Integrated electromyographic activity of masseter and anterior temporal muscles was recorded using bipolar surface electrodes in 33 young adults. Subjects were skeletally classified according to ANB angle reading corrected both for maxillary position and rotation of the jaw.

Postural activity for both muscles was higher in Class III subjects than in Class I and Class II, whereas in Class I and II subjects activity was similar. During swallowing, masseter muscle activity in Class III subjects was higher than Classes I and II, whereas anterior temporal muscle activity was not different between Classes III and I. During maximal voluntary clenching, activity was not different among classes. High correlations between electromyographic activity and corrected ANB angle as well as with overjet were observed.

Skeletal classification used in the present study may have clinical relevance regarding treatment and prognosis, as well as in the assessment of the relationship between muscular activity and craniofacial characteristics.

Skeletal facial type, Cephalometry, Electromyography, Tonic activity, Swallowing activity
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Author notes

R. Miralles is an assistant professor in the Department of Physiology and Biophysics, Faculty of Medicine at the University of Chile

R. Hevia is a research fellow in the Department of Physiology and Biophysics, Faculty of Medicine at the University of Chile

L. Contreras is a research fellow in the Department of physiology and Biophysics, Faculty of Medicine at the University of Chile

R. Carvajal is an assistant professor in the Department of Orthodontics, Faculty of Odontology at the University of Chile

R. Bull is an assistant professor in the Department of Physiology and Biophysics, Faculty of Medicine at the University of Chile

A. Manns is an associate professor in the Department of Physiology and Biophysics, Faculty of Medicine at the University of Chile

Edward H. Angle Society of Orthodontists
1991