TMJ
What Is TMJ?
'TMJ' stands for temporomandibular joint, or the jaw joint. In fact, there are really two TMJs, one in front of each ear. The TMJ is the joint formed by the temporal bone of the skull (temporo) with the lower jaw or mandible (mandibular). These joints move each time we chew, talk or swallow. Unlike the shoulder or knee, which are ball-and-socket joints, the TMJ is a sliding joint. The sliding allows for pressure placed on the joint to be distributed throughout the joint and not just in one area. Adding to the joint's complexity is that between the two bones that make up the TMJ (the temporo and mandibular) is a disc, just like those between the bones on your back. Made primarily of cartilage, in the TMJ the disc acts like a third bone. Because it is attached to a muscle, the disc actually moves with certain movements of the TMJ.
One of the difficulties with diagnosing a TMJ disorder is identifying the exact source of the problem. For example, the nerve to the TMJ is a branch of the trigeminal nerve. An injury to this nerve in the TMJ may be confused with neuralgia because the symptoms appear to be the same. The two bones of the TMJ are held together by a series of ligaments, any of which can be damaged. A damaged TMJ ligament usually results in a dislocation of the disc, the lower jaw, or both. Another possible problem may be from muscles that are connected to the bone. A muscle injury may produce pain in the TMJ or abnormal movement of the lower jaw. Careful diagnostic study and testing is needed to determine the precise source of any TMJ problem.
A TMJ disorder is simply a disruption in the action of the jaw, usually accompanied by pain. There are a number of conditions affecting the function of the jaw that can cause one of these disorders. Fortunately, because the jaw is made up of bone and other living tissue, it is alive, making it capable of repair and healing.
Any malfunction prevents the complex system of muscles, bones and joints working together in harmony. The result is a TMJ disorder ' also known as TMD or CMD (cranio-mandibular dysfunction). Generally, a malfunction of one or both of these jaw joints is caused by trauma, whiplash, bad bite (malocclusion), poor posture, teeth grinding or skeletal malformation. It is estimated that one in every four people suffer from TMJ symptoms.
Do you have a TMJ problem?
People with TMJ problems generally experience one or more of the following symptoms:
- Chronic recurring headaches
- Clicking, popping or grating sound in the jaw joints
- Earaches, congestion or ringing ears
- Limited jaw opening or locking
- Dizziness
- Pain when chewing
- Neck and/or throat pain
- Difficulty in closing the teeth together
- Tired, tight jaws
- Pain behind the eyes
- Scalp tenderness
- Swallowing difficulty
- Pain in the tongue, gums or cheek muscles
- Teeth grinding or clenching
How Is TMJ Diagnosed?
Depending on the nature and severity of the problem, the evaluation of hard tissues my be accomplished using x-rays and CT scans. Soft tissue is evaluated using MRIs.
The evaluation process will include:
Detailed Medical and Dental History
A complete medical history must be documented, including all past medical and/or dental problems and treatments, any history of trauma (especially to the head and neck region), specific questions about your symptoms, and the nature and duration of any pain and jaw problems.
Physical Examination.
A complete physical examination for a TMJ problem will likely include:
1. Postural exam to discover any musculoskeletal problems that either contribute to or are the result of TMJ problems. This includes scoliosis, lower back pain and short leg syndrome, among others.
2. A cranial examination to evaluate the planes of the skull, including the alignment of the jaw joints and mouth to the rest of the body (dental plane of occlusion).
3. Dental examination to evaluate the shape of the dental arches, swallowing patterns, tooth wear or fractures, missing teeth, existing dental restorations or other clues. The dentist will usually make models of the mouth so that the teeth and dental arches can be more closely examined.
4. Neurologic examination to test for nerve or brain damage that may cause TMJ symptoms.
5. TMJ examination to look at the ranges of motion, gait, speed and smoothness of jaw movement. Additionally, the TM joints will be checked for internal joint inflammation, pain and the presence of joint sounds.
Causes of TMD
Statistics indicate that the vast majority of TMJ problems are caused by trauma. By trauma, we mean an injury as obvious as a blow to the jaw with a fist or something as subtle as a whiplash injury from a car accident that causes direct trauma to the head or jaw.
The most common forms of trauma that cause TMD are:
- Whiplash (cervical acceleration/deceleration)
- Air bag deployment
- Opening the jaw too wide
- Bruxism
- Bad bite (malocclusion)
- Orthodontics
- Ligament laxity
- Stress
- Systemic diseases
Whiplash (Cervical Acceleration/Deceleration)
Whiplash injuries often damage the soft tissue in the neck, back and TMJs. Usually these injuries happen when a car is hit in the rear. The violent motion of the head being thrown from a still state backwards and then forwards again often causes the mouth to be forced open. This produces stretching and/or tearing of the ligaments and connective tissues in one or both TMJs, and possibly bleeding and displacement of the disc in the TMJ. Common complaints after a whiplash injury include neck pain, neck stiffness or difficulty in turning the head, headaches (especially where the neck attaches to the head), TMJ pain, limited ability to open the mouth, TMJ noises, face and/or ear pain, change in bite, dizziness, visual changes (such as light sensitivity or blurry vision) and swallowing difficulties or hoarseness.
