Journal of Dental Research, Vol 65, 441-447, Copyright © 1986 by International & American Associations for Dental Research Online Journals
Comparison of the reproducibility of EMG signals recorded from human masseter and lateral pterygoid muscles
J. Dahan and C. Boitte
EMG recordings of the left and right masseter and lateral pterygoid muscles
were repeated three times in 15 young adults to test the reproducibility of
the signals. Two tests were made on the same day (morning and afternoon)
and one test three days later (morning). Needle and hook electrodes were
used for the masseter muscle and needle electrodes for the lateral
pterygoid muscle. The superficial areas of recording were tattooed on the
skin. An intra-oral approach was selected for the lateral pterygoid muscle.
The subjects were asked to perform three definite tasks for the masseter
muscle (intercuspid occlusion, maximum protrusion, and centric relation
with a bite opening of 3mm) and two for the pterygoid muscle (maximum
opening and maximum protrusion). The EMG signals were directly integrated,
and root mean squares of the AC components were computed. The selection of
the signals to discard possible artefacts was performed by displaying EMG
and RMS outputs on a six-channel UV oscillograph. The selected RMS values
were submitted to different analyses of variance to define additive and
non-additive models of effects. The results may be summarized as follows:
The between-day sessions showed more variation than the within-day
sessions. The variations related to the method accounted for a very high
percentage of the total variance (48.9%). The recordings with needle
electrodes displayed a large percentage of the individual variation
(masseter, 31.2%; lateral pterygoid muscle, 65.9%) and significantly lower
values for the variations related to the session or the side of recording.
The one-side recordings were more suitable for distinguishing the
biological variations than were the bilateral ones.(ABSTRACT TRUNCATED AT
250 WORDS)
