Abstract
The purpose of this study was to examine how
the periodontal sensory inputs of working-side
maxillary posterior teeth affect nonworking-side
anterior temporalis activities at the starting jaw
position of the slow-closing phase in mastication.
Six subjects with normal occlusion were asked to
bite an incisal block to maintain the initial jaw position
of the slow-closing phase and to generate jawclosing
muscle activities. Bipolar needle electrodes
were inserted into the nonworking-side
anterior temporalis to record spike discharges
from a single motor unit. To stimulate the periodontal
mechanoreceptors, mechanical stimulations
were applied to the working-side maxillary
first molar, first and second premolar in buccopalatal,
palato-buccal, and apical directions.
Meanwhile, we examined changes in the discharge
frequency of the motor unit activities of the
nonworking-side anterior temporalis. We found
that the palato-buccal stimulation to the workingside
maxillary first molar and the apical stimulation
to each working-side maxillary posterior tooth
significantly increased the nonworking-side anterior
temporalis activities; however, palato-buccal
and bucco-palatal stimulations applied to the first
and second premolar didn’t. Thus, differential
responses of the nonworking-side anterior temporalis
are found by the working-side maxillary first
molar and premolar stimulations. These findings
may be due to some differences in function
between molar and premolar.
