Clinical signs in patients with disk displacement versus patients with myogenic craniomandibular disorders.

Patients with disorders of the masticatory system were clinically examined with reference to tender TMJs and sore muscles of the head and neck, jaw movement range, occlusal interferences, and aberrations of the bite. The 158 patients were divided into three groups according to diagnosis: 46 with reducing disk displacement, 57 with nonreducing disk displacement, and 55 with myogenic CMD. Unilateral symptoms were found in 83% of the two TMJ groups and 47% of the myogenic CMD group. At intraoral palpation, significantly more patients with nonreducing disk displacement displayed tender sites on the symptomatic side. Tender TMJ, crepitation, and restricted condylar translation on the symptom side were significantly more common in the group with nonreducing disk displacement. Mean maximal mouth opening was 31 mm in the nonreducing disk displacement, 42 mm in the reducing disk displacement, and 47 mm in the myogenic CMD group. Total laterotrusion was significantly less in the nonreducing disk displacement group. Myogenic CMD patients had more interferences in retruded position on the symptomatic side and more tender neck and shoulder muscles. Patients with nonreducing disk displacement displayed more signs from the masticatory system than those with myogenic CMD.