眶部骨密度对种植体－骨界面应力影响的三维有限元研究

目的：探讨眶部受植区不同骨密度对种植体骨界面应力分布的影响。方法：建立8个不同 HU 值（300～10000）骨密度的眶部种植体－颅颌面骨三维有限元模型,给予沿种植体轴向20 N 的载荷,记录 Von-Mises 应力峰值和位移峰值,分析其应力分布。结果：随着骨密度值增高,应力峰值和位移峰值均出现下降,在800～1000 HU 条件下,应力峰值和位移峰值下降不明显。结论：眶部受植区骨密度小于800 HU 时,骨密度对种植体的成功率有直接影响。     

眶部种植体载荷角度对骨界面应力的影响

目的:探讨不同角度载荷的眶部种植体对骨界面应力分布的影响。方法:建立直径3.75 mm、长度6 mm的眶部种植体-颅颌面骨三维有限元模型,给以20 N的载荷,载荷角度分别为:垂直载荷、10°、20°、30°、45°和水平载荷,记录并分析不同情况下的应力分布。结果:在0°、10°、20°、30°、45°和水平20 N加载条件下,眶部种植体应力峰值(MPa)分别为3.173、6.535、10.506、14.168、18.949和24.755,位移峰值(μm)范围为1.761、3.654、7.665、11.567、16.774和25.072。结论:载荷角度对界面应力分布有明显影响。     

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.     

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。     

种植体螺纹位置对应力分布影响的有限元研究

目的研究集中载荷下,螺纹不同位置设计对种植体及其周围骨组织应力分布的影响,探讨种植体表面螺纹分布的优化设计。方法应用Solidworks 2005 plus自动化软件和Cosmos/works 7.0分析软件比较在垂直和斜向45°载荷下,螺纹分别位于种植体上1/3（模型A）、中1/3（模型B）、下1/3（模型C）以及遍及整个种植体（模型D）4种情况下种植体-骨界面应力分布状况。结果模型C颈部皮质骨Von-Mises应力、拉应力、压应力峰值最低,但斜向载荷下模型C种植体和松质骨应力显著高于模型A。模型B应力分布明显集中,垂直载荷下各应力均显著高于其他3种模型。模型A和D应力分布较均匀。应力集中主要出现在种植体颈部、皮质骨上缘与种植体接触处和种植体底部最下一个螺纹。斜向载荷下界面的应力显著高于垂直载荷下应力。结论螺纹位置影响种植体-骨界面的应力分布,种植体设计时应谨慎考虑,斜向载荷在种植修复中应尽可能避免。     

Tension More种植体骨界面的光弹应力分析

目的 研究不同锥度设计的Tension More（TM）种植体对种植体骨界面应力分布的影响。方法 医用纯钛制作5组种植体,分别为圆柱状螺纹种植体、上1/3 TM种植体（锥度长度为3 mm）、中1/2 TM种植体（锥度长度为5 mm）、下1/3 TM种植体（锥度长度为7 mm）、全长变化TM种植体（锥度长度为10 mm）。每组种植体各自包埋于由松质骨及1 mm皮质骨构成的复合光弹模型中,共建立5个复合光弹模型。每一模型先后分别予以垂直及斜向（45°）静态加载力。利用光弹应力分析法比较5组种植体骨界面的生物力学特征。结果 垂直加载下,上1/3 TM种植体、中1/2 TM种植体、下1/3 TM种植体比圆柱状螺纹种植体在皮质骨区及松质骨区的局部应力集中小;斜向加载下,4组TM种植体皮质骨区局部应力集中均低于圆柱状螺纹种植体。无论在垂直、斜向加载下,上1/3 TM种植体皮质骨区局部应力集中均最小。结论 合理锥度设计的TM种植体周围皮质骨、松质骨应力分布均匀合理,在不同载荷条件下,上1/3 TM种植体骨界面生物力学表现最优。     

