Methods: Bilateral Transcranial Doppler ultrasound examination during free gum chewing, gum chewing on the right side and gum chewing on the right side at a rate of 1.0 Hz was performed in 25 healthy subjects (11 males and 14 females, age 27.3±4.0 yrs.). To compare the middle cerebral artery blood flow velocities (MCAVs) during the pre-task (3 min), on-task (5 min) and post-task periods (5 min), we calculated area under effect curve (AUEC) by averaged data at every 5 sec on the tracing. Then the means and 95% confidence intervals (CIs) of the AUEC for the on-task and post-task periods were determined using the random effect model with replication data. Furthermore AUECs were compared among three kinds of chewing tasks by using Friedman test. Statistical significance was set at P<0.05.
Results: On-task bilateral MCAVs during each chewing task were significantly higher than in the pre-task and post-task periods (P<0.0001-P<0.01). There was no significant difference in the AUECs among three kinds of chewing tasks.
Conclusions: From the results of this study, it was suggested that cerebral blood flow was activated by gum chewing, and the state of activation was not influenced by volitional control in the masticatory side and rate during chewing.