Am J Orthod Dentofacial Orthop 1999 Nov;116(5):481-93
Abnormal cervical muscle function can cause abnormal head posture, adversely affecting the development and morphology of the cervical spine and maxillofacial skeleton, which in turn leads to facial asymmetry and occlusal abnormality. There can be morphologic abnormalities of the mandibular fossa, condyle, ramus, and disk accompanying the imbalance of the cervical and masticatory muscles activities. Two normally growing Japanese female patients with Class II Division 1 malocclusion presented with TMJ symptoms and poor head posture as a result of abnormal sternocleidomastoid and trapezius cervical muscle activities. One patient underwent tenotomy of the two heads of the sternocleidomastoid muscle and the other patient did not. In addition to orthodontics, the 2 patients received physiotherapy of the cervical muscles during treatment. Both were treated with a functional appliance as a first step, followed by full multi-bracketed treatment to establish a stable form of occlusion and to improve facial esthetics with no head gear.
This interdisciplinary treatment approach resulted in normalization of stomatognathic function, elimination of TMJ symptoms, and improvement of facial esthetics. In the 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. Based on the result, early occlusal improvement, combined with orthopedic surgery of the neck muscles or physiotherapy to achieve muscular balance of the neck and masticatory muscles, was found to be effective. Two patients illustrate the potential for promoting symmetric formation of the TMJ structures and normal jaw function, with favorable effects on posttreatment growth of the entire maxillofacial skeleton.