支抗种植体外形对骨界面应力分布的影响

目的：探讨三种圆柱状支抗种植体外形差异对骨界面应力分布的影响，以筛选最佳支抗种植体。方法：用三维有限元方法给种植体施加150g近远中方向的载荷，分别对刃状螺纹型、矩形螺纹型及光滑型支抗种植体-骨界面进行应力和位移分析。结果：三种种植体颈部的Von-Mises应力值分别为0．5330MPa、1．1600MPa、0．8900MPa；位移分别为0．1630μm、0．1690μm、0．1460μm。结论：刃状螺纹种植体做支抗时，其颈部应力值最低，而三种种植体颈部的齿槽骨位移差异不显著，敌刃状螺纹型种植体比较适合做支抗种植体。     

支抗种植体不同螺纹顶角对骨界面应力分布的影响

目的 研究刃状螺纹型支抗种植体的螺纹顶角改变对骨界面应力分布的影响,以供临床筛选合适的支抗种植体。方法 用三维有限元方法给种植体施加150g近远中方向的载荷,分别对螺纹顶角为60°、75°、120°的三种支抗种植体-骨界面进行应力分析。结果 三种螺纹顶角种植体颈部的Von-Mises应力值分别为0.533 0 MPa、0.632 0 Mpa、0.591 0 Mpa;位移值分别为0.1630μm、0.1590μm、0.1520μm。结论 螺纹顶角为60°的种植体适合作正畸支抗体。     

皮质骨厚度对支抗种植体-骨界面应力分布的影响

目的：研究皮质骨厚度改变对支抗种植体-骨界面应力分布的影响，供临床参考。方法：用三维有限元方法，对分别种植于皮质骨厚度为0．5mm、1．0mm、2．0mm颌骨模型中的种植体施加150g近远中方向的载荷，分析支抗种植体-骨界面应力分布情况：结果：三者种植体颈部的Von-Mises应力值分别为0．6040MPa、0．5330MPa、0．5380MPa；位移值分别为0．2110μm、0．1630μm、0．1250μm：结论：皮质骨在一定厚度内，植入体颈部皮质骨越薄，骨界面应力值就越大：但皮质骨超过一定厚度后，骨界面应力并不随其厚度的增加而做相应递减。皮质骨的厚度与界面骨的位移成反比.     

支抗种植体长度对骨界面应力分布的影响

目的：研究不同长度支抗种植体对骨界面应力分布的影响，以供临床筛选合适的种植体。方法：用三维有限元方法给种植体施加150g近远中方向的载荷，分别对长度为7mm、10mm、15mm的支抗种植体-骨界面进行应力分析。结果：三种长度种植体颈部的Von-Mises应力值分别为0．5450MPa、0．5330MPa、0．5320MPa；位移值分别为0．1690μm、0．1630μm、0．1610μm。结论：在种植体承受侧向力载荷时，增加种植体长度可提高其承载能力，临床上在选择正畸支抗种植体时，应尽量选择长种植体作正畸支抗体。     

骨质量和种植体螺纹对种植稳定性影响的三维有限元分析

目的:探讨骨质量和种植体螺纹对种植体稳定性的影响。方法:建立三角型和锯齿型螺纹种植体植于4种骨类型下颌骨的三维有限元模型8个,种植体顶部中心节点加垂直和45°倾斜力200N,分析种植体的位移和界面骨的应力分布。结果:随骨弹性模量的减小,界面骨应力和种植体位移均增加;锯齿型螺纹种植体的位移都小于三角型,斜向力在4种骨和垂直力在Ⅳ类骨中锯齿型的应力小于三角型。结论:骨类型和螺纹形态都影响种植体的稳定性。骨质越好种植体越稳定,界面骨应力越小;锯齿型螺纹种植体的稳定性比三角型螺纹好。     

种植体螺纹形状对骨界面应力分布的影响

目的研究种植体表面不同螺纹形状对种植体-骨界面应力分布的影响,以供临床筛选合适的种植系统。方法采用三维有限元法,分别对种植体施加30牛顿垂直和斜向45°两种方向的集中载荷,对不同螺纹顶角螺纹形状分别为对称、上平下斜、上斜下平的种植体-骨界面进行应力分析。结果螺纹形状为上平下斜式种植体的应力峰值较小;各组模型的最大位移值相近,但螺纹形状对称、顶角为30°者位移极值最小,为3.84×10-4mm和85.61×10-4mm。结论螺纹形状对种植体-骨界面的应力分布有影响,设计和选择种植系统时应全面考虑。     

