Examination of lower facial skin movements during left- and right-side chewing.

PURPOSE

The purpose of this study was to temporally and spatially analyze movements of lower facial skin during left- and right-side chewing in order to examine, from the viewpoint of kinematics, whether functional differences existed between these movements on the two sides.

METHODS

Ten healthy young subjects (aged 24-32 years, mean age 26.7 years) were included in this study. The test bolus used in this study was sufficiently softened chewing gum. The cycle time, mean square error value and mean difference vector value of chewing paths were used as parameters.

RESULTS

Cycle times of movements of lower facial skin during gum chewing were invariant and stable on each chewing side, and showed no significant differences between the sides. The similarities of chewing paths and directions of movements of lower facial skin during gum chewing showed mirror-image relationships between the sides. Furthermore, these relationships during gum chewing were stable on both sides.

CONCLUSIONS

Based on these findings, it was found that movements of lower facial skin during left- and right-side chewing in healthy subjects were temporally and spatially invariant, stable and similar on both sides. Moreover, the present results suggest, from the viewpoint of kinematics, that a functional difference may not exist between these movements on the two sides.