Department of Basic and Oral Biology, Ribeirão Preto School of Dentistry, University of São Paulo, São Paulo, Brazil.
Department of Nursing, Faculty Anhanguera, Ribeirão Preto, Brazil.
PLoS One. 2020 Dec 15;15(12):e0243495. doi: 10.1371/journal.pone.0243495. eCollection 2020.
The maintenance of postural balance can be influenced by the lifestyle of a population. This study aimed to determine the electromyographic activity of the masseter and temporalis muscles during mandibular tasks and habitual and non-habitual chewing in indigenous individuals to reveal the differences among white Brazilian individuals. Sixty Brazilians (18 and 28 years) were divided into two groups: 30 Xingu indigenous individuals and 30 white Brazilian individuals, with 20 men and 10 women in each group. The individuals were assessed using the normalized electromyographic activity of mandibular tasks (rest, protrusion, right and left laterality) and electromyographic activity of masticatory cycles in habitual (peanuts and raisins) and non-habitual (Parafilm M) chewing. Data were analyzed using Student's t-test (p < .05). Comparisons between the groups demonstrated significant differences. Indigenous individuals group presented a decrease in the normalized electromyographic activity of the masticatory muscles during mandibular rest [right masseter (p = .002) and left masseter (p = .004) muscles]. There was increase in the normalized electromyographic activity during protrusion [left temporal (p = .03) muscle]. There was increase in the electromyographic activity during chewing: peanuts [right masseter (p = .001), left masseter (p = .001) and right temporal (p = .01) muscles], raisins [right masseter (p = .001), left masseter (p = .002), right temporal (p = .008), left temporal (p = .01) muscles] and Parafilm M [left masseter muscle (p = .05)]. From the findings of this study, we concluded that in the comparison between indigenous and white individuals, positive changes were observed in the electromyographic pattern of the masticatory muscles in the mandibular postural conditions, with greater masticatory efficiency in the indigenous group.
姿势平衡的维持可能受到人群生活方式的影响。本研究旨在确定下颌任务期间咀嚼肌（咬肌和颞肌）的肌电图活动，并揭示巴西本土个体与白种巴西个体之间的差异。60 名巴西人（18 岁和 28 岁）分为两组：30 名欣古土著个体和 30 名白种巴西个体，每组各有 20 名男性和 10 名女性。通过下颌任务（休息、前伸、右侧和左侧偏侧）的肌电图活动的正常化和习惯性（花生和葡萄干）及非习惯性（Parafilm M）咀嚼的咀嚼周期的肌电图活动评估个体。使用 Student's t 检验（p <.05）分析数据。组间比较显示出显著差异。土著个体组在下颌休息期间咀嚼肌的肌电图活动正常化减少[右侧咬肌（p =.002）和左侧咬肌（p =.004）]。在前伸时肌电图活动增加[左侧颞肌（p =.03）]。咀嚼时肌电图活动增加：花生[右侧咬肌（p =.001）、左侧咬肌（p =.001）和右侧颞肌（p =.01）]、葡萄干[右侧咬肌（p =.001）、左侧咬肌（p =.002）、右侧颞肌（p =.008）、左侧颞肌（p =.01）]和 Parafilm M[左侧咬肌（p =.05）]。从本研究的结果可以得出结论，在本土个体与白种个体之间的比较中，下颌姿势状态下咀嚼肌的肌电图模式观察到积极的变化，在土著个体组中咀嚼效率更高。
