翼外肌对可复性颞下颌关节盘前移位的作用机制

目的 分析可复性关节盘移位中翼外肌作用下颞下颌关节的应力分布情况。方法 利用已建立的可复性关节盘前移位颞下颌关节数字化仿真模型,在单纯翼外肌加载下进行生物力学分析。结果 关节盘应力集中于关节盘中间带偏外侧区域;髁突及关节窝应力主要集中于与关节盘相接触的功能面。在颞下颌关节盘的位移分布中,从关节盘前带至关节盘中间带,位移趋势逐渐增大,关节盘中间带与关节盘后带之间出现位移撕裂带,从关节盘中间带至关节盘双板区位移逐渐递减;而颞下颌关节整体位移最大值出现在关节囊前份的翼外肌上头附着区。结论 在可复性关节盘前移位中翼外肌可导致关节盘中间带偏外侧区域的应力集中,可能导致此区域关节盘变薄、穿孔甚至撕裂。     

正常颞下颌关节应力分布的三维有限元研究

目的:探讨正常人牙尖交错位紧咬牙时颞下颌关节内的应力分布情况,了解生理状况下TMJ生物力学特点。方法:应用ANSYS 6.1对以往研究所建正常颞下颌关节三维有限元模型进行分析。加载情况接近正常生理。由ANSYS 6.1进行求解。在后处理器中研究分析应力分布与形变。结果:正常人牙尖交错位紧咬牙时颞下颌关节内拉压应力并存,存在剪切应力,分布较均匀,无特别明显应力集中表现。髁突前斜面等效应力值高于后斜面,而前斜面外侧区的应力值又明显高于内侧、中间区。关节盘腹面平均应力值大于背面,且背面应力分布较腹面均匀。腹面应力分布,外侧区最高,最大应力值0.244位于后带与双板区交界处;后带与中间带差别不大,但都明显大于前带。关节盘的变形量明显大于髁突及颞骨关节窝。颞骨关节窝前部即关节结节后斜面等效应力较大。结论:正常牙尖交错位紧咬牙时颞下颌关节内的应力分布,与髁突、关节盘、颞骨关节窝的解剖生理之间,具有良好的功能适应性。     

七种不同（牙合）型对颞下颌关节应力影响的三维有限元分析

目的　探讨由形态变化产生的根尖主应力变化对颞下颌关节 (TMJ)应力的影响。方法　取光弹法测得的正中载荷作用下 7种型各牙根尖应力参数 ,在所建下颌骨三维有限元模型上加载 ,比较其TMJ应力。结果　 (1)髁突前斜面及其表面软骨和关节盘中部主要承受压应力 ,髁突后斜面及其表面软骨和关节盘后部主要承受拉应力 ;(2 )与正常相比 ,平面、远中、部分后牙反、缺牙的TMJ应力均有不同程度变化 ,其中平面的变化最明显。单侧上颌第三磨牙伸长、单侧下颌第三磨牙伸长的TMJ应力变化均不明显。结论　由型改变导致的正中咬合时根尖主应力变化 ,对关节应力性质的影响不明显 ,但对应力大小有一定影响。     

Stress analysis in human temporomandibular joint affected by anterior disc displacement during prolonged clenching

Parafunctional habits, such as prolonged clenching and bruxism, have been associated with dysfunctional overloading in the temporomandibular joint (TMJ). In this study, stress distributions in the TMJ were analysed during prolonged clenching, using three‐dimensional finite element (FE) models of the TMJ with and without disc displacement. The aim of this study was to investigate stress distribution of the cartilaginous tissues in the TMJ with and without disc displacement. Finite element models were developed on the basis of magnetic resonance images from two subjects with and without anterior disc displacement. Condylar movements recorded during a 5‐min clenching were used as the loading condition for stress analysis. In the asymptomatic model, the highest von Mises stresses were located in the lateral area (4·91 MPa) of the disc surfaces, and after 5‐min clenching, the higher stresses were still located at the lateral area (3·65 MPa). In all the cartilaginous tissues, 30–50% of stress reduction occurred during 5‐min clenching. In contrast, the von Mises stress in the cartilaginous tissues of the symptomatic model with disc displacement was markedly lower, compared with the asymptomatic model. However, in the condylar cartilage, stress relaxation during clenching was not recognised. Furthermore, relatively high stresses were observed in the retrodiscal tissues throughout clenching. The present results indicate that disc position could be involved in the stress distribution of the TMJ components during prolonged clenching.     

