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Task-dependence of Activity/ Bite-force Relations and its Impact on Estimation of Chewing Force from EMGDepartment of Prosthodontics, University Dental Clinic, University of Erlangen-Nürnberg, Glueckstrasse 11, D 91054 Erlangen, Germany; Correspondence: * corresponding author, peter.proeschel{at}rzmail.uni-erlangen.de 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.
Key Words: activity bite-force relation mastication clenching estimated chewing force
Journal of Dental Research, Vol. 81, No. 7,
464-468 (2002) |
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