Journal of Dental Research, Vol 70, 1417-1421, Copyright © 1991 by International & American Associations for Dental Research Online Journals
Electromyographic-force characteristics in the assessment of oral function
S. J. Lindauer, T. Gay and J. Rendell
Department of Orthodontics, Medical College of Virginia School of Dentistry, Richmond 23298.
The purpose of this investigation was to examine the utility of EMG-force
characteristics as reliable and valid parameters by which to assess oral
function. Masseter-muscle activity was recorded during controlled isometric
biting exercises performed at various bite openings and force levels on two
separate occasions. Measured muscle-activity levels, as well as the
EMG-force characteristics of slope and y-intercept, were compared between
bite openings and experimental trials. Sensitivity, assessed as the ability
to detect statistically significant differences in muscle function due to
changes in muscle length, was found to be acceptable for all measurements,
except the y-intercept parameter, and during production of minimal forces.
Reproducibility, evaluated as the correspondence between values recorded at
different experimental sessions, was best for the EMG-force parameter of
slope and during production of higher forces. The results from this study
support the following conclusions: (1) Substantial variations in muscle
function exist between individuals; (2) acceptable reliability and
sensitivity of quantitative EMG values can be achieved, especially at
higher muscle-activity levels, by rigidly controlling and quantifying
functional activities during experimental trials; (3) the slope of an
EMG-force curve is a reproducible, quantitative, and functionally sensitive
measurement for assessment of muscle function; and (4) the EMG-force
y-intercept is not a reliable quantity by which muscle-function
characteristics may be studied.