牙齿磨耗后颞下颌关节应力分布的三维有限元研究

目的：计算机模拟牙齿不同程度磨耗、颌垂直距离减小时，三维有限元分析颞下颌关节内的应力分布变化。方法：应用以往研究所建正常颞下颌关节三维有限元模型，分别将下牙列分层删除从上至下1／3、1／2及全部的单元，并改变咀嚼肌加力方向。应用ANSYS6．1分析颞下颌关节内的应力变化。结果：随着磨耗程度的加重，髁状突表面的应力增加较多。关节盘等效应力增加的速度较髁状突、关节窝要大；关节盘的后带后缘，还有关节盘中带、后带的中间、外侧区有应力集中表现；磨耗越重，变形越大，关节盘越薄。颞骨关节窝不但应力值增加，最大应力的位置也由关节结节后斜面向顶部移动。结论：牙齿磨耗可造成颞下颌关节应力的明显增加及特定的应力集中区。     

下颌前伸时颞下颌关节应力分布的三维有限元研究

目的探讨下颌前伸运动时颞下颌关节内的应力分布情况。方法利用可视化人体图像建立包括上下牙列、下颌骨、颞下颌关节在内的三维有限元模型,在Patran中采用位移加载的方法模拟下颌前伸运动至对刃位,在Marc中计算并分析接触情况和应力分布特性。结果关节盘随髁突向前、下运动,髁突的前斜面首先与关节盘中间带中央部发生接触,随后髁突的外斜面与关节盘的中间带外侧部、关节窝的顶部与关节盘的后带发生接触。关节盘的中间带外侧部(3.10 Mpa)和髁突的前斜面(5.05 Mpa)等部位的应力值较大。结论在前伸运动时,应力集中区位于关节盘的中间带外侧部和髁突的前斜面。     

颏兜力作用下颞下颌关节及下颌骨受力的三维有限元分析

目的：用三维有限元法观察颏兜力作用下颞下颌关节的受力状况和整个下颌骨的应力分布,探讨颏兜的作用机制及颏兜力作用与TMD的关系。方法：模拟颏兜力的作用,在下颌骨颏点处施加5．88N的力,力的方向为颏点与髁突连线在矢状面上的投影。采用ANSYS有限元结构分析软件在计算机中进行计算和分析。结果：髁突表面最大受力区域位于髁突前斜面。关节盘受拉应力最大的区域位于相当于关节盘中间带的部位,受压最大的区域位于关节盘后带后缘中部。关节窝表面受力最大区域位于关节结节后斜面。下颌骨较大压应力区位于力的作用线周围区域,较大拉应力区位于下颌支后部及下颌角附近区域。结论：颏兜力可对TMJ的应力分布产生影响,但颏兜力作用下是否会造成TMD还有待进一步研究。     

下颌前方牙齿缺失修复前后对颞下颌关节应力分布影响的三维有限元研究

目的:研究因前牙缺失导致的根尖主应力变化对颞下颌关节(TM J)应力分布的影响。方法:将光弹法测得的正中咬合时各牙合型牙根主应力数据,在三维有限元模型上加载,比较TM J各部应力变化。结果:1)髁突前斜面及所对应的关节软骨和关节盘的中部主要承受压应力,髁突后斜面及关节盘的后部主要承受拉应力。2)前牙5-5缺失可以导致TM J应力明显减小,修复后可有效的消除这种影响。结论:前牙缺失可引起TM J应力变化,有可能进一步导致关节病的发生,应当及时修复。     

