The temporomandibular joint – the TMJ - is the joint between the lower jawbone - the
mandible - and the temporal bone of the skull. The TMJ is responsible for jaw movement and
enables chewing, talking and yawning. Temporomandibular disorders, or TMD, refer to a group of conditions
characterized by pain in the jaw area and limited movement of the mandible. TMD may
be caused by problems in the joint itself or in the muscles surrounding the joint. Problems
in the joint include: arthritis, inflammation and internal derangements. When the problem
is in the muscles, the condition is called myofascial pain syndrome.
Myofascial pain syndrome is very common and can occur in patients with a normal temporomandibular
joint. The syndrome is characterized by presence of hyperirritable spots located in skeletal
muscles called trigger points. A trigger point can be felt as a nodule of muscle with harder
than normal consistency. Palpation of trigger points may elicit pain in a different location.
This is called referred pain. Trigger points are developed as a result of
muscle overuse. Commonly, the muscles of chewing, or mastication, are overworked when patients
excessively clench or grind their teeth unconsciously during sleep. The medical term for this condition
is “nocturnal bruxism”. A trigger point is composed of many contraction knots where
individual muscle fibers contract and cannot relax. The sustained contraction of muscle
sarcomeres compresses local blood supply, resulting in energy shortage of the area.
This metabolic crisis activates pain receptors, generating a regional pain pattern that follows
a specific nerve passage. The pain patterns are therefore consistent and are well documented
for various muscles. Trigger points in the masseter refer pain
to the cheeks, lower jaw, upper and lower molar teeth, eyebrow, inside the ear and around
the TMJ area. Trigger points in the temporalis are also associated with headache and toothache
from upper teeth. The main culprits of myofascial pain in the TMJ area are the pterygoid muscles.
Trigger points in medial pterygoid refer pain to the TMJ region in front of the ear, inside
the mouth and upper outside of the neck. They may also manifest as sore throat and difficulty
swallowing. Pain from lateral pterygoid trigger points can be felt in front of the ear and
on the upper jaw. Treatments aim to address bruxism, to relieve
muscle spasm and release trigger points. Treatment options include:
- Therapies: stress management, behavior therapy, biofeedback - to encourage relaxation.
- Dental night guards: Splints and mouth guards - to protect the teeth from damage.
- Medication: pain relievers, muscle relaxants, botox injections.
- Trigger points release techniques such as needling and “spray and stretch”.