Animal models of temporomandibular joint disorders: implications for tissue engineering approaches.

Animal models for temporomandibular joint disorder (TMD) or degradation are necessary for assessing the value of current and future tissue engineering therapies. After reviewing the literature, it is quite apparent that most TMD animal studies can be categorized into chemical approaches or surgical/mechanical approaches. Overall, it was found that the top five cited manuscripts for all chemical models were cited by almost 40% more manuscripts than the top five manuscripts for surgical/mechanical models. It is clear that the chemical approaches have focused on the inflammatory aspect of TMDs and its relationship to pain. However, chemical irritants must be tested in larger animal models, and the effect of short-term inflammation on the mechanical properties of the fibrocartilage must be examined. Nevertheless, therapeutic approaches aimed at reducing or controlling inflammation could use the established chemical methods. Surgical/mechanical methods can be used as negative controls for first generation TMJ tissue engineering approaches when the therapy is applied immediately after injury. Next generation tissue engineering approaches will require testing on tissues degenerated for a few months after the surgical/mechanical methods, with enhanced functional assessment techniques.