颞下颌关节盘前移位后关节组织中S-100的表达

目的：探讨颞下颌关节盘前移位后关节组织中S-100表达的变化及其意义。方法：26只日本大耳白兔，在建立颞下颌关节盘前移位动物模型后，分别于术后1周、2周、4周、6周、8周、10周和12周处死，用免疫组织化学方法检测关节组织内S-100的分布。结果：正常时S-100的表达主要位于关节盘前带和后带的软骨细胞中，双板区内无软骨细胞亦无S-100的表达。1周时下板内有少量成纤维细胞和纤维软骨细胞弱表达S-100，2周时出现少量弱表达S-100的游离软骨细胞。以后软骨细胞数目逐渐增多、S-100表达逐渐增强。10周时，可见多数强表达S-100的软骨细胞，12周时，滑膜层亦可见软骨细胞的出现及S-100的表达。结论：关节盘前移位后双板区出现软骨细胞及S-100的表达，S-100的表达可能与双板区组织的适应性改建有关。     

Three-dimensional finite-element model of the human temporomandibular joint disc during prolonged clenching

In the temporomandibular joint (TMJ), overloading induced by prolonged clenching appears to be important in the cascade of events leading to disc displacement. In this study, the effect of disc displacement on joint stresses during prolonged clenching was studied. For this purpose, finite-element models of the TMJ, with and without disc displacement, were used. Muscle forces were used as a loading condition for stress analysis during a time-period of 10 min. The TMJ disc and connective tissue were characterized as a linear viscoelastic material. In the asymptomatic model, large stresses were found in the central and lateral part of the disc through clenching. In the retrodiscal tissue, stress relaxation occurred during the first 2 min of clenching. In the symptomatic model, large stresses were observed in the posterior part of the disc and in the retrodiscal tissue, and the stress level was kept constant through clenching. This indicates that during prolonged clenching the disc functions well in the asymptomatic joint, meanwhile the retrodiscal tissue in the symptomatic joint is subject to excessive stress. As this structure is less suitable for bearing large stresses, tissue damage may occur. In addition, storage of excessive strain energy might lead to breakage of the tissue.     

一侧下颌角受力对双侧关节盘及髁突软骨的影响

目的:利用三维有限元分析法,从生物力学角度探讨一侧下颌角受力瞬间双侧颞下颌关节(TMJ)关节盘及髁突软骨的相应变化及其与临床实际的关系。方法:建立下颌骨和TMJ共5个不同开口度(闭口位及1、2、3、4cm开口位)的三维有限元数字模型;于左侧下颌角下缘向上,施以与眶耳平面垂直的1000N压力。获取受力后双侧关节盘和髁突软骨产生的平均主应力的分布及其峰值大小。结果:(1)闭口位时,双侧关节盘和髁突软骨的平均主应力(EQV应力)峰值明显较小;(2)在不同开口位,关节盘EQV应力峰值多位于后带,髁突软骨则多位于前斜面;(3)关节盘EQV应力峰值始终是左侧大于右侧,而髁突软骨在闭口位及1、4cm开口位时左侧EQV应力峰值大于右侧,2、3cm开口位时则是右侧大于左侧;(4)双侧关节盘和髁突软骨的EQV应力峰值出现的部位基本对称。结论:(1)本组模型较精确地反映了实物,并且实验结果与临床实际相接近,解决了以往实验中遇到的一些问题,为TMJ的生物力学研究提供了新的途径。(2)稳定的咬合关系可以明显减小TMJ的间接损伤。(3)关节盘后带病变及髁突器质性病变可能由下颌骨一次性暴力创伤后造成的TMJ间接损伤引起;受力侧关节盘比对侧更易受损伤,而双侧髁突软骨都有受到严重损伤的可能。     

A preliminary study on the clinical application of temporomandibular joint arthroscopy

The temporomandibular joint arthroscopy was performed on 24 joints of 18 patients. The procedure was carried out under local anaesthesia by inferiolateral approach. Main changes of upper compartments were showed on the bilaminar zone, including disc perforation and anterior displacement and capsular loosening. The abnormal discoveries of lower compartments were mainly erosion of the condylar cartilage. The indications and techniques of arthroscopy of TMJ were discussed and described.     

