颞下颌关节盘磁共振影像及其组织学基础的研究

【作者】 贺建军；

【导师】 王美青；

【作者基本信息】 第四军医大学 ， 口腔基础医学， 2002， 硕士

【摘要】 颞下颌关节盘是颞下颌关节重要的组成部分，关节内紊乱是最常见的目前认为以关节盘位置和完整性异常为主要内容的口腔颌面部疾病，其诊断主要基于影像检查，其病因始终未能得到充分论证，而基于盘移位理论的盘复位治疗，效果并不理想。另一方面在早期的研究报道中即有学者注意到，关节盘变形与关节内紊乱之间存在密切的相关关系，异常形态的关节盘容易表现出盘突关系异常的影像特征，这说明关节的退行性改变与关节内紊乱具有非常密切的关系。颞下颌关节盘作为特殊的纤维软骨性结构，具有较强的自身形态、结构调节能力，在关节内紊乱时会出现明显形态变化，其发生病理性变化的组织学基础值得进一步探讨。 本研究首先确定了对尸体颞下颌关节磁共振检查技术参数，然后分别对17具32侧和12具23侧尸体TMJ的MRI冠状面、矢状面影像形态进行测量分析，结果表明，颞下颌关节间隙的大小与关节盘截面积的大小呈明显的正相关关系，关节盘的形态与关节间隙的形态密切相关，说明关节盘对骨关节面改建后关节间隙大小变化具有较强的适应能力。矢状面MR影像显示的关节间隙内密度增高的软组织影像(一般临床上被认为是关节盘影像)，总体上能够反应关节盘在体内的形态变化趋势，但是有10／23侧(16／92层面)不能完全反应关节盘形态，这与关节盘组织结构特点有关。关节盘穿孔者，穿孔层面和非穿孔层面，MR影像均显示为异形关节盘影像，外侧份关节盘影像常显示不清，可能与外侧份关节盘较薄的特性有关。因此关节盘组织结构的正常与否及其致密程度，对磁共振影像有较大影响。从大小来看，组织学上关节盘边界不确切，因此与磁共振影像结果间的关系不密切。 在测量关节盘大小时，我们注意到关节盘后区的变化非常大，对12具23侧尸体TMJ关节盘的组织学观察结果表明，关节盘颞后附着短而疏 第四军医大学硕土学位论文 松，下颌后附着长而致密，而且下颌后附着的纤维从关节盘后带的上表面 开始出现，顺骸状突后方转向下行，形成较为粗大的胶原纤维束，在咬合 时，这种粗大、致密的下颌后附着，对踝状突向后方转动的幅度具有重要 的限制作用。当踝状突向后转动的力量较大时，或者受到较大的与纤维排 列方向（前后向）不同的剪切负荷作用时，可能是造成关节盘附着或关节 盘不同部位的纤维变性、断裂、直至穿孔的重要病理学机制，磁共振显示 的穿孔关节盘非穿孔部位磁共振影像异常，即反映了这种组织学变化对磁 共振影像质量的影响。观察还发现，有些关节盘后带后方纤维束，在向下 走行时与关节盘后带之间有明显的转角——转纤维，而且多见于有咬合干 扰者的关节中，但是MM显示其盘位正常率较高，这些关节的关节盘相对 较厚，说明这些咬合干扰对关节运动中受力情况有影响，一方面使关节盘 后带后方、向后下固定关节盘的纤维力量增强，以维持关节盘相对于踝状 突的正常位置，另一方面垂直向负荷增大，关节盘增厚以缓冲这种负荷带 来的损伤刺激。那些没有明显咬合干扰，但有过度前伸或过度闭曰功能需 要的关节（如前牙反合，后牙缺失垂直距离降低者等），关节盘相对较薄， 后带后方纤维成束，形成较长的前后走行的纤维性结构，称为第四带，其 对抗前后向拉负荷的能力较强，但它的交叉纤维含量极少，承受非前后向 拉负荷的能力明显减弱。可见，关节盘可以随着咬合功能的需要作适当的 形态结构的改建，表现在厚度、纤维走行方向以及第四带的形成等方面。 关节盘组织结构的这种改建特点，在关节盘病变中具有重要意义，值得进 一步研究。而且因本文材料来自陈旧尸体，故不适宜作其他染色观察，有 关内容有待进一步探讨。 另外对30例40个老年穿孔关节盘的观察表明，关节盘后带后方边缘部 以及关节盘中带，均是关节盘穿孔的好发部位。 通过上述研究得到以下结论： ］、关节矢状和冠状间隙的大小与关节盘大小密切相关，关节盘具有 －3－ 第四军医大学硕士学位论文 较强的适应关节间隙变化而发生形态、大小变化的潜力； 2、关节盘组织结构的变化，对MR影像有一定的影响。 3、关节盘后方附着区域的组织结构比较复杂，是关节盘适应咬合功 能进行改建的重要部位。 4、关节盘中带和关节盘后缘处均是关节盘的穿孔好发部位，与该处 纪构单一灼组织学特征有关。 5、关节盘组织结构与形态的改建可能是出现关节内紊乱重要?更多还原

