种植体直径和长度对支持组织应力分布的影响

目的：观察种植体直径、长度变化时由种植体支持的下颌种植覆盖义齿,在牙合力作用下其支持组织——牙槽骨及种植体周围的应力分布状况,探讨种植体长度和直径变化对支持组织应力分布的影响规律。方法：用三维光弹应力冻结切片法,对４种不同长度,３种不同直径的种植体支持的种植覆盖义齿,在牙合力作用下的应力状况进行应力冻结,并在相应部位切片观察,以了解各种状况下其支持组织的应力分布状况。结果：种植体长度变化对种植体周围骨界面及牙槽骨应力的大小有较大的影响,两者呈负相关关系;而在临床常用的几种直径种植体中,直径变化对种植体周围骨界面及牙槽骨应力的影响不大。结论：在种植义齿设计时,应着重考虑种植体长度变化对种植体周围骨界面及牙槽骨应力的影响,种植体直径变化可不作考虑。     

种植体数目对支持组织应力分布的影响

目的：了解不同数目骨融合种植体所支持的下颌覆盖义齿,在承受牙合力时其支持组织——牙槽骨及种植体周围的应力分布状况,探讨种植体数目变化对支持组织应力分布的影响规律。方法：应用三维光弹应力冻结切片法,对分别由２、４、６颗种植体所支持的下颌覆盖义齿,在垂直载荷下的应力状况进行冻结,并在相应部位切片观察,以了解在几种不同情况下的覆盖义齿的内部应力分布规律。结果：在不同数目种植体为基牙的覆盖义齿中,牙槽骨及种植体骨界面的应力值随着种植体数目的增加而减少,两者呈负相关关系。结论：在条件允许的情况下,应尽可能多地选用种植基牙。     

不同连接设计种植全口义齿的三维光弹应力分析

目的：研究常规半口义齿、种植杆卡覆盖义齿及种植固定义齿在牙合力作用下其支持组织——牙槽骨及种植体周围的应力分布状况。方法：用三维光弹应力冻结切片法,对在牙合力作用下的应力状况进行应力冻结,并分别在切牙区、尖牙区、前磨牙区、第一磨牙区、第二磨牙区作３ｍｍ厚切片;并在４颗种植体周围作包含种植体的５ｍｍ厚切片,分析其内部的应力分布状况。结果：种植覆盖义齿的种植体周围骨界面,牙槽骨的应力值均比常规义齿及种植固定义齿低,无论是哪种形式的种植义齿,都易发生远中种植体受力过大而松动。结论：种植覆盖义齿具有良好的力学特性;在义齿设计时应采取措施保护远中种植体。     

种植体数目与分布对下颌种植覆盖义齿骨组织应力变化的影响

目的：建立下颌种植覆盖义齿三维有限元模型,研究咬合力作用下种植体数目与位置分布对牙槽骨组织应力分布的影响因素。方法：临床采集患者下颌骨及其原有义齿CT数据,使用逆向工程软件建立种植体数目与位置不同的下颌种植覆盖义齿实体模型。通过Abaqus有限元软件分析咬合力作用下种植体数目与位置分布对种植体周围以及下颌后端牙槽骨应力变化的影响。结果：在咬合力作用下,下颌骨Mises应力主要分布在种植体周围骨组织,种植体远中颈部呈现应力集中,下颌后端区域应力较小且分布均匀。随着种植体数目的增加,后端种植体周围骨应力上升,远端牙槽骨应力降低。当牙弓前、后端种植体距离增加时,种植体周围骨应力增大,远端牙槽骨应力降低。结论：采用2植体支持的下颌种植覆盖义齿种植体周围骨吸收风险较小,但远端牙槽嵴骨吸收风险增大。4植体义齿所承受的咬合力主要由植体承担,修复时应注意前后植体的距离和咬合力在义齿上的合理分布。     

