The patient's jaw is "out" and will not close, usually following a yawn, or perhaps after laughing, a dental extraction, jaw trauma or a dystonic drug reaction. The patient has difficulty speaking ans may have severe pain anterior to the ear. A depression can be seen or felt in the preauricular area and the jaw may appear prominent.
What to do:
If there was no trauma (and especially if the patient is a chronic dislocator) proceed directly to attempt reduction. If there is any possibility of an associated fracture, obtain x rays first.
Have the patient sit on a low stool, his back and head braced against something firm--either against the wall, facing you, or with the back of his head braced against your body, facing away from you.
With gloved hands, wrap your thumbs in gauze, seat them upon the lower molars, grasp both sides of the mandible, lock your elbows, and, bending from the waist, exert slow, steady pressure down and posteriorly. The mandible should be at or below the level of your forearm.
In a bilateral dislocation, attempt to reduce one side at a time.
If the jaw does not relocate easily or convincingly, you may want to reassess the dislocation with x rays, and try again using intravenous midazolam to overcome the muscle spasm and 1-2ml of intraarticular 1% lidocaine to overcome the pain. Inject directly into the palpable depression left by the displaced condyle.
After reducing the dislocation it will be comforting to apply a soft cervical collar to reduce the range of motion at the temperomandibular joint (TMJ). Recommend a soft diet and instruct thepatient to refrain from opening his mouth too widely. Prescribe analgesics if needed.
If reduction cannot be obtained using the above techniques, then consider admission for reduction under general anesthesia.
What not to do:
Try not to get your thumbs bitten when the jaw snaps back into position. Maintain firm, steady traction and protect your thumbs with gauze.
Do not put pressure on oral prostheses that could cause them to break.
Do not attempt to reduce a TMJ dislocation with the patient's jaw at the height of your shoulders or above. You will need the leverage you get from having the patient in a lower position.
Do not try to force the patient's jaw shut.
The mandible usually dislocates anteriorly, and subluxes when the jaw is opened wide. Other dislocations imply the presence of a fracture and require referral to a surgeon. Dislocation is often a chronic problem (avoided by limiting motion) and associated with temporomandibular joint dysfunction. If dislocation is not obvious, then consider other conditions, such as fracture, hemarthrosis, closed lock of the joint meniscus, and myofascial pain.
Luyk NH, Larsen PE: The diagnosis and treatment of the dislocated mandible. Am J Emerg Med 1989;7:329-335.