Effect of teeth clenching on swallowing motor patterns in humans

The purpose of this study was to investigate the effect of teeth clenching on swallowing motor patterns. Seven healthy humans participated in this study. Electromyograms (EMGs) were recorded from the right masseter muscle, the suprahyoid muscles, and the right infrahyoid muscles. Three motor tasks were performed while the EMGs were recorded: swallowing without teeth clenching, and two tasks of swallowing with teeth clenching, one with masseter EMG activity at 20% of maximum, and one with masseter EMG activity at 40% of maximum. The duration of suprahyoid EMG activity with teeth clenching was significantly longer than that without teeth clenching. The duration of infrahyoid EMG activity with teeth clenching was significantly shorter than that without teeth clenching. The whole duration of swallowing with teeth clenching was significantly shorter than that without teeth clenching. Teeth clenching changes the swallowing motor pattern, indicating that activity of the masticatory center affects activity of the swallowing center.