包含真实螺纹形态的牙种植体三维有限元模型的建立

目的：建立包含真实螺纹形态的牙种植体三维立体有限元模型，为深入研究螺纹型牙种植体骨界面力学规律和种植体的外形优化设计提供模型支持。方法：采用画图软件SolidWorks绘出螺纹型牙种植体和局部下颌骨骨块三维立体模型，利用ABAQUS有限元分析软件，建立三维有限元模型：对种植体上端施加一斜向载荷，分析骨块内应力、应变分布情况。结果：建立了与螺纹型牙种植体实体相一致的三维有限元模型，施加载荷，确定应力、应变的大小及分布。结论：探索了一种可行的建立包含真实螺纹形态的种植体三维立体有限元模型的方法，建立的种植体有限元模型与实体具有高度的相似性，可用于研究螺纹型种植体骨界面应力、应变的分布规律，并为种植体螺纹形态的力学优化设计研究提供模型支持。     

种植体颈部微螺纹结构对种植稳定性影响的三维有限元分析

目的：通过分析种植体颈部螺纹结构,以及Von-Mises应力和应变分布情况,为种植体结构设计提供生物力学实验数据和理论参考依据。方法：本文通过运用三维计算机辅助设计CAD软件,设计建立颈部有螺纹和无螺纹三维种植体模型,利用CT扫描数据重建下颌骨三维模型,牙齿咬合面与上颌骨长轴面形成的倾角为45。,沿此方向施加120N的力作用在牙冠顶部,以模拟实际咬合状态受力。利用有限元分析软件模拟即刻负荷（即骨一种植体之间摩擦系数0．3）和骨愈合后期（即骨一种植体之间为绑定接触）两种加载情况下种植体与周围骨组织之间Von-Mises应力和应变峰值大小及分布状况进行比较和分析。结果：在即刻负荷的条件下,Von-Mises应力、应变在颈部光滑的种植体与皮质骨之间分布均匀,峰值分别为28．654MPa、0．01334mm;而颈部有螺纹种植体与皮质骨之间的Von-Mises应力、应变峰值分别为52．630MPa、0．015864mm。在骨愈合后期,颈部光滑的种植体,在相同咬合力作用下,皮质骨Von-Mises应力、应变峰值分别为36．975MPa、0．010272mm;而具有颈部螺纹设计的种植体所引起的Von-Mises应力、应变峰值分别为35．857MPa、0．010234mm。在骨愈合后期,增加种植体颈部的螺纹设计使得皮质骨所受Von-Mises应力减小1．118MPa、应变峰值也有减小的趋势。结论：即刻负载种植时,增加种植体颈部螺纹结构,在种植体一骨愈合后期,颈部的微螺纹结构可使种植体一骨接触界面的Von-Mises应力和应变峰值有所减小,并且有效改善了接触界面的应力分布状况,有助于其长期稳定性及种植成功率的提高。     

不同形态种植体与颌骨结合强度的研究

目的 :研究三种形态的钛合金种植体与骨的结合强度。方法 :成年杂种雄犬4只 ,分别拔除其双侧下颌3颗前磨牙 ,每侧拔牙窝内即刻种植螺纹状、圆柱状、叶状种植体各1枚 ,共24枚。于手术后6个月处死动物。摄X线片观察 ,并通过推出实验和轴向拉出实验测试种植体 -骨界面的结合强度。结果 :三种种植体和骨界面X线表现相似 ,均无骨质破坏 ;螺纹状种植体与骨的结合强度要高于圆柱状和叶状种植体 (P<0.05) ,后两者无显著差异。结论 :三种种植体和骨均可形成较好的结合 ,其中以螺纹状种植体和骨的结合强度较好。     

正畸力作用方向对支抗种植体-骨界面应力分布的影响

目的：研究正畸力不同作用方向对种植体-骨界面应力分布的影响，以指导临床选择合适方向的正畸载荷。方法：用三维有限元方法给种植体施加150g近远中向、颊舌向及轴向载荷。对支抗种植体一骨界面进行应力分析。结果：三种方向载荷下种植体颈部，(1）Von—Mises应力值分别为：(a)近远中向——0．5330MPa；(b)颊舌向——颊侧为0．51520MPa，舌侧为0．6470MPa；(c)龈he向——颊侧为0．0702MPa，舌侧为0．0791MPa，近远中向为0．0517MPa。(2)位移值分别为：(a)近远中向——0．1630μm；(b)颊舌向——颊侧为0．2070μm，舌侧为0．1950μm；(c)龈he向——颊侧为0．0496μm，舌侧为0．0467μm，近远中向为0．0484μm。结论：在植入支抗种植体时。应根据正畸载荷力的形式．适当调整种植体的部位，尽量不要过于偏颊、舌侧，以免造成应力的过分集中，导致骨组织损伤。     

