Overview
An estimated 75% of the U.S. population has experienced one or more signs or symptoms of temporomandibular joint disorders (TMD). Most TMD symptoms are temporary and come and go over time, requiring little or no professional intervention. An estimated 5% to 10% of the U.S. population will require professional treatment. People with TMD usually have more than one symptom. The disorder rarely has a single cause.

TMJ Anatomy
The temporomandibular joint is a "loose-fitting," rotating-sliding joint with a fibrocartilage covered, football-shaped ball (condyle), fibrous pad (disc), fibrocartilage lined socket (fossa), ligaments, tendons, blood vessels and nerves. The fibrous disc functions as a moving shock absorber and stabilizer between the condyle and the fossa. As the jaw opens, the condyle rotates and slides forward with the disc.

The jaw muscles (called the muscles of mastication) connect the lower jaw (mandible) to the upper jaw (maxilla), skull and neck. The jaw muscles open, close, rotate and protrude the jaw, enabling you to talk, chew and swallow. The neck and shoulder muscles (supporting muscles) stabilize the skull on the neck during jaw function.

There are two types of TMD — muscle related and joint related.

• Myogenous TMD (muscle related) usually results from overwork, fatigue or tension of the jaw and supporting muscles. This type of TMD causes jaw-ache, headache and/or an ache in the back of your neck.
• Arthrogenous TMD (joint related) usually results from inflammation, disease or degeneration of the hard or soft tissues within the TMJ. Inflammation, disc dislocation and degenerative arthritis are the most common arthrogenous disorders of the TMJ.

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Causes of TMD
Causes of TMD are unclear — TMD usually involves more than one symptom and rarely has a single cause. Experts believe TMD results from several factors acting together, including jaw injuries (trauma) and joint disease (arthritis).

Tooth clenching and grinding (called bruxism) and head/neck muscle tension have not been scientifically proven to be a cause of TMD, but they may make TMD symptoms worse or last longer. Bruxism and head and neck muscle tension often need to be controlled to reduce and manage TMD symptoms.

It is important for people with TMD to understand that the disorder can be chronic in nature. Many factors, such as stress, psychological health and emotional stability can influence how severe a person's symptoms are and how long they last. Because there is no quick fix or immediate cure for TMD, the most successful and scientifically supported treatments focus on self-management and control of factors that make the disorder worse.

Factors associated with TMD

• Trauma: Direct trauma to the jaws has been scientifically associated with the onset of TMD symptoms. Direct trauma to the jaws can occur from a blow to the jaw, hyperextension or overstretching of the jaw, and in some cases, compression of the jaw. Lengthy or forceful dental procedures, intubation for general anesthesia and surgical procedures of the mouth, throat, esophagus and stomach can traumatize the TMJs.
• Abnormal habits: Habits such as tooth/jaw clenching, tooth grinding (bruxism), lip biting, fingernail biting, gum chewing and abnormal posturing of the jaws are common and have not been proven to cause TMD. These jaw habits often are associated with TMD and may be contributing factors that make ongoing TMD symptoms worse and/or last longer.
• Occlusion: Dental occlusion refers to the way the teeth fit together or the bite. Historically, dental professionals believed that abnormal bite (called malocclusion) was a frequent cause of TMD, but recent research studies do not support this. Large studies have shown that most patients with TMD have normal occlusion and the majority of people with malocclusion do not have TMD. Poor occlusion can be a contributing factor in the etiology of TMD but it is not usually a significant single cause.
• Psychological factors: Many patients with TMD say that their symptoms begin or become worse when they experience depression, anxiety or an increase in emotional stress. Scientific studies show that many patients with TMD experience higher levels of depression or anxiety than people without the disorder. Doctors and dentists do not know whether depression or anxiety is present before the onset of TMD and contributes to its cause, or whether the chronic pain associated with TMD leads to depression and anxiety. Many patients will increase their level of tooth clenching and grinding when they experience emotional stress, psychological imbalance or pain.
• Diseases of the TMJs: Several types of arthritis may develop in the TMJs like any other joint in the body. It is common for osteoarthritis to be present in the aging population. Many other diseases such as Parkinson's disease, myasthenia gravis, strokes and amyotrophic lateral sclerosis (Lou Gehrig's disease) may lead to excessive or uncontrollable jaw movements. Diseases such as tetanus (lock jaw) may lead to uncontrolled jaw muscle contracture.
• Other factors: Abuse of drugs and the use of certain prescription medications can affect the central nervous system and muscles and can contribute to TMD

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TMD Evaluation
Screening for TMD should be part of routine dental and medical examinations. Your doctor or dentist may ask you if you experience or have experienced any of the following:

• jaw pain,
• headache,
• neck ache,
• noises in the TMJs,
• catching or locking of the jaws,
• injuries to the jaw, head and/or neck and
• previous TMD or orofacial pain treatment.

During the examination, your dentist may

• measure your jaw opening and evaluate side to side movements,
• examine jaw deviation on opening,
• feel (palpitate) the TMJs, jaw, head and neck muscles to localize painful areas,
• identify joint noises, and
• evaluate the gums, oral soft tissue and teeth for disease, excessive tooth wear from bruxism and general symmetry of the jaw, face and head.

