Pain or other discomfort may arise in or around the articulation of the mandibular condyle with the glenoid fossa of the temporal bone. The pain may be mild or severe, acute or long-standing, and sharp or dull in character. Facial pain originating from the area of the temporomandibular joint (TMJ) may be due to intraarticular disease, disorders of adjacent structures outside the joint, or a combination of both.

Question the patient about the character of the pain and whether it remains localized or spreads to adjacent areas such as the ear, angle of the mandible, or neck. TMJ pain is often a dull, constant ache that is aggravated by opening the mandible or chewing. There may be a complaint of limited jaw opening and frequent "clicking," "popping," or "grinding" noise within the joint associated with mandibular movement or mastication. Associated symptoms may include tinnitus, changes in hearing, facial numbness, and headache. Symptoms may be worse in the morning, particularly if the patient clenches or grinds the teeth during sleep. Questioning of the patient's bed partner is helpful in this regard.

A history of systemic disease (e.g., rheumatoid arthritis) that can manifest itself in the TMJ, ear infection, or trauma to the mandible (e.g., motor vehicle accident, altercation, difficult tooth removal, prolonged jaw opening during dental treatment) should be sought. The patient may be taking medications (e.g., phenothiazine tranquilizers) that can cause dystonic movements of the masticatory muscles or have a neuromuscular disorder (e.g., parkinsonism) in which involuntary dislocation of the TMJ occurs. The patient should be questioned about possible job, marital, or other interpersonal conflicts that might enhance stress-related habits (e.g., clenching, bruxism, habitual subluxation).

The normal function of the temporomandibular joint depends on coordination, both at rest and during mandibular movement, of joint position, masticatory muscle activity, and occlusion of the teeth. Highly sensitive proprioceptive nerve endings in all these structures provide input that maintains equilibrium of function in the normal state. In such a delicately balanced anatomic area of the body, improper function is easily initiated in the susceptible patient.

Aside from injuries and systemic illnesses that occasionally involve the TMJ, the vast majority of disorders are stress related. Parafunctional habits (e.g., bruxism, clenching) are responsible for sustained contraction of masticatory muscles, which can become self-perpetuating and chronic (the so-called myofascial pain–dysfunction syndrome, or MPDS). The vast majority of MPDS patients are young, otherwise healthy females.

Sensory nerve supply to the TMJ is principally from branches of the auriculotemporal nerve, a component of the mandibular division of the trigeminal nerve. Pain from disease in the mandible or mandibular teeth can, therefore, easily be referred to the preauricular area and misinterpreted as originating from within the TMJ. Conversely, intra- or periarticular TMJ pain may be perceived by the patient as an "earache," and treatment may be sought on that basis.

The differentiation of pain originating within the joint from that coming from extraarticular structures is essential to successful treatment. The distinction cannot always be made from the history, however, and both intra- and extraarticular structures may be involved simultaneously.

The patient with stress-related MPDS usually complains of constant, dull pain that may or may not be exacerbated by mastication or mandibular movement and relieved by jaw rest. Quite often, this pain is worse in the morning, if related to nighttime parafunctional clenching or bruxism. The patient with intraarticular TMJ pain due to arthritis has the pain relieved by jaw rest and may be pain free except when moving the mandible or masticating solid food. Unfortunately, intraarticular TMJ disease often involves the masticatory muscles secondarily so that both types of pain (intra- and extraarticular) are experienced simultaneously by the patient.

Joint noise during function is highly suggestive of intraarticular disease. Grinding or crepitus often indicates an arthritic or other degenerative process and is caused by contact of roughened bony surfaces during function. Clicking or popping in the joint is usually associated with displacement of the fibrocartilaginous disk (meniscus) that separates the joint into upper and lower compartments.

Limitation of mandibular opening may be due to reflex spasm of masticatory muscles secondary to MPDS, to fibrous or bony ankylosis of the joint, to fracture of the mandibular condyle, or to total anterior displacement of the joint meniscus that blocks normal forward movement of the mandibular condyle.

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