Force‐controlled biting alters postural control in bipedal and unipedal stance

Abstract

Human posture is characterised by inherent body sway which forces the sensory and motor systems to counter the destabilising oscillations. Although the potential of biting to increase postural stability has recently been reported, the mechanisms by which the craniomandibular system (CMS) and the motor systems for human postural control are functionally coupled are not yet fully understood. The purpose of our study was, therefore, to investigate the effect of submaximum biting on postural stability and on the kinematics of the trunk and head. Twelve healthy young adults performed force-controlled biting (FB) and non-biting (NB) during bipedal narrow stance and single-leg stance. Postural stability was quantified on the basis of centre of pressure (COP) displacements, detected by use of a force platform. Trunk and head kinematics were investigated by biomechanical motion analysis, and bite forces were measured using a hydrostatic system. The results revealed that FB significantly improved postural control in terms of reduced COP displacements, providing additional evidence for the functional coupling of the CMS and human posture. Our study also showed, for the first time, that reductions in the sway of the COP were accompanied by reduced trunk and head oscillations, which might be attributable to enhanced trunk stiffness during FB. This physiological response to isometric activation of the masticatory muscles raises questions about the potential of oral motor activity as a strategy to reduce the risk of falls among the elderly or among patients with compromised postural control.

Postural stability and the influence of concurrent muscle activation – Beneficial effects of jaw and fist clenching

“…First, in Ringhof et al [2] COP displacements were reported to be less under submaximum biting as compared to a mandibular rest position, i.e., nonbiting. Hence, the question remained whether these effects were the result of submaximum biting, in terms of decreased postural sway, or the result of nonbiting, in terms of increased postural sway.…”

“…Recently, submaximum clenching of the jaw was reported to significantly improve postural stability and to decrease the sway of cranial body segments in upright unperturbed stance [1][2][3]. The authors concluded that these improvements were induced by modulation of somatosensory input, particularly of the neck muscles [4], and facilitation of ankle extensor and flexor muscles [5,6], concomitant with attenuated reciprocal Ia inhibition [6].…”

“…One limitation of the abovementioned studies [1][2][3], however, is the lack of active controls, as used by Miyahara et al [5]. The authors reported that soleus H reflex was not only increased by voluntary clenching of the teeth, but also by isometric contraction of the wrist extensors or by clenching of the fists.…”

“…The authors reported that soleus H reflex was not only increased by voluntary clenching of the teeth, but also by isometric contraction of the wrist extensors or by clenching of the fists. Ringhof et al [2], hence, suggested that sway reductions might also be observed among active controls.…”

Efeitos imediatos de interferência oral nos músculos mastigatórios e de interferência podal nas funções orofaciais, oclusão e postura corporal em jovens saudáveis

“…Uma delas analisa se há efeito de mudanças na postura mandibular, na oclusão ou na contração voluntária dos músculos elevadores da mandíbula sobre a postura corporal/equilíbrio. Baseados nos resultados alguns autores afirmam que sim Milani et al, 2000;Takada et al, 2000;Yoshino;Higashi;Nakamura, 2003;Bracco;Deregibus;Piscetta, 2004;Bergamini et al, 2007;Sakaguchi et al, 2007;Tardieu et al, 2009;Cuccia, 2011;Ohlendorf et al, 2014;Iqbal, 2015a,b;Hellmann et al, 2015;Ringhof et al, 2015;, mas outros não Perinetti, 2006;Perinetti et al, 2010;Baldini et al, 2013;Marini et al, 2013).…”