If your dentist notices evidence of TMD, he or she will recommend a more comprehensive history and clinical examination.

Comprehensive TMD Evaluation
A comprehensive TMD evaluation may include:

• Comprehensive history of all jaw, head and neck symptoms and medical history, dental history, personal history, family story and psychological history.
• Comprehensive physical evaluation of TMJs, cervical spine, muscles of the jaw, head and neck, neurological-neurovascular structures, teeth, gum and soft tissues.
• Psychological evaluation, including a brief interview and testing when indicated.
• Addition tests including x-rays and diagnostic imaging, biopsies, blood tests, urinalysis, neurological tests and diagnostic injections.

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Managing TMD
Because there is no known "cure" for TMD, people with TMD manage their disorder in a way that is similar to how people with arthritis or diabetes manage their disease. The goals of managing TMD include decreasing harmful pressure or loading on the jaw joints, restoring function of the jaw and resuming normal daily activities. These goals are best achieved by identifying all factors that make your TMD worse and following a well-defined management program to treat both physical and emotional or psychological factors.

Managing TMD is similar to other musculoskeletal disorders found in the body (such as rheumatoid arthritis or carpal tunnel syndrome). Like many musculoskeletal conditions, the signs and symptoms of TMD may be temporary without serious long-term effects. For these reasons, special effort should be made to avoid aggressive or nonreversible therapy such as surgery, extensive dental treatment or orthodontic treatment.

Conservative management techniques such as behavior modification, physical therapy, medication, jaw exercise and orthopedic appliances (orthotics) have proven to be safe and effective in most patients with TMD. Most patients suffering from TMD achieve good long-term relief with conservative therapy. Scientific research demonstrates that more than 50% of TMD patients treated with conservative management have few or no ongoing symptoms of TMD.

Patient self-care
If you have TMD, there are ways to care for yourself.

• Limit opening your jaw (yawning, etc.) no further than within a pain free range.
• Rest your jaw by avoiding heavy chewing (e.g. gum, bagel, tough meats).
• Avoid grinding and clenching of your teeth by keeping the teeth slightly apart and the jaw relaxed.
• Avoid leaning or sleeping on the jaw.
• Avoid tongue thrusting and chewing fingernails or non-food objects.
• Avoid playing wind, brass and string instruments that stress, retrude or strain the jaw.
• Use ice packs or moist heat compresses as directed by your doctor or physical therapist.
• Use over-the-counter medications such as aspirin, ibuprofen, naproxen or acetaminophen as directed.

Behavioral intervention
Behavioral intervention is often necessary to help people change harmful behavior or habits that contribute to pain. Maladaptive behavior and persistent habits such as tooth clenching or nail biting may play a significant role in making TMD symptoms worse or last longer. You may be able to control such behavior and habits once you become aware that you are doing them, but a behavior modification program developed and monitored by a trained expert often is necessary for long-term control. Clinical behavior modification programs may include habit reversal programs, lifestyle counseling, progressive relaxation, autogenic training, hypnosis and biofeedback. Programs combining comprehensive stress management, progressive relaxation, lifestyle modification and biofeedback often yield the best long-term result.

Psychological or emotional conflicts can be a major part of TMD and chronic pain behavior. Your doctor may refer you to a mental health professional such as a psychologist or psychiatrist for evaluation and treatment while you undergo physical treatment.

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Physical therapy
Physical therapy performed by a licensed physical therapist is well recognized as an effective and conservative treatment for musculoskeletal disorders such as TMD. Physical therapy helps in identifying and reducing contributing factors to musculoskeletal problems, reducing inflammation, restoring function and promoting repair and regeneration of injured tissues.

Physical therapy techniques may include spinal, head, jaw and tongue posture training.

Exercises prescribed by the physical therapist or doctor are important to maintain normal muscle and joint function and comfort, improve joint range of motion, increase muscle strength, develop normal coordination and stabilize the TMJs. Exercises should be specifically prescribed and monitored by your physical therapist or doctor as improper or excessive exercise therapy can aggravate TMD symptoms.

Techniques to manually move the jaw (mobilize) may be helpful for people with decreased range of motion and pain related to jaw muscle contracture, disc displacement and adhesion in the joints. A patient usually has to use pain relievers and muscle relaxation techniques before his or her physician can mobilize the jaw.

Other types of physical treatment options for TMD management include:

• electrotherapy, such as electrogalvanic stimulation (EGS), transcutaneous electrical nerve stimulation (TENS) and microcurrent,
• ultrasound,
• anesthetic agents, such as Vapocoolant spray or a topical pain reliever and
• stretching and
• massage.

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Medications for TMD
Medications can be very effective in reducing pain and inflammation. The most effective drugs for managing pain related to TMD include

• Non-narcotic analgesic drugs such as acetaminophen (Tylenol).
• Non-steroidal anti-inflammatory drugs (NSAIDs) such as aspirin, Trilisate, ibuprofen, naproxen and prescription strength NSAIDS.
• Muscle relaxant drugs such as methocarbamol (Robazin), orphenadrine citrate (Norflex) metaxalone (Skelaxin) or cyclobenzaprine (Flexeril).
• Tricyclic anti-depressant medications such as amitriptyline (Elavil), nortriptyline (Pamelor) and doxepin (Sinequan).
• Short-term use of opioid medications such as tramadol, codeine, propoxyphene or hydrocodone.