无牙颌一侧上颌骨缺抽种植修复设计的准三维光弹应力分 …

目的：了解种植体数目和植入部位对赝复体支持组织应力分布的影响。方法：采用三维光弹应力冻结切片法,对应用种植杆卡式赝复体修复无牙颌一侧上颌骨缺损的不同种植体数目（２、４或６个）和不同种植部位在生趣载荷下的应力进行冻结,并在相应部位切片观察。结果：发现腭部、牙槽骨、种植体周围骨界面的应力值与种植体的数目呈负相关。结论：对此类缺损的修复,应在切牙区、尖牙区、前磨牙区、磨牙区植入４只种植体为宜。     

无牙颌一侧上颌骨缺损种植修复设计的准三维光弹应力分析(Ⅰ)--种植体数目和植入部位对赝复体支持组织应力分布的影响

目的：了解种植体数目和植入部位对赝复体支持组织应力分布的影响。方法;采用三维光弹应力冻结切片法,对应用种植杆卡式赝复体修复无牙颌一侧上颌骨缺损的不同种植体数目（２、４或６个）和不同种植部位在垂直载荷下的应力进行冻结,并在相应部位切片观察。结果：发现腭部、牙槽骨、种植体周围骨界面的应力值与种植体的数目呈负相关。结论：对此类缺损的修复,应在切牙区、尖牙区、前磨牙区、磨牙区植入４只种植体为宜。     

口腔种植学

种植体-基台连接形式对种植体周围骨组织应力分布的影响;Ankylos SynCone基台覆盖义齿即刻种植修复的护理配合;圆柱形螺纹种植体螺纹的优化设计和应力分析;天然牙-种植体联合支持式固定义齿的临床观察;牙种植外科骨收集器内骨碎屑成骨活性的研究     

无牙颌一侧上颌骨缺损种植修复设计的准三维光弹应力分 …

目的：采用三维光弹应力冻结切片法对杵臼附着体、杆卡附着体种植固位设计,在功能状态下种植体及支持组织应力分布状况进行评价。方法：在无牙颌一侧上颌骨缺损的光弹性模型中于１、３、５和７位植入４个种植体,分别设计杵臼式和杆卡式附着体,在单侧和双侧垂直向载荷下观察种植体及其支持组织的应力分布状况。结果：发现杵臼附着式固位的种植赝复体在行使功能时其腭部、牙槽骨、种植体周围骨界面的应力值均远高于杆卡附着式固位的     

全下颌牙种植义齿及支持组织应力的三维有限元分析Ⅵ.不同上部结构对覆盖种植义齿应力分布的影响

采用三维有限元方法 ,考察了不同的上部结构设计 ,包括套筒冠、杆卡式附着体、改良杆卡式附着体对全下颌种植覆盖义齿及其支持组织在正中情况下应力分布的影响。结果发现杆卡式附着体的使用可降低种植体及剩余牙槽嵴表面的应力 ,但使界面应力增加。改良杆卡式附着体不利于种植体及骨界面的应力分布。     

球帽式与套筒冠式下颌种植覆盖义齿的三维有限元分析

目的:应用三维有限元分析,比较球帽式和套筒冠式附着体对下颌种植覆盖义齿的应力分布的影响。方法:本实验应用三维有限元法分析,模拟下颌覆盖义齿在正中咬合状态下的受力情形。结果:两种模型中,骨组织界面应力主要都集中在种植体颈部周围的皮质骨中。球帽式附着体模型中牙槽嵴表面上的最大压应力峰值为-1.601Mpa,而套筒冠式附着体模型的压应力峰值为-0.296Mpa。套筒冠式附着体模型的中央种植体、侧方种植体上的应力峰值均小于球帽式附着体的种植体。结论:套筒冠式覆盖义齿较球帽式可降低种植体及剩余牙槽骨表面的应力,更有助于保存牙槽骨组织和种植体。     