【Abstract】 Articular disc is an important part of TMJ and internal derangement is the most common oral and maxillofacial disease that mainly involves in abnormity in position and integrality of articular disc. The cause of the disease was not quite clear yet, and its diagnosis till now mainly based on radiological examination. Clinical investigation revealed that the disc repositioning therapy for curing the disease based on the disc displacement theory didn’t work well. In fact that at the very beginning researchers had noticed that there was a close relationship between disc deformation and internal derangement, and abnormal shaped disc could often show an image of abnormal relationship between the disc and the mandibular condyle. Because of its special fibrocartilage structure, articular disc has strong ability to adjust its shape and structure. An obvious change in its shape would occur v,’hen internal derangement existed. The histopathological basis of this change is worth investigation further.In present study 55 sides of TMJ in 28 corpses were selected the MR images of coronal and sagittal planes were takem, then the sizes and shapes of the disc on the images were measured. The result showed that the size of TMJ spacial area was of direct proportion to that of the disc, and the shape of the space was closely related to that of the disc. Jt implied that articular disc have strong adjusting ability to the change of TMJ gap after the reconstruction of the osteo-surface. The MR iamges of the soft tissues with raised density in TMJ space on sagittal plane could mirror the shape change of the disc in most of the cases, while 10/23 of the cases couldn’t fully reflect the disc shape due to its special tissues structure. In those with disc perforation, both perforatedand unperforated layer demonstrated abnormal disc images. The lateral part of disc couldn’t be seen clearly on the images, which might be influenced by its thinness. Thus, the tissues structure and density of the articular disc had effect on its MR image.The retrodiscal tissues varied greatly in different cases. Histopathological examination on 23 sides of 12 corpes showed that the posterior temporal attachment was short and loose, while the posterior mandibular attachment was long and dense. The fibres of posterior mandibular attachment originated from superior surface of posterior band, run down along the back of condyle and formed thick collagen fibre bundles which would restrict the range of backward movement of the condyle. The force drawing condyle to rotate backwards and continuous shearing load on the disc might be the reason of degeneration and breaking of the fibres in attachment area or other part of the disc and even perforation of the disc. Abnormal MR image in unperforated area of the perforated disc indicated that histological change of the disc could affect the MR image. Our research also showed that some posterior fibre bundles of posterior band formed obvious angle with posterior band on the way of running down. These fibre bundles could often be found in patients with occlusal interference, and most of patients showed normal disc position in MR images. The disc containing these kind of fibres was comparatively thick, suggesting that the occlusal interference may have effect on the stress applied on the disc during its movement. On one hand, the stress applied on the disc through fibres in post-posterior-band region increased to keep normal disc-condyle relationship. On the other hand, articular disc became thicker to reduce the possible injure caused by increasing vertical load. Those patients without obvious occlusal interference but need of excessive protrusion orclosing movement (such as patients with cross-bite of anterior teeth, lower occlusal height because of posterior teeth loss) usually had a thinner disc, their post-posterior-band fibre bundles could form a fibrous structure in anterior-posterior direction, called "the fourth band", which had a stronger ability to resist the load in anterior-posterior directio更多还原