Occlusal force pattern during rhythmic human tapping movement

The dynamic occlusal force patterns associated with the performance of rhythmic tapping movement were analysed in normal subjects, who were instructed to make tapping movements at four frequencies, 2, 2.5, 3.3 and 5 Hz, with as constant a magnitude of force as possible. The occlusal force recorded by an intra-oral customized device showed a triphasic pattern which could be divided into two components, and this pattern was more clearly defined during slower tapping movements. Of the two components, the first was relatively stable, regardless of changes in tapping frequency, while the second was highly dependent on the tapping cycle duration, and its duration was shortened with increases in tapping frequency. Furthermore, there was a significant correlation between the changes in the occlusal power phase and those in the burst duration of the masseter EMG simultaneously recorded by a pair of surface electrodes. On the basis of these findings, it is suggested that the tapping rhythm is modulated by the duration of the occlusal power phase and the associated jaw elevator muscle activity.