种植全口义齿的三维有限元分析--种植体颈狭部直径对应力的影响

目的：研究种植体颈狭部直径变化对种植全口义齿及其支持组织应力状况的影响。方法：用三维有限元方法,按义齿连接设计的不同,分析比较种植体颈狭部直径为４ｍｍ与２ｍｍ、１ｍｍ时的种植全口义齿应力状况。结果：种植全口固定义齿的种植体颈狭部直径由４ｍｍ减少到１ｍｍ时,种植体中的应力峰值增加了约５７３％;种植全口覆盖义齿的种植体颈狭部直径由４ｍｍ减少２ｍｍ时,种植体中的应力峰值增加了约１０３％;上述直径变化对骨界面、基托、人造牙列及粘膜应力影响不大。结论：改进种植体颈狭部设计、增加其直径,对降低应力峰值、减少其折断发生率有重要意义。     

Magnitude and direction of mechanical stress at the osseointegrated interface of the microthread implant

Background: The mechanism by which the microthread implant preserves peri‐implant crestal bone is not known. The objective of this research is to assess the effect of microthreads on the magnitude and direction of the stress at the bone–implant interface using finite element analysis modeling. Methods: Three‐dimensional finite element models representing the microthreaded implant (microthread model) and smooth surface implant (smooth model) installed in the mandibular premolar region were created based on microscopic and computed tomography images. The mesh size was determined based on convergence tests. Average maximum bite force of adults was used with four loading angles on the occlusal surface of the prosthesis. Results: Regardless of the loading angle, principal stresses at the bone–implant interface of the microthread model were always perpendicular to the lower flank of each microthread. In the smooth model, stresses were affected by the loading angle and directed obliquely to the smooth interface, resulting in higher shear stress. The interfacial stresses decreased gradually in the apical direction in both models but with wavy pattern in the microthread model and smooth curve for the smooth model. Although peak principal stress values were higher around the microthread implant, peri‐implant bone volume exhibiting a high strain level >4,000 μ was smaller around the microthread implant compared to the smooth implant. Conclusion: Stress‐transferring mechanism at the bone–implant interface characterized by the direction and profile of interfacial stresses, which leads to more compressive and less shear stress, may clarify the biomechanical aspect of microthread dental implants.     

无牙下颌固定种植义齿带末端悬臂的应力分析

目的:比较不同悬臂设计下颌种植支持全口义齿的骨及种植体应力分布特点,为临床种植修复提供生物力学分析依据。方法:建立3组下颌6个种植支持全口义齿的三维有限元模型,悬臂分别为3、6、9 mm。在悬臂末端垂直加载100 N的力。结果:种植全口义齿悬臂末端垂直加载时,末端种植体骨应力集中,易发生松动失败;末端种植体及中间种植体颈部应力集中,易发生植入体与基桩连接失败;连梁应力集中在与末端种植体连接处,此处易发生折断。悬臂长度增加骨应力、种植体应力及连梁应力明显增加。结论:悬臂越短越有利于力的均匀分布。6个种植体支持短悬臂修复设计较符合生物力学分布原理。     

不同螺距种植体集中载荷的有限元分析

目的:用三维有限元方法分析不同螺距种植体-骨界面应力分布状况,确定利于应力均匀分布的最佳螺纹参数设计.方法:建立包含上部结构的牙种植体、局部下颌骨块三维有限元模型,利用Cosmos/works软件分析在垂直、斜向45° 2 种集中载荷下螺距分别为0.6、 0.8、 1.0 mm的3 种种植体与骨界面的应力分布状况.结果:螺距为0.8 mm种植体周围Von-Mises应力、拉应力、压应力峰值较小,应力分布最均匀;同一螺距种植体斜向载荷下应力显著高于垂直载荷;应力集中主要出现于种植体颈部、皮质骨上缘和种植体末端最下一个螺纹处.结论:螺纹种植体螺距影响骨界面的应力分布和(牙合)力传导,为避免应力集中种植体末端螺纹应进行适当的截齿处理,种植义齿设计和修复时应尽可能减小或避免非轴向力.     

