两种牵张方向对下颌骨体部牵张成骨的影响

目的:研究下颌骨体部模拟牵张成骨时牵张方向对下颌骨体部牵张成骨的影响.方法:建立优化的下颌骨牵张成骨的三维有限元模型,进行2种不同方向的牵引,测量小同加载条件下,下颌骨的Von Mises应力、位移.结果:当牵张器平行于下颌骨体放置时,模型中的最大应力是牵张器平行于矢状轴模型中最大应力的2倍.平行于下颌骨体组模型存在明显的侧方力,使牵张后的下颌骨形态发生变化,导致关节功能的紊乱.牵引装置平行于矢状轴放置时,这种反作用力可降至最低程度.结论:牵张器平行于矢状轴优于平行于下颌骨体,此项研究为牵张器在临床应用中的放置位置和牵引方向提供了理论依据.     

2种牵张方向对下颌骨体部牵张成骨应力分布与位移的影响

目的建立下颌骨牵张成骨三维有限元模型,研究下颌骨体部模拟牵张成骨时牵张方向对下颌骨体部牵张成骨的影响。方法建立下颌骨牵张成骨三维有限元模型,测量不同牵张位移加载条件下,下颌骨的Von Mises应力、骨结合点位移。结果当牵张器平行于下颌骨体放置时,模型中的最大应力是牵张器平行于矢状轴模型中最大应力的2倍。Von Mises应力集中主要发生在加载部位（牵张器与骨的结合点）和髁突的颈部前下方区域,由于这2处有应力集中,可能导致局部骨质吸收,从而造成螺钉松动,影响牵张器的稳固性。当模型的加载位移增加时,最大应力与加载位移值成线性关系。结论平行于下颌骨体组模型存在明显的侧方力,牵引装置所产生的反作用力使它的后臂产生向外侧位移。牵引装置平行于矢状轴放置时,这种反作用力可降至最低程度,此项研究为牵张器在临床应用中的放置位置和牵引方向提供了理论依据。     

两种牵张方向对下颌骨体部牵张成骨影响的实验研究

目的:研究2种不同牵张方向对下颌骨体部牵张成骨的影响.方法:新西兰大白兔10只.随机分2组,每组5只,在动物颏孔前0.5 cm处截骨安牵张器.A组牵张器沿延伸轴放置;B组牵张器沿矢状轴放置,在牵张后4、8周时分别进行放射学检查及组织学检查,探索出牵张器哪一种牵张方向更有利于牵张器的稳固,加快成骨速度,提高成骨质量.结果:牵张器平行于下颌骨矢状轴放置优于平行于延伸轴放置.结论:牵张器平行于矢状轴放置成骨速度快,成骨质量高.     

牵张方向对下颌骨体部牵张成骨应力分布与位移的影响

目的:研究牵张方向对下颌骨体部牵张成骨的影响。方法:建立下颌骨牵张成骨三维有限元模型,在下颌骨体部模拟牵张成骨,测量不同加载条件下,下颌骨的VonMises应力、颏顶点和右侧下颌角点的位移。结果:应力、位移量与加载力值成线性关系。应力集中在加载部位,双侧加载、与牙合平面平行方向加载时,VonMises应力更大,颏顶点、下颌角点表现为X、Z轴向的正位移和Y轴向的负位移;与下颌骨下缘平行方向的加载应力小,颏顶点、下颌角点表现为X、Y轴向的正位移和Z轴向的负位移。结论:单侧加载时下颌骨向对侧偏斜多,双侧加载时矢状向位移趋势大。与上颌牙合平面平行的加载较与下颌骨体下缘平行的加载应力大,但不会造成前牙开牙合。     

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。     

文摘

1．两种牵张方向对下颌骨体部牵张成骨影响的实验研究／刘志辉…∥实用口腔医学杂志．-2009，25（1）．-18～21 新西兰大白兔10只，随机分2组，每组5只，在动物颏孔前0．5cm处截骨安牵张器。A组牵张器沿延伸轴放置；B组牵张器沿矢状轴放置，在牵张后4、8周时分别进行放射学检查及组织学检查，探索出牵张器哪一种牵张方向更有利于牵张器的稳固，加快成骨速度，提高成骨质量。结果表明：牵张器平行于下颌骨矢状轴放置优于平行于延伸轴放置。     

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。     

下颌角部牵张成骨的有限元分析

目的应用力学相似性较高的下颌骨三维有限元模型,分析角部牵张成骨对下颌内部应力分布及位移趋势的影响。方法在有限元模型的下颌角部模拟骨皮质切开并加载。结果获得角部单、双侧牵张成骨条件下,下颌骨内部应力分布和各部分位移的趋势。发现下颌骨角部牵张成骨应力集中在牵张部位。(牙合)平面有顺时针旋转的趋势,单侧加载较双侧加载下颌整体向对侧的位移趋势大。     

有限元法探讨犬下颌单侧不全截骨牵张时非牵张侧位移趋势

目的 分析犬下颌单侧不全截骨牵张成骨有限元模型,计算下颌骨非牵张侧各部分在牵张过程中位移状况.方法 模拟犬下颌单侧不全截骨牵张成骨,当滑动骨块受力未被牵开和被牵开时观察非牵张侧关节、下颌角、喙突及牙齿等6个标志点的位移情况.结果 当滑动骨块未被牵开时,非牵张侧下颌骨各标志点所受Von Mises应力为0,在空间X、Y、...     

