Myoelectric activity during unilateral chewing in healthy subjects: cycle duration and order of muscle activation.
BACKGROUND
Craniomandibular disorders, unilateral mastication, and asymmetry of masticatory muscles appear to be related to each other. Thus, it is of interest to investigate masticatory muscle activity during unilateral mastication in healthy subjects.


OBJECTIVE
This study monitored contractile activity of the right and left masticatory muscles during right- and left-side gum chewing.


METHODS
Electromyographic techniques were used to determine chewing cycle duration and duration of contractile activity of the masticatory muscles (right and left masseter and anterior temporalis muscles) during unilateral chewing in 40 subjects without orofacial pain. The time-course of activation of the 4 muscles was also investigated.


RESULTS
Electromyographic traces showed extensive interindividual variation. In both right- and left-side chewing tests, and regardless of whether the masseter or the temporalis muscles were considered, mean duration of the contraction phase did not differ significantly between the working and nonworking sides. The working side temporalis contracted first, whether alone or at the same time as the other muscles.


CONCLUSIONS
In healthy subjects, no significant differences in masticatory muscle activity should be expected between either the right and left or the working and nonworking sides.
Rilo
B
B
Prosthodontics Department, School of Dentistry, Santiago de Compostela University, Spain.
da Silva
J L
JL
Gude
F
F
Santana
U
U
D000328:Adult; D002638:Chewing Gum; D017271:Craniomandibular Disorders / Q000503:physiopathology; D004576:Electromyography; D005260:Female; D006801:Humans; D007091:Image Processing, Computer-Assisted; D008297:Male; D008406:Masseter Muscle / Q000502:physiology*; D008409:Mastication / Q000502:physiology*; D009119:Muscle Contraction / Q000502:physiology; D012815:Signal Processing, Computer-Assisted; D013703:Temporal Muscle / Q000502:physiology*; D013997:Time Factors
D002638:Chewing Gum