(See also Dental Emergencies: Mandibular Dislocation, Facial Trauma: Temporal Bone Fractures, and Tumors of the Head and Neck: Jaw Tumors.)

The term temporomandibular disorders is an umbrella term for conditions causing dysfunction of the jaw joint or pain in the jaw and face, often in or around the temporomandibular joint (TMJ), including masticatory and other muscles of the head and neck, their fascia, or both. A person is considered to have a temporomandibular disorder only if pain or limitation of motion is severe enough to require professional care.

Temporomandibular disorders typically are multifactorial in origin, but most are related to problems with muscles or joints. Internal derangements of the TMJ cause disturbed movement of the mandibular condyle in the glenoid fossa or against the cartilaginous articular disk (see Fig. 1: Temporomandibular Disorders: The temporomandibular joint.). This disk, shaped like a mature red blood cell, serves as a cushion between bone surfaces. Causes for this disturbed movement include clenching and grinding of the teeth, trauma, arthritis, and malocclusion and missing teeth. Even persistent gum chewing can lead to symptoms.

Fig. 1
The temporomandibular joint. The joint is formed by the mandibular condyle and the glenoid fossa of the temporal bone; a cartilaginous articular disk functions as a cushion between the joint surfaces.

Diagnosis

Disorders of the TMJ must be distinguished from the many conditions that mimic them (see Table 1: Temporomandibular Disorders: Some Conditions That Mimic Temporomandibular Disorders). Pain exacerbated by finger pressure on the joint when the mouth is opened implicates the TMJ.

Table 1
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Some Conditions That Mimic Temporomandibular Disorders Symptom Condition Headaches Sinusitis Temporal arteritis Tension, migraine, and cluster headaches Pain Postherpetic neuralgia Reflex sympathetic dystrophy or traumatic neuroma after head or neck surgery Toothache Trigeminal neuralgia Pain accompanied by hearing problems Obstruction of the ear canals or eustachian tubes Otitis media Pain in the head, neck, and other areas of the body Fibromyalgia Generalized myofascial pain Pain, numbness Intracranial aneurysm Metastatic tumors Pain that radiates to the temporomandibular joint region Whiplash injuries affecting muscle or cervical spine Pain that worsens when the patient swallows or turns the head Cervical spine or muscle disorders Eagle syndrome (calcified styloid process) Glossopharyngeal neuralgia Subacute thyroiditis Trismus Depressed fracture of the zygomatic arch Infection Osteochondroma of the coronoid process Pericoronitis

Patients are asked to describe the pain and designate painful areas. The muscles of mastication (temporalis, masseters, and medial and lateral pterygoids) and cervical and occipital muscles are palpated for general tenderness and trigger points (spots that radiate pain to another area). Patients are observed opening the mouth as wide as is comfortable. When patients open and close their mouth with the junction of the maxillary and mandibular central incisors (normally in the midline) lined up against a vertical straight edge, the mandibular midline typically deviates toward the painful side. Palpation and auscultation of the joint during opening and closing may reveal tenderness, catching, clicking, crepitus, or popping. Condylar motion can best be palpated by placing the 5th fingers into the external ear canals and exerting very gentle forward pressure as patients move the jaw. The average-sized patient can open the mouth at least 40 mm (measured between upper and lower central incisors). To account for differences in patient size, a patient should be able to fit 3 fingers (index, middle, ring) in the mouth on top of each other up to the first joint.

Last full review/revision January 2013 by Noshir R. Mehta, DMD, MDS, MS