微小种植体正畸支抗生物力学的三维有限元分析

目的:建立微小种植体正畸支抗的三维有限元模型,分析以不同倾斜角度植入微小种植体时,种植体-骨界面的生物力学变化,为微小种植体正畸支抗系统的设计和临床应用提供理论依据。方法:利用ANSYS6.1大型通用有限元分析软件,建立倾斜角度分别为30°、40°、50°、60°、70°、80°、90°的7个微小支抗种植体模型。分析在200g水平力作用下,种植体-骨界面应力及位移的分布情况。结果:随种植体倾斜角度的增大,种植体颈部的Von-Mises应力值峰值分别为1.0792、1.0104、0.8848、0.8181、0.7583、0.6339及0.5608MPa。位移峰值分别为5.5513、4.9900、3.7419、3.1264、2.5874、1.3624及0.8027μm。结论:微小种植体可在任何倾斜角度上承载200g的水平向正畸力。增加种植体的倾斜角度,可以提高其承载水平向正畸力的能力,提示临床应选择垂直于颊侧牙槽骨的方向植入微小支抗种植体。     

Bone stress and interfacial sliding analysis of implant designs on an immediately loaded maxillary implant: a non-linear finite element study

OBJECTIVES: This study investigated the surrounding bone stress and the implant-bone interfacial sliding of implant designs and implant sizes of immediately loaded implant with maxillary sinus augmentation by using three-dimensional (3D) non-linear finite element (FE) analysis. METHODS: Twenty-four FE models including four implant designs (cylindrical, threaded, stepped and step-thread implants) and three implant dimensions (standard, long and wide threaded implants) with a bonded and three levels of frictional contact of implant-bone interfaces were analyzed. The maxillary model was constructed from computer tomography (CT) images of a human skull and all 3D implant models were created via the computer-aided design (CAD) software. RESULTS: The use of threaded implants decreased the bone stress and sliding distance obviously about 30% as compared with non-threaded (cylindrical and stepped) implants. Increasing the implant's length or diameter reduced the bone stress by 13-26%. Employing a immediately loaded implant with smooth machine surface (mu=0.3, mu represents frictional coefficient) increased the bone stress by 28-63% as compared with the osseointegrated (bonded interfaces) implants. Roughening the implant surface (mu>0.3) did not reduced the bone stress, however it did decrease the interfacial sliding between implant and bone. CONCLUSIONS: For an immediately loaded implant placed with sinus augmentation, using threaded implant could decrease both the bone stress and implant-bone sliding distance which may improve the implant initial stability and long-term survival. Rough surface of implants shows no benefit to reduce the bone stress but they could lower the interfacial sliding. On the contrary, employing long or wide implants decrease the bone stress but they cannot diminish the interfacial sliding.     

Peri-implant bone response to orthodontic loading: Part 1. A histomorphometric study of the effects of implant surface design.

INTRODUCTION: Bone response to orthodontic loading was compared histomorphometrically around 2 different types of osseointegrated implants (porous surfaced and machined threaded) to determine their suitability for orthodontic anchorage. METHODS: Five beagles each received 3 implants of each design in contralateral mandibular locations. After a 6-week initial healing period, abutments were placed, and, 1 week later, the 2 mesial implants on each side were orthodontically loaded for 22 weeks. All implants remained osseointegrated throughout orthodontic loading except for 1 threaded implant that loosened. Light miscroscopy and back-scattered scanning electron microscopy were used to compare responses around the 2 implant designs. RESULTS: Porous-surfaced implants had higher marginal bone levels (P +/- .025) and less relative implant displacement than threaded implants. CONCLUSIONS: Differences in implant surface design can lead to differences in peri-implant bone height and bone-to-implant contact. Porous-surfaced implants might be successful as orthodontic anchorage units.     

