Degenerative changes in masseter and temporalis muscles in limited mouth opening and TMJ ankylosis

Abstract

The masseter and temporalis muscles were studied ultrastructurally in eight cases suffering from restricted mouth opening and TMJ ankylosis. The changes varied from slight degeneration of muscle fibers, such as accumulation of lipid or lipofuscin deposits, Z-band streaming and derangement of myofilaments, in one case to moderate or severe changes of muscle atrophy and necrosis in the remaining seven cases. Nemaline bodies were also observed in one of these seven cases. In addition to these muscle changes neural degeneration especially of myelinated nerves were found in three of the cases studied. The present findings showed that in spite of the diversity of the underlying factors affecting the joint, there was many similarities in the changes observed within the muscle. It is postulated that these degenerative muscle changes probably play an important role in restricted mouth opening and TMJ ankylosis, and that some of these muscle pathology may be the result of neural involvement.

Mandibular Kinematics in Patients With Alloplastic Total Temporomandibular Joint Replacement—A Prospective Study

“…In cases of mandibular hypomobility associated with restricted mouth opening, the temporalis and masseter muscles were found to adapt by shortening, 34 and show atrophy and degeneration. 35 The limitation of mandibular movement therefore is caused not only by articular but also by muscular restriction. 15 Therefore, postsurgical passive distraction (TheraBite, Atos Medical, Hörby, Sweden) and physical therapy to prevent secondary immobilization are just as important as postsurgical exercises to increase the contractile force of the elevators.…”

Outcome of Surgical Protocol for Treatment of Temporomandibular Joint Ankylosis Based on the Pathogenesis of Ankylosis and Re-Ankylosis. A Prospective Clinical Study of 14 Patients

“…[7][8][9][10][11][12][13][14][15] The purpose of this study was to evaluate the surgical outcomes of the present protocol for the treatment of TMJ ankylosis for improvements in mouth opening and the prevention of recurrence.…”

Satisfaction of orthognathic surgical patients in a Malaysian population.

“…It has been reported that any Table 5 Comparison of present study with published results trauma or pathological diseases affecting the temporomandibular joint would cause degenerative change within the masticatory muscles (20). Therefore, electromyographic study of the masticatory muscles needs to be done to find out if there is indeed improved muscle activity after orthognathic surgery.…”