Title: Comparing Peak Chewing Muscle Activity of Dysfunctional Subjects to Controls
John Radke (Presenter)
Bio Research Inc.
Objectives: Compare timing of peak muscle activity during chewing between dysfunctional subjects and controls. Null hypothesis = no difference.
Methods: Bilateral masseter (Mm) and temporalis (Ta) EMG activity, together with incisor-point jaw motion, were recorded during the chewing of gum and a tough bolus on the left and right sides from dysfunctional subjects (17 F, 13 M) and controls (15 F, 15 M), matched for age (p = 0.73). The time from peak activity of each muscle was measured relative to the reference time at the end of closure.
Results: No significant difference was found in any measurement between genders or between boluses for the dysfunctional group. For the control group, males chewed faster and had a shorter mean closing time (p < 0.05). The control group’s mean time (all muscles) from the peak muscle activity to the end of closure was 48.6 (+/-17.2) ms. The dysfunctional group’s comparable mean time was -8.3 (+/-18.0) ms., for a significant total mean difference of 56.9 ms. (p = 0.0000). The individual muscle (Mm & Ta) mean values were all significantly different between groups (p < 0.00003 for all).
Conclusions: The control group’s mean peak muscle activity occurred during the crush of the bolus 48.6 ms before the end of closure, but the dysfunctional group delayed their peak muscle activity significantly until 8.3 ms after the bolus was fully crushed, 56.9 ms later.