Correlations of head and trunk sways, and sitting and foot pressure distributions during chewing in the sitting position

Abstract

Purpose:The head plays an important role in the postural control. Chewing co-activates jaw and neck muscles leading to coordinated jaw and head-neck movements. Therefore, examination of the relationships among head and trunk sways, and sitting and foot pressure distributions during chewing is helpful in the attempt to understand an interrelationship between chewing and posture control system in the sitting position. This purpose of this study was to examine what kind of correlation exists among head and trunk sways, and sitting and foot pressure distributions during chewing in the sitting position. Methods: A total of 32 healthy young male subjects were evaluated. The CONFORMat TM and MatScan TM system were used to analyze changes in sitting pressure distribution (center of sitting pressure: COSP) and changes in foot pressure distribution (center of foot pressure: COFP) respectively, and the three-dimensional motion analysis system was used to analyze changes in head and trunk positions while subjects remained sitting position with rest position, centric occlusion, and chewing. Data were analyzed using Spearman's rank correlation coefficients. Results: There was a significant positive correlation between head and trunk sways in all three studied test conditions (correlation 0.76 to 0.92, P < 0.01). During chewing, significant positive correlations were also found between head sway and the displacement of COFP (correlations 0.64 and 0.65, P < 0.05) and between trunk sway and the displacement of COSP (correlations 0.66 and 0.75, P < 0.05). Conclusions: This study confirmed that there were significant positive correlations between head and trunk sways, between head sway and foot pressure distribution, and between trunk sway and siting pressure distribution during chewing in the sitting position.