Radiologic examination of trismus as a complication of cancrum oris.

In the radiologic examination of trismus complicating cancrum oris, abnormalities can be detected in the soft tissues, osseous tissues, and temporomandibular joint. In the soft tissue, scar formation may show as a depression in the normal smooth, convex contour of the lateral aspect of the face. There may be a myositis ossificans in the soft tissue, producing bony bars that lead to extra-articular ankylosis. By far the most important changes are in the temporomandibular joint, where there can be varying degrees of joint narrowing, sclerosis of the articular cortex, flattening of the mandibular condyle and occasionally also of the eminentia articularis, osteophytosis, and intra-articular bony ankylosis. Hypoplasia may involve the entire hemimandible or be restricted to its condyloid process. The latter may lead to compensatory enlongation and hypertrophy of the coronoid process. Bony ankylosis of the coronoid process to the posterior wall of the maxilla was seen in three cases. The pathogenesis of these changes is discussed.