Mandible (TMJ) Dislocation Workup

Updated: Sep 17, 2021
  • Author: Meher Chaudhry, MD; Chief Editor: Trevor John Mills, MD, MPH  more...
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Imaging Studies

Imaging studies should be obtained prior to reduction to identify any fractures. In rare cases of recurrent dislocations, imaging studies may be deferred, based on the discretion of the treating physician.

Fractures associated with nontraumatic anterior mandibular dislocations are rare. However, traumatic dislocations are often associated with mandibular fractures. Isolated trauma to the mandible can be evaluated by using an orthopanoramic radiograph and a mandible posteroanterior (PA) view with maximal mouth opening. This is an acceptable option for patients with chronic recurrent dislocations and a nontraumatic mechanism. However, certain fractures, such as nondisplaced mental fractures, may not be recognized on panoramic and PA radiographs because of the overlapping spine obscuring the image. In addition, restricted mouth opening can result in inadequate projection of the condylar process on the PA view, resulting in missed fracture of the mandibular ramus.

The use of CT scanning for mandible injuries is increasing because CT scan provides greater sensitivity in diagnosing mandibular abnormalities. The use of CT in traumatic mandible injuries is increasing. [29] The ability to obtain reconstructed images along the sagittal and coronal plane and along the alveolar ridge to create panoramic-like images further contributes to improved visualization of the fractures and acceptability of CT as the initial imaging modality in stable patients with traumatic mandible injury.

Although MRI is not the first-line imaging modality in patients with mandible dislocations, it is useful in assessing the integrity of the TMJ, articular disks, and associated structures. MRI is also informative in patients with chronic recurrent dislocations while planning further long-term management. MRI is highly sensitive in detecting complications of mandibular injuries, such as pseudoarthrosis from fragment nonunion of traumatic fractures, ischemic necrosis of the condylar head, and traumatic damage to the articular disk. Both CT and MRI can be used to assess for posttraumatic osteomyelitis. [29]