Study Of Matrix Metalloproteinases And It's Inhibitor In The Condyle Of TMJ After Indirect Trauma

With the social progress and the industrial development, the injury ratio in the oral maxillofacial region was gradually increasing. As a special synovial joint, the temporomandibular joint (TMJ) located in the base of skull. So traumatic TMJ disease can be caused by indirect force to the mandible, which may lead to soft tissue with effusion into the joint space, local pain, dislocation (luxation) or fracture. If it was not treated in time, it might lead to irreversible changes of TMJ including temporomandibular disorders (TMD) and TMJ Osteoarthrosis (TMJOA) and TMJ fibrous or bony ankylosis which would affect severely the physical and mental health of the patients. The characteristic change of Osteoarthrosis (OA) which was a chronic degeneration was the destruction of articular cartilage, and it's initial change was the degeneration of the matrix of cartilage. Recently it was recognized that matrix metalloproteinases (MMPs) played a very important role in the process of degeneration of articular cartilage. Previous reports on the injury of TMJ mostly focused on the shape and the function of the TMJ after condylar fractures treated by different motheds. The pathologicalchanges were poorly understood.The aim of this study was to examine developmentally the change of expression of matrix metalloproteinases-13(MMP-13) matrix metalloproteinases-3 ( MMP-3 ) and tissue inhibitor of matrix metalloproteinase-1(TIMP-1) in the articular cartilage of the goat TMJ model for osteoarthrosis after the indirect trauma with immunofluorescence histochemistry means. And tried to study the possible pathogenesis of osteoarthrosis.In this study, a total of 25 healthy immature goats were divided into five subgroups (A, B, C, D, E) including five animals in each group at random. In the A, B, C, D groups, a impact to the goat left and right mandibular angle which gave birth to energy of 1.41 J/cm2 in the impacted area were achieved with the self-made device under anesthesia. The force direction paralleled the line between the midpoint of the temple inferior fovea and mandibular angle. The E group was used as control before trauma. The injured animals were killed after 7 days, 1 month, 3 month and 6 month respectively by carotid artery letting blood. Following the death, left and right TMJs were removed from all animals totally. Routine decalcification defatting desiccation and being embedded in paraffin blocks. The paraffin blocks were sectioned serially by the midst of condyle process. The serial sections were stained with histological and immunohistochemical means.Histological results: it was mainly observed that the laceration of joint soft tissue and degeneration of condylar cartilage after indirect trauma. And in the later stage, the absorption and destruction of condylar cartilage and osteophyte and the proliferation of synovium -like tissue were found. Immunohistochemica results: 1. The strong positive expression of MMP-13 was observed in the condyle of TMJearly after indirect trauma, then became weaker gradually. The stronger expression was observed in the hypertrophic layer and the synovium-like tissue of destroyed area of condyle. 2. The strong positive expression of MMP-3 was observed in the condyle of TMJ 1 month after indirect trauma, and became stronger later. The stronger expression was observed in the hypertrophic layer and the synovium-like tissue and destroyed area of condyle and bone marrow. 3. The strong positive expression of TIMP-1 was observed in the condyle of TMJ early after indirect trauma. The stronger expression was observed in the hypertrophic layer and the synovium-like tissue of destroyed area of condyle. In addition, the stronger staining was found in the hypertrophic layer in the earlier and middle stage. In the last stage it was found in the synovium-like tissue of destroyed area of condyle. These factors were negative in the normal condyle.Conclusion: Our animal study supports that indirect trauma on the TMJ can cause TMJOA. The MMP-13 MMP-3 and TIMP-1 are mainly derived from these chondr...