title: Task-dependence of activity/ bite-force relations and its impact on estimation of chewing force from EMG.
abstract: Estimation of chewing force from electromyograms (EMGs) calibrated in isometric biting yielded strikingly high force values. We tested the hypothesis that EMG-based force predictions are excessive because of differing activity/bite-force relations in mastication and isometric biting. In nine patients, unilateral bite forces and EMGs of 4 elevator muscles were recorded during chewing and isometric clenching on a bite-fork. We estimated chewing force by substituting chewing EMGs of each muscle into isometric activity/bite-force regressions. The estimates were compared with actual chewing forces recorded by intra-oral transducers. In all muscles except the balancing-side masseter, the activity/bite-force ratio was significantly higher in chewing than in isometric biting. The actual mean chewing force amounted to 220 N, while EMG-based estimates ranged from 273 to 475 N, depending on the muscle used for estimation. The results indicate that different activity/force characteristics in dynamic and isometric biting can cause overestimation when chewing force is predicted from masticatory EMGs.
authors.affiliation: Department of Prosthodontics, University Dental Clinic, University of Erlangen-Nürnberg, Glueckstrasse 11, Germany. peter.proeschel@rzmail.uni-erlangen.de
authors.forename: P A
authors.initials: PA
authors.lastname: Proeschel
authors.forename: T
authors.initials: T
authors.lastname: Morneburg
mesh_terms: D000465:Algorithms; D001732:Bite Force; D002638:Chewing Gum; D004576:Electromyography / Q000295:instrumentation / Q000379:methods; D005260:Female; D006801:Humans; D007537:Isometric Contraction / Q000502:physiology; D008297:Male; D008406:Masseter Muscle / Q000502:physiology*; D008409:Mastication / Q000502:physiology*; D008875:Middle Aged; D012044:Regression Analysis; D012815:Signal Processing, Computer-Assisted; D013223:Statistics as Topic; D013314:Stress, Mechanical; D013703:Temporal Muscle / Q000502:physiology*; D016474:Weight-Bearing
chemical_list: D002638:Chewing Gum