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。     

人工种植牙直径对骨界面应力分布的影响

本文应用二维有限元方法，对３ｍｍ、４ｍｍ、５ｍｍ三种不同直径的螺旋型种植牙进行了对比分析，实验结果表明：螺旋型种植牙直径的增加，对骨界面的总体应力分布规律影响不大，应力值均以根端部皮质骨为最大，其次为根侧部皮质骨，再以颈部皮质骨，最小的为松质骨，但随着种植牙直径的增加，各部位骨界面应力随之降低，种植牙－骨界面的相对位移运动也相应减小，有利于骨界面的应力分布。提示临床种植时，根据颌骨的具体解剖形态，尽可能选择直径稍粗一些的种植牙，可减小骨界面的应力分布及位移运动，取得更好的临床种植效果。     

有限元法分析犬下颌不全截骨牵张时特定标志点应力状况

目的:利用犬不完全截骨牵张成骨有限元模型计算牵张过程中下颌骨特定点受力状况。方法:有限元模型模拟不完全截骨(截骨处剩1mm舌侧皮质骨),观察下颌骨特定标志点所受最大主应力和Von Mises应力。结果:犬下颌不全截骨牵张时,在牵张侧下颌角、喙突受到较大应力,第五臼齿、髁状突前斜面前缘中点和髁状突后斜面后缘中点VonMises应力分别为:0.3726 MPa、0.2408 MPa、0.1051 MPa,并且前两点所受最大主应力为压应力、后缘中点为拉应力,在非牵张侧应力为0。结论:犬下颌骨不全截骨牵张成骨时,牵张侧受到不同程度应力影响,在非牵张侧不受应力影响。     

种植牙根端接触骨质类型对骨界面应力分布影响的三维有限元分析

目的为了探讨种植牙根端接触骨质类型对种植牙周骨界面应力分布的影响方法应用三维有限元方法对螺旋型种植牙周骨界面应力分布进行了分析结果种植牙根端与密质骨或与松质骨接触时在骨界面应力分布上有较大的差异种植牙根端与松质骨接触时最大压应力位于颈周而与密质骨接触时则位于根端骨内结论种植牙根端与密质骨接触可降低种植牙颈周骨内应力减小骨界面的位移运动但增加了根端骨内的应力从减小颈周骨内应力的角度出发种植牙根端与密质骨接触也是一种良好有效的手段     

下颌骨形态对种植体-骨界面应力分布影响的研究

目的　模拟单个下颌磨牙缺失的种植修复 ,分析不同下颌骨形态对种植体 骨界面应力分布的影响。方法　采用三维有限元法 ,根据下颌骨测量资料建立不同颌骨截面形态的种植修复模型并进行分析。结果　不论垂直载荷或斜向载荷 ,不同颌骨形态模型骨界面应力分布规律及应力值差异均无显著性。其中Von Mises应力最大差异为 6 4% ,压应力最大差异为 2 8% ,拉应力最大差异为 6 2 %。结论　在有限元研究中将下颌骨形态简化为规则形态是合理的     

全下颌牙种植固定义齿及支持骨应力的三维有限元分析——种植体植入不同深度应力的比较

本研究应用CT扫描法借助ANSYS软件建立了全下凳牙种植固定义齿的三维有限元模型．比较了双颏孔间区螺旋柱状种植体植入深至下颌骨下缘皮质骨及未深至下颌下缘两种不同情况下全下颌种植固定义齿受载时应力分布规律。结果表明：种植体底部是否深至下颌下缘皮质骨，对种植体一支架应力的影响不大，而对周围骨的应力影响较大，在双颏孔间区将种植体深至下颌下缘皮质骨，更有利于应力均匀分布。     

