experiment 7, twelve 3D FEA models with an implant of different thread shape were created: three square designs (S), three V-shaped designs (V), three buttress designs (B), and three reverse buttress designs (R). The stress distributions in jaw bones and Max displacement of implant-abutment complex were compared. The results showed that, under AX load, S-2, V-3, B-3, R-1, R-2, and R-3 showed better stress distribution than others. And under BL load, S-1, S-2, V-3, B-3, R-2, and R-3 showed better stress distribution than others. The results imply that S-2, V-3, B-3, R-1, R-2, and R-3 thread shapes all appear to be suitable for use in a cylinder implant.In experiment 8, three 3D FEA models with an implant of single-thread, double-thread, and triple-thread were created. The Max EQV stresses in jaw bones and Max displacement of implant-abutment complex were compared. The results showed that, under AX load, the Max EQV stresses in cortical bone and cancellous bone of double-thread implant increased by 10.4% and 9.2% compared with that of single-thread implant respectively. Under BL load, the Max EQV stresses in cortical bone of double-thread implant increased by 9.1% and Max EQV stresses in cancellous bone of triple-thread implant decreased by 14.2% compared with that of single-thread implant respectively. The results imply that single-thread implant appears to be suitable for use in a screwed implant.In experiment 9, implant transgingival height (H) was set as DV. H ranged from 1.0mm to 0.4mm. OBJ setting and evaluation were same as experiment 3. The results showed that, under BL load, the Max EQV stresses in cortical and cancellous bones decreased by 17.3% and 18.5% respectively with H variation. And under AX load, the Max EQV stresses in cortical bone decreased by 4.7%. The Max displacement of implant-abutment complex decreased by 4.1% and 48.9% under AX and BL load respectively. When H ranged from 1.7mm to 2.8mm, the tangent slope rate of OBJ response curves ranged from -1 to 1. The results imply that implant transgingival height ranging from 1.7mm to 2.8mm is optimal selection for a cylinder implant.To conclude, the effect order of each implant macrostructure parameter in biomechanics transmission are shown as follows: implant diameter, length, thread height, neck taper, thread pitch, transgingival height, taper, thread width, end fillet. The range of optimum macrostructure parameters are: implant diameter exceeding 3.9mm, length exceeding 9.5mm, thread height ranging from 0.33mm to 0.48mm, neck taper ranging from 64°to 73°, thread pitch exceeding 0.8mm, transgingival height ranging from 1.7mm to 2.8mm, taper less than 1.2°, thread width ranging from 0.18mm to 0.30mm, and end fillet exceeding 0.8mm.更多还原