The incidence of TMJ 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, 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 stuck, joint function is limited (the most important is chewing food pain). Because the disease is self-limiting, that is, the development to a certain extent will limit itself, many people slowly self-recovery, or slowly get used to it is not too concerned. However, some patients will need professional medical intervention when they reach a certain level of development. 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 joint disc (reversible anterior displacement, irreversible anterior displacement, rotational displacement of the joint disc, internal and external displacement of the joint disc, etc.), expansion of the joint capsule and relaxation or avulsion of the joint disc attachments. 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 of this disease alone, but it can be accompanied by 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. Not to expand too much here, but I would like to share the most common causes of morbidity with you, ask yourself if you have these bad habits or reasons: 1, unilateral chewing: TMJ is a weight-bearing joint, each chewing, especially biting hard objects can be interpreted as a slight wear and tear, long-term unilateral chewing is bound to increase the load on one side of the joint, causing joint cartilage degeneration and unilateral masticatory muscle burden increased. 2, like to hold the chin: the same as the previous article, will increase the load on the joint. 3, like to open the mouth: often open the mouth will lead to ligament and joint capsule relaxation around the joint, if accompanied by other triggers, it is easy to trigger the second major type of internal disorders of the joint type of problems, the occurrence of joint disc reversible displacement, or even slowly transformed into irreversible displacement. 4, malocclusion and orthodontic history: It is not that malocclusion and orthodontics will necessarily lead to TMJ disorder, but occlusal problems can also interfere with the joint and secondary to this disease. 5, clenched teeth: In fact, it is not necessary to clench 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. 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, will occur joint movement disorders, accumulate subtle damage, inducing this disease. 6, mental stress: mental tension, or stressful times people tend to involuntarily show shrugging shoulders and clenched teeth, so that the shoulders neck and chewing muscles will be tense, temporomandibular joint and cervical spine can be considered the same system, all related problems will occur. 7, poor posture of the cervical spine: 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 to prove 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 relaxation and habitual clenching, so that the occurrence of internal disorders joint disc reversible displacement of the chances of greatly increased, so that is also one of the reasons why many patients occur joint popping. 8, the spirit is prone to depression or prone 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 despair about their condition, their own exaggeration of their condition and so on. 9, trauma: directly lead to injury, affecting the function. 10, like to eat snacks, especially hard, chewy food, singing, chatting: you do not give the joints a rest, the joints want you to look good la. These are common triggers for the onset of the disease, we rush to see if they have such problems, if so, first change these they can change.