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Bilateral masseteric contractile activity in unilateral gum chewing: differential calculus
Author(s) -
CHRISTENSEN L.V.,
MOHAMED S.E.
Publication year - 1996
Publication title -
journal of oral rehabilitation
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.991
H-Index - 93
eISSN - 1365-2842
pISSN - 0305-182X
DOI - 10.1111/j.1365-2842.1996.tb00905.x
Subject(s) - isometric exercise , chewing gum , electromyography , masseter muscle , concentric , anatomy , medicine , mastication , muscle contraction , orthodontics , dentistry , mathematics , physical medicine and rehabilitation , chemistry , geometry , food science
SUMMARY Twelve healthy subjects performed 10 s, 15 s, 20 s, and 25 s of right‐sided and, subsequently, left‐sided gum chewing. The contractile activities of the ipsilateral (chewing side) and contralateral (non‐chewing side) masseter muscles, mainly the concentric contractions of the phase of jaw closing and the isometric contractions of the phase of dental occlusion, were recorded through cumulative surface electromyography (EMG). A linear function (y = ax + b) described the association between an increase in the duration (x) of unilateral gum chewing and the cumulative EMG (y) of both the ipsilateral and the contralateral masseter muscle, and because of different slopes (a) of the two straight lines a geometric function (y = aqx) described the progressively larger differences between the paired and straight lines. When differential calculus was applied to the exponential functions, it became evident that the chewing forces generated by the ipsilateral masseter muscle continually exceeded those generated by the contralateral masseter muscle, and that the positive work (force x distance) produced by the concentric contractions of the ipsilateral masseter muscle continually exceeded that produced by the concentric contractions of the contralateral masseter muscle. It was inferred that mechanophysical work plays a major role if clinical muscle fatigue develops during prolonged unilateral gum chewing.