Electromyography of the temporalis and masseter muscles in children with unilateral cross-bite.

Abstract

Abstract— Unilateral cross‐bite is a morphologic trait observed in the intercuspal position. The present report deals with its influence on the activity in the muscles of mastication as studied by electromyography. In 12 children 8–11 years of age with unilateral cross‐bite the action of the temporal and masseter muscles was studied (1) with the mandible at rest, i. e. without tooth contact, and (2) during maximal bite in the intercuspal position. With the mandible at rest the activity in the anterior temporal muscle was strongest on the side of normal occlusion and in the posterior temporal muscles it tended to be strongest on the side of the cross‐bite. During maximal bite the action of the posterior temporal muscles was reduced on the side with normal occlusion as compared with the side of the cross‐bite. The activity in the masseter muscles was not modified. As a whole the pattern of activity at rest and during full effort indicated adaptation to the transverse occlusion.