When we speak, eat and make facial expressions, we are all involved in one joint of the face: the temporomandibular joint. When the TMJ becomes diseased, it not only affects the normal performance of these facial movements, but also makes it difficult for people to open their mouths. So, what exactly are the diseases of TMJ, how do they manifest themselves and how can they be treated? This is what we will talk about below. 1.What is TMJ? The temporomandibular joint is a movable joint in front of the ear on both sides of the face. The temporal part of the skull forms an articular fossa underneath, and the two ends of the mandible in the lower part of the face form an articular head, also known as the condyle; there is a pad formed by fibrocartilage between the articular fossa and the condyle, called the articular disc, and the joint is surrounded by the joint capsule. 2.Function (i.e. what role does the TMJ play?) Temporomandibular joint is the most complex and the only bilaterally linked joint in the whole body, and it is also the only joint in the whole body that can make sliding movements, while other joints can only make rotational movements, the temporomandibular joint only has rotational movements when making small openings, and sliding movements when making large openings. The TMJ is also the busiest joint in the body. In addition to being busy during the day, it still insists on working at night, especially for those who have a history of grinding their teeth at night, which increases the load on the joint and can easily damage it. The main function of the temporomandibular joint is to participate in eating, speaking, singing, swallowing and facial expressions. 3.What are the temporomandibular joint disorders? Because of the high usage rate of the TMJ, it is prone to injury and lesions. There are many types of TMJ disorders, the most common of which is temporomandibular joint disorder. TMJ disorders can be clinically classified into four major categories with a total of eleven diseases: first, disorders of masticatory muscles; second, disorders of joint structure, including reversible anterior displacement of joint disc, irreversible anterior displacement of joint disc, joint capsule expansion with loosening of joint disc attachment; third, inflammatory diseases, mainly referring to acute and chronic inflammation of synovial membrane and joint capsule; fourth, osteoarthrosis, including The fourth category, osteoarthrosis, includes joint disc perforation and rupture, osteoarthrosis, joint disc perforation and rupture with osteoarthrosis. In addition, there are temporomandibular joint dislocation, temporomandibular joint ankylosis, condylar fracture, joint soft and hard tissue tumors, and congenital and acquired developmental deformities of the temporomandibular joint. 4. Prevalence: TMJ is closely related to people’s daily life, and it is necessary to use TMJ for speaking, eating, singing, even talking in sleep and grinding teeth at night. According to the statistics of domestic and foreign experts, 25-50% of people in the population suffer from TMJ disorder, and the disease is most common in young and strong people, with the highest prevalence and consultation rate in 20-30 years old. In recent years, with the increase of traffic accidents, the cases of TMJ trauma and condylar fracture have also increased significantly, and there are more cases of TMJ ankylosis and TMJ dislocation, but tumors in the TMJ area are less common. With the improvement of living standard and people’s pursuit of aesthetics, the number of people coming for surgery due to secondary deformities of the maxillofacial area caused by joint diseases has been increasing in recent years. 5. Pathogenesis: (1) The most people suffer from TMJ disorder, so what factors can cause TMJ disorder? The etiology of TMJ disorder is not completely clear yet, and there are many etiological theories, which are generally considered to be related to the following factors: ① Psychological factors: Patients suffering from TMJ disorder often have mental symptoms such as anxiety, irritability, nervousness, agitation and insomnia. These may be related to work tension, study and life stress, and family factors. ②Jaw factors: that is, disorders of the occlusal-jaw relationship, such as jaw interference, early cusp contact, severe lockjaw, deep overjet, absence of most posterior teeth, and low vertical distance caused by excessive tooth wear. ③Immune factors: Some scholars believe that the disease is an autoimmune disease. ④Excessive joint load: unilateral chewing, grinding teeth at night, clenching teeth, eating hard objects frequently, getting high on melon seeds for a long time, chewing gum, etc. can increase the joint load. ⑤ Joint anatomical factors: TMJ with human evolution makes the joint more dexterous to adapt to more complex jaw movements such as speech and facial expressions, which makes the joint, muscles and ligaments significantly weaker and the weight-bearing capacity of the joint reduced. (6) Other factors: cold stimulation of the joint area, long-term poor posture, etc. (2) What are the causes of some other TMJ disorders? Condylar fractures are mostly caused by car accidents, external blows and jaw bruises. Temporomandibular joint ankylosis is mainly caused by joint trauma, especially condylar fracture, and inflammation is also an important cause of ankylosis, especially otitis media that is not controlled and causes inflammation to spread to the joint area. Temporomandibular joint dislocation is related to large open mouth, trauma and relaxation of joint capsule due to old age and weakness. 