Mechanical properties of human articular disk and its influence on TMJ loading studied with the finite element method

The present study was designed to investigate the elastic modulus of human temporomandibular joint (TMJ) disk under tension and its influences on TMJ loading. Seven human TMJ disks served as specimens. Continuous tensile stress was applied to each specimen, and the elastic moduli of human TMJ disks were calculated at 2% strain. Furthermore, using a three-dimensional finite element model of the mandible including the TMJ, changes in the TMJ stresses during clenching were evaluated in association of varying elastic moduli of the articular disk determined by the tensile tests. The elastic moduli at 2% strain varied from 27.1 to 65.2 MPa with a mean of 47.1 MPa. A significant correlation was found between the elastic moduli and age (P < 0.01). On the surface of condyle, compressive stress in the anterior area and tensile stress in the posterior area increased when the elastic moduli of the TMJ disk was varied from 25 to 65 MPa. In the TMJ disk, shear stresses in all the areas became larger with greater stiffness. In conclusion, it is shown that the elastic modulus of human TMJ disk is increased with age and that higher stiffness of the disk exerts substantial influences on mechanical loading for the TMJ structures.     

Disc-like changes and type II collagen mRNA expression in the bilaminar zone of rabbit temporomandibular joint following disc displacement]

OBJECTIVE: To study the adaptive alteration in bilaminar zone of rabbits' temporomandibular joint following disc displacement. METHODS: Twenty-six Japanese white rabbits were used in this study. Among these rabbits,6 were used as controls. The right discs of other 20 rabbits were displaced anteriorly by operation. Four of these rabbits were killedatn 1, 2, 4, 6 and 8 weeks respectively after surgery. The TMJS were studied by HE staining, Alcin bluen staining and in situ detection of type II collagen mRNA expression. RESULTS: There appeared cartilage metaplasia after one week following disc displacement. Typical chondrocytes could be found in the bilaminar zone. The new chondrocytes expressed type II collagen. CONCLUSIONS: The bilaminar zone of TMJ will be remodeled following disc displacement and become a disc-like tissue to function as a disc.     

Morphology of the articular eminence in temporomandibular joints and condylar bone change

The purpose of the present study was to investigate the relationship between the inclination of the articular eminence and temporomandibular joint (TMJ) pathology in orthognathic surgery patients with signs and symptoms of TMJ disorders. Twenty-one female orthognathic surgery patients with signs and symptoms of TMJ disorders were examined using pre-treatment helical computed tomography scans. The slope of the eminence in the medial, central and lateral sections of the subjects with osteophyte formation was significantly less than in the subjects with no bone change, and the medial section of the subjects with osteophyte formation was also significantly less steep than in the subjects with erosion. The central and lateral sections in the subjects with anterior disc displacement with reduction were significantly steeper than in subjects with anterior disc displacement without reduction. These results suggest that eminence flattening might occur during changes from erosion to osteophyte formation and from anterior disc displacement with reduction to anterior disc displacement without reduction. This appears to represent adaptation of the condyle, articular disc and articular eminence to changes in loading.     

颞下颌关节盘前移位关节盘及盘后区超微结构变化的实验研究

目的通过建立关节盘前移位实验动物模型的方法,研究颞下颌关节盘前移位后关节盘及盘后区早期超微结构的变化。方法10只兔左侧关节经手术诱导为关节盘前移位模型,右侧为手术对照组;2只为正常对照组。术后24小时、1周、2周、3周、4周,麻醉下活体各切取2只手术组实验动物同一部位的关节盘和关节盘后区组织,制成透射电镜标本观察。结果关节盘组织中软骨样细胞逐渐增多,细胞周围的淡区逐渐变小并消失,胞浆中微丝增加,胶原纤维间排列紊乱数量减少,并见新生毛细血管及神经纤维,最后软骨样细胞转化为纤维母细胞和肌纤维母细胞。盘后区早期出现幼稚的软骨样细胞,有排列相对致密的胶原纤维,最后转化成类似于关节盘样组织。结论颞下颌关节盘前移位后,关节盘失去纤维软骨盘的特性转化为纤维结缔组织;盘后区则由疏松的结缔组织变成纤维软骨盘样组织。     

