Miralles Rodolfo, Gutiérrez Carolina, Zucchino Geannella, Cavada Gabriel, Carvajal Raúl, Valenzuela Saúl, Palazzi Carmen
Oral Physiology Laboratory, Biomedical Sciences Institute, Faculty of Medicine, University of Chile, Santiago, Chile.
Cranio. 2006 Apr;24(2):98-103. doi: 10.1179/crn.2006.016.
The purpose of this study was to record the pattern of electromyographic (EMG) activity of supra- and infrahyoid muscles at different body positions and jaw posture tasks. The sample included 22 healthy subjects with natural dentition, bilateral molar support, and absence of posterior occlusal contacts during mandibular protrusion. Bipolar surface electrodes were located on the left supra- and infrahyoid muscles for EMG recordings. In each subject EMG activity was recorded while standing and in the lateral decubitus position, during the following jaw posture tasks: swallowing of saliva, maximal clenching in the intercuspal position, grinding from intercuspal position to protrusive edge-to-edge contact position, and grinding from retruded contact position to intercuspal position. Suprahyoid EMG activity was significantly higher in the intercuspal position than in all the other jaw positions studied (mixed model with unstructured covariance matrix). Suprahyoid EMG activity was similar in both body positions studied. Infrahyoid EMG activity in the intercuspal position was significantly higher than grinding from intercuspal position to protrusive edge-to-edge contact position, similar to swallowing of saliva, and significantly lower than grinding from the retruded contact position to intercuspal position. Infrahyoid EMG activity in the lateral decubitus position was significantly higher than in the standing position. The EMG pattern observed could be of clinical importance in the presence of parafunctional habits, i.e., clenching and/or grinding. The neurophysiological mechanisms involved are discussed.
本研究的目的是记录舌骨上肌群和舌骨下肌群在不同身体姿势及下颌姿势任务时的肌电图（EMG）活动模式。样本包括22名天然牙列、双侧磨牙支持且下颌前伸时无后牙咬合接触的健康受试者。将双极表面电极置于左侧舌骨上肌群和舌骨下肌群以进行EMG记录。在每位受试者站立和侧卧位时，记录以下下颌姿势任务中的EMG活动：吞咽唾液、牙尖交错位最大紧咬、从牙尖交错位磨至前伸边缘对边缘接触位，以及从后退接触位磨至牙尖交错位。在牙尖交错位时，舌骨上肌群的EMG活动显著高于所研究的所有其他下颌位置（采用非结构化协方差矩阵的混合模型）。在所研究的两种身体姿势下，舌骨上肌群的EMG活动相似。牙尖交错位时舌骨下肌群的EMG活动显著高于从牙尖交错位磨至前伸边缘对边缘接触位，与吞咽唾液时相似，且显著低于从后退接触位磨至牙尖交错位。侧卧位时舌骨下肌群的EMG活动显著高于站立位。观察到的EMG模式在存在偏侧咀嚼习惯（即紧咬和/或磨牙）时可能具有临床意义。文中对所涉及的神经生理机制进行了讨论。