犬下颌骨单侧不全截骨牵张时牵张侧位移状况有限元分析

目的 运用犬下颌单侧不全截骨牵张成骨有限元模型,计算下颌骨在牵张过程中牵张侧各部分位移状况。方法 有限元模型模拟犬下颌单侧不全截骨牵张,观察当滑动骨块未被牵开和被牵开时牵张侧关节、下颌角、喙突及牙齿等6个标志点的位移状况。结果 下颌滑动骨块未被牵开时牵张侧第五臼齿、髁状突前斜面前缘中点所受最大主应力为压应力,髁状突后斜面后缘中点为拉应力,各标志点在空间X、Y、Z三轴位移不明显;当下颌骨滑动骨块被牵开1 mm时,上述各点位移明显增加。结论 从牵张侧观察,牵张侧下颌骨在矢状平面上和冠状平面上都有以髁突顶点(横嵴中点)为中心的逆时针旋转趋势。     

有限元法探讨犬下颌不全截骨牵张的最佳截骨量

目的 利用不完全截骨牵张成骨重建犬下颌节段缺失的有限元模型,控制截骨程度,探讨最佳截骨量.方法 有限元模型模拟不完全截骨,在加力(12N)牵张过程中观察犬下颌皮质骨逐渐加大截骨量时截骨部位的Von Mises应力,并与犬下颌骨的极限抗拉强度比较,以获得牵引时不发生断裂(骨折)的最少剩余皮质骨量.结果 牵张过程中当连接处骨片剩余1mm时,滑动骨块和骨片的连接处Von Mises应力是47.76MPa,最接近犬下颌骨的极限抗拉强度(约49.35MPa).结论 犬下颌行半侧不全截骨牵张成骨时,当连接骨片的剩余宽度小于1mm时,将大大增加牵张区骨折的危险性.     

Animal model for evaluation of strain gauge in mandibular distraction osteogenesis in rabbits

AIM: To design and assemble a distraction device with a strain gauge, and establish an animal model for testing it during mandibular distraction osteogenesis. METHODS: An osteotomy was made in the same position at the junction of mandibular angle and body in 12 rabbits. A customised distraction device attached to a strain gauge was used to distract the mandible. To find out which was the better material, both polyurethane and silicone were used as encapsulation material. After distraction, radiographs were taken, and specimens were examined histologically to record bone formation. RESULTS: Distraction osteogenesis was carried out successfully on all rabbits when the device used polyurethanes as the encapsulation material, it did not transfer the strain signals, but those made with silicone did. CONCLUSION: The device with silicone used as the encapsulation material can be used for strain-testing during mandibular distraction osteogenesis in a rabbit model.     

经缝牵引成骨术治疗唇腭裂患者面中部发育不全的临床研究与三维有限元分析

目的　通过临床研究和三维有限元分析，探讨经缝牵引成骨术治疗唇腭裂患者的生物力学机制，为临床应用该方法纠正面中部发育不足提供理论依据。方法　通过对1例单侧完全性唇裂患者经缝牵引前后头颅三维CT影像进行重建，生成头颅骨骼三维模型影像，然后将其注册进入同一空间坐标体系进行拟合配准，分析并测量骨缝在三维方向上的形态学改变。同时采用三维有限元法，建立患者颅上颌复合体模型，模拟经缝牵引成骨，获取骨缝应力分布。结果　牵引结束后，患者面部形态获得显著改善，面中部凹陷畸形消失。骨缝在三维方向上不等量移位，在前后向上，翼颌缝有着最大前移量；在垂直向上，鼻旁区的鼻颌缝、额颌缝标志点表现为明显的上移，而靠近上颌骨下方的翼颌缝表现为明显的下移；在左右向上，各骨缝标志点位移较小。在健侧，Von Mises应力最大值出现在颧颌缝，患侧Von Mises应力比健侧Von Mises应力更大，最大值位于蝶颌缝及颧颌缝。结论　经缝牵引成骨术可以实现整个面中部骨骼的生长前移。各缝区生长潜能的不同，造成了面中部骨骼群自上而下的渐进式不等量前移。     