The influence of implant location and length on stress distribution for three-unit implant-supported posterior cantilever fixed partial dentures

STATEMENT OF THE PROBLEM: The influence of implant location for an implant-supported cantilever fixed partial denture (FPD) on stress distribution in the bone has not been sufficiently assessed. PURPOSE: This study examined the influence of location and length of implants on stress distribution for 3-unit posterior FPDs in the posterior mandibular bone. MATERIAL AND METHODS: Each 3-D finite element model included an FPD, mesial and distal implants, and supporting bone. The mesial implant with a length of 10 mm or 12 mm was placed in locations where its long axis was 3 mm to 11 mm posterior to the remaining first premolar. The distal implant with a length of 10 mm was fixed at the same distance from the premolar on each model. A buccally-oriented oblique occlusal force of 100 N was placed on each occlusal surface of the FPD. RESULTS: The maximum equivalent stresses were shown at the cervical region in the cortical bone adjacent to the mesial or the distal implants. Relatively high stresses of up to 73 MPa were shown adjacent to the mesial implant located 9 mm or more posterior to the first premolar. The use of a 12-mm-long mesial implant demonstrated a relatively weak influence on stress reduction. CONCLUSION: The implant location in the cantilever FPDs was a significant factor influencing the stress created in the bone.     

Influence of implant length and bicortical anchorage on implant stress distribution

Background: Short implants present superior failure rates for everybody. Purpose: The aim of this theoretic study was to assess to what extent implant length and bicortical anchorage affect the way stress is transferred to implant components, the implant proper, and the surrounding bone. Materials and Methods: Stress analysis was performed using finite element analysis. A three‐dimensional linear elastic model was generated. All implants modeled were of the same diameter (3.75 mm) but varied in length, at 6, 7, 8, 9, 10, 11, and 12 mm (Branemark System®, Nobel Biocare AB, Gothenburg, Sweden). Each implant was modeled with a titanium abutment screw and abutment, a gold cylinder and prosthetic screw, and a ceramic crown. The implants were seated in a supporting bone structure consisting of cortical and cancellous bone. An occlusal load of 100 N was applied at a 30° angle to the buccolingual plane. Results: With the selected model and bone properties, the coronal cortical anchorage was dominating, and the bone stress concentrated to that area. Conclusions: The maximum bone stress was virtually constant, independent of implant length and bicortical anchorage. The maximum implant stress, however, increased somewhat with implant length and bicortical anchorage.     

Two dental implants designed for immediate loading: a finite element analysis

PURPOSE: The aim of this study was to evaluate by finite element analysis the influence of the design of 3 different dental implants on micromovements, cervical shearing stress intensity, and stress distribution after occlusal loading. MATERIALS AND METHODS: The first investigated implant was a classical cylinder, the second was reinforced by 2 bicortical locking pins, and the third was an expanding dental implant. The parameters analyzed were the implant's geometry, the quality of the cancellous bone, and the orientation of occlusal loading. RESULTS: It was found that initial stability of the locking pin implant was greater than the initial stability of the other investigated implant designs, regardless of the quality of cancellous bone and orientation of occlusal loading; in low-rigidity cancellous bone, under a horizontal load (500 N), decreasing displacement compared to those of the other investigated implants was 16 microm. The apical expansion and locking pin implants exhibited favorable behavior regarding the distribution and intensity of cervical shearing stresses; in low-rigidity cancellous bone, under horizontal load, decreasing cervical stresses compared with those of the cylindric implant were 10 MPa for the apical expansion implant and 150 MPa for the locking pin implant. DISCUSSION: For the cylindric implant, stresses were concentrated in the neck region; for the apical expansion implant, stresses were evenly distributed from the neck to the apex of the implant. For the locking pin implant, stresses around the neck were moderate and appeared concentrated around the pins. CONCLUSIONS: Initial stability of the pin implant was greater than that of the expanding implant, but the expanding implant showed the most favorable stress distribution.