Temporomandibular joint disorder

Temporomandibular joint disorder
Classification and external resources
Temporomandibular joint
ICD-10	K07.6
ICD-9	524.60
DiseasesDB	12934
MedlinePlus	001227
eMedicine	neuro/366 radio/679 emerg/569
MeSH	C05.500.607.221.897.897

Temporomandibular joint disorder, TMJD (in the medical literature TMD), or TMJ syndrome, is an umbrella term covering acute or chronic pain, especially in the muscles of mastication and/or inflammation of the temporomandibular joint, which connects the mandible to the skull. The primary cause is muscular hyper- or parafunction, as in the case of bruxism, with secondary effects on the oral musculoskeletal system, like various types of displacement of the disc in the temporomandibular joint. The disorder and resultant dysfunction can result in significant pain, which is the most common TMD symptom, combined with impairment of function. Because the disorder transcends the boundaries between several health-care disciplines — in particular, dentistry and neurology — there are a variety of treatment approaches.

The temporomandibular joint is susceptible to many of the conditions that affect other joints in the body, including ankylosis, arthritis, trauma, dislocations, developmental anomalies, neoplasia and reactive lesions.

An older name for the condition is "Costen's syndrome", after James B. Costen, who partially characterized it in 1934.

The main signs and symptoms of TMD are pain and tenderness around the TMJs and muscles of mastication, limitation and incoordination of jaw movement, joint sounds (clicking or grating from the joints), headaches and tinnitus.

Definitions

Many different terms and definitions surround this topic. For example:

Temporomandibular disorders - "a group of conditions with similar signs and symptoms that affect the termporomandibular joints, the muscles of mastication, or both."

Bruxism - "stress induced para-functional activity [of the masticatory system]."

Temporomandibular joints

Unlike a typical finger or vertebral junctions, each TMJ actually has two joints, which allows it to rotate and to translate (slide). With use, it is common to see wear of both the bone and cartilage components of the joint. Clicking is common, as are popping and deviations in the movements of the joint. Some people may even experience cracking. Pain is the most conventional signifier of TMJD.

The surfaces in contact with one another (cartilage) do not have any receptors to transmit the feeling of pain. The pain therefore originates from one of the surrounding soft tissues, or from the trigeminal nerve itself, which runs through the joint area. When receptors from one of these areas are triggered, the pain can cause a reflex to limit the mandible's movement. Furthermore, inflammation of the joints or damage to the trigeminal nerve can cause constant pain, even without movement of the jaw.

Due to the proximity of the ear to the temporomandibular joint, TMJ pain can often be confused with ear pain. The pain may be referred in around half of all patients and experienced as otalgia (earache). Conversely, TMD is an important possible cause of secondary otalgia. Treatment of TMD may then significantly reduce symptoms of otalgia and tinnitus, as well as atypical facial pain. Despite some of these findings, some researchers question whether TMJD therapy can reduce symptoms in the ear, and there is currently an ongoing debate to settle the controversy.

The dysfunction involved is most often in regards to the relationship between the condyle of the mandible and the disc. The sounds produced by this dysfunction are usually described as a "click" or a "pop" when a single sound is heard and as "crepitation" or "crepitus" when there are multiple, rough sounds.^{[citation needed]}

Teeth

Disorders of the teeth can contribute to TMJD. Impaired tooth mobility and tooth loss can be caused by destruction of the supporting bone and by heavy forces being placed on teeth. The movement of the teeth affects how they contact one another when the mouth closes, and the overall relationship between the teeth, muscles, and joints can be altered. Pulpitis, inflammation of the dental pulp, is another symptom that may result from excessive surface erosion. Perhaps the most important factor is the way the teeth meet together: the equilibration of forces of mastication and therefore the displacements of the condyle. Many report TMJD after having their wisdom teeth extracted.^{[citation needed]}

Signs and symptoms

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.

Symptoms associated with TMJ disorders may be:

• Blinking
• 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
• Tinnitus
• Neck and shoulder pain
• Dizziness

Cause

There are many external factors that place undue strain on the TMJ. These include but are not limited to the following:

A majority of TMJD patients believe bruxism to be a contributory factor, and the onset of TMJ pain has been positively (though not significantly) correlated with bruxism . Over-opening the jaw beyond its range for the individual or unusually aggressive or repetitive sliding of the jaw sideways (laterally) or forward (protrusive). These movements may also be due to parafunctional habits or a malalignment of the jaw or dentition. This may be due to:

