Experimental Dynamic Testing for Wear of TMJ Prosthesis Component in a Multiaxial Join Simulator

The temporomandibular joint (TMJ) is primarily considered a bi-arthrodial and ginglymoarthrodial joint. The former term describes its capacity to facilitate movements in all three anatomical planes. It is enveloped by an articular capsule that provides protection against internal and external forces, preventing separation of the articular surfaces of the mandibular condyle, the articular disc, the glenoid fossa, and the articular eminence. This capsule stabilizes the joint and retains synovial fluid, which serves several essential functions: preventing joint wear, reducing friction between articular surfaces, and providing nutrients. The TMJ has two convex surfaces: the articular eminence and the mandibular condyle. These surfaces, along with the articular disc, bear the primary loads generated during mandibular movements. The latter condition pertains to rotation and translation movements in the inferior and superior cavities, respectively. These movements result from the position of the articular disc situated between the glenoid fossa and the mandibular condyle. Temporomandibular disorders (TMD) can arise from various factors, including malocclusion, teeth grinding, jaw injuries, torn TMJ ligaments, congenital TMJ disorders, or trauma to the TMJ. TMDs, as described in the literature, are prevalent among individuals aged approximately 20–40 years old. Common symptoms include migraine-like headaches, ear pain, clicking sounds during jaw movements, jaw blockages when attempting to open or close the mouth fully, which may lead to dislocation or jaw muscle pain. These symptoms often reduce an individual's confidence, impacting both their professional and personal lives. TMDs can be managed through conservative or surgical treatments. The focus of this research paper is on surgical treatment, specifically, the analysis of a TMJ prosthesis in an in vitro setting. The objective is to develop an in vitro test capable of evaluating the longevity of TMJ prostheses. This need arises due to a lack of wear analysis tests for TMJ prosthetic systems available on the market. Mechanical properties and wear resistance play a pivotal role in determining the lifespan of TMJ prostheses. This testing could potentially prevent the need for additional surgeries due to prosthesis failure, thereby avoiding revision or replacement surgery altogether. This is crucial because the life expectancy of a total TMJ replacement is inversely correlated with the number of revision surgeries required.