Change Of Temporomandibular Joint Disc After Indirect Trauma

Trauma to the mandible may indirectly cause injury to the temporomandibular joint (TMJ), resulting in TMJ Internal Derangement (TMJOA), TMJ Osteoarthrosis (TMJOA) or TMJ Ankylosis. Traumatic TMJ disease can be caused by indirect force, which may lead to soft tissue with effusion into the joint space, dislocation (luxation) or fracture, if it was not treated in time, it might lead to irreversible changes of TMJ, although the pathological changes are poorly understood, few studies , however , are available in which the effect of indirect trauma to the TMJ has been examined in experimental animal. The relationship between indirect trauma of the TMJ and TMJOA or TMJID is still controversial. The pathogenesis of TMJOA resulted from indirect trauma is unclear .The objective of the present study is to evaluate an experimental model in an attempt to analyses the effect of indirect trauma on the disc of goats TMJ.20 young, growing goats were used in this study. The goats were fed a normal diet and were divided into 4 groups.the animal was impacted on angle of mandibule by self-made apparatus in direction of angle-temporol fossa, the impacting end is 3cm in diameter and 200g in weight, with a speed of 10 m/sec, and impacting of 10J. An intensity of pressure of 1.41J/cm2 can be produced in the impacted area. The animals were killed 2h, 1 month, 3 months and 6 months after trauma. The joint area was removed carefully with a band saw. All specimens were immediately fixed in 10% buffered formaldehyde solution. The specimens were further embedded in paraffin wax and sectioned at 5μm. They were stained with hematoxylin and eosin.RESULT:1, The parts of the discs were thinned. Posterior band of articular disc wouldperforated . The histological examination showed: The discs severelywere denatured and the fibre of articular disc were denatured. 2, The surface of disk was destroyed; the underlaying collagenfibrils wereloosed, disordered and exposed. 3, The strong positive expression of MMP-13 was observed in the disc ofTMJ after indirect trauma. The negative expression of MMP-13 wasobserved in the normal disc of TMJ CONCLUSION1, Indirect trauma on the goat TMJ can cause articular disc to destroy. 2, Indirect trauma on the TMJ can damage its natural barrier, expose thecollagen fibrils and start autoimmunity, then cause TMJ osteoarthrosis. 3,MMP-13 may play an important role in the pathogenesis of the disc ofTMJ after indirect trauma.