TMJ (Temporomandibular Joint) or TMD (Temporomandibular Joint Disorder or Dysfunction) involves pain or loss of function of the temporomandibular (jaw) joint and surrounding muscles. It can cause long-term hypersensitivity of the nerves surrounding the immediate area. It is not a progressive or degenerative disorder, and its prevalence does not increase with age. Approximately 7 million adults have pain on or near the TMJ. It occurs in all age groups, seems to affect women more frequently than men. TMD is currently the most common orofacial disorder seen by health care workers today.
The TMJ, located just anterior the external ear, is a hinge joint and with its disk, acts as a moveable socket. The two temporomandibular joints consisting of soft tissues such as joint capsules, masticatory muscles, and ligaments connect the mandible to the skull which is cushioned by an articular disk. The TMJ and surrounding muscles consist of:
* mandible - jaw
- lateral pterygoid : opens, protrudes mandible, allows side-to-side movement
* The neural innervation of the muscles of mastication is from the mandibular
division of the trigeminal nerve; blood is supplied by the muscular branches
of the maxillary artery.
Etiologies of TMJ
* muscle or nerve damage
* genetic abnormalities of bone
* trauma (to the mandible itself)
* arthritis, juvenile rheumatoid arthritis
* bad posture
* malocclusion and hyperactivity that goes along with this condition
* enlarged mandibular condyles
* decreased joint space
* missing teeth
* faulty occlusion
* bimaxillary protrusion – occlusion is normal but the entire dentition is forward with respect to the facial profile.
* systematic inflammatory disease, infections, or viruses (measles, mumps, infectious mono)
* clenching and bruxism
* prolonged opening of the mouth
* singing and gum chewing
* mouth breathing
Trauma - causes muscle guarding due to the pain-spasm cycle, which increases the pull of the lateral pterygoid muscle on the disc, resulting in a stretching of the posterior and lateral collateral ligaments.
Stress - causes overactivity of the muscles of mastication, which results in a clenching or gnashing of the mandible (buxism).
Clinical Signs and Symptoms
* pain in the TMJ (jawache, earache, and/ or headache with possible dizziness)
* pain in the muscles of mastication
* restricted mandibular movement (locking of the jaw)
* joint sounds (clicking, popping, or grating in the TMJ and mandibular movements) (~ noise by themselves are not considered TMD and approx. 44% of the general population has clicking)
* pain when chewing
* facial pain
* sinus pain
* hearing loss
* ear pain or stuffiness in the ear
* nasopharyngeal symptoms such as swallowing difficulties or numbness or burning sensations in the tongue, palate, or throat.
* related pain may be felt in the dorsum of the neck, sternocleidomastoid region, or trapiezius muscle
Evaluating the TMJ (protocol)
I. During interview ask:
- chief complaint
- mechanism of injury
- date of onset
- past medical history
- what increases and decreases symptoms
- pain ranking and intensity
- recent and past dental history
II. Examine general facial appearance and posture
- visually check if body is in correct alignment (no forwardness of arms, shoulders, and head)
- facial symmetry
- hypertrophy of the masseter muscle ( the masseter is easily seen by having the person clench the jaw closed very tightly and there should be equal size bilaterally)
III. Palpation of the TMJ region
This is usually quick and simple:
*masseter: during contraction and relaxation
*temporalis: muscle palpated over its origin
Anterior- The lateral aspect of the TMJ space is palpated just anterior to the ear, and chief findings of inflammation or trauma to the joint are swelling, increased temperatures, or pain with palpation. Have patient open and close mouth while palpating bilaterally.
* normal - should move smooth and equally
* abnormal - feel one side rotate before other
- shift laterally while mandible is moving
Posterior- Put little fingers inside ears, press gently anteriorly. Have patient open and close mouth several times, assessing for pain and equal motion bilaterally
* normal - should have equal motion
* abnormal - pain upon closing is indicative of posterior capsulitis
(caused by mandibular condyle positioned too far posteriorly)
IV. Range of motion testing // Visual
Opening of the mouth varies in degrees of motion available based on the physical size of individuals. General guideline for mandibular opening is see if the patient can place two knuckles or fingers in the open mouth.
* If they cannot, then this is a positive finding of hypomobility
* If they can place 3 or more knuckles in mouth, this is positive for hypermobility
Opening and closing of the mouth during range of motion should be examined very carefully visually. Often lateral deviation.....