Air Bag Deployment
While air bags have undoubtedly saved lives, they have also been implicated in causing TMJ problems. Patients who have been injured with air bags often experience one or more of the following symptoms: burned or abraded skin on the chin, face or nose; almost immediate TMJ pain; swelling of the TMJs; limited mouth opening; neck pain; and change in the dental occlusion (bite).
Opening the Jaw Too Wide
All joints have limitations to movement, and the TMJ is no exception. If you open wide for a long time or if your mouth is forced wide open, ligaments may be torn, swelling and bruising develop and disc dislocation may occur.
Bruxism
Bruxism is the abnormal grinding of the teeth. Bruxism usually occurs during sleep, which is why many people dont realize they are doing it. But when grinding continues, TMJ problems may develop. An indication that a person is grinding their teeth in their sleep is sore jaw muscles when waking. Minimally, bruxism may produce muscle pain, tooth sensitivity or worn teeth. In some cases, the pressure to the TMJ from constant grinding of teeth leads to ligament injuries, which might cause the disc to dislocate.
Bad Bite (Malocclusion)
A bad bite, or malocclusion, may be produced by poor development of the jaws, removal of teeth without replacement, a high dental restoration, a poor fitting denture or partial denture, or a displaced TMJ disc.
Orthodontics
Some dentists feel that orthodontic treatment, or braces, might be a cause of TMJ. By moving teeth with orthodontic appliances, malocclusion is produced during treatment. That's probably why many people undergoing orthodontics report sensitive teeth, pain in the jaw muscles or even bruxism. However, there is no scientific proof that orthodontic treatment produces TMJ problems, particularly once the treatment has been completed.
Ligament Laxity
People who appear to be double-jointed suffer from a problem termed aligament laxity. When this occurs, a joint appears to be double - or loose. This does happen to the TMJ. Ligament laxity is a fairly common problem in active young women who suffer with TMJ problems and, often, injuries to other joints.
Stress
Stress has many effects on our bodies: some good and some bad. Physiological changes can produce muscle tightness and pain. When a person is subjected to chronic stress, these physical changes may produce harmful effects. When it comes to TMJ problems, stress is like throwing gasoline on a fire. The gasoline doesn't produce the fire, but it does make it worse. Similarly stress intensifies TMJ problems. Muscles tighten, teeth clench, abnormal pressure is forced against the TMJ disc, and if the ligaments are weak or if the patient is one that has ligament laxity, the disc may dislocate.
Systemic Diseases
Various diseases can cause or aggravate TMJ problems. Immune disorders, such as rheumatoid arthritis, psoriatic arthritis and systemic lupus erythematosus, can produce inflammation in the TMJ. Additionally, viral infections, such as mononucleosis, mumps and measles, can cause damage to the surfaces of the TMJ, which can lead to an internal derangement.
There are a number of other pain disorders that are often confused with TMJ because they involve pain in the jaw. Most common among these are:
- Temporal Tendinitis
- Ernest Syndrome
- Occipital Neuralgia
- Trigeminal Neuralgia
- Atypical Trigeminal Neuralgia
- Atypical Face Pain
- Neuralgia Inducing Cavitational Osteonecrosis (NICO)
Temporal Tendinitis - The 'Migraine Mimic'
Temporal tendinitis has been called 'the migraine mimic' because so many of its symptoms are similar to migraine headache pain. It is characterized by TMJ pain, ear pain and pressure, temporal headaches, cheek pain, tooth sensitivity and neck and shoulder pain. Treatment consists of injecting local anesthetics and other medications, a soft diet, applying moist heat, using muscle relaxants and anti-inflammatory medications, and physiotherapy. In very rare cases (less than 4%), surgery may be needed.
Ernest Syndrome
This TMJ-like problem involves a tiny ligament structure that connects the base of the skull with the mandibular or lower jaw. If injured, the structure can produce pain in the face, head, neck, temple, ear, cheek eye, throat and/or TMJ. Treatment of Ernest Syndrome, which is successful about 80% of the time, consists of injections of local anesthetic and medication (like cortisone or Sarapin), physiotherapy and, at times, the use of an intraoral splint.
Occipital Neuralgia
This disorder is characterized by pain radiating to one or both sides of the head, temples, cheek and forehead and particularly pain above and behind the eye.
Trigeminal Neuralgia
Also known as tic douloureux, this is a disorder of the trigeminal, or fifth cranial nerve. It is characterized by sharp electrical pain, which lasts for seconds. The pain is triggered by touching a specific area of the skin, as when washing, shaving, applying makeup, brushing the teeth, kissing or even from exposure to cold air. The pain is often very severe.
Atypical Trigeminal Neuralgia
In contrast to the typical type, atypical trigeminal neuralgia produces constant pain that increases or decreases in intensity. There are trigger zones, but there is also an area of dull aching. A common cause of this disorder is trauma, especially after a surgical incision or blow to the face.
Atypical Face Pain
While the same trigeminal nerve is involved in atypical face pain, in this case the facial pain seems to affect people who are under a tremendous amount of stress or have a history of psychiatric problems.
Neuralgia Inducing Cavitational Osteonecrosis (NICO)
Also known as osteocavitational lesions or Ratner's bone cavities, this disorder produces pain similar to that of typical and atypical trigeminal neuralgia as well as referred pain patterns. There are trigger areas for the pain, which, in this case, develop directly over areas of dead bone. Generally, the lower jaw is affected more often than the upper jaw.
