Role of Disc in Function of Temporomandibular Joint

Objective: The role of the TMJ disc function remains controversial. Our lab has reported the arrangement of disc collagen fiber in the rat posterior teeth loss model. There is no significantly affected by changes in disc loading. Results indicated that the role of the rat TMJ disc is mainly to assist condyle movement instead of load bearing. However, rat model cannot mimic human completely because of rat masticatory mechanics are different to human. Recently, many studies have compared the TMJ disc biochemical properties, joint anatomy, function and diet in different animal models. porcine model is most similar to the human. The objective of this research was to investigate the TMJ disc in porcine posterior teeth loss models to clarify the role of the disc function. Method: Four porcine were divided randomly into experimental and control groups. Each group composed of 2 porcine. Posterior teeth of these animals were extracted at the beginning of this experiment. After six months, porcine were sacrificed. Condyle of each porcine were observed by computed tomography (CT). Collagen arrangement in the disc of porcine was observed by scanning electron microscope (SEM). Result: Under SEM, the collagen fiber showed anterior-posterior in direction. There was no difference in the arrangement of the collagen fiber between these two groups. There was no difference in the condyle structure between experimental and control groups could be observed in CT. Conclusion: The main arrangement of collagen fiber in the TMJ disc is anterior-posterior direction and in accordance with the functional direction of the TMJ. Result indicated the role of the disc in TMJ function may mainly assist condyle movement instead of load bearing in the porcine models.