Practice Essentials
The temporal mandibular joint (TMJ) is the synovial joint that connects the jaw to the skull. These two joints are located just in front of each ear. Each joint is composed of the condyle of the mandible, an articulating disk, and the articular tubercle of the temporal bone. The movements allowed are side to side, up and down, as well as protrusion and retrusion. This complicated joint, along with its attached muscles, allows the movements needed for speaking, chewing, and making facial expressions. [1]
Pain and functional disturbances related to the TMJ are common, and are collectively termed TMJ syndrome or temporomandibular disorders (TMD). [2, 3] An international group has identified 12 of the most common pain-related and intra-articular TMJ disorders, which include myalgias, myofascial pain, arthralgia, disk displacement disorders, degenerative joint disease, and subluxation (see DDx/Diagnostic Considerations).
Signs and symptoms
Symptoms of TMJ syndrome consist of the following:
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Chronic pain in the muscles of mastication described as a dull ache, typically unilateral; pain may radiate to the ear and jaw and is worsened with chewing
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Locking of the jaw when attempting to open the mouth
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Ear clicking or popping, usually when displacement of the articular disk is present
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Headache and/or neck ache
Characteristic findings on physical examination include the following:
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Limitation of jaw opening (normal range is at least 40 mm as measured from lower to upper anterior teeth)
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Palpable spasm of facial muscles (masseter and internal pterygoid muscles)
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Unilateral facial swelling
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Clicking or popping in the TMJ
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Tenderness to palpation of the TMJ
See Presentation and DDx/Diagnostic Considerations for more detail.
Workup
Along with clinical examination, imaging studies are valuable for identifying causes of TMJ disorders and determining their severity. Imaging techniques used in this setting include the following [4] :
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Plain radiography; this includes intraoral x-rays and panoramic (panorex) x-rays (radiographs that provide a full view of the upper and lower jaws, teeth, TMJs, and sinuses)
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Computed tomography; cone-beam CT [5] and multidetector CT
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MRI
See Workup for more detail.
Treatment
Signs and symptoms of TMJ disorders improve over time with or without treatment for most patients. Initial management of TMJ disorders is with a conservative multimodal approach. A number of therapies are in use, although data supporting their efficacy is often mixed or weak and at best moderate, and reviews and guidelines offer contradictory recommendations on some therapies. [6, 7, 8] More invasive options can be considered when conservative measures have been exhausted.
See Treatment and Medication for more detail.
See also Temporomandibular Disorders.
Pathophysiology
The pathophysiology of TMJ syndrome is not entirely understood. The etiology is thought to be likely multifactorial, with contributing factors including the following [7] :
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Abnormal dental occlusion
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Bruxism [8]
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Joint capsule inflammation
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Muscle spasm
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Abnormalities in the intra-articular disk
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Pyschological stress, anxiety
Both local insults and systemic disorders may be involved. Local problems frequently arise from articular disc displacement and hereditary conditions affecting the structures of the joint itself, such as hypoplastic mandibular condyles. A study by Tallents et al found TMJ displacement in 84% of patients with symptomatic TMJ versus 33% of asymptomatic subjects. [9]
The TMJs can also be affected by conditions such as rheumatoid arthritis, juvenile idiopathic arthritis, [10] osteoarthritis, and diseases of the articular disks. In addition, hypermobile TMJs, nocturnal jaw clenching, nocturnal bruxism, jaw clenching due to psychosocial stresses, and local trauma also play a significant role.
A study of 299 females aged 18-60 years suggests that compared with nonsmokers, female smokers younger than 30 years had a higher risk of temporomandibular disorder than older adults. [11]
As described by Hegde, a strong understanding of how the trigeminal nerve innervates the TMJ and surrounding structures explains the pain and referred pain patterns of TMJ disorders. [12] Irritation of the mandibular branch (V3) of the trigeminal nerve results in pain locally at the TMJ and also to other areas of V3 sensory innervation, which include the ipsilateral skin, teeth, side of the head, and scalp.
Epidemiology
Frequency
United States
Currently, an estimated 10 million people have TMJ disorders, and roughly 25% of the population have symptoms at some point in their lives.
Mortality/Morbidity
The morbidity of the disorder is related to significant pain on movement of the jaw. While some patients' symptoms may resolve within weeks, others may have chronic symptoms that persist even with extensive therapy.
One study by Rammelsberg et al followed 235 patients over 5 years. [13] In this study, roughly one third of patients had complete resolution of pain, one third had continuous pain over the 5 years, and one third had recurrent episodes with periods of remission.
Race-, Sex-, and Age-related Demographics
See the list below:
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No apparent association with race exists.
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Female-to-male ratio is roughly 4:1.
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Highest incidence of TMJ syndrome is in adults aged 20-40 years
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TMJ syndrome is found infrequently in the pediatric population
Prognosis
See the list below:
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Prognosis of TMJ disorders is improved with early diagnosis.
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TMJ disorders often progress to a chronic state.
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Some cases may be self-limiting.
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Patients with ear symptoms tend to have a prolonged course of illness.
Patient Education
Patient education measures may include the following:
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Instruct patients to apply moist heat to affected area for no longer than 15 minutes per application.
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Educate patients about bruxism and the need to avoid clenching and grinding teeth.
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Suggest that stress can play a major role in illness; teach stress reduction strategies and provide behavior modification and counseling.
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Prescribe a soft diet for patients with chewing pain, and advise them to chew more slowly and take smaller bites.
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Instruct patient in jaw-opening exercises.
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For patient education information, see What Is TMJ (or TMD)?.
