1.What is temporomandibular disorders (TMJ)? Temporomandibular disorders (TMDs) is a common disease in oral and maxillofacial surgery, which is most common in female young adults, with the highest prevalence in 20-40 years old. The clinical manifestations of TMJ disorders are mainly: joint popping, pain, restricted mouth opening, eating and speech and other jaw dysfunction, which seriously affect the quality of life of patients. 2.Why does TMJ disorder occur? Some scholars have confirmed that joint trauma is a common cause of TMJ disorder. Due to biting hard objects, opening the mouth for too long (such as treatment of teeth, yawning and teachers or singers) and external trauma, etc., the posterior attachment ligament of the joint disc is relaxed and the tiny blood vessels in the joint capsule bleed and exude. This leads to displacement of the articular disc, synovitis and increased joint effusion, as well as the formation of adhesions in the joint cavity, roughness and deformation of the surface of the articular disc. Clinical manifestations include jaw movement disorders (joint popping, restricted mouth opening, deviation) and pain in and around the joint. 3.How to treat TMJ disorder? In the past, patients with TMJ disorder were mainly treated conservatively, and joint pain and mouth opening restriction were relieved by adjusting the joint, drugs, local physiotherapy, dental plates and sealing. However, due to the structural disorders in the joint cavity (e.g., formation of adhesions, displacement of the joint disc, etc.), which cannot be solved by conservative treatment, open general anesthesia surgery is traditionally used for those who do not respond to conservative treatment. With the continuous development of endoscopic medicine, clinical application confirms that TMJ surgery fully embodies the characteristics of minimally invasive surgery: small incision (about 0.5cm in size), little damage to surrounding tissues, short operation time, local anesthesia, little bleeding, hidden scar, and few complications, which are easily accepted by patients. 4.How does TMJ surgery treat TMDs? Endoscopic treatment of TMJ diseases has a wide range of indications and is most commonly used to treat pain, restricted mouth opening, reversible and irreversible anterior displacement of joint discs, intracapsular fibrous adhesions, intractable joint pain, certain organic joint lesions, etc. It can also be used to treat traumatic intracapsular hemorrhage, septic arthritis, synovial chondromatosis, etc. The procedures include: joint lavage, adhesion release, joint disc repositioning and free body removal. Arthroscopic surgery is performed by puncturing into the joint cavity and accurately flushing the supracapsular fluid, scraping away exudate, separating adhesions, releasing and repositioning the joint disc under direct vision to achieve the treatment purpose. TMJ arthroscopic surgery has the advantages of safety, less damage, direct action, short treatment time and clear efficacy, etc., and has a bright application prospect.