基于CBCT的下颌后牙区骨内重要解剖结构研究

目的利用锥形束CT（cone beam computed tomography,CBCT）软件分析系统NNTViewer对活体下颌骨三维影像重建测量,研究下颌神经管与邻近解剖结构之间的关系。方法选取100例CBCT影像资料,在下颌骨横截面上测量：①下颌第一前磨牙至同侧第二磨牙各牙牙根中点、根尖与颊舌侧骨壁的距离;②下颌神经管与每个后牙根尖之间及与之相对应的颊舌侧骨壁、牙槽嵴顶和下颌骨下缘的距离。结果下颌第一前磨牙至同侧第二磨牙各牙牙根与颊、舌侧骨壁之间的距离,在牙根中点处分别为1．26—5．02mm、3．74～4．45mm,在根尖处分别为3．85—9．23mm、5．43—7．94mm;下颌第二前磨牙至同侧第二磨牙各牙根尖与下颌神经管之间的距离为5．31～8．19mm。下颌第二前磨牙至同侧第二磨牙各牙根尖下方处的下颌神经管与颊、舌侧骨壁之间的距离分别为3．71～7．62mm、2．91～4．12mm,与牙槽嵴顶之间的距离为17．09-19．22mm,与下颌骨下缘之间的距离为8．22～9．28mm。结论下颌后牙（下颌第三磨牙除外）牙根及下颌神经管与颊侧骨壁之间的距离由前往后逐渐变大。下颌神经管距离第二磨牙远中根最近,距离第一磨牙两根最远;与牙槽嵴顶的距离,在第一磨牙处最大,第二磨牙处最小;与下颌骨下缘的距离,在第二磨牙处最大,第一磨牙近中根处最小。     

单个下颌磨牙缺失种植修复体尺寸对骨界面应力分布的影响

目的：分析单个下颌磨牙缺失采用种植修复时，种植体尺寸对骨界面的应力分布的影响。方法：采用三维有限元法，模拟单个种植体及双种植体修复单个缺失下颌第一磨牙的情况，在保证其它因素不变的条件下，分析种植体尺寸(包括种植体长度和直径)对种植体一骨界面应力分布的影响。结果：不论单种植体修复或双种植体修复单个缺失磨牙时，种植体直径变化对种植体一骨界面应力影响较大，斜向载荷时更为明显；而种植体长度对骨界面应力影响较小。结论：建议临床尽量采用直径较大的种植体修复单个缺失下颌磨牙。     

下颌骨体部牵张成骨的三维有限元研究

目的：用三维有限元法研究下颌骨体部不同牵张方向对下颌骨应力分布与位移的影响。方法：采用螺旋CT技术与计算机软件相结合,建立人下颌骨牵张成骨三维有限元模型。测量不同加载条件下,下颌骨的Mises应力、颏顶点和右侧下颌角点的位移。结果：建立了人下颌骨牵张成骨三维有限元模型。Mises应力集中在加载部位。双侧、与聒平面平行方向加载应力大,位移趋势为对侧前上方;单侧、与下颌骨下缘平行方向加载应力小,位移趋势为对侧后下方。单侧加载下颌骨向对侧偏斜多,双侧加载矢状向位移趋势大。结论：临床上应根据矫治需要,确定理想的牵张方向。     

基于CBCT对下颌管位置的测量分析

目的：应用CBCT对正常人群下颌管在第二前磨牙及第一、二磨牙根尖处位置的测量,来确定其正常位置关系。方法：测量120例18岁以上正常人群第二前磨牙及第一、二磨牙根尖处位置的3个距离：①下颌管中心（ A）到下颌骨下缘最下点（ B）的距离;②下颌管中心（ A）到与A点在同一水平线的颊侧点（ C）的距离;③下颌管中心（ A）到与A点在同一水平线的舌侧点（ D）的距离。每个距离测量3组,取其平均值。结果：男性第二前磨牙根尖处的下颌骨下缘骨壁最厚,其舌侧骨壁厚于颊侧骨壁。在第一磨牙及第二磨牙处,下颌骨下缘骨壁、舌侧骨壁、颊侧骨壁均增厚,且颊侧骨壁厚于舌侧骨壁;女性测量结果及规律与男性相同,其骨壁厚度略较男性骨壁为薄。结论：利用这3个空间距离来确定正常人下颌管在第二前磨牙及第一、二磨牙根尖处的位置,对正颌手术中下颌骨矢状劈开术,囊肿刮治术,种植术等提供理论依据。     