2种接连方式种植体的骨界面应力分析

目的建立2种包含实体种植体的下颌骨三维有限元模型,研究2种接连方式种植体（Replace和Replace Select）的骨界面应力状态。方法测量2种种植体各部件的数据和利用螺旋CT扫描下颌骨截面形态,分别建立2种种植体的三维骨内模型,对模型采用轴向加载200 N、30°侧向加载100 N载荷,分析2种种植体的骨界面的应力分布趋势。结果2种种植体骨界面应力分布特点均为从种植体颈部至根尖部逐渐减小,应力主要集中在皮质骨区和种植体颈部狭窄处的骨界面;侧向加载时骨界面的应力值均高于轴向加载。无论轴向加载还是侧向加载,ReplaceSelect种植体骨界面的应力值均高于Replace种植体。结论临床修复时应避免种植体受到过大的力,尤其是侧向力,以防出现颈部骨吸收,Replace Select种植体更应注意。     

种植体与天然牙联冠修复应力分布的三维有限元分析I．垂直集中载荷对种植体、天然牙骨界面应力的影响

目的：探讨种植体与天然牙联冠修复在垂直集中载荷作用下,种植体、天然牙骨界面应力分布情况及受力的相互影响,为临床优化设计提供生物力学的理论依据。方法：采用三维有限元法建立模型并计算、分析。结果：种植体与天然牙联冠修复时,种植体、天然牙骨界面颈部和根尖部出现应力集中;种植体与稳定的天然牙联合修复时种植体－骨界面应力分布较均匀。结论：种植体与天然牙可共同承担载荷;当天然牙受垂直集中载荷时,种植体未过载;种植体最好与稳定的天然牙联合修复。     

种植体与天然牙联冠修复应力分布的三维有限元分析1.垂直集中载荷对种植体、天然牙骨界面应力的影响

目的探讨种植体与天然牙联冠修复在垂直集中载荷作用下,种植体、天然牙骨界面应力分布情况及受力的相互影响,为临床优化设计提供生物力学的理论依据.方法采用三维有限元法建立模型并计算、分析.结果种植体与天然牙联冠修复时,种植体、天然牙骨界面颈部和根尖部出现应力集中;种植体与稳定的天然牙联合修复时种植体-骨界面应力分布较均匀.结论种植体与天然牙可共同承担载荷;当天然牙受垂直集中载荷时,种植体未过载;种植体最好与稳定的天然牙联合修复.     

种植体与天然牙联冠修复应力分布的三维有限元分析 Ⅰ.垂直集中载荷对种植体、天然牙骨界面应力的影响

目的 :探讨种植体与天然牙联冠修复在垂直集中载荷作用下 ,种植体、天然牙骨界面应力分布情况及受力的相互影响,为临床优化设计提供生物力学的理论依据。方法 :采用三维有限元法建立模型并计算、分析。结果 :种植体与天然牙联冠修复时 ,种植体、天然牙骨界面颈部和根尖部出现应力集中 ;种植体与稳定的天然牙联合修复时种植体-骨界面应力分布较均匀。结论 :种植体与天然牙可共同承担载荷 ;当天然牙受垂直集中载荷时 ,种植体未过载 ;种植体最好与稳定的天然牙联合修复     

Three-dimensional finite element analysis of implant stability in the atrophic posterior maxilla: a mathematical study of the sinus floor augmentation

