TMJ Disorders: An Evidence-Based NIDCR Overview

The temporomandibular joint (TMJ) is the joint that connects the lower jaw (mandible) to the temporal bone of the skull, just in front of the ear. You have a TMJ on each side of your face. These joints — together with the muscles, ligaments, and disks that work with them — allow you to talk, chew, yawn, and swallow.

TMJ disorders (also called TMD or TMJDs) are a group of more than 30 conditions that cause pain and dysfunction in the jaw joint and the muscles that control jaw movement. TMJDs can range from mild and self-limiting to severe and chronic.

According to the National Institute of Dental and Craniofacial Research (NIDCR), an estimated 11 to 12 million adults in the United States have pain in the region of the temporomandibular joint.

• TMJDs are about twice as common in women as in men, especially women of reproductive age.
• Symptoms often appear between the ages of 20 and 40.
• TMJDs frequently coexist with other chronic pain conditions — fibromyalgia, chronic fatigue syndrome, irritable bowel syndrome, headache disorders, sleep disorders, and anxiety or depression. NIDCR research suggests that TMJDs may share underlying mechanisms with these conditions.

There are three main categories:

1. Disorders of the joint (intra-articular)

These include:

• Disc displacement — when the small disc between the jawbone and the skull moves out of its normal position. May cause clicking, popping, or in some cases, the jaw locking open or closed.
• Degenerative joint disease — wearing away of the joint surfaces, similar to osteoarthritis elsewhere in the body.
• Inflammatory arthritis — including rheumatoid arthritis affecting the TMJ.

2. Disorders of the muscles (myofascial pain)

The most common form of TMJD. Involves pain in the muscles that control jaw function, often accompanied by jaw tenderness, headaches, and limited jaw movement. Stress, jaw clenching, and tooth grinding (bruxism) are common contributing factors.

3. Headaches associated with TMJD

Chronic headaches — particularly in the temples or behind the eyes — can be associated with TMJ-related muscle tension.

• Pain or tenderness in the face, jaw joint area, neck, and shoulders, and in or around the ear when chewing, speaking, or opening the mouth wide
• Limited ability to open the mouth wide
• Jaws that get stuck or lock in the open or closed mouth position
• Clicking, popping, or grating sounds in the jaw joint when opening or closing the mouth or chewing
• A tired feeling in the face
• Difficulty chewing or sudden uncomfortable bite
• Swelling on the side of the face

Less common symptoms include toothaches, headaches, neck aches, dizziness, earaches, hearing problems, upper shoulder pain, and ringing in the ears (tinnitus).

The causes of TMJDs are not well understood. Researchers believe TMJDs result from a combination of factors, including:

• Genetic predisposition
• Hormonal factors (which may explain the female predominance)
• Trauma — a direct blow to the jaw, neck injury (such as whiplash), or repetitive strain
• Jaw clenching or grinding (bruxism), which may worsen but does not necessarily cause TMJDs
• Anxiety and stress, which can increase muscle tension
• Other chronic pain conditions

Despite popular belief, research has NOT shown that bite alignment problems or routine orthodontic treatment cause TMJDs.

No widely accepted standardized test exists to diagnose TMJDs. Diagnosis is based on:

• Patient history — pain location, timing, and patterns
• Clinical examination — observation of jaw movement, palpation of the joint and muscles, listening for joint sounds
• Imaging — typically only when conservative treatment fails or when other conditions are suspected. Plain X-rays, MRI, or CT may be used.

Because many other conditions can cause similar symptoms — including ear infections, sinus problems, dental abscesses, neuralgia, and headaches — your provider will work to rule these out.

NIDCR's central message is one of caution: most TMJDs are self-limiting, and conservative, reversible treatments should be tried first.

Conservative, reversible treatments (recommended first-line)

• Patient education and reassurance — many TMJD symptoms resolve on their own with time
• Eating soft foods during flare-ups
• Applying ice or moist heat to the jaw
• Avoiding extreme jaw movements (wide yawning, loud singing, gum chewing)
• Gentle jaw stretching and relaxation exercises — often guided by a physical therapist
• Short-term use of over-the-counter pain relievers (NSAIDs)
• Stress management and behavior modification (cognitive behavioral therapy can be very effective for chronic cases)
• Stabilization splints ('bite guards') — short-term use only; NIDCR notes that the evidence for long-term splint therapy is limited

Why caution about irreversible treatments?

NIDCR specifically warns against several treatments that have been promoted for TMJD but lack strong scientific evidence:

• Major bite adjustment (extensive grinding of teeth to 'correct' the bite)
• Orthodontic treatment performed solely to treat TMJD
• Full-mouth restoration to alter the bite
• Surgery on the jaw joint in most cases
• Implants and replacement joint devices — some of which have been recalled due to safety concerns

Quote from NIDCR: 'Because more studies are needed on the safety and effectiveness of most treatments for jaw joint and muscle disorders, experts strongly recommend using the most conservative, reversible treatments possible. Conservative treatments do not invade the tissues of the face, jaw, or joint, or involve surgery. Reversible treatments do not cause permanent changes in the structure or position of the jaw or teeth.'

Surgery is considered a last resort and is reserved for:

• Severe degenerative joint disease that has not responded to conservative treatment
• Severe joint dysfunction such as locked jaw that cannot be opened
• Confirmed structural problems demonstrated on imaging

Even in these cases, the decision should be made in consultation with an experienced oral and maxillofacial surgeon, and ideally with a second opinion.

TMJ disorders are common, complex, and often misunderstood. For most people, conservative reversible treatments — patient education, soft diet, jaw rest, gentle exercises, stress management, and short-term pain medication — provide significant relief without permanent changes. Beware of any provider who recommends extensive irreversible treatment as a first-line therapy for TMJD pain.

This article is adapted from public-domain content published by the U.S. National Institute of Dental and Craniofacial Research (NIDCR) and the National Institutes of Health (NIH).