Department of Paediatric Dentistry and Orthodontics, Universidade Federal do Rio de Janeiro, Avenida Professor Rodolpho Rocco, 325, Ilha do Fundão, 21941-617 Rio de Janeiro, Brazil.
Department of Physiology, Universidade Federal de Juiz de Fora, Minas Gerais, Brazil.
Int Orthod. 2021 Dec;19(4):652-658. doi: 10.1016/j.ortho.2021.07.004. Epub 2021 Sep 17.
To evaluate the response of the myoelectric activity of levator labii superioris (LLS), levator labii superioris alaeque nasi (LLSAN), and minor zygomatic (Zm) muscles in individuals with gummy smile, volunteers to botulinum toxin type A (BTX-A) application, with a follow-up of 6 months.
Thirteen individuals were submitted to clinical evaluation and photographic records to monitor the variations of the gingival display (GD) during posed smile. The recording of the surface electromyography (sEMG) signal of muscles studied was performed in three tasks: posed smile (PS), upper lip elevation (ULE) and nose wing elevation (NWE). The root-mean-square value, an amplitude sEMG signal parameter, was extracted from the sEMG signals. One and three-way ANOVA were applied, and the level of significance set at 5%.
There were significant differences (P<0.05) in the sEMG signal activity from the control condition (before BTX-A application - T0) to the 8th week of follow up, which was accompanied by clinical evaluation for the gingival display (P<0.05). The peak of the reduction in sEMG signals occurred 2 weeks after T0 for all the studied tasks, with the exception of the left hemiface in the PS, which showed a peak of reduction 4 weeks after T0.
BTX-A led to a decrease in the sEMG signal amplitude over 2 to 4 weeks after application in the muscles, although differently concerning each hemiface when recruited to perform other mouth tasks. During the PS, the recruitment level of the upper lip elevator muscles was compatible with the clinical response obtained in the follow-up period in this study, which corroborates the sEMG assessment to clinical data.
评估上唇提肌（LLS）、上唇鼻翼提肌（LLSAN）和小颧肌（Zm）的肌电活动对接受肉毒毒素 A（BTX-A）治疗的笑龈患者的反应，随访时间为 6 个月。
13 名患者接受了临床评估和摄影记录，以监测微笑时牙龈显露（GD）的变化。在三个任务中进行了研究肌肉的表面肌电图（sEMG）信号记录：微笑（PS）、上唇抬高（ULE）和鼻翼抬高（NWE）。从 sEMG 信号中提取均方根值（RMS），这是一个振幅 sEMG 信号参数。应用单因素和三因素方差分析，显著性水平设为 5%。
与 BTX-A 应用前（T0）相比，在第 8 周的随访中，sEMG 信号活性有显著差异（P<0.05），同时伴有牙龈显露的临床评估（P<0.05）。在所有研究任务中，除 PS 左侧外，sEMG 信号的峰值在 T0 后 2 周内降低，PS 左侧的峰值在 T0 后 4 周内降低。
BTX-A 在应用后 2 至 4 周内导致肌肉的 sEMG 信号幅度降低，尽管在执行其他口部任务时，每侧肌肉的募集情况不同。在 PS 中，上唇提升肌的募集水平与本研究随访期间获得的临床反应相匹配，这支持了 sEMG 评估与临床数据的一致性。