Management of a patient with a failed transmandibular implant

The Transmandibular Implant System (TMI) had been developed in order to provide a patient with a severely resorbed mandible with a stable and retensive implant-supported overdenture. Failure of the transmucosal posts may necessitate removal of the transmandibular implant in total and treatment with an implant-supported prosthesis. The purpose of this paper is to describe overcoming failure of a transmandibular implant without removal and synchronous placement of endosseous dental implants in the interforaminal region, providing an implant-retained overdenture to the patient. CLINICAL RELEVANCE: Transmandibular implants are rarely used nowadays and management of a failed transmandibular implant is reported even less often. Where bone height is adequate, dental implants may be placed in the anterior mandible, even when the failed transmandibular implant is not completely removed.     

二单位式与四单位式种植牙周骨界面应力分布规律差异的三维有限元分析

为了探讨人工种植牙的数目、上部结构对种植牙周骨界面应力分布的影响，本实验应用三维有限元分析方法，对二单位和四单位式杆式覆盖种植义齿种植牙周骨界面的应力分布规律进行了探讨。结果表明：最大压应力、最大拉应力二单位式与四单位式均位于颈周密质骨，二单位式大于四单位式，两者有显著差异性，（Ｐ＜０．００１）。四单位式最大拉、压应力，远中种植牙要大于近中种植牙。最大位移运动二单位式小于四单位式，四单位式近中种植牙大于远中种植牙。二单位式与四单位式位、压应力主要集中于颈部，其它部位与颈部相比有非常显著的差异性，（Ｐ＜０．０００１）。结论：种植牙数目的增加，可以减小种植牙周颈部密质骨内的最大应力值。四单位式种植义齿颈周骨内应力要小于二单位式种植牙，从这点上看，四单位式种植义齿要优于二单位式种植义齿。多个种植牙种植时，杆的连接，改变了种植牙周骨内的应力分布规律，其应力主要由种植牙颈周密质骨来承担     

种植牙即刻负载与延期负载的生物力学三维有限元分析

目的比较即刻负载和延期负载对种植体骨界面生物力学分布的影响。方法采用CT扫描和自主开发的USIS软件建模,用有限元法计算分析即刻负载和延期负载时种植体骨界面的应力、应变及种植体的位移。结果即刻负载时种植体骨界面的VonMises应力稍小于延期负载,均集中于种植体颈部骨皮质,底部骨松质次之;但VonMises应变有较明显的增加,均集中于种植体底部骨松质和螺纹部位;种植体的位移较延期负载略有增大。即刻负载种植体和延期负载种植体在受到颊舌向力时,VonMises应力、应变及位移均有不同程度的增加。结论即刻负载时种植体骨界面的生物力学分布规律与延期负载时相似,受到侧向力时应力、应变增大。种植牙即刻负载技术是可行的。     

不同种植体外形设计对上颌窦提升术后种植体周围应力分布的影响

目的：比较不同种植体外形设计对上颌窦提升术后种植体周围生物力学的影响。方法：在D3型上颌骨简化模型上利用三维有限元法分析3种不同外形设计的种植体在植骨与不植骨条件下的应力分布情况。假设所有材料都是线弹性、连续材料,向种植体施加150 N的倾斜力,测量种植体周围骨组织的最大等效力（equivalent von-Mises,EQV）。采用Ansys Workbench 14.5软件包对数据进行测量分析,采用SPSS 17.0软件包对数据进行统计学分析。结果：各组应力集中区域均位于种植体颈部皮质骨区域。不同种植体外形设计对种植体周围皮质骨最大EQV值无显著影响,但锥形种植体较其他种植体的周围松质骨最大EQV值显著上升,上颌窦提升术后植骨可以降低各组种植体周围最大EQV值。结论：锥形种植体用于上颌后牙区种植修复时,可能引起种植体周围松质骨应力变大,增加种植体周围骨吸收的风险。上颌窦提升后植骨,可降低种植体周围压力负载。     

