4 种表面形态种植体对支持组织应力分布的影响

目的：观察４种常见不同形态种植体所支持的下颌覆盖义齿,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,从生物力学角度为种植体形态设计提供参考。方法：用三维光弹应力冻结切片法,对光滑圆柱形、光滑圆锥形、螺纹圆柱形、螺纹圆锥形４种不同形态种植体所支持覆盖义齿,在牙合力作用下的应力状况进行应力冻结,并在相应部位进行切片观察,以了解不同情况下其支持组织的应力分布状况。结果：种植体不同的表面形态对支持组织应力分布有较大影响,圆柱形种植体比圆锥形种植体,带螺纹种植体比光滑种植体其牙槽骨及骨界面应力值小。结论：不同表面形态的种植体对种植体骨界面及牙槽骨的应力会产生不同的影响。     

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。     

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     

杆卡附着体下颌种植覆盖义齿牙槽骨的三维光弹应力分析

目的：研究杆卡附着体下颌种植覆盖义齿在各种咬合状态时下颌牙槽骨的应力分布。方法：制作杆卡附着体下颌种植覆盖义齿光弹模型,采用三维冷冻光弹法分析正中、前伸、侧向咬合状态下种植体周围与余留牙槽嵴的应力。结果：三种咬合状态下,种植体颈部和尖周牙槽骨应力值较大,尖周应力值大于颈部应力值;余留牙槽嵴最大应力值出现在磨牙区。侧向牙合工作侧各牙位切片的最大应力值出现于唇颊侧,平衡侧各牙位切片的最大应力值出现于舌侧;前伸牙合侧切牙区唇侧应力最大,中线区及后牙区应力最大值出现于舌侧。结论：杆卡式种植覆盖义齿在正中、前伸、侧向咬合状态下,种植体周围骨组织应力值较大,不利于种植体的健康,因此应用杆卡式附着体时,可考虑增加种植体,扩大基托面积,依据平衡牙合排牙以分散牙合力。     

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。     

磁性附着体下颌种植覆盖义齿牙槽骨的三维光弹应力分析

目的：研究磁性附着体下颌种植覆盖义齿在各种咬合状态时下颌牙槽骨的应力分布。方法：选取标准无牙颌模型,在双侧尖牙区植入种植体,连接磁性附着体,翻制下颌环氧树脂模型,制作生物功能性全口义齿,分别在正中、前伸、侧向咬合时加载应力,冻结切片,观测各牙位应力条纹。结果：磁性附着体下颌种植覆盖义齿在正中、侧向、前伸咬合应力加载时种植体周围牙槽骨应力值最大,余留牙槽嵴后牙区所受应力大于前牙区。正中、前伸磨牙区最大应力值出现于颊侧,切牙区最大应力值出现于舌侧。侧向工作侧最大应力值出现于唇颊侧,平衡侧最大应力值出现于舌侧。结论：磁性附着体种植覆盖义齿各向咬合时,应力既分布到种植体,也分布到剩余牙槽嵴,可以明显降低种植体周围骨组织的受力,有利于种植体的健康。     

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。     

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目的系统地分析和比较支抗种植体骨内段的直径、长度和锥度(锥体直径/锥体长度)对种植体与骨界面应力分布的影响及相互作用。方法2007年10月至2008年12月在烟台市口腔医院、山东大学机械工程学院,通过三因素两水平析因设计建立包含不同直径、主体长度和锥度的支抗种植体的上颌骨前磨牙区域骨块模型共8个,分别对种植体施加1.96N(200gf)与种植体成90°角的拉力,得到8种植体与骨界面的VonMises应力。比较三种设计因素(直径、长度、锥度)对种植体与骨界面应力分布的影响及相互作用关系。结果随着种植体直径和锥度的增加,骨组织内的应力明显降低,具有统计学意义。种植体长度的改变对应力的影响则不具有统计学意义。结论使用直径较粗、具有锥度的种植体可以降低种植体周围骨界面应力。     