6.What are the manifestations of TMJ disease and how to prevent and treat it? (1) Clinical manifestations or clinical symptoms: ① Pain: mainly in the joint area or muscle pain around the joint during opening and chewing movements, usually without spontaneous pain, but acute synovitis also has spontaneous pain. ② popping and murmur: normal joints in the jaw movement without obvious popping and murmur, but the disease common abnormal sounds are: a. popping sound: that is, the opening and closing of the mouth movement in the “card, card” sound, mostly monotone, sometimes double sound, the joint disk displacement is mostly such sound; b. broken sound: that is, the opening movement in the The sound of “kaboom, kaboom”, mostly double or multiple sounds, can appear in the joint disc perforation, rupture or displacement; c. Friction sound: that is, there is a continuous sound like rubbing through the cellophane in the opening movement, osteoarthrosis, cartilage surface roughness can appear such sound. (iii) Abnormal jaw movement: the natural opening degree is 3.7cm in normal people, and the opening pattern is not skewed, but when there is disease, the opening degree changes (too large or too small), the opening pattern skew changes and the symptoms of joint locking appear. Traumatic joint injury mainly includes pain, restricted mouth opening, abnormal jaw movement and misalignment of the occlusal jaw joint. Joint dislocation mainly includes the inability to close the jaw automatically after opening the mouth and pain. Joint ankylosis mainly shows difficulty in opening the mouth or even complete inability to open the mouth, and sometimes the face is accompanied by developmental deformities. For example, the patient could not open his mouth and could only open two fingers. The arthrographic film showed that the contrast agent in the supra-articular cavity on the left side was only a little bit, and the movement of the joint condyle was limited when opening the mouth, while the normal contrast agent should fill the whole supra-articular cavity. On the other side of the patient (right side), there is a perforation of the articular disc, and the arthrographic film shows the flow of contrast from the superior to the inferior joint cavity. In this patient, the main problem is pain and restriction of mouth opening, in addition to which the movement of the jaw is skewed to one side. In addition to this, the patient’s movement will be deviated to one side. After a long time, it will destroy the head of the joint, which we call the condyle, and the patient will not be able to eat hard things, and the mouth will not be able to open wide, and there will be pain, and pain at night. (2) Diagnosis: TMJ disease is mainly diagnosed through medical history, specialist examination, and then X-ray, CT, MRI and arthrography. In addition, the development of joint micro-trauma surgery has made TMJ endoscopy the “gold standard” for diagnosis of TMJ disease. (3) Treatment: There are many treatment methods for TMJ disorders, but one treatment principle should be followed, that is, the first choice of reversible conservative treatment, such as: medication, physical therapy, closure and jaw plate; then irreversible conservative treatment, such as adjustment, orthodontic treatment; and finally, the choice of arthroscopic surgery and various surgical treatment. Specifically, for masticatory muscle disorders and inflammatory diseases, reversible conservative treatment such as closure, physiotherapy and medication can be used, and generally speaking, these diseases are more effective; those with displaced joint discs can wear repositioning jaw plates to restore the normal disc-protrusion relationship, and if they cannot be repositioned, arthroscopic surgical repositioning can be used, and if necessary, open surgery can be performed to reposition the joint disc; for those with joint capsule relaxation, arthroscopic injection of sclerosing agent can be used. For those with joint capsule laxity, sclerosing agent can be injected under direct vision; for joint disc perforation, rupture and osteoarthrosis, it is generally difficult to be cured by conservative treatment, which can only relieve the symptoms or slow down the process of the disease, and for those who still have recurrent pain after comprehensive treatment, with restricted opening and affecting the function, surgery can be adopted. The treatment method of the case cited above: the left joint cavity adhesion, we see the adhesion site through arthroscopy, the main adhesion site is the adhesion between the upper cavity of this joint and the joint disc, and then the mouth cannot be opened, so we peel off the adhesion site through arthroscopy, flush the synovial inflammation inside with saline constantly, and aspirate it to get out the flocculent and fibrous material caused by the inflammation. The inflammation of the synovial membrane is flushed with saline and aspirated to remove the inflammatory flocculent and fibrous material. After this treatment, the patient’s opening can be increased and the inflammation can be eliminated and the pain can be relieved. On the other side (right side), the joint disc perforation cannot be completely treated by arthroscopy alone, so surgery is needed to open the joint and suture up the perforated joint disc, after suturing, the bone to bone contact between the condyle and the joint will not be made because of the perforation. destruction was relieved. This way, his mouth can be opened wide and he can eat hard things after the bone lesion is improved slowly. So this is a better result. This patient was treated with both endoscopic and surgical procedures. What is the treatment method for other TMJ diseases such as joint ankylosis and joint dislocation? Joint ankylosis can only be treated surgically by chiseling away the adherent bone to form a prosthetic joint. Joint dislocation can be treated by repositioning and fixing the mandible by manipulation, while habitual dislocation can be treated by injection of sclerosing agent, or surgery if it is not effective. (3) Prognosis: All joint diseases have a good prognosis after treatment by a regular specialist.