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。     

螺旋形种植体骨界面初始应力的三维有限元分析

目的：分析螺旋形种植体植入下颌骨后骨界面初始应力的分布。方法：用三维有限元的方法对不同弹性模量和不同直径种植体植入后骨界面的初始应力进行分析。结果：螺旋形种植体植入下颌骨后，骨界面的初始应力大小为23．2MPa。主要分布在种植体和骨密质接触的颈部。结论：初始应力的大小与种植体弹性模量无关；随着种植体直径的增加，初始应力逐渐增大。     

种植体-骨界面的生物力学研究进展

种植体-骨界面的生物力学反应是影响种植义齿远期成功率的重要因素之一。过大或过小的应力都会引起种植体周围的骨发生吸收或是萎缩从而导致种植失败。种植体周的应力分布受颌骨骨质、种植体形态、上部结构设计、力和材料等多方面的影响。下面就上述几方面对种植体-骨界面的生物力学特性作一综述。     

三维有限元法分析上颌支抗磨牙及其支持组织的生物力学

目的；分析Ｂｅｇｇ细丝技术第一期上颌支抗磨牙及其支抗组织的生物力学效应。方法：三维有限元法，模型采用人上颌第一麻磨平均几何尺寸，包括５１６个单元。结果：１支抗磨牙所受的合力为伸长力，牙及牙周组织的应力分布不均匀，拉应力，压应力混合存在。２．根分叉周围是应力集中区和缓冲带．３．牙体     

种植体在上颌骨复合体应力的三维有限元分析

目的：比较种植体在上颌骨复合体前，中、后3个部位，在垂直和水平载荷下的应力分布，讨论种植体丰颌骨复合体中的生物力学行为。方法：采用三维有限元法。结果：种植体在上颌骨复合体内，加载后，上颌骨复合体各部位应力均较小，较加载部位和种植体内应力小，上颌骨复合体前、中、后3个种植体比较，种植体和上颌骨复合体应力后牙大于尖牙大于前牙。结论：上颌骨复合体具有良好的使集中受力分散的作用。上颌骨复合体内种植具有良好的生物力学可行性。     

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     

种植体直径对骨界面应力分布影响的三维有限元分析

目的：种植直径对种植体骨界面应力的影响,引起了许多学者的关注,国内外研究报告的观点不一。本研究是为了进一步探讨种植体直径对种植体骨界面应力的影响。方法：采用三维有限元的方法对6种不同直径的种植体在受垂直和侧向力时骨界面的应力进行分析。结果：种植体受垂直和水平加载时,随着种植体直径的增加,种植体骨界面的应力值和应和集中值下降,应力趋向均布。结论：增加种植体的直径可以提高种植牙的轴向和侧向的承受力,临床上在选择种植体时,应昼地选择粗直径的种植体。     

弹性模量和初始应力对种植体骨界面应力分布影响的三维有限元分析

目的:分析种植体弹性模量与骨界面应力分布的关系。方法:用三维有限元的方法对不同弹性模量种植体在各种载荷下骨界面的应力大小和分布进行分析。结果:种植体周围界面骨组织应力强度随着材料弹性模量的增大而增大。结论:低弹性模量的钛合金材料作为种植材料时具有更好的生物力学相容性。初始应力在分析种植体骨界面应力分布时必须加以考虑。     

螺旋形种植体弹性模量与骨界面应力分布关系的三维有限元分析

目的：分析螺旋形种植体弹性模量与骨界面应力分布的关系。方法：用三维有限元法对不同弹性模量种植体在各种载荷下骨界面的应力大小和分布进行分析。结果：种植体周围界面骨组织应力强度随着材料弹性模量的增大而增大。结论：低弹性模量的钛合金材料作为种植材料时具有更好的生物力学相容性。     

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。     

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.     

Bivariate Evaluation of Cylinder Implant Diameter and Length: A Three-Dimensional Finite Element Analysis

Purpose: To evaluate continuous and simultaneous variations of implant diameter and length for an experimental cylinder implant.
Materials and Methods: A finite element model of a mandible segment with implant was created. The range of implant diameter (D) was set from 2.5 to 5.0 mm, and that of implant length (L) from 6.0 to 16.0 mm. The maximum Von Mises stresses in the mandible were evaluated, and the sensitivity of the stresses in the mandible to the variables was also evaluated.
Results: Under axial load, the maximum von Mises stresses in cortical and cancellous bones decreased by 73.3% and 69.4%, respectively, with D and L increasing. Under buccolingual load, those decreased 83.8% and 79.2%, respectively. When D exceeded 3.9 mm and L exceeded 10.0 mm, the tangent slope rate of the maximum von Mises stress response curve ranged from −1 to 0. The variation of the maximum von Mises stresses in the mandible was more sensitive to D than to L.
Conclusions: Buccolingual force is apt to be influenced by the two implant parameters; implant diameter and length favor stress distribution in cortical bone and cancellous bone, respectively. Implant diameter exceeding 3.9 mm and implant length exceeding 10.0 mm are the optimal choice for type B/2 bone in a cylinder implant. The implant diameter is more important than length in reducing bone stress.     