冲击载荷下下颌种植覆盖总义齿与下颌常规总义齿应力分布特点的比较研究

目的比较分析下颌种植覆盖总义齿及下颌常规总义齿的应力分布特点。方法应用ＣＴ扫描法建立下颌种植覆盖总义齿及下颌常规总义齿的三维有限元模型,并采用更为接近　力性质的冲击载荷,将咀嚼动态过程引入有限元研究,比较分析两种义齿应力分布特点。结果①种植体内部应力最大值出现于侧方种植体内,骨界面及软组织界面应力最大值出现于侧方种植体远中舌侧皮质骨及粘骨膜内;②下颌种植覆盖总义齿种植体的应用降低了剩余牙槽嵴表面压应力峰值;③下颌常规总义齿及种植覆盖总义齿基托应力峰值分别出现于前牙区舌侧基托及侧方种植体顶部基托处。结论①下颌种植覆盖总义齿机械并发症易发生于侧方种植体内及侧方种植体骨界面处;②种植体的应用有利于保护剩余牙槽嵴,减缓骨吸收;③二种义齿基托易折部位不同。     

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.     

Biomechanical Evaluation of Tooth‐ and Implant‐Supported Fixed Dental Prostheses with Various Nonrigid Connector Positions: A Finite Element Analysis

Purpose: In the tooth‐ and implant‐supported fixed dental prosthesis (FDP), rigid and nonrigid connector (NRC) designs have been preferred by clinicians for many years. The aim of this study was to analyze the stress distribution on the connecting areas of the superstructure and supporting structure of the tooth‐ and implant‐supported FDP designs under both static vertical and oblique occlusal loads. Materials and Methods: Four 2D finite element analysis (FEA) models were prepared presuming that the first and second molars were missing, and that the implant (3.80‐mm diameter × 13‐mm length) was placed in the second molar NRC design and patrix‐matrix position supported by teeth/implants. Nonlinear contact elements were used to simulate a realistic interface fixation within the implant system and the sliding function of the NRC. Supporting periodontal ligament and alveolar bone (cortical and trabecular) were also modeled. Linear static analysis was performed on the prepared 2D solid models with a total masticatory force of 250 N (50 N for premolar, 100 N for first molar, 100 N for second molar), 0° (at a right angle) and 30° to the long axis of the supports. The maximum equivalent Von Mises (VM_Max) was analyzed around the supporting teeth/implant and connector areas on tooth‐ and implant‐supported FDP. Results: The simulated results indicated that the highest level of VM_Max (400.377 MPa) was observed on the NRC with the matrix positioned on the implant site of tooth‐ and implant‐supported FDP under vertical occlusal load. The highest level of VM_Max (392.8 MPa) under oblique occlusal load was also observed on the same model; however, the lowest VM_Max value around implants was observed with the NRC when the patrix was positioned on the implant site of the FDP. Under vertical occlusal loads, in designs where the NRC was placed on the implant site, the stress formed around the implant decreased when compared to the designs where the NRCs were positioned on the tooth site. Conclusions: The efficiency of the NRC exhibited varying behavior depending on the direction of the load applied. The use of the patrix part of the NRC on the implant site may be more efficient in reducing the stress formation around the implant.     

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。     

Effect of Compromised Cortical Bone on Implant Load Distribution

Purpose: To investigate photoelastically the difference in load distribution of dental implants with different implant neck designs in intact and compromised bone. Materials and Methods: Composite photoelastic models were fabricated using two different resins to simulate trabecular bone and a 1‐mm thick layer of cortical bone. The following parallel‐sided, threaded implants were centrally located in individual models representing intact and compromised cortical bone: Straumann (4.1‐mm diameter × 12‐mm length), AstraTech (4.0‐mm diameter × 13‐mm length), and 3i (3.75‐mm diameter × 13‐mm length). The compromised cortical bone condition was simulated by contaminating a 1‐mm neck portion with Vaseline to impair the implant–resin interface. Vertical and oblique static loads were applied on the abutments, and the resulting stresses were monitored photoelastically and recorded photograhphically. Results: For the fully intact condition, the highest stresses were observed around the crest and apical region for all implant designs under vertical and inclined loads. There were no appreciable differences in magnitude or distribution between implant types. With compromised cortical bone, for all designs and load directions, higher stresses in the supporting structures were observed. Increased stresses were noted especially at the cortical bone–trabecular bone interface. Somewhat lower stress levels were observed with the 3i implant. Conclusions: The condition of implant–cortical bone contact has considerable influence on stress distribution. A compromised cortical bone condition caused higher level stresses for all implant designs tested.