Abstract
Purpose: It is believed that occlusal interference has an effect on normal masticatory function. Yet, the relationship between masticatory movement and higher brain function during occlusal interference is not clearly understood. The aim of this study was to investigate the physiological effects of experimental occlusal interference during mastication of kamaboko on the interference side.
Method: Eight healthy dentate dental students were selected as subjects. Simultaneous recordings were made with electromyograms and electroencephalograms, and analyzed, before and after mastication of kamaboko. Evaluation by visual analogue scale questionnaires was also done. Twelve-session experiments were carried out over a period of 12 days. Each session included periods before and after application of an occlusal interference, the interference period, removal of the interference, and subsequent observation of interference. Daily changes of masticatory muscle activity, six comfort parameters, and changes of electroencephalograms and electromyograms caused by premature contact, were analyzed.
Results: Discomfort, which was described by the visual analogue scale, did not disappear during the interference period. Masticatory movement tended toward corticalization in analysis of grouping voltage, but recovered the following day. On the other hand, in electromyograms of masticatory muscles, the bilateral coordination pattern indicated a tendency toward the collapse of predominantly working masseter muscle activity, and it was not recovered even after the second day following removal. No daily change was observed in electroencephalograms before mastication; however %α, in electroencephalograms after mastication, decreased significantly compared with the control during the interference period, as verified by visual analogue scale evaluation.
Conclusion: It is suggested that the decrease of %α in electroencephalograms after mastication may be caused by premature contact influence on the masticatory system, reflected in the presence of discomfort during occlusion.
