Differential roles of periodontal mechanoreceptors of working-side posterior teeth in triggering nonworking-side temporalis activities.
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 jaw-closing 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 bucco-palatal, 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 working-side 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.
Kirimoto
Hiroaki
H
Orthodontic science, Graduate school, Tokyo Medical and Dental University, Bunkyo-ku Tokyo, Japan. kiri.orts@tmd.ac.jp
Seki
Yoichiro
Y
Soma
Kunimichi
K
D000328:Adult; D001641:Bicuspid / Q000294:innervation*; D004558:Electric Stimulation; D004576:Electromyography; D005260:Female; D007839:Functional Laterality / Q000502:physiology*; D006801:Humans; D008297:Male; D008409:Mastication / Q000502:physiology*; D008465:Mechanoreceptors / Q000502:physiology*; D008963:Molar / Q000294:innervation*; D009046:Motor Neurons / Q000502:physiology; D010513:Periodontal Ligament / Q000294:innervation / Q000502:physiology; D012815:Signal Processing, Computer-Assisted; D018709:Statistics, Nonparametric; D013703:Temporal Muscle / Q000294:innervation*