正畸支抗种植体骨整合与稳定性的实验研究

目的　考察正畸支抗种植体的骨整合与稳定性以及二者之间的关系。方法　将HA涂层钛种植体、钛浆喷涂钛种植体、未涂层钛种植体植入狗股骨 ,愈合期后施加 1 96N正畸力 2个月。测量施力后种植体的位置变化和种植体—骨界面的剪切结合强度 ,用扫描电镜观察界面。结果　 3种种植体位移分别为 (- 0 5 0± 1 78)mm、(- 0 0 5± 1 76 )mm、(0 2 9± 1 77)mm ,统计学分析结果显示 ,还不能认为 3种种植体出现移动。 3种种植体—骨界面的剪切结合强度分别是 (2 88± 0 5 5 )MPa、(1 89± 0 81)MPa和 (2 14± 0 49)MPa。HA涂层种植体与骨紧密结合 ,其界面结合强度最高 ;另外 2种种植体与骨的结合强度差异无显著性。结论　虽然HA涂层种植体与骨结合最牢固 ,但 3种种植体—骨界面均可形成骨整合 ,在常规正畸力作用下不会发生明显移动。本项研究结果表明 ,种植体可用作短期的正畸支抗。     

Biological reactions of alveolar bone to orthodontic loading of oral implants

Enosseous oral implants have been suggested as anchorage for orthodontic appliances in cases where the existing dentition cannot provide sufficient stability. Long-term studies of oral implants have suggested that excessive loading may contribute as an etiologic factor in the pathogenesis of failing implants. The purpose of the present study was to perform a histomorphometric analysis of tissue reactions around implants subjected to a well-defined force system. The analysis was performed on undecalcified sections cut perpendicularly to the long axis of the implant. The degree of osseointegration, bone density at varying distances from the implant as well as the relative extent of resorption and formation of alveolar bone adjacent to the implant-bone interface were evaluated. The results were correlated with the local strain of the tissue estimated by the means of a finite element analysis. It was found that loading significantly influenced both the turnover and the density of the alveolar bone in the proximity of the implants. However, even unloaded implants tended to maintain the bone characteristics of the alveolar process. On the other hand, the degree of osseointegration appeared to be independent of the loading of the implant.     

Threaded versus porous-surfaced implants as anchorage units for orthodontic treatment: three-dimensional finite element analysis of peri-implant bone tissue stresses

PURPOSE: A 3-dimensional finite element model was developed to investigate the cause of different crestal bone loss patterns observed around sintered porous-surfaced and machined (turned) threaded dental implants used for orthodontic anchorage in a previously reported animal study. MATERIALS AND METHODS: Twenty-noded structural solid elements with parabolic interpolation between nodes were used for modeling the bone-implant interface zone. A 3-N traction force acting between either 2 porous-surfaced or 2 machined threaded implants placed in canine premolar mandibular sites and bone profiles observed at initiation and 22 weeks of orthodontic loading were modeled. RESULTS: Higher maximum stresses in peri-implant bone next to the coronal region of the implants were predicted with the machined threaded implants at both the initial and final time points, with the values 20% greater than those predicted after the 22-week loading period. These values were approximately 200% greater than those predicted for the porous-surfaced implants, for which a more uniform stress distribution was predicted. DISCUSSION: The finite element model results indicated that the observed greater retention of crestal bone next to the porous-surfaced implants was attributable to lower peak stresses developing in crestal peri-implant bone with this design, which decreased the probability of bone loss related to local overstressing and bone microfracture. CONCLUSION: The predicted lower stresses were a result of the more uniform transfer of force from implant to bone with the porous-surfaced implants, which was a consequence of the interlocking of bone and implant possible with this design.     

微型支抗种植钉加载时机的动物实验研究

目的 建立支抗种植钉的动物模型,分析不同愈合期加载对种植钉稳定性的影响。方法 于绵羊牙槽骨上植入微型支抗种植钉,建立颌骨-支抗种植钉的动物模型,随机分为4组（不加力为A组,即刻加力为B组,植入2周加力为C组,植入4周加力为D组）,截取带有种植钉的上、下颌骨组织标本;上颌骨块制作不脱钙的骨磨片,光镜下观察种植钉与骨组织界面的愈合情况,下颌骨块用材料性能试验机检测种植钉与骨组织松脱瞬间的最大剪切力值,并进行统计分析。结果1）4组种植钉的剪切力值总体上有差别,A、B组的剪切力低于C、D组。2）骨纵磨片显示：种植钉与周围组织界面的结合方式在种植钉的压力侧和张力侧无明显区别;横断磨片显示：4组界面既有纤维性结合,又有骨性结合,A、D组界面以骨性结合为主,B、C组界面以纤维性结合为主,C组种植钉周围可见新生的骨组织潜行生长。结论加载时机对支抗种植钉的稳定性有一定的影响。     

全下颌牙种植义齿及支持组织应力的三维有限元分析：Ⅴ.种植…

采用三维有限元的方法，分别考察了由柱状和状种植体支持的全下颌种植覆盖义齿、种植体、骨界面及牙槽嵴在三种Ｈｅ下的应力分布情况。发现叶状种植体及其骨界面的应力较高，不利于 应力分布。     

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。