牙尖交错位紧咬时颞下颌关节接触特征及应力分布的三维有限元研究

目的研究正常人牙尖交错位紧咬时颞下颌关节的接触特征及应力分布情况。方法建立颞下颌关节三维有限元模型,在Marc软件中定义髁突、关节盘和关节窝三者间的接触关系,运用接触模式,采用自动探测的方法求解有限元分析软件。结果牙尖交错位紧咬时,关节盘后带与双板区的交界处和髁突的后斜面首先发生接触,随后髁突的顶部、内侧面与关节盘的后带,髁突的前斜面与关节盘的中间带也发生接触。同一矢状面上Von Mises应力平均值的大小依次为:髁突>关节盘腹面>关节盘背面>关节窝。结论Marc所提供的接触分析模块能较为真实地反映牙尖交错位紧咬时颞下颌关节的接触特征;颞下颌关节各结构通过相互接触及关节盘的缓冲使应力分散和传递,反映颞下颌关节各解剖结构与生理功能之间具有良好的适应性。     

正常人牙尖交错位紧咬牙时颞下颌关节无单元—有限元耦合法三维生物力学研究

目的应用无单元—有限元耦合法探讨正常人牙尖交错位紧咬牙时颞下颌关节内的应力分布情况。方法利用中国可视化人体图像数据建立包括上下牙列、下颌骨、颞下颌关节在内的三维有限元模型和三维无单元—有限元耦合模型,用自行编制的耦合程序对已建立的正常颞下颌关节三维无单元—有限元耦合模型进行应力分析。结果无单元—有限元耦合模型与有限元模型所反映的颞下颌关节应力分布特点基本相同,但耦合模型对关节盘的应力分析更精细。颞下颌关节关节盘最薄弱的中间带区是应力最集中的地区,双板区也是高应力分布区,提示这两处是关节盘最易受损伤的区域。结论无单元—有限元耦合法是一种有效的数值模拟方法,计算过程大大简化,计算精度显著提高,在生物力学研究中有推广应用前景。     

颞下颌关节盘前移位后双板区组织软骨化生机制的实验研究

目的:探讨颞下颌关节盘前移位后双板区内化生软骨细胞的来源。方法:将12只日本成年大耳白兔随机分为A、B两组,每组包括4只实验兔和2只对照兔,实验兔的右侧关节盘被手术前移并固定在前方的颧弓上,A组用于HE染色和抗增殖细胞核抗原(PCNA)、抗成纤维细胞生长因子受体3(FGFR3)免疫组化检测,B组用于透射电镜观察。结果:所有实验组动物的关节盘双板区内均出现了软骨细胞化生,部分化生软骨细胞内PCNA和FGFR3均为阳性。超微结构观察可见:部分细胞具有成纤维细胞和软骨细胞的双重特征,部分软骨细胞具有幼稚细胞的特征。结论:颞下颌关节盘前移位后,双板区内化生的软骨细胞可能部分由间充质干细胞增殖分化而来。     

Elastic fibers in the human temporo-mandibular joint disc

The elastic fiber content of 12 articular discs, removed from 12 patients with complete anterior or medio-anterior disc displacement, was examined. Eight to 12 sagittal sections (3 microm each) were acquired for each disc and stained with modified resorcin-fuchsin for visualization of elastic fibers. The program "CUE-2 Image Analyzer Morphometry" digitized all sections with 800x magnification, calculated the elastic fiber content and reconstructed it 3-dimensionally. The calculated volume density of the entire disc was a mean x(tot)= 0.339 +/- 0.060% of the total tissue. The highest fiber content of 2-4% was found in the posterior area at the transition to the bilaminar zone. 61% of the elastic fibers were located in the bilaminar zone, 10% in the posterior, 2% in the intermediary and 26% in the anterior band. There were substantially more fibers in the cranial part of the posterior region and at the medial edge as compared to the mean fiber distribution of the posterior band and the bilaminar zone. A third of these fibers were found in the inferior layer, particularly in the lateral part. Exactly the opposite fiber distribution was seen in the anterior band. The fibers frequently appeared in the caudal layer, especially in the lateral periphery, but there were fewer fibers in the medial cranial layer.