MASSETER MUSCLE-ACTIVITY IN DENTURE WEARERS WITH SUPERIOR AND POOR MASTICATORY PERFORMANCE

A cross-sectional study tested the hypothesis that denture wearers wit h superior and poor chewing ability use similar masseter muscle effort and biting forces during mastication. Masticatory performance tests o n the preferred chewing side and swallowing threshold tests were condu cted with peanuts and carrots in 70 denture wearers, 35 with superior (SP) ((x) over bar 46.3%) and 35 with poor (PP) ((x) over bar 30.7%) m asticatory performance, Right and left masseter muscle electromyograph ic (EMG) activity was recorded during the masticatory tests and peak b ite force during chewing was estimated from the bite force-EMG ratios on guided maximal biting trials, Bite force under maximal pressure did not differ significantly between the two groups, Neither the total me an EMG activity of the preferred and nonpreferred side masseter muscle s nor the mean peak biting forces exerted by the two groups differed s ignificantly (p > 0.05). This was true when denture wearers restricted chewing to their preferred side for a given number of strokes or chew ed the test food freely until ready to swallow, The only significant d ifferences (p < 0.05) were evident in the ratios of the preferred to n onpreferred side masseter EMG activity during chewing, The ratios were 1.2 for peanuts and 1.3 for carrots in the SP group compared to 1.8 f or both foods in the PP group, Similar patterns of bilateral activity in the SP group and unilateral activity in the PP group were evident f or the swallowing threshold tests, The results indicated that applicat ion of more equivalent force by the right and left masseter muscles du ring unilateral chewing is consistent with improved chewing ability in denture wearers.