Features and treatment of skeletal class III malocclusion with severe lateral mandibular shift and asymmetric...

To highlight the effectiveness of orthodontic treatment and bilateral equalization of the vertical occlusal dimension, along with the correction of asymmetric cervical and masticatory muscle activities in patients with Class III malocclusion with lateral deviation of the mandible and severely asymmetric condyle and ramus.

Two normally growing and one nongrowing Japanese patients with severe lateral deviation of the mandible, asymmetric vertical occlusal dimension, and severely asymmetric temporomandibular joints are discussed. In addition to orthodontic treatment, all patients received physiotherapy of the cervical muscles and gum-chewing training for elimination of the masticatory muscular imbalance. Patients also had postural training during treatment. All patients were treated with a bite plate to equalize the bilateral posterior vertical dimension, followed by full multi-bracketed treatment to establish a stable form of occlusion and to improve facial esthetics.

This interdisciplinary treatment approach resulted in normalization of stomatognathic function, elimination of temporomandibular joint dysfunction symptoms, and improvement of facial appearance and posture. In growing patients, the significant response of the fossa, condyle, and ramus on the affected side during and after occlusal correction contributed to the improvement of cervical muscle activity. In contrast, less improvement was observed in the growing patient who did not receive physiotherapy of the neck muscles, postural training, or masticatory habit training during the posttreatment period. The nongrowing patient showed little morphologic improvement of the cervical spine, condyle, and fossa during treatment and after retention, even with physiotherapy of the neck muscles and attention to posture and masticatory habits.

Based on these results, early occlusal improvement, combined with physiotherapy to achieve muscular balance of the neck and masticatory muscles, was found to be effective. It is important to assess the morphology and function of the neck muscles and cervical spine prior to occlusal therapy in patients with an asymmetric vertical dimension, lateral deviation of the mandible, and asymmetric temporomandibular joint structures. Therapy should correlate orthopedic and surgical patient management as needed.