Temporomandibular Joint Dysfunction Syndrome (TMJDS) is one of the common diseases in the oral and maxillofacial region. Among temporomandibular joint disorders, this condition is the most prevalent. It predominantly affects young adults, with the highest incidence occurring between the ages of 20 and 30.

bubble_chart Etiology

Temporomandibular joint disorder syndrome mostly occurs in young and middle-aged adults. The {|###|}pathogenesis{|###|} is not yet fully understood. The main features of this condition include soreness and pain in the joint area, clicking sounds during movement, and restricted mouth opening. Most cases involve joint dysfunction and have a good prognosis; however, a very small number of cases may develop organic changes.

1. Traumatic factors: Many patients have a history of local trauma, such as acute injuries from external force impacts, sudden biting of hard objects, or excessive mouth opening (e.g., yawning). Other factors include frequent chewing of hard foods, nighttime teeth grinding, and unilateral chewing habits. These factors may lead to joint {|###|}contusion{|###|} or strain, and dysfunction of the masticatory muscle groups may also contribute to the onset of this condition.

2. Occlusal factors: Many patients exhibit significant occlusal disturbances, such as overly high cusps, excessive tooth wear, extensive loss of molars, poorly fitted dentures, or excessively low intermaxillary distance. Disordered occlusal relationships can disrupt the functional balance within the joint structure, promoting the occurrence of this condition.

3. Systemic and other factors: Neuropsychological factors may play a role in this disease. For example, some patients exhibit emotional irritability, mental stress, or heightened excitability. Additionally, some patients have a history of Bi disease, while others may experience onset related to exposure to cold.

The main clinical manifestations of temporomandibular joint disorder syndrome include local soreness or pain, clicking sounds, and movement disorders. The pain may occur in the joint area or surrounding regions and can be accompanied by varying degrees of tenderness. Joint soreness or pain is particularly noticeable during chewing and mouth opening. Clicking sounds occur during mouth-opening movements and may appear at different stages of mandibular motion, manifesting as clear single clicks or fragmented continuous sounds. Common movement impairments include restricted mouth opening, but excessive mouth opening or jaw deviation during opening may also occur. Additionally, symptoms such as temporal pain, dizziness, and tinnitus may be present.

bubble_chart Diagnosis

Based on the medical history, diagnosing temporomandibular joint disorder syndrome is not difficult given the presence of the aforementioned primary symptoms. Common auxiliary diagnostic methods include: ①X-ray plain films (Schüller’s view and transcranial lateral view of the condyle), which can reveal changes in joint space and bone structure, such as sclerosis, bone destruction, hyperplasia, and cystic changes. ②Joint arthrography (upper joint space arthrography is more commonly used due to its ease of operation, while lower joint space arthrography is less frequently applied domestically), which can detect disk displacement, perforation, alterations in disk attachments, and changes in the cartilage surface. In recent years, many scholars have employed arthroscopy, which can identify early-stage changes of the disorder, such as hyperemia, bleeding, adhesions in the disk and synovial membrane, and the formation of "joint mice" by undifferentiated chondroid tissue. Since this disorder has many types with varying treatment approaches, a specific diagnosis should be made, such as lateral pterygoid muscle spasm, reducible disk displacement, or disk perforation.

Specific treatment measures include:

1. Correcting occlusal relationship: Examination and treatment by a dental specialist.

2. Block therapy: Use 0.25–0.5% procaine (3–5 ml) for lateral pterygoid muscle block. The puncture point is at the midpoint of the sigmoid notch, with vertical needle insertion to a depth of about 2.5–3 cm. Inject the medication after confirming no blood is aspirated. Commonly used for patients with excessive mouth opening.

3. Ethyl chloride spray combined with tuina can relieve masticatory muscle spasms. The spray should be mist-like and applied intermittently, combined with tuina to prevent frostbite disease. Protect the eyes and ears, and keep away from fire sources.

4. Acupuncture therapy: Acupoints include Xiaguan (ST7), Tinggong (SI19), Jiache (ST6), Hegu (LI4), supplemented by Yifeng (SJ17), and Taiyang (EX-HN5).

5. Local physiotherapy such as ultrashort wave, iontophoresis, electrostimulation, and magnetic therapy can provide certain therapeutic effects.

During treatment, it is necessary to correct bad habits (such as unilateral chewing) and prevent excessive mouth opening.

bubble_chart Differentiation

Since many other diseases often present with the above three main symptoms, it is necessary to differentiate them from the following conditions:

1. Tumors

Deep-seated tumors in the maxillofacial region can also cause difficulty in mouth opening or trismus. Because these tumors are difficult to detect in deep tissues, they may be misdiagnosed as temporomandibular joint disorder syndrome, leading to inappropriate treatment and missing the optimal window for early radical treatment of the tumor. Therefore, when difficulty in mouth opening occurs, especially when accompanied by cranial nerve symptoms or other symptoms, the possibility of tumors in the following areas should be considered: ① Benign or malignant tumors of the temporomandibular joint, particularly osteosarcoma of the condylar process. ② Tumors of the infratemporal fossa. ③ Tumors of the pterygopalatine fossa. ④ Carcinoma of the posterior wall of the maxillary sinus. ⑤ Malignant tumors of the parotid gland. ⑥ Nasopharyngeal carcinoma, etc.

① Acute suppurative arthritis of the temporomandibular joint: Redness and swelling are visible in the joint area, with obvious tenderness, especially the inability to occlude the upper and lower teeth. Slight pressure can cause severe pain in the joint area. ② Rheumatoid arthritis of the temporomandibular joint: Often accompanied by systemic migratory and polyarticular arthritis, particularly affecting the small joints of the limbs. In advanced stages, joint ankylosis may occur.

3. Otogenic Diseases

Furuncles in the external auditory canal and inflammation of the middle ear can also radiate pain to the joint area, affecting mouth opening and mastication. Careful otologic examination can easily differentiate these conditions.

4. Cervical Spondylosis

This can cause pain in the neck, shoulder, back, retroauricular area, and lateral face, leading to misdiagnosis. However, the pain is unrelated to mouth opening or mastication but is often associated with neck movement and posture. Some cases may also present with numbness and motor abnormalities in the hands. X-rays can help diagnose whether there are bony changes in the cervical spine for differentiation.

5. Elongated Styloid Process

In addition to pharyngeal pain and paresthesia during swallowing, it often causes pain in the posterior condylar region during mouth opening and mastication, as well as referred pain in the posterior joint area, retroauricular region, and neck. X-ray examination can easily confirm the diagnosis.

6. Hysterical Trismus

If hysterical trismus is accompanied by other muscle spasms or spasm symptoms elsewhere in the body, diagnosis is relatively easier. This condition is more common in young women with a history of hysteria and unique personality traits. It usually occurs after psychological triggers, leading to sudden difficulty in mouth opening or trismus. Treatment with verbal suggestion or indirect suggestion (combining other therapies with verbal suggestion) is often effective.

7. Tetanic Trismus

Tetanus is an acute specific infection caused by Clostridium tetani, characterized by paroxysmal muscle spasms and tonic contractions. Since the initial stage may present as difficulty in mouth opening or trismus, patients may visit the dental department. It should be differentiated from temporomandibular joint disorder syndrome to avoid delaying early treatment. Tetanic trismus usually has a history of trauma. Spasms typically start in the masticatory muscles, initially with slight tension, making the patient feel restricted in mouth opening, followed by tonic spasms leading to trismus. Concurrently, the tightening of facial muscles may result in a characteristic "sardonic smile" and may be accompanied by facial muscle spasm.