Comparison of Mouth Opening Length and Masseter Thickness in Subjects with and without Temporomandibular Joint Pain

Abstract

The temporomandibular joint (TMJ) is a complex lubrication joint between the mandibular fossa of the temporal bone and the articular process of the mandible. The TMJ consists of a synovial membrane, a joint pocket, a joint disc, and bone tissue. Unlike other synovial joints, the articular cartilage of the TMJ is characterized by a layer of connective tissue. The TMJ is one of the most used joints in the human body, and it moves more than 2,000 times a day. About 40–60% of the population has a TMJ disorder and has been reported to experience pain and limitation of the TMJ range of motion. Symptoms of TMJ disorders include a limited range of motion of the mandible, masticatory and joint pain, joint sounds (clicking, popping, or bone fricative sounds), fascia pain, and functional limitations. The most common symptoms of TMJ disorders are reportedly joint and muscle pain. TMJ disorders are caused by various and complex factors; the main factors are overactivity of the muscles and abnormal functional activities (e.g., incorrect biting) due to factors such as trauma, emotional stress, and malocclusion. The two TMJs are bilateral, and because both sides of the mandible roll or slide together, one TMJ cannot be moved Comparison of Mouth Opening Length and Masseter Thickness in Subjects with and without Temporomandibular Joint Pain