Long-term training effects on masticatory muscles

Abstract

Neuromuscular adaptations during skill acquisition have been extensively investigated for skeletal muscles. Motor rehabilitation is the main target for application of motor training. Such measures are also relevant for the musculature of the jaw, but few data are available for motor adaptation of the masticatory system. The objective of this study was to evaluate and compare long-term training effects of different motor tasks on masseter and temporal muscles. In 20 healthy subjects, the electromyographic response to unilateral and bilateral maximum voluntary tooth clenching, balancing the mandible on a hydrostatic system under force-feedback-controlled conditions, and unilateral chewing was investigated in an initial session and then in two follow-up sessions separated by 2 and 10 weeks from baseline. Motor tasks were repeated three times for chewing, nine times for maximum biting (MB) and 24 times for the coordination tasks (CT). The sequences of the various motor tasks were applied once in the first session and twice in the second and third sessions. No effects of training were observed for MB tasks except for MB in intercuspation, for which significant yet transient avoidance behaviour occurred in the second session. No significant effects were found for chewing tests. For the CT, however, a robust significant long-term training effect was detected which reduced the electric muscle activity in session 2 by approximately 20% and in session 3 by approximately 40% compared with the initial measurements. The study showed that the masticatory muscles are remarkably prone to motor adaptation if demanding CT must be accomplished.

Small vertical changes in jaw relation affect motor unit recruitment in the masseter

“…Simulation of different vertical jaw distances was achieved by the use of a hydrostatic system described in detail elsewhere (Fig. ).…”

Static balancing behaviour of the mandible

“…The vertical force component was measured by use of a hydrostatic system consisting of liquid‐filled plastic pads (components of a commercially available intraoral hydrostatic device; Aqualizer; Bausch, Köln, Germany) which were mounted on individually made paraocclusal attachments. The vestibular attachment was fixed by Rush anchors between the first and second lower molars (Fig.…”

Efeito de exercícios motores orofaciais e laserterapia nos sintomas de desordem temporomandibular e funções orofaciais

“…Dessa forma, a modulação da atividade neuronal cortical induzida por input periférico ou central envolvidas no treinamento e aprendizado de novas habilidades motoras (AviviArber et al, 2011) pode contribuir para reverter a plasticidade mal adaptada e consequentemente diminuir a dor , à medida que pequenas modificações na tarefa motora podem levar ao recrutamento de diferentes unidades motoras, desligando ou reduzindo o recrutamento de unidades motoras dolorosas (Hellmann et al, 2011). Estas estratégias têm sido consideradas na reabilitação motora das desordens de dor musculoesquelética, na tentativa de maximizar a extensão das mudanças neuroplásticas e oferecer maior potencial para o sucesso da reabilitação (Boudreau et al, 2010).…”

“…Estas informações são relevantes para o tratamento de dor nos músculos mastigatórios de pacientes com DTM, à medida que pequenas modificações na tarefa motora podem levar ao recrutamento de diferentes unidades motoras, desligando ou reduzindo o recrutamento de unidades motoras dolorosas (Hellmann et al, 2011).…”

“…Apesar destes estudos citados anteriormente terem envolvido experimentos com sujeitos saudáveis e treinamento de apenas uma ou poucas tarefas, estas informações são relevantes para se pensar o tratamento das alterações das funções motoras orofaciais em pacientes com DTM, à medida que pequenas modificações na tarefa motora podem levar ao recrutamento de diferentes unidades motoras, desligando ou reduzindo o recrutamento de unidades motoras dolorosas (Hellmann et al, 2011).…”