* deviation occurring early in motion opposite side of involvement is usually caused by muscle spasms.
* midrange - muscle imbalance
* deviation to the involved side at end range of opening is most often due to posterior capsulitis.
- Also look for protrusion or jutting of jaw forward using teeth as landmarks.
V. Masticatory Muscle Tests
Identifies pathological conditions that may exists in the muscles. This will be evidenced by pain that will be elicited upon application of maximum resistance. To effectively test the muscles of mastication, the following rules should be observed: 1) The head must be supported to eliminate head movement or rotation. 2) the mouth should be partially opened (about 1 cm), 3) the application of force must be gradual enough to enable the client to build maximal resistance, and 4) hand contact with the TMJ should be avoided; pain elicited in the presence of acute joint disease might be confused with the results of muscle testing.
- Resistive lateral excursion. This tests the medial and lateral pterygoid muscle simultaneously. A weak lateral pterygoid muscle might not be obvious on resistive opening muscle tests but would be evident bt comparison with the opposite
- Resisted protrusion muscle test is some times used to test the main opening jaw muscles. The client opens and protrudes the jaw slightly. The therapist’s supports the client’s occiput and attempts to force the jaw posteriorly as the client resists. This test
might be used to corroborate a vagus response to the resisted opening test..
VI. Listen for Joint Noise
This is the most beneficial for TMD because it involves
mediate auscultations. You assess for the presence of osteoarthritis in
TMJ which will present with grinding and crepitis at end range of motion
and can help in disc derangement. Use the stethoscope to listen for joint
noise. (* Joint noise should serve only as a confirmation of TMJ after
range of motion loss and pain with palpation .
* reduced derangement - (reciprocal click)
VII. Oral Cavity Evaluation
The tongue should be evaluated with regard to its size, position at rest, function, length of frenulum, and oral habits. Tongue size is an important factor. A small tongue (microglossia) will not exert enough pressure against the teeth, while a large tongue (macroglossia) will exert too much pressure. In addition, an extremely large tongue may interfere with occlusion. A good buccinator muscle tone is also important in maintaining good oral function.
VIII. Imaging Techniques
Imaging techniques such as radiographs, computerized tomography scans, and MRI are commonly used by dentist and physicians to view TMJ region.
- Radiographs are taken in a panoramic view and in open and closed mouth positions. They are indicated if osteoarthritis is suspected, but not very beneficial in diagnosing disc derangements.
- CT scans and MRI are considered the most accurate imaging methods for evaluating soft tissues in TMJ, but are costly.
- Bio (EMG) electromyography can be used to record jaw movements and bite positions in TMD patients. It can also be used to measure chewing muscle activity and helps to diagnose type of TMD.
The cause and treatment of TMD are not always straight forward and pain may persist.
* Traditional dental treatment for jaw and facial pain involves creating a mouth appliance for the patient to wear. The mouth appliance, or mouth splint, improves headaches, joint and ear symptoms, and facial and back pain after one month of use.
* Limit the degree of opening and to rest the joint. This includes a liquid or soft diet, limited movement, and refraining from talking or singing.
* Application of heat or cold is systematically effective in reducing acute inflammation and associated muscle spasm.
* Physical therapy and stress reduction.
* Electronic stimulation of jaw muscles maybe used in biofeedback.
* Isometric jaw exercises.
* Those with more severe symptoms can be treated surgically.
* Medication may help treat TMJ. Certain drugs may reduce or eliminate hypersensitivity.
Research is scanty but supports the following:
- Low doses of certain antidepressants may help, but caution must be used in patients with heart disease.
- Benzodiazepine drugs may help when pain appears due to muscular or skeletal problems, but they can cause sedation, dependency, or worsen depression.
- Drugs such as aspirin, acetaminophen, or ibuprofen may help when inflammation is involved, but long-term use can cause serious gastrointestinal or kidney complications.
- Repeated injections of Corticosteroids can damage joints.
- Narcotics should be reserved for cases where all other measures have failed.
Effects on Lifestyle
Persistent pain in the jaw seems to interfere with psychological well-being, especially in chronic situations. ( Study showed that they have more frequent diagnosis of anxiety, affective disorders, and paranoid personalities).
From 20% to 30% of TMD patients may have difficulty coping with pain, and may experience some degree of disability are psychological distress.
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