engleski

Maximal Voluntary Isometric Activity of Elevator Masticatory Muscles at Different Occlusal Positions of the Mandible in Subjects with Normal Occlusion

Mean voltages of right temporal and masseter muscle (RAT, RM) and left temporal and masseter muscle (LAT, LM) during maximum voluntary clenching in maximal intercuspal position (MI), retruded contact position (RKP), incisal position (P) and right (RO) and left (LO) occlusal positions were examined. There was no significant difference between the sexes in none of the examined positions (p<0.05). For symmetric positions of the lower jaw (MI, P, RKP), there was a slightly higher muscle activity on the right side, although not significant (p<0.05). The biggest reduction of masseter muscle was in RKP and the biggest reduction of temporal muscle was in P, indicating masseter muscle being more responsible for the protrusive isometric contraction and temporal muscle for the retrusive isometric activity. In P all muscles reduced activity significantly, indicating the reflexive inhibitory input on the nucleus motorius n. trigemini from the periodontal receptors of the frontal teeth. Except in P, the biggest reduction of temporal muscle activity during voluntary clenching was in RO and LO on the side without lateral occlusal contact (contralateral side), indicating that temporal muscle is more sensitive to the reduction of the posterior teeth contact than the masseter muscle.

maximal voluntary isometric activity; masticatory muscles; occlusion; electromyography

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