Temporomandibular joint model: anatomical comparison between human and rat

Abstract

Aim:To compare the features of human and rat TMJ anatomically.Objective: To analyze and evaluate human and rat TMJ from an anatomical point of view and make a comparison between them to set an alternate and easy model of TMJ. Background:The human TMJ is a group of anatomical structures that with a special group of muscles, is responsible for the movement of the mandible during mastication. This joint has a unique structure and function as compared with other diarthrodial joints. TMJ disorders and other related pathologies are very common and little is known about their underlying pathogenesis. Invitro studies and animal models may be used for these purposes. In particular, rats may be used since they are easy to handle and inexpensive to maintain in a bioterium, making them a convenient animal for use in experimental studies. Materials and Methods:Formalin fixed twelve adult male Wistar Albino rat specimens were used in this procedure. The various anatomical structures of TMJ were evaluated such as condyle, mandibular fossa, disc, articular tubercle and temporal bone of rat was compared to that of humans. Results:The TMJ is surrounded by a thin capsule, consisting of fibrous tissue and a synovial lining. The mandibular angle has a prominent shape. The glenoid fossa is flat, with no eminences. Conclusion:Morphologically the articular structure of rats is, on the whole, similar to that of humans. In these animals there is no articular eminence. INTRODUCTIONThe human temporomandibular joint (TMJ) is a group of anatomic structures that, with a special group of muscles, is responsible for the movement of the mandible during mastication. It consists of the condylar process of the mandible, the mandibular fossa of the temporal bone, a thin articular disc, and a loose joint capsule, which is strengthened by a fibrous lateral ligament [1]. This joint, which is classified as a hinge-sliding joint, has a unique structure and function as compared with other diarthrodial joints [2].Innumerous diseases, such as neoplasias, trauma, ankylosis and degenerative diseases may affect the TMJ and lead to the loss of its structures. This pathological condition of TMJ is regarded as the TMJ disorder. For all these diseases there are specific treatments, each of which has a wide range of success. As a result there is always a need for progress in the treatment of some of these diseases. Furthermore much of the research in this area cannot be done on humans for ethical reasons. Studies in vitro and animal models may be used for this purpose [3]. In particular, rats may be used since they are easy to handle and inexpensive to maintain in a bioterium, making them a convenient animal for use in experimental studies, giving rise to new ideas in the quest for new treatments for TMJ diseases. However it is not known how similar the TMJ of the rat is to the human TMJ, which is important for the validation of the studies, realizing that these studies could be extrapolated to humans because of similar TMJ anatomical features. MATERIALS AND METHOD...