JOURNAL OF OSAKA DENTAL UNIVERSITY

Vol. 42 No. 1      APRIL - 2008

ISSN: 0475-2058      UBIC: 172

SUMMARY

We attempted to clarify how the mandibular rest position is affected by psychological stress and by relaxation brought about by auditory stimulation. The jaw movements of ten subjects were recorded with a mandibular kinesiograph together with electromyograms of the bilateral anterior temporalis and masseter muscles, and electroencephalograms at Cz. White noise and relaxation sounds at 90 dB were used as auditory stimulation. When the subjects were exposed to the white noise, the interocclusal rest space significantly decreased, and jaw-closing muscle activity and beta waves significantly increased, compared to the periods of silence or exposure to relaxation sound. In addition, synergistic effects between the restraint stress and sound stimulation were expressed in jaw-closing muscle activity. The effect of white noise exposure on interocclusal rest space and jaw-closing muscle activity diminished as the experiment was repeated. Thus, it was shown that unpleasant stress, such as white noise, affected the mandibular rest position. These results indicate special care is required for patients with stress when recording the interocclusal record determined from mandibular rest position when there is no occlusal vertical support. For this purpose, relaxation music might help the patient relax during registration of the interocclusal relationship. (J Osaka Dent Univ 2008; 42: 75-82) Key words: Mandibular rest position; Auditory stimulation; Mandibular kinesiograph; Electromyography; Electroencephalogram.

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