Sinus lifting is performed with a variety of materials and techniques without a precise knowledge of the quantity of augmentation. This study based on three-dimensional finite element analysis was designed to show which surgical procedure and which amount of peri-implant packing yields the best bony support for dental implants. Eight 3D-FE models were used. Four modeled standard situations simulated quantitatively different packing situations produced by differences in surgical approach: i. no packing; ii. thin 1 mm bony sheath; iii. oblique subcomplete packing; iv. complete bony peri-implant packing up to the implant end. A fifth model compared a standard implant with a length of 13.5 mm and a diameter of 3.75 mm with a 7-mm-long and 5-mm-thick implant. In three additional models the stress response of the bone-implant system was evaluated in the absence of a cortical layer, thus simulating an extreme degree of maxillary atrophy. In all models the modeled implants were loaded at their points of emergence with an assumed force of 100 N. The vector of the loading force was inclined 30 degrees posteriorly relative to the implant axis and 30 degrees away from the sagittal plane. The bone-implant interface was assumed to be perfect simulating full osseointegration. The final evaluation of the FE models showed complete peri-implant packing to reduce displacements of the implant tip by 32% vs. no sheathing/packing. Van Mises' equivalent stresses were used to assess the stresses in both human bone and titanium alloy implants. The highest stress levels in bone were predicted for the case without sufficient implant sheathing. In the models with adequate bony implant support, intrabony stresses were generally reduced by up to - 40%. The structural stiffness of the bone-implant system increased with the extent of sinus floor elevation. The results indicate that more extensive peri-implant packing reduces implant displacement, intrabony stresses and stresses at the bone-implant interface.     

微型种植体长度对骨界面应力分布的影响

目的 探讨微型种植体长度对骨组织内应力分布的影响.方法建立直径1.6mm,长度分别为6、8、10、12 mm的种植体-下颌骨三维有限元模型,垂直植入种植体,给以1.96 N的水平向前及前上方向的载荷,记录并分析不同情况下的应力分布.结果 种植体水平向前载荷的应力峰值范围为3.500～3.765 MPa,位移峰值范围为1...     

The biomechanical analysis of relative position between implant and alveolar bone: finite element method

Background: The purpose of this study is to analyze biomechanical interactions in the alveolar bone surrounding implants with smaller‐diameter abutments by changing position of the fixture–abutment interface, loading direction, and thickness of cortical bone using the finite element method. Methods: Twenty different finite element models including four types of cortical bone thickness (0.5, 1, 1.5, and 2 mm) and five implant positions relative to bone crest (subcrestal 1, implant shoulder 1 mm below bone crest; subcrestal 0.5, implant shoulder 0.5 mm below bone crest; at crestal implant shoulder even with bone crest; supracrestal 0.5, implant shoulder 0.5 mm above bone crest; and supracrestal 1, implant shoulder 1 mm above bone crest) were analyzed. All models were simulated under two different loading angles (0 and 45 degrees) relative to the long axis of the implant, respectively. The three factors of implant position, loading type, and thickness of cortical bone were computed for all models. Results: The results revealed that loading type and implant position were the main factors affecting the stress distribution in bone. The stress values of implants in the supracrestal 1 position were higher than all other implant positions. Additionally, compared with models under axial load, the stress values of models under off‐axis load increased significantly. Conclusions: Both loading type and implant position were crucial for stress distribution in bone. The supracrestal 1 implant position may not be ideal to avoid overloading the alveolar bone surrounding implants.     

Finite element analysis of the influence of implant inclination,loading position,and load direction on stress distribution

The selection of the appropriate alignment of an implant and the position of implantation are vital for its longterm success. Excessive load is generated around inclined implants, causing microcracks in the bone, which result in implant loosening and eventual failure. This study was designed to analyze the stress distribution caused by varying the degree of inclination of an implant body and varying the loading position and direction, using the finite-element method of stress analysis. Buccal and lingual two-dimensional simulation models of a cylinder implant, embedded in the first molar edentulous cross-section of the mandible, were prepared, and the stress distribution and maximum principal stresses were recorded. Regardless of the point and direction of loading, compressive stresses were relatively greater when the implant was inclined. This tendency became more pronounced when a 45° loading direction and eccentric loading were tested. For the inclined model, with a 45° loading direction, the compressive stress was observed on the cortical bone adjacent to the direction of inclination, while tensile stress was observed on the opposite side.     

