Effect of the unilateral loss of posterior occlusal support on masticatory function

Abstract

We examined electromyograms (EMG) of the masticatory muscles during unilateral gum chewing and tapping on the mandibular incisors using a Mandibular Kinesiograph on three subjects whose posterior occlusion was altered on one side. All three had full crowns on 567 on one side. Tests were carried out as each crown was removed in sequence starting from the distal. Loss of support at 7 or 67 did not significantly change the tapping points and the EMG. However loss of 567 significantly shifted the tapping points to the opposite side and scattered them. In addition, this significantly increased the coefficient of variation (CV) in many of the EMG parameters and decreased burst activity. In particular, this significantly increased the CV of burst duration outlasting tooth contact, and decreased burst activity outlasting tooth contact, during gum chewing on the contralateral side. These results suggest that loss of unilateral 567 support adversely affects masticatory function. Shika Igaku (J Osaka Odontol Soc) 1997 Sept； 60(3)：173-183．