种植体周围骨内应力分布的三维有限元分析

目的针对不同类型的牙槽骨科学地选用种植体,提高种植体临床疗效,延长使用寿命。方法采用三维有限元分析方法,将圆柱状、螺纹状和台阶状种植体分别植入4类骨质结构中,对此12种情况进行应力分析。结果在同种骨质模型中,圆柱状种植体颈部周围骨内的应力集中最小;就同种形态种植体而言,较低的骨质密度不利于种植体的应力分布。结论圆柱状是一种最有利于降低颈部骨质吸收的形态结构。螺纹状种植体周围骨内应力最大值大于圆柱状,而螺纹自身非力学优势极大的拓展了该型种植体的使用范围,但螺纹尖端处的高应力区域和螺纹之间的低应力区域是影响其长期使用效果的潜在不利因素。台阶状种植体相对较适合骨质好的情况,其根部出现局部高应力区域,若应力处于骨生理承受范围之内,将有利于减少根部骨质疏松。     

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.     

Loading conditions of endosseous implants in an edentulous human mandible: a three-dimensional, finite-element study

The design of dental superstructures influences the loading on dental implants and the deformation of the anterior interforaminal bone in an edentulous mandible. This deformation causes stress in the bone around the implants and may lead to bone resorption and loss of the implant. The stress distribution around dental implants in an edentulous mandible was calculated by means of a three-dimensional, finite-element model of the anterior part of the jaw. This model was built from data obtained from slices of a single human mandible and was provided with four endosseous implants in the interforaminal region. The implants were either connected with a bar or remained solitary. The solitary implants or the bars were loaded either uniformly or non-uniformly. In case of a non-uniform distribution, either the central bar or the central implants were loaded or the lateral bars or the lateral implants were loaded. The most extreme stresses in the bone were always located around the neck of the implant. In the case of the uniform distribution of the loading there were more or less equal extreme principal stresses around the central and lateral implants. If the load was not uniformly distributed on the superstructure then the implant that was nearest to the place of loading showed the highest stress concentration; with connected implants there was a reduction in the magnitude of the extreme principal stresses compared to solitary implants.     

Implant–Bone Interface Stress Distribution in Immediately Loaded Implants of Different Diameters: A Three-Dimensional Finite Element Analysis

Purpose: To establish a 3D finite element model of a mandible with dental implants for immediate loading and to analyze stress distribution in bone around implants of different diameters. Materials and Methods: Three mandible models, embedded with thread implants (ITI, Straumann, Switzerland) with diameters of 3.3, 4.1, and 4.8 mm, respectively, were developed using CT scanning and self‐developed Universal Surgical Integration System software. The von Mises stress and strain of the implant–bone interface were calculated with the ANSYS software when implants were loaded with 150 N vertical or buccolingual forces. Results: When the implants were loaded with vertical force, the von Mises stress concentrated on the mesial and distal surfaces of cortical bone around the neck of implants, with peak values of 25.0, 17.6 and 11.6 MPa for 3.3, 4.1, and 4.8 mm diameters, respectively, while the maximum strains (5854, 4903, 4344 μ?) were located on the buccal cancellous bone around the implant bottom and threads of implants. The stress and strain were significantly lower (p < 0.05) with the increased diameter of implant. When the implants were loaded with buccolingual force, the peak von Mises stress values occurred on the buccal surface of cortical bone around the implant neck, with values of 131.1, 78.7, and 68.1 MPa for 3.3, 4.1, and 4.8 mm diameters, respectively, while the maximum strains occurred on the buccal surface of cancellous bone adjacent to the implant neck, with peak values of 14,218, 12,706, and 11,504 μm, respectively. The stress of the 4.1‐mm diameter implants was significantly lower (p < 0.05) than those of 3.3‐mm diameter implants, but not statistically different from that of the 4.8 mm implant. Conclusions: With an increase of implant diameter, stress and strain on the implant–bone interfaces significantly decreased, especially when the diameter increased from 3.3 to 4.1 mm. It appears that dental implants of 10 mm in length for immediate loading should be at least 4.1 mm in diameter, and uniaxial loading to dental implants should be avoided or minimized.     

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。