TMJ Tempro Mandibular Joint
TMJ Temporo-Mandibular Joint is the joint of the jaw and is frequently referred to as TMJ. There are two TMJs, one on each side, working in unison. The name is derived from the two bones which form the joint: the upper temporal bone which is part of the cranium (skull), and the lower jaw bone called the mandible. The unique feature of the TMJ’s is the articular disc. The disc is composed of fibrocartilagenous tissue (like the firm and flexible elastic cartilage of the ear) which is positioned between the two bones that form the joint. The TMJs are one of the few synovial joints in the human body with an articular disc, another being the sternoclavicular joint. The disc divides each joint into two. The lower joint compartment formed by the mandible and the articular disc is involved in rotational movement—this is the initial movement of the jaw when the mouth opens. The upper joint compartment formed by the articular disk and the temporal bone is involved in translational movement—this is the secondary gliding motion of the jaw as it is opened widely. The part of the mandible which mates to the under-surface of the disc is the condyle and the part of the temporal bone which mates to the upper surface of the disk is the glenoid (or mandibular) fossa.
Pain or dysfunction of the temporomandibular joint is commonly referred to as “TMJ”, when in fact, TMJ is really the name of the joint, and Temporomandibular joint disorder (or dysfunction) is abbreviated TMD. This term is used to refer to a group of problems involving the TMJs and the muscles, tendons, ligaments, blood vessels, and other tissues associated with them. Some practitioners might include the neck, the back and even the whole body in describing problems with the TMJs
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Signs and symptoms of temporomandibular joint disorder vary in their presentation and can be very complex, but are often simple. On average the symptoms will involve more than one of the numerous TMJ components: muscles, nerves, tendons, ligaments, bones, connective tissue, and the teeth. Ear pain associated with the swelling of proximal tissue is a symptom of temporomandibular joint disorder.
- Biting or chewing difficulty or discomfort
- Clicking, popping, or grating sound when opening or closing the mouth
- Dull, aching pain in the face
- Earache (particularly in the morning)
- Headache (particularly in the morning)
- Hearing loss
- Migraine (particularly in the morning)
- Jaw pain or tenderness of the jaw
- Reduced ability to open or close the mouth
- Neck and shoulder pain
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Restoration of the occlusal surfaces of the teeth – If the occlusal surfaces of the teeth or the supporting structures have been altered due to inappropriate dental treatment, periodontal disease, or trauma, the proper occlusion may need to be restored. Patients with bridges, crowns, or onlays should be checked for bite discrepancies. These discrepancies, if present, may cause a person to make contact with posterior teeth during sideways chewing motions. These inappropriate contacts are called interferences, and if present, they can cause a patient to subconsciously avoid those motions, as they will provoke a painful response. The result can be excessive strain or even spasms of the chewing muscles. Treatment could include adjusting the restorations or replacing them. (Christensen 1997, A Consumer’s Guide to Dentistry).
Occlusal splints (also called night guards or mouth guards) reduce nighttime clenching in some patients, while increasing clenching activity in other patients. Thus, while occlusal splints do prevent loss of tooth enamel from grinding, use of a “one size fits all” splint can worsen TMJ disorder symptoms for some people.
All appliances are not equal in effectiveness. When patients have a problem 24 hours/ day 7 days a week the use of a nighttime appliance may not be the best approach. An orthotic is worn all day and night and allows for permanent healing of the joints and muscles. A neuromuscular orthotic that is made to a physiologic rest position is one of the most effective treatments but usually requires a long term correction. Neuromuscular dentistry addresses the healthy muscle physiology and body posture as well as the TM joints.
Frequently patients with TMJ disorders also have sleep apnea or UARS, upper respiratory airway resistance syndrome and receive the most benefit from a night-time airway appliance and a daytime orthotic. Patients with long-term chronic pain respond extremely well to this type of therapy.
Nighttime EMG biofeedback (for instance by using a biofeedback headband or biofeedback device) can be used to reduce bruxism and thus reduce or eliminate the ongoing nightly cycle of damage that contributes to the majority of TMJ disorder symptoms. This treatment is non-invasive.
While conventional analgesic pain killers such as paracetamol (acetaminophen) or NSAIDs provide initial relief for some sufferers, the pain is often more neurologic in nature, which often does not respond well to these drugs. An alternative approach is for pain modification, for which off-label use of low-doses of anti-muscarinic tricyclic antidepressant such as amitriptyline or the less sedative nortriptyline generally prove more effective.
In TMJD the muscles are unbalanced. Biofeedback using EMG is successful in balancing these muscles. A mirror can be used as a biofeedback device. The patient, watching in the mirror, relaxes the jaw vertically while exhaling. With daily practice the jaw opens midline and the symptoms usually abate. Low level laser therapy may be effective in reducing pain from TMJD, however, further research is still required to determine the optimal treatment protocols.
It is suggested that before the attending dentist commences any plan or approach using medications or surgery, a thorough search for inciting para-functional jaw habits must be performed. Correction of any discrepancies from normal can then be the primary goal.
Patients may employ a nighttime biofeedback instrument such as a biofeedback headband or biofeedback device to help them modify para-functional jaw habits which take place in sleep. In addition, there are various treatment modalities which a well-trained experienced dentist may employ to relieve symptoms and improve joint function.
An approach to eliminating para-functional habits involves the taking of a detailed history and careful physical examination. The medical history should be designed to reveal duration of illness and symptoms, previous treatment and effects, contributing medical findings, history of facial trauma, and a search for habits that may have produced or enhanced symptoms. Particular attention should be directed in identifying perverse jaw habits, such as clenching or teeth grinding, lip or cheek biting, or positioning of the lower jaw in an edge-to-edge bite. All of the above strain the muscles of mastication (chewing) and result in jaw pain. Palpation of these muscles will cause a painful response.
Treatment is oriented to eliminating oral habits, physical therapy to the masticatory muscles, and alleviating bad posture of the head and neck. A biofeedback headband or biofeedback device may be worn at night to help patients train themselves out of the para-functional habit of nighttime clenching and grinding (bruxism). A flat-plane full-coverage oral appliance, e.g. a non-repositioning stabilization splint, reduces bruxism in some patients, and can take stress off the temporomandibular joint, although some individuals may bite harder on it, resulting in a worsening of their conditions. The anterior splint, with contact at the front teeth only, may prove helpful to some patients, but for those patients who bite harder on this type of splint, even more damage may occur. Thus, different types of splint therapy may work for different patients.
In line with the recommendations of the National Institute of Dental and Craniofacial Research (NIDCR) of the National Institutes of Health (NIH), treatments for TMJD should not permanently alter the jaw or teeth, but need to be reversible. To avoid permanent change, over-the-counter or prescription pain medications may be prescribed.
Stabilization splint (biteplate, nightguard) is a common but unproven treatment for TMJD. A splint should be properly fitted to avoid exacerbating the problem and used for brief periods of time. The use of the splint should be discontinued if it is painful or increases existing pain.
Cognitive Behavioral Therapy (CBT). Psychosocial risk factors have also been linked to TMJ syndrome. Studies have shown that changes in psychosocial issues can help reduce pain and increase jaw movement.
Attempts in the last decade to develop surgical treatments based on MRI and CAT scans now receive less attention. These techniques are reserved for the most difficult cases where other therapeutic modalities have failed. The American Society of Maxillofacial Surgeons recommends a conservative/ none surgical approach first. Only 20% of patients need to proceed to surgery.
One option for oral surgery is to manipulate the jaw under general anaesthetic and wash out the joint with a saline and anti-inflammatory solution in a procedure known as arthrocentesis. In some cases, this will reduce the inflammatory process.