牵张力作用下颞下颌关节受力的三维有限元研究

目的 研究不同方向牵张力作用下颞下颌关节的受力状况,探讨下颌骨牵张成骨过程中牵张力合理的方向.方法 通过建立颞下颌关节及下颌骨的三维有限元模型,在模型上模拟牵张力的作用,得到下颌骨牵张成骨过程中,颞下颌关节的受力状况.牵张力的方向为平行于下颌骨下缘或平行于正中矢状面.分别观察牵张延长1 mm、3 mm、5 mm的应力分布状况.结果 不同方向牵张力作用下颞下颌关节的受力情况是不同的.当牵张力平行正中矢状面时,颞下颌关节的受力较大.结论 在下颌骨牵张成骨过程中,牵张力的方向具有重要的生物力学效果.     

Biomechanical evaluation of the consolidation period of alveolar distraction osteogenesis with three-dimensional finite element analysis

In this study, three-dimensional (3D) modeling and finite element analysis were used to determine the optimum consolidation period for implant loading under forces of different directions and amounts after alveolar distraction osteogenesis. A 3D model of an atrophic edentulous alveolar crest was prepared. Distraction osteogenesis with the required bone height was simulated. After a consolidation period of 4, 8, 12 and 16 weeks, horizontal, vertical and oblique forces were applied to the conical endosseous implants embedded in the distracted bone. The effects of loading on the distracted cortical bone and the callus were evaluated in the 3D models by finite element analysis. To determine the appropriate consolidation period, displacement, Von Mises stress, principal maximum and minimum stress, and principal maximum and minimum elastic strain values were evaluated. After the 8th week of the study, the callus distributed the corresponding loads homogeneously, and displacement in the distracted cortical bone after distraction osteogenesis was minimal. This result suggests that the ideal timing for implantation is after 8 weeks, and earlier attempts at implantation may lead to unsuccessful results.     

Original sagittal split osteotomy revisited for mandibular distraction

Introduction: A malformed mandible and an abnormally positioned mandibular foramen make it difficult to plan an ideal osteotomy line for mandibular distraction. In addition, there have been reports of such complications as nonunion, damage and stretch injury of the inferior alveolar nerve and tooth germ damage when conventional osteotomy or corticotomy are used for mandibular distraction. The authors utilized the original sagittal split ramus osteotomy for mandibular distraction. Patients and Methods: Five patients (three unilateral hemifacial microsomia, one bilateral hemifacial microsomia, and one mandibular retrusion) were included in this study of distraction osteogenesis using the sagittal split ramus osteotomy. Extraoral distraction devices were applied to the first four patients. An intraoral device with mono-cortical screw fixation was used for the fifth patient. Result: In all five cases, the results of the distraction were satisfactory. Complications (as listed) of conventional osteotomy when used for distraction were avoided. Satisfactory results were achieved and these were also well maintained postoperatively (mean follow up: 36 months). Conclusion: The authors believe that sagittal osteotomy for mandibular distraction osteogenesis makes it possible, to avoid injury to the inferior alveolar nerve during operation and stretching injury during distraction and to prevent tooth germ injury. It is also possible to diversify the osteotomy line for various force vectors to enlarge the bony contact surface area. Therefore, we suggest that sagittal split ramus osteotomy should be used as a preferred modification of osteotomy for mandibular distraction. Copyright 2001 European Association for Cranio-Maxillofacial Surgery.     

Original sagittal split osteotomy revisited for mandibular distraction.

INTRODUCTION: A malformed mandible and an abnormally positioned mandibular foramen make it difficult to plan an ideal osteotomy line for mandibular distraction. In addition, there have been reports of such complications as nonunion, damage and stretch injury of the inferior alveolar nerve and tooth germ damage when conventional osteotomy or corticotomy are used for mandibular distraction. The authors utilized the original sagittal split ramus osteotomy for mandibular distraction. PATIENTS AND METHODS: Five patients (three unilateral hemifacial microsomia, one bilateral hemifacial microsomia, and one mandibular retrusion) were included in this study of distraction osteogenesis using the sagittal split ramus osteotomy. Extraoral distraction devices were applied to the first four patients. An intraoral device with mono-cortical screw fixation was used for the fifth patient. RESULT: In all five cases, the results of the distraction were satisfactory. Complications (as listed) of conventional osteotomy when used for distraction were avoided. Satisfactory results were achieved and these were also well maintained postoperatively (mean follow up: 36 months). CONCLUSION: The authors believe that sagittal osteotomy for mandibular distraction osteogenesis makes it possible, to avoid injury to the inferior alveolar nerve during operation and stretching injury during distraction and to prevent tooth germ injury. It is also possible to diversify the osteotomy line for various force vectors to enlarge the bony contact surface area. Therefore, we suggest that sagittal split ramus osteotomy should be used as a preferred modification of osteotomy for mandibular distraction.