The Pathologic Changes In Synovial Membrane Of The Anterior Disc Displacement Of Temporomandibular Joint

Temporomandibular joint (TMJ) is a unique diarthroidal joint and crucial to the everyday functioning of modern man. Anterior Disc displacement of temporomandibular Joint refers to the relative changes of the postion amonge joint disc and glenoid fossa and articular eminence of the temporal bone and joint condyle .In the normal position joint disc lies between gleniod fossa , articular eminence and joint condyle. Center of posterior band of joint disc is right above axial rigde of condyle. There are tight attachments and sustainment from the ligments. The joint disc is the biconcave contour, and is divided into three sections: anterior band, center one and posterior one,center band is the thinnest part ,which is directly correspondent to the joint condyle and articular eminence .Therefore, there is no significant displacement of the disc in the normal open mouth position. There are TMJ dysfunctions to some degree after the disc displacement. It is statistical that the dysfunction of the joint by 25-30% among the people, which demonstrate that Anterior Disc displacement of TMJ is common disease with high frequency. But the etiology and pathogenesis of Anterior Disc displacement of TMJ remain an enigma and relationship of Anterior Disc displacement of TMJ to pain, mandibular dysfunction and osteoarthrosis is controversial.TMJ is synovial joint, of which synovial membrane covers surface of joint cavity ,and consists of two layers of soft tissue.The first layer is lining cell layer within the cavity, the second layer is sustainable layer .Synovial lining cell divided into type A and type B, that type B cells can synthesis and modify all ECM (Extracellular matrix ECM) and synovial fluid ,and type A cells mainly deal with metabismic wastes from joint cavity and ECM. The synovialtissue is predominantly important in the initial, progressive and transferring processes of TMD. But recently most of animal model experiments focused on the researches of joint disc and cartilage without dealing with the synovial membrane. So our experiments construct an animal model of Anterior Disc displacement of TMJ, and systemic study pathologic changes and significance in the initial, progressive and transferring processes of Anterior Disc displacement. The objective of these researches is to build animal model, and to observe the pathologic process of the synovial membrane tissue of Anterior Disc displacement of TMJ by nude eyes, x-ray, microscope, eletromicroscope and histochemistry methods, which can for a base for further explanation of pathologic process in Anterior Disc displacement of TMJ.These researches can be indivded into six parts:First, Study on synovial membrane the animal model of Anterior Disc displacement of TMJ; Second, Histological changes of synovial membrane in the animal model of Anterior Disc displacement of TMJ; Third, Ultrastructure histological changes of synovial membrane in the animal model of Anterior Disc displacement of TMJ; Forth, Expressions of iNOS in the synovial membrane of the animal model of Anterior Disc displacement of TMJ; Fifth, Expressions of VEGF in the synovial membrane of the animal model of Anterior Disc displacement of TMJ.In the first three parts, twenty-four young adult white rabbits (4 to 6 months) were used in this study. The disc was surgically displayed anteriorly, like the lateral pterygoid muscle traction generating human ADD, in one side joint in each of 20 rabbits. In this way, the joint space and disc attachment were left intact. The other joints were served as surgical controls and 4 rabbits without any disease were regarded as normal controls. The tissues in joints were took out en bloc 1, 2, 4 and 8 weeks after induction of ADD according to the experimental groups. The tissue were studied radiographically and histologically under X rays and transmission electron microscope.The results under the unaided eyes showed that different damage occurred with time,including disc perforation in two cases at 2 weeks after induction, anterior-lateral discdisplacement in 2 c...