(See also Dental Emergencies and Mandibular Dislocation.)
Mandibular dislocation usually occurs in people with a history of such dislocation. It typically occurs when the mouth is opened wide (eg, biting into a large sandwich, a wide yawn, or during a dental procedure).
Indications
Contraindications
Complications
Equipment
TMJ dislocations can typically be reduced without procedural sedation or local anesthetic injection of the TMJ, but such measures may be necessary for uncooperative patients or when dislocation has been present for more than a few hours. Additional material needed includes:
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Procedural sedation supplies: Injectable diazepam or midazolam and an opioid such as fentanyl; equipment for peripheral venous catheterization
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Injectable local anesthesia supplies: Lidocaine 2% without epinephrine; 27-gauge, 2-cm long needle; 3-mL syringe, topical antiseptic (eg, chlorhexidine, povidone iodine)
Additional Considerations
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Do TMJ reduction promptly. Reduction becomes more difficult with passing time.
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TMJ dislocation can be painful and patients are sometimes anxious, but this can often be ameliorated by gentle, calm reassurance. Local anesthetic injection of the joint and muscles of mastication is rarely needed.
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Procedural sedation is usually not needed. The need for sedation vs the risks (particularly in older patients) and increased time required should be weighed carefully.
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If readily available, do a panoramic jaw x-ray for patients with a possible non-anterior TMJ dislocation. However, an x-ray is not always needed for a nontraumatic dislocation, especially if the patient has a history of prior dislocations.
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Do a CT scan for traumatic TMJ dislocation.
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Closed-reduction attempts may fail and require reduction under general anesthesia.
Relevant Anatomy
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The TMJ is formed by the mandibular condyle and the glenoid fossa of the temporal bone.
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Anterior TMJ dislocation occurs when a condyle moves forward out of the fossa and becomes lodged anteriorly in front of the articular eminence.
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TMJ dislocation stretches the ligaments of the masseter, medial and lateral pterygoid, and temporalis muscles, causing painful spasms (trismus). Trismus prevents the condyle from returning to the mandibular fossa, which prevents closure of the mouth.
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When the condyle is restored into the fossa, the jaw will snap closed under the force of the muscles in spasm, which puts both the patient's tongue and the operator's thumbs in danger of being bitten.
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Spontaneous TMJ dislocations are more often bilateral than unilateral.
Positioning
Step-by-Step Description of Procedure
Elicit patient relaxation and cooperation
It is important to allay anxiety and obtain cooperation before attempting reduction.
In a calm, reassuring voice, explain to the patient that the
If the patient remains unable to relax and cooperate with the reduction, give IV procedural sedation and analgesia as needed.
Optional: Local anesthetic injection:
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Externally palpate the TMJ space, just below the zygoma and about 2.5 cm anterior to the tragus.
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Swab the area with antiseptic solution and allow it to dry for at least 1 minute.
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Insert the needle perpendicularly to the skin and advance it medially, about 0.5 cm, into the joint space.
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Aspirate, to rule out intravascular placement.
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Slowly inject about 1 mL anesthetic.
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Massage the site to hasten the onset of anesthesia.
Distract the condyles and reduce the jaw:
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Instruct the patient to completely relax the mouth and jaw.
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Stabilize the head. Instruct the patient to keep the head still and firmly braced against the headrest.
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Wear nonsterile gloves.
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Place your thumbs on the external oblique ridge on either side of the mandible, lateral to the third molar area. Alternatively, wrap your thumbs with layers of gauze and place them as posteriorly as possible on the occlusal surface of the lower molars bilaterally (this increases the risk of being bitten during reduction).
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Curl your other fingers around and under the mandible, with the index fingers behind the rami. Fingers should be in contact with the bony mandible, not the soft tissues beneath the tongue.
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First, apply firm and continuous downward force on the back of the jaw, using your thumbs to distract the condyles inferiorly. This is a steady, firm force, not a sudden, jerking, thrusting force.
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Simultaneously apply a reciprocal upward force on the anterior mandible (ie, rock the chin upward), which may enhance the condylar distraction.
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Then, maintaining these distraction forces, apply posterior force on the dislocated side, or both sides if the dislocation is bilateral, to reduce the condyle(s) (ie, push the mandible back into normal position).
The key is to first apply significant pressure downward in the back of the jaw, then slowly guide the entire mandible posteriorly: "Down … then back." Often the mandible will snap into position as the condyles clear the articular eminence.
Determine successful TMJ reduction:
Aftercare
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Instruct the patient to apply moist heat and if needed take a nonsteroidal anti-inflammatory drug (NSAID), such as ibuprofen, 600 mg orally 3 times a day for 5 to 7 days.
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Have the patient avoid wide mouth-opening for 4 to 6 weeks.
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Recommend a soft diet eaten with small bites.
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Instruct the patient who needs to yawn to place a closed fist beneath the chin and press upward to prevent wide opening.
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Wrap the patient's head in a figure 8 (Barton's) bandage (stretch gauze or an elastic wrap) to restrict jaw opening for 2 to 3 days. Patient compliance may be an issue.
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Arrange a follow-up visit with the oral surgeon or otolaryngologist within 1 to 2 days.
