Imaging of temporomandibular joint ankylosis. A new radiographic classification.

OBJECTIVES: To compare the pre-operative clinical and radiographic findings of temporomandibular joint (TMJ) ankylosis with those found at operation and propose new classification. METHODS: Thirty-three patients were treated for TMJ ankylosis. There were 18 unilateral and 12 bilateral cases. All patients underwent pre-operative clinical and radiographic examination, (consisting of a panoramic radiograph, axial and coronal CT. The surgical findings were compared with the imaging features. RESULTS: Post-contrast coronal CT was the best imaging modality for planning surgery as it displayed the anatomical relationship between the ankylosed segment and the surrounding vital structures, particularly where the sphenoid and temporal bones were involved. CONCLUSIONS: Surgical planning should be based on coronal and axial CT. A new classification of TMJ ankylosis based on the CT findings is proposed.