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。     

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。     

Influence of Apical Root Resection on the Biomechanical Response of a Single-rooted Tooth: A 3-dimensional Finite Element Analysis

Introduction

Apical root resection is a biologically essential component in endodontic microsurgery. However, because it reduces the total root length and supported root surface, it changes the biomechanical response of the tooth. The purpose of this study was to analyze the biomechanical effect of apical root resection and to compare apical root resection with periodontal bone loss from a biomechanical standpoint.

Methods

Finite element models of the maxillary central incisor were reconstructed. First, preoperative and surgically treated models were generated to assess the factors altering the biomechanical response of the tooth. Then, apically resected models with different amounts of resection (3, 4, 5, 6, 7, and 8 mm) were created to estimate the clinically applicable limit of apical root resection. Periodontally destructed models with varying degrees of bone loss (0.5, 1, 1.5, 2, and 3 mm) were also created to compare the effect of apical root resection with periodontal bone loss. Stress distribution, tooth displacement, and effective crown-to-root ratio (α) were analyzed for each condition.

Results

Apical root resection did not significantly alter the maximum von Mises stress or tooth displacement until it reached 6 mm (α = 0.67) when the tooth was supported by normal periodontium. In contrast, periodontal bone loss had a greater impact on biomechanical response change compared with apical root resection.

Conclusions

For a tooth supported by normal periodontium, 3 mm of apical root resection (α = 1.07) appeared to be mechanically acceptable. The biomechanical influence of apical root resection was weak compared with that of periodontal bone loss.     

光滑柱状颈部构型的微型种植体-骨界面应力分布的三维有限元分析

目的:探索微型种植体颈部柱状构型对骨界面应力分布的影响。方法:设定种植体颈部为光滑柱状结构,高度分别为0mm、0.5mm、1mm、1.5mm、2mm。分别建立1mm、2mm皮质骨厚度的微型种植体-颌骨有限元模型,比较正畸加载下骨组织内应力分布的情况。结果:颈部柱状种植体-骨界面应力分布明显均匀,传统螺纹种植体-骨界面应力分布较集中。颈部柱状高度的变化对骨界面应力分布影响不大。结论:本三维有限元分析结果表明颈部柱状结构能明显改善微型种植体-骨界面应力分布。     

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     

Influence of Tapered and External Hexagon Connections on Bone Stresses Around Tilted Dental Implants: Three‐Dimensional Finite Element Method With Statistical Analysis

Background: The purpose of this study is to analyze the tension distribution on bone tissue around implants with different angulations (0°, 17°, and 30°) and connections (external hexagon and tapered) through the use of three‐dimensional finite element and statistical analyses. Methods: Twelve different configurations of three‐dimensional finite element models, including three inclinations of the implants (0°, 17°, and 30°), two connections (an external hexagon and a tapered), and two load applications (axial and oblique), were simulated. The maximum principal stress values for cortical bone were measured at the mesial, distal, buccal, and lingual regions around the implant for each analyzed situation, totaling 48 groups. Loads of 200 and 100 N were applied at the occlusal surface in the axial and oblique directions, respectively. Maximum principal stress values were measured at the bone crest and statistically analyzed using analysis of variance. Stress patterns in the bone tissue around the implant were analyzed qualitatively. Results: The results demonstrated that under the oblique loading process, the external hexagon connection showed significantly higher stress concentrations in the bone tissue (P <0.05) compared with the tapered connection. Moreover, the buccal and mesial regions of the cortical bone concentrated significantly higher stress (P <0.005) to the external hexagon implant type. Under the oblique loading direction, the increased external hexagon implant angulation induced a significantly higher stress concentration (P = 0.045). Conclusions: The study results show that: 1) the oblique load was more damaging to bone tissue, mainly when associated with external hexagon implants; and 2) there was a higher stress concentration on the buccal region in comparison to all other regions under oblique load.     

牵引器放置方位对骨-牵引器界面生物力学影响的三维有限元分析

目的：建立双侧下颌骨牵引成骨的三维有限元模型,探讨牵引器不同放置方位对骨一牵引器界面的生物力学影响。方法：模拟牵引器放置平行于下颌骨体部及平行于牵引轴方向两种状况,分析下颌骨牵引延长不同工况下骨一牵引器界面位移、综合应力情况。结果：牵引器放置平行于下颌骨体部时,骨一牵引器界面侧向位移、综合应力均大于牵引器放置平行于牵引轴方向的情况。结论：实验结果提示牵引器应尽量放置平行于牵引轴方向,避免可能发生的不良并发症。