An electromyographic study on the masticatory muscles in the crossbite patients before and after orthodontic treatment.

In recent orthodontic practice, the introduction of multi-banded appliances has contributed heavily to the advancement of orthodontics and, thanks to them, it is possible to rectify the anomaly of jaws to a certain extent. In final analysis, however, the ultimate object of an orthodontic treatment is directed to an improvement of morphologic and esthetic aspects, and sufficient attention is not paid to the functional change of muscles in the oral region. It is also true that, even if the morphology and esthetics have been satisfactorily improved, there is a possibility of relapse unless various gnathofacial components are brought into harmony. In the present study, therefore, the author was concerned with the examinations of muscle function in malocclusal patients; especially with reference to muscle function of the crossbite patients before, during and after orthodontic treatments to elucidate what changes would take place in these stages.