平台转换种植体周围应力分布的三维有限元分析

目的:分析平台转换种植体周围的力学分布特点。方法:利用CATIA画图软件,建立种植体支持的上颌第一前磨牙三维模型,分析垂直向和斜向加载条件下平齐对接(PM)和平台转换(PS)种植体周围的应力分布差异;比较不同材料基台平台转换冠修复后种植体周围的应力分布差异。结果:①PS型种植体在垂直加载和斜向加载时种植体周围骨组织内最大von Mises应力值均较PM型小。②不同材料基台种植体周围应力分布云图相似,应力均集中在种植体颈部。结论:①PS种植体周围骨组织最大应力值较PM种植体小,但基台、中央螺丝、种植体的应力增大。②斜向加载较垂直向加载种植体周围应力值大大增加,特别是基台及种植体部位较为明显。③基台材料对种植体周围应力值无明显影响。     

8mm种植体骨内应力分布的三维有限元研究

目的 探讨在不同骨质条件中、达到骨整合时(40%的骨结合率),不同直径的8 mm种植体骨界面应力分布的变化规律,为短种植体的临床应用提供一定的参考和实验依据.方法 采用三维有限元方法分析6种不同直径的8 mm种植体在Ⅰ~Ⅳ类骨质条件中,受垂直和侧向力时,种植体骨界面的应力值大小及分布规律.结果 在~Ⅳ类骨质中,无论垂直或是斜向加载,应力值随着种植体直径增加,呈现减小的趋势.种植体直径3.3～5 mm时,最大应力值大小变化较为明显(曲率约为-1);种植体直径5.5～7.1mm时,变化趋于平缓(曲率接近0).另一方面,随着骨质密度降低,种植体骨界面的最大应力逐渐增大:Ⅳ类>Ⅲ类>Ⅱ类>Ⅰ类.在Ⅰ、Ⅱ类骨质中最大应力分布接近,Ⅲ、Ⅳ类骨质最大应力分布相近.结论 在临床应用短种植体时,可尽量选择较粗直径的种植体(直径3.3~5 mm),但当种植体直径足够大时(直径大于5.5 mm),再增加种植体直径对临床效果的改善不明显;实验结果显示,Ⅲ、Ⅳ类骨质时的应力值远大于Ⅰ、Ⅱ类骨质,提示在临床实践中,可以将Ⅲ、Ⅳ类的骨质通过骨挤压、骨移植等方式来提高骨密度,以保证远期成功率.     

Stress analysis in platform-switching implants: a 3-dimensional finite element study

The aim of this study was to evaluate the influence of the platform-switching technique on stress distribution in implant, abutment, and peri-implant tissues, through a 3-dimensional finite element study. Three 3-dimensional mandibular models were fabricated using the SolidWorks 2006 and InVesalius software. Each model was composed of a bone block with one implant 10 mm long and of different diameters (3.75 and 5.00 mm). The UCLA abutments also ranged in diameter from 5.00 mm to 4.1 mm. After obtaining the geometries, the models were transferred to the software FEMAP 10.0 for pre- and postprocessing of finite elements to generate the mesh, loading, and boundary conditions. A total load of 200 N was applied in axial (0°), oblique (45°), and lateral (90°) directions. The models were solved by the software NeiNastran 9.0 and transferred to the software FEMAP 10.0 to obtain the results that were visualized through von Mises and maximum principal stress maps. Model A (implants with 3.75 mm/abutment with 4.1 mm) exhibited the highest area of stress concentration with all loadings (axial, oblique, and lateral) for the implant and the abutment. All models presented the stress areas at the abutment level and at the implant/abutment interface. Models B (implant with 5.0 mm/abutment with 5.0 mm) and C (implant with 5.0 mm/abutment with 4.1 mm) presented minor areas of stress concentration and similar distribution pattern. For the cortical bone, low stress concentration was observed in the peri-implant region for models B and C in comparison to model A. The trabecular bone exhibited low stress that was well distributed in models B and C. Model A presented the highest stress concentration. Model B exhibited better stress distribution. There was no significant difference between the large-diameter implants (models B and C).     

