抄録
A quantitative analysis of electromyographic activity from the masticatory muscles was performed when the position of working-side guidance was altered. Without increasing the vertical dimension of the natural dentition, artificial steep occlusal guidances made of Ni-Cr alloy and methacrylic resin were at random overlaid on the maxillary canines, second premolars and second molars. While a mandibular lateral excursion with occlusion of voluntary medium force was carried out on each of the guidances, the EMG activity in the superficial masseter and posterior temporal muscles was recorded bilaterally by means of bipolar surface electrodes.
During the excursion on the second molar, both the EMG activity and total EMG activity of all muscles tested were greater than on the canine. According to the ratio of each muscle activity to the total EMG activity, the working-side muscles were responsible for the results, and depending on the case, the masseter muscles showed more activity than the temporal muscles and vice versa. These phenomena appeared especially in the closing phase.
