Methods: Four complete denture wearers (2 men, 2 women; age: 76-85 years; average age: 79.5 years) were included in present study. Occlusal vertical dimension established three types (normal, 5mm increase, and 3mm decrease). The subjects were seated in a resting position with their eyes closed in a semi-anechoic examination room at Tsurumi University Dental Hospital. After confirming that electroencephalogram (EEG) was detected for 3 seconds, the EEG was recorded using ESA-pro (Brain Function Laboratory, Inc., Kanagawa, JAPAN) and 21 pasteless electrodes in a helmet. To evaluate emotional state, an EEG was taken for three minutes both before and after gum chewing. The extracted EEG were analyzed in time series by using four emotional indexes based on ESAM: stress, depression, joy and relax. The data were statistically analyzed using Bonferroni (α = 0.05) to compare emotional indexes before and after gum chewing.
Results: Emotional indexes were divided into the negative index (stress and depression) and the positive index (joy and relax). No significant differences were observed the negative index and the positive index (p>0.05). However, there were observed the tendency to increase most the negative index by 3mm decrease in the occlusal vertical dimension, and the tendency to increase most the positive index by 5mm increase in the occlusal vertical dimension.
Conclusions: The results of this study suggest that the low occlusal vertical dimension tend to have large psychological burden.