All medications have specific benefits and side effects. The extended use of opioid medications and sedative psychotropic drugs such as Valium, Xanax, and Ativan may lead to depression, drug tolerance and addiction, although addiction is rare. Use of these medications, which often give temporary relief from pain, is discouraged for long-term pain management.

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Occlusal therapy
Occlusal therapy involves changing the bite to reduce pressures in the joint. These therapies include orthodontics, surgery, placing multiple crowns or other dental restorations, or selective grinding on the teeth (equilibration). Since poor occlusion is not a common cause of TMD, using irreversible bite changes to treat TMD is usually not necessary, and not well supported by research. There are cases, however, that require permanent bite changes in order for their joints to stabilize.

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Oral orthopedic appliances
Oral orthopedic appliances are routinely used in TMD management. Oral orthopedic appliances are commonly referred to as occlusal splints, orthotics, night guards or bruxism appliances. Oral orthopedic appliances are usually made from hard acrylic, are removable and cover the upper or lower teeth. Oral orthopedic TMD appliances are designed to redistribute the occlusal forces (the bite), prevent wear, reduce mobility of teeth, reduce bruxism/clenching, reduce jaw muscle pain and alter structural relationships within the TMJ.

All oral orthopedic appliances should be periodically checked and adjusted by an experienced dentist as the potential exists for harmful changes to the teeth and jaws if improperly used. Complications such as dental caries, gingival inflammation, mouth odors, speech difficulties, tooth movement and psychological dependence on the appliance can occur with excessive or incorrect use of oral orthopedic appliances.

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TMJ Arthrocentesis
Arthrocentesis is also known as joint aspiration, a procedure during which a specially trained dentist uses a sterile needle and syringe to drain fluid from a joint. TMJ arthrocentesis consists of using a pain reliever to numb (anesthetize) the affected TMJ with local anesthetic and then flushing the joint with a sterile solution such as Lactated Ringers Solution. The effect of TMJ arthrocentesis is to lubricate the joint surfaces and reduce inflammation. Corticosteroids or other anti-inflammatory agents can be injected into the joint following arthrocentesis. Gentle manipulation of the jaw is often utilized following arthrocentesis to improve the jaw range of motion and in some cases break fibrous adhesions that limit normal jaw opening.

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TMJ Surgery
TMJ surgery can be an effective treatment for specific joint disorders for some patients. The complexity of surgical techniques, potential for serious complications, frequency of behavioral and psychological contributing factors and the availability of non-surgical approaches make TMJ surgery a procedure that should be used on very select patients. TMJ surgery should only be considered after reasonable reversible treatment techniques have been tried without success.

TMJ surgical procedures include closed surgical techniques (arthroscopy) and open surgical techniques (arthrotomy), as well as total joint replacements.

TMJ arthroscopy may be effective in treating painful joint hypomobility secondary to displaced discs, fibrous adhesions and arthritis. TMJ arthroscopic surgery has significant limitations related to the limited size of the arthroscopic instruments and limited space within the joint. Recent studies suggest that TMJ arthrocentesis may be as effective as TMJ arthroscopic surgery.

TMJ arthrotomy (open joint surgery) may be required in severe fibrous adhesion removal, ankylosis (bony or fibrous), tumor removal, chronic dislocation, painful non-reducing disc dislocation and severe osteoarthritis that have not responded to less invasive treatments such as medications and physical therapy. TMJ arthrotomy may range from simple removal of adhesions, disc repair or replacement to total joint replacement using cartilage and bone grafts or vitallium metal implants. Patients with TMD should be aware that there is no guarantee for successful surgical outcome and should seek several expert opinions before deciding on TMJ surgery.

Total joint replacement is available for advanced cases of TMD with considerable joint damage.

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Conclusion
Extensive research is being conducted on the safety and effectiveness of TMD/orofacial pain treatments. Most researchers, dentists and physicians strongly recommend reversible and conservative treatments for TMD. Even when TMD symptoms are long lasting and severe, most TMD patients do not require invasive treatment. Treatments designed to permanently change the bite or reposition the jaw with orthodontics or dental reconstruction should be avoided.

Specially trained dentists, physical therapists, psychologists and physicians are usually the best source for the proper diagnosis and management of TMD/orofacial pain. If your health care provider recommends irreversible treatment for TMD/orofacial pain, you should get a reliable second opinion from a trained expert.

This information was produced by the American Academy of Orofacial Pain (www.aaop.org). Adapted and printed with permission of the American Academy of Orofacial Pain.

The American Academy of Orofacial Pain is an organization of health care professionals dedicated to alleviating pain and suffering through the promotion of excellence in education, research and patient care in the field of orofacial pain and associated disorders.

This section is intended to provide general information on TMJ disorders and is not a substitute for careful evaluation by a physician or orofacial pain specialist.

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