The incidence of temporomandibular joint disorder is still quite high, 70% of people in foreign countries have had the disease at least once in their lives, and women are the most prevalent group of this disease, and among young people from 13-35 years old is the most prevalent age group, the most important manifestations are pain in the joint area or face, reduction of mouth opening, joint rattling, joint strangulation, joint function is limited (the most important is the pain of chewing food). Because the disease is self-limiting, that is, it will develop to a certain extent to limit its own development, many people slowly recover themselves, or slowly get used to it and do not pay much attention to it. However, some patients develop to a certain extent and need professional medical intervention. TMJ disorder is actually not a single disease, it is a collective name for many different diseases. The latest classification criteria were unified in 2002 and divided into the following 4 categories: 1. Masticatory muscle disorders: including myofascial pain, myositis, myospasm, degenerative contracture of muscle fibers and unclassified limited myalgia. These diseases are extra-articular diseases. 2. Structural disorders: Abnormal changes in the normal organic structural relationship of the joint, including various displacements of the articular disc (reversible anterior displacement, irreversible anterior displacement, rotational displacement of the articular disc, internal and external displacement of the articular disc, etc.), expansion of the joint capsule, and relaxation or avulsion of each attachment of the articular disc. In cases of joint capsule dilatation, relaxation, and loosening or tearing of the disc attachments, joint subluxation is often associated with joint subluxation. During the progression from a reversible anterior displacement to an irreversible anterior displacement, there is often an intermediate state, which is characterized by recurrent temporary locking during the opening process and failure of the disc to return to its normal position. There should be no degenerative changes in the bony joint structure on X-ray alone, but there may be mild to moderate osteoarthrosis-like changes. 3, inflammatory joint disease: including synovitis and (or) arthritis, can be divided into acute and chronic. Clinical manifestations are localized joint pain, which is aggravated by functional activity, especially with upward and posterior joint weight-bearing pressure and palpation; such cases should be free of osteoarthrosis and structural disorders on imaging; however, they can be accompanied by or secondary to osteoarthrosis and structural disorders. 4, osteoarthrosis: according to the etiology and clinical situation can be divided into primary osteoarthrosis and secondary osteoarthrosis. In clinical practice, we see the most patients in the first two categories, mainly manifesting as pain in the joint area, joint popping, joint griping and jamming, and restricted mouth opening. Without expanding too much, I would like to share with you the most common causes of morbidity, and ask yourself if you have these bad habits or causes: (1) Unilateral chewing: TMJ is a weight-bearing joint, and each chewing, especially biting hard objects, can be interpreted as a slight wear and tear, and long-term unilateral chewing is bound to increase the load on one side of the joint, causing articular cartilage degeneration and increased burden on unilateral chewing muscles. (2) like to hold the chin: the same as the previous article, will increase the load on the joints. (3) Preferring to open the mouth wide: frequent opening of the mouth wide can lead to laxity of the periarticular ligaments and joint capsule, which, if accompanied by other triggers, can easily lead to the second major type of internal joint disorder, with reversible displacement of the joint disc, or even slowly changing to irreversible displacement. (4) History of malocclusion and orthodontics: It is not that malocclusion and orthodontics necessarily lead to TMJ disorders, but occlusal problems can also interfere with the joint and secondary to this disease. (5) Clenching: Actually, it is not necessary to clench the teeth, our patients, not to say 100%, but more than 80% have the same problem, that is, when not talking, the upper and lower teeth are in contact with each other. Many patients do not understand what this has to do with this disease, in fact, this is really a big impact. The movement of the jaw is controlled by the movement of the chewing muscles, people are upright animals, the jaw is affected by the gravitational pull of the earth is theoretically falling down, if you keep maintaining the upper and lower teeth contact, is to do the muscle of the closed mouth action in contraction, and is always contracting, although the endurance of the chewing muscles is very good, but the endurance is good, but also fatigue, fatigue will have a sore feeling, and in the normal opening and closing of the mouth and chewing can not be very good Work, joint movement disorders will occur, accumulate subtle damage, and induce this disease. (6) mental stress: mental tension, or stressful times people tend to involuntarily show shrugging shoulders and clenching teeth, so that the shoulder neck and chewing muscles will be tense, the temporomandibular joint and cervical spine can be considered the same system, and related problems can occur. (7) poor cervical posture: mainly modern people often face the computer, recently there is a popular ipad. all day low, or like the picture below this posture, there are many studies have proved that in the case of head forward, the muscles around the hyoid bone will pull the jaw bone, will affect the movement of the jaw trajectory, interference with the joint. If the patient also has joint capsule laxity and habitual clenching, the chance of internal disorder of the joint disc reversible displacement is greatly increased, which is also one of the reasons why many patients have joint popping. (8) Spiritual easily depressed or easy to go to extremes: psycho-psychological factors are increasingly found to be directly related, many of our clinical patients have such more or less problems, such as feeling desperate for their own condition, exaggerating their own condition and so on. (9) Trauma: directly causes damage and affects function. (10) Like to eat snacks, especially hard, chewy food, singing, chatting: if you do not give the joint a rest, the joint will have to look good for you.