穿下颌种植体周围骨界面应力分析

目的：探讨穿下颌种植体数目，钛金基板对穿通下颌骨种植体周围骨界面应力分布的影响。方法：本研究采用ANsys5．7三维有限元分析软件对经CT扫描后的无牙下颌骨进行建模分析，得出不同条件下穿下颌种植体（二单位、四单位，加与未加基板）周围骨界面颈部骨皮质，松质骨上1／3，松质骨中1／3，松质骨下1／3，下颌骨下缘骨皮质及种植体尖部的最大拉应力，最大压应力，位移值。结果以统计直方图，应力分布图等表示。结果：二单位加连接杆加基板穿下颌种植受唇舌向加载时，最大拉应力及压应力均表现在颈部骨皮质的唇侧及舌侧，受近远中向加载时，最大拉应力表现在左侧种植体左侧的骨皮质颈部，最大压应力表现在右侧种植体的右侧骨皮质颈部，受垂直向加载时，最大拉应力表现在种植体的尖部，最大压应力表现在颈部骨皮质及种植体尖部。位移分布规律与应力分布相对应。四单位加连接杆加基板穿下颌种植在受各向加载时，应力分布及位移分布规律基本同二单位式，但相对的应力值较小。未加基板穿下颌种植在受各向加载时，其应力分布规律与加基板者基本相似，但加基板种植的根部应力小于未加基板者，而种植体尖部应力较大。结论：增加穿通式种植体的数目，可以减小种植体周颈部密质骨的最大应力值，加基板多个穿通式种植可以分散下颌骨下缘应力集中。提示：在进行穿通式种植覆盖义齿修复的临床应用中，应考虑增加种植体的数目并在下颌骨下缘使用基板连接。     

Influence of implant length and diameter on stress distribution: a finite element analysis

STATEMENT OF PROBLEM: Masticatory forces acting on dental implants can result in undesirable stress in adjacent bone, which in turn can cause bone defects and the eventual failure of implants. PURPOSE: A mathematical simulation of stress distribution around implants was used to determine which length and diameter of implants would be best to dissipate stress. MATERIAL AND METHODS: Computations of stress arising in the implant bed were made with finite element analysis, using 3-dimensional computer models. The models simulated implants placed in vertical positions in the molar region of the mandible. A model simulating an implant with a diameter of 3.6 mm and lengths of 8 mm, 10 mm, 12 mm, 14 mm, 16 mm, 17 mm, and 18 mm was developed to investigate the influence of the length factor. The influence of different diameters was modeled using implants with a length of 12 mm and diameters of 2.9 mm, 3.6 mm, 4.2 mm, 5.0 mm, 5.5 mm, 6.0 mm, and 6.5 mm. The masticatory load was simulated using an average masticatory force in a natural direction, oblique to the occlusal plane. Values of von Mises equivalent stress at the implant-bone interface were computed using the finite element analysis for all variations. Values for the 3 most stressed elements of each variation were averaged and expressed in percent of values computed for reference (100%), which was the stress magnitude for the implant with a length of 12 mm and diameter of 3.6 mm. RESULTS: Maximum stress areas were located around the implant neck. The decrease in stress was the greatest (31.5%) for implants with a diameter ranging from of 3.6 mm to 4.2 mm. Further stress reduction for the 5.0-mm implant was only 16.4%. An increase in the implant length also led to a decrease in the maximum von Mises equivalent stress values; the influence of implant length, however, was not as pronounced as that of implant diameter. CONCLUSIONS: Within the limitations of this study, an increase in the implant diameter decreased the maximum von Mises equivalent stress around the implant neck more than an increase in the implant length, as a result of a more favorable distribution of the simulated masticatory forces applied in this study.