1. Bruxism (repetitive clenching or grinding of teeth, often at night, in which case aching jaw muscles may occur upon waking).
2. Loss of bite height (bite collapse), leading to an unnatural position of the lower jaw while chewing. Often occurs in patients over the age of 40 due to the natural aging process and/or bruxism. Overzealous equilibration by inexperienced staff or the improper use of air abrasion can also lead to the loss tooth height.
3. Trauma (e.g. sports related injuries; whiplash from any automobile accident; accidental injuries from any source to one's chin to cause ones chin to move in an upward/backward direction).
4. Mal-alignment of the occlusal surfaces of the teeth due to genetics, defective crowns, restorative procedures, lack of cooperation during orthodontic treatment.
5. The controversial practice of extracting 4 bicuspids in orthodontic treatment of patients with small jaws and overcrowding, which has been shown to lead to joint dysfunction. It is now discouraged in favor of a palate expander based treatment plan.^{[citation needed]}
6. Jaw thrusting (causing unusual speech and chewing habits).
7. Parafunctional habits other than bruxism: excessive gum chewing, nail biting, eating very hard foods.^{[citation needed]}
8. Exaggerated opening of mouth, when eating large sized foods, excessive opening during yawning/sneezing and in difficult cases of third molar (wisdom tooth) extraction.
9. Degenerative joint disease, such as osteoarthritis or organic degeneration of the articular surfaces, recurrent fibrous and/or bony ankylosis, developmental abnormality, or pathologic lesions within the TMJ.
10. Myofascial pain syndrome.
11. Lack of overbite or cuspid protected occlusion will result in excessive forces directed to posterior teeth and hence, more stress to muscles of mastication.

Patients with TMD often experience pain such as migraines or headaches, and consider this pain TMJ-related. There is some evidence that some people who use a biofeedback headband to reduce nighttime clenching experience a reduction in TMD. The dentist must ensure that a diagnosis does not mistake trigeminal neuralgia as a temporomandibular disorder. Oromandibular dystonia is another rare diagnosis which might cause some confusion

Diagnosis

Various diagnostic systems have been desecribed. Some consider the Research Diagnostic Criteria (RDC/TMD) method the gold standard. This method involves 2 diagnostic axes, namely axis I, the physical diagnosis, and axis II, the psychologic diagnosis. Axis I contains 3 different groups which can occur in combinations of 2 or all 3 groups.:

• Group I: muscle (myofascial) pain with tenderness of muscles when palpated.
• Group II: disk displacements with and without reduction, where there is clicking from the TMJs and locking of the jaw respectively.
• Group III: TMJ pain and degeneration. Group III can include arthralgia (joint pain), where there is local TMJ tenderness, arthrosis, where there is crepitus (grating from the TMJ), and arthritis, with crepitus and local TMJ tenderness.

Treatment

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.^{[citation needed]} 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).

Splint

Occlusal splints (also called night guards or mouth guards) reduce nighttime clenching in some patients, while increasing clenching activity in other patients.^{[citation needed]} 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.^{[citation needed]}

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 biofeedback

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.

Pain relief

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.

Long-term approach

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.^{[citation needed]} They include:

• Manual adjustment of the bite by grinding the teeth (occlusal adjustment). This, too, is not a widely accepted practice and should be avoided as it is irreversible.
• Nighttime biofeedback for para-functional habit modification
• Mandibular repositioning splints which move the jaw, ligaments and muscles into a new position and myofunctional therapy
• Reconstructive dentistry
• Orthodontics
• Arthrocentesis (joint irrigation)
• Surgical repositioning of jaws to correct congenital jaw malformations such as prognathism and retrognathia
• Replacement of the jaw joint(s) or disc(s) with TMJ implants (this should be considered only as a treatment of last resort)

Elimination of para-functional habits

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.

Reversible treatments

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.

Other interventions include:

• 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.

Surgery

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.

Jaw dislocation

Main article: Dislocation of jaw

The jaw can dislocate if a person opens his/her mouth too wide, particularly when a person attempts to open the jaw widely in an effort to stretch the facial muscles i.e. to relieve tense facial muscles as the wisdom teeth develop and emerge.

The jaw can also "slide out" as the person is sleeping on his/her side.

See also

• Condylar resorption
• Dentomandibular Sensorimotor Dysfunction
• The American Academy of Orofacial Pain (www.aaop.org)
• AES – Leaders in Occlusion and TMD (www.aes-tmj.org)
• Dentomandibular Sensorimotor Dysfunction

References

• Okeson, Jeffrey P. (2003). Management of temporomandibular disorders and occlusion (5th ed.). St. Louis: Mosby. ISBN 0-323-01477-1. 
• Edward F. Wright (2009). Manual of Temporomandibular Disorders (2 ed.). John Wiley and Sons. ISBN 978-0-8138-1324-0. 
• Gremillion, Henry A. (2003). "Temporomandibular Disorders". In Edwab, Robert R. Essential dental handbook: clinical and practice management advice from the experts (illustrated ed.). PennWell Books. pp. 251–309. ISBN 978-0-87814-624-6.