Occlusal forces during chewing and swallowing as measured by sound transmission.

Forces during the phase of occlusal contact during chewing and swallowing are surprisingly high (36.2% and 41%), about 40% of the subject's maximum biting force. Previous studies using transducers in fixed partial dentures measured only a portion of the total force and have given the impression that chewing forces are much less than the data reported in this study. The importance of occlusal stability in the intercuspal position is of utmost clinical significance. Steep anterior guidance does not appear to expose the teeth to extreme lateral forces. The gliding contacts of the teeth while entering and leaving the intercuspal position have been shown to be of short duration and low magnitude when compared with the forces generated in the intercuspal position. During chewing, the peak occlusal force occurred well after the peak EMG activity. EMG activity by itself does not directly correlate with the force generated during chewing. The sound transmission method for measuring interjaw force during chewing, which was developed as part of this project, proved to be practical for research purposes. No intraoral devices are required, and the time relationship to force is accurate to within 15 ms.