Journal of Dental Research, Vol 67, 1081-1085, Copyright © 1988 by International & American Associations for Dental Research Online Journals
The influence of tonic muscle activation on human jaw displacement tremor
R. S. McCarroll and J. H. De Vries
Department of Masticatory Function, University of Amsterdam, The Netherlands.
Jaw displacement tremor was investigated. Both tremor amplitude and tremor
frequency were found to increase with increasing muscle activation.
Co-contraction of jaw elevator and jaw depressor muscles was employed in
order to vary muscle activation levels without the teeth being in
occlusion. Reproducibility of tremor changes was statistically significant
for each individual investigated. The relationship between tremor frequency
and tremor amplitude, over the range of muscle activation investigated,
varied per individual. It is hypothesized that the physiological basis for
this inter-individual variation is differences in the development of jaw
stiffness with increasing muscle activation between subjects. This
explanation may be the basis, at least in part, for the clinical presence
of objective jaw stiffness in one subject and its absence in another.
