Effect of masticatory movements on head and trunk sways, and sitting and foot pressure distributions during sitting position

Abstract

BackgroundThe 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, to examine effect of masticatory movements on head and trunk sways, and sitting and foot pressure distributions during mastication is helpful in the attempt to understand the interrelationship between stomatognathic function and posture control system in the sitting position.ObjectivesThe purpose of this study was to test the hypothesis in healthy subjects that masticatory movements affect head and trunk sways and sitting and foot pressure distributions during sitting position.MethodsA total of 30 healthy male subjects with an average age of 25.3 years (range, 22–32 years) were evaluated. The CONFORMat™ and MatScan™ system were used to analyse 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 analyse changes in head and trunk postures while subjects remained sitting position with rest position, centric occlusion and chewing. The total trajectory length of COSP/COFP, COSP/COFP area, and head and trunk sway values were compared between the three conditions to evaluate whether masticatory movement affected the stability of head and trunk sways and sitting and foot pressure distributions.ResultsTotal trajectory length of COSP and COSP area during chewing were significantly shorter and smaller respectively than it was in rest position and centric occlusion (p ⟨ .016). Head sway value during chewing was significantly larger than it was in rest position and centric occlusion (p ⟨ .016).ConclusionMasticatory movements affect sitting pressure distribution and head movements during sitting position.

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

“…The CONFORMat TM (Tekscan Inc., South Boston, MA, USA, Nitta Corp., Osaka, Japan) [14,18,19] was used to analyze the pressure distribution on the sitting surface. This pressure mapping device measures sitting pressure distribution and changes in the position of the center of sitting pressure (COSP) on the sitting surface during a standard measuring period, and consists of 1,024 pressure sensors that are connected in a flexible way to minimize the hammocking effect.…”

“…The MatScan TM system (Tekscan Inc., South Boston, MA, USA, Nitta Corp., Osaka, Japan) [13,14,[20][21][22] was used to analyze foot pressure distribution. This instrument provided a dynamic evaluation of foot pressure distribution.…”

“…The three-dimensional motion analysis system (Library Co., Ltd., Tokyo, Japan) was used to analyze head and trunk sways [13,14]. This instrument enabled measurement of three-dimensional movements of target points on the surface of the facial skin and body surface simultaneously.…”

“…The movements of target points were recorded by three charge coupled device (CCD) cameras, and the three-dimensional coordinates were calculated by using analyzing software (Library Co., Ltd, Tokyo, Japan). Target points on the skin of the face and the trunk were marked by attaching 4 points respectively [13,14] (Figure 2). The center of 4 target points was calculated in each sampling frame.…”

“…A recent study [14] has reported that masticatory movements affect sitting pressure distribution and head movements during sitting position. However, studies to investigate the relationship between mastication and sitting posture are still lacking and the mechanism by which mastication affects sitting posture could not be yet fully understood to our knowledge.…”