Effect of three different jaw positions on postural stability during standing

Abstract

Studies in the literature show that jaw and neck regions are linked anatomically, biomechanically and neurologically. Voluntary clenching has been shown to improve muscle strength and performance of various motor tasks. Information from the neck sensory-motor system is reported to be important for posture. Hence it is reasonable to believe that activation of the jaw sensory-motor system has the potential to modulate posture. In a sample of 116 healthy subjects, we compared center of gravity (COG) velocity during quiet standing on a foam surface during three test positions: i) resting jaw, ii) open jaw, and iii) clenching; these were tested in two conditions: with eyes open and with eyes closed. The COG velocity decreased significantly during clenching in comparison to both open and resting jaw positions (p<0.0001). This suggests that the jaw sensory-motor system can modulate postural mechanisms. We conclude that jaw clenching can enhance postural stability during standing on an unstable surface in both the presence and absence of visual input in healthy adults and suggest that this should be taken into consideration in treatment and rehabilitation planning for patients with postural instability.

Figure 1

Mean and 95% confidence intervals of COG velocity values of all subjects (n=116) for quiet standing on a relatively unstable surface with eyes closed during three test positions. Note significant differences (p=0.0001) in COG values between the three test conditions and the lowest mean value for the clenched jaw condition.

Figure 2

Mean and 95% confidence intervals of COG velocity values of all subjects (n=116) for quiet standing on relatively unstable surface with eyes open during three test positions. Note significant differences (p=0.0001) in COG values between the three test conditions and the lowest mean value for the clenched jaw condition.

Figure 3

In comparison to the resting jaw position, the relative reduction in COG velocity during the open jaw and clenched jaw positions with eyes open and eyes closed.