Development of pathophysiology and clinical research diagnostic criteria for tooth clenching habit

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First part of this research project was conducted to assess the occurrence and the modality of spontaneous orofacial behaviors of waking non-pain healthy subjects unaware of bruxism during wakefulness. Subjects read silently for 30 minutes while polygraphic recordings were made with simultaneous audio video monitoring. Orofacial behaviors were scored and the activity and duration of masseter muscle bursts was calculated for the types of orofacial behaviors. Among spontaneous orofacial behaviors, swallowing was most frequently observed. Out of all masseter muscle bursts detected, Fiftey-five percent of all masseter bursts were associated with functional orofacial behaviors while 45% were regarded as non-functional. Most masseter bursts lasted for less than 2 seconds with an activity less than 20% of maximal voluntary clenching. These values did not differ between the types of associated orofacial behaviors. Spontaneous orofacial behaviors can be specifically identified with polygraphic … More recording and thereby non-functional masseter EMG activity can be differentiated from functional masseter EMG activity.The second part of the project aimed to compare the occurrence and the modality of spontaneous orofacial behaviors and masseter activity between subjects with and without awareness of tooth clenching habit, using polygraphic and audio-video recordings. Neither the number of events for orofacial behaviors, subjective psychological/sensory measures nor unstimulated whole salivary flow rate did not differ between the groups. However, masseter bursts unrelated to the above behaviors occurred more frequently in subjects with awareness than controls although the burst activity and duration did not differ between two groups. The results suggest that non-pain subjects with awareness of tooth clenching showed the increased number of non-functional masseter bursts under non-stressful laboratory condition. Thus, the results suggest that the physiological diagnostic criteria could be established using EMG measures in the future study. Less