Department of Oral Science, University G. d'Annunzio, Chieti, Pescara, Italy.
Eur J Orthod. 2010 Dec;32(6):747-52. doi: 10.1093/ejo/cjq024. Epub 2010 Aug 26.
This study investigated the pattern of masticatory, neck, and trunk muscle activity in patients with posterior crossbites and associated mandibular displacement. The test group consisted of 75 patients [45 males mean age 19.5 years, SD 5.6 years, and 30 females mean age 20.4 (SD 3.2) years]. Of this group, 25 patients presented a left posterior crossbite, 25 a right posterior crossbite, and the remaining 25 patients a bilateral posterior crossbite. A control group of 25 subjects (19 males and 6 females aged 22.5 ± 5.8 years) without any crossbite were included. Surface electromyographic (sEMG) activity was recorded bilaterally, in the mandibular rest position and during maximum voluntary clenching (MVC), at the following sites: anterior and posterior temporal, masseter, sternocleidomastoid (SCM), upper and lower trapezius, and cervical muscles. In the mandibular rest position, patients with unilateral crossbites showed a significant difference (P < 0.05) in sEMG activity of the anterior temporal muscle, with the greatest activity being detected on the side to which the mandible displaced. Control subjects demonstrated significantly lower (P < 0.05) sEMG activity but only in the SCM muscle when compared with patients with bilateral posterior crossbites; no such differences were detected in relation to unilateral crossbites. During MVC, control subjects showed significantly lower (P < 0.01) sEMG activity in both the SCM and the posterior cervical muscles compared with patients demonstrating both unilateral and bilateral crossbites. The findings of the present study indicate that the presence of a crossbite can affect electromyography activity of masticatory, neck, and trunk muscles.
本研究调查了后牙反合伴下颌偏斜患者的咀嚼肌、颈肌和躯干肌的活动模式。实验组由 75 名患者组成[45 名男性,平均年龄 19.5 岁,标准差 5.6 岁,30 名女性,平均年龄 20.4 岁(标准差 3.2 岁)]。其中 25 名患者表现为左侧后牙反合,25 名患者表现为右侧后牙反合,其余 25 名患者表现为双侧后牙反合。纳入了一个由 25 名无牙合患者(19 名男性和 6 名女性,年龄 22.5 ± 5.8 岁)组成的对照组。双侧记录下颌休息位和最大自主紧咬(MVC)时的表面肌电图(sEMG)活动,记录部位包括:颞肌前、后区、咬肌、胸锁乳突肌(SCM)、上、下斜方肌和颈肌。在下颌休息位时,单侧后牙反合患者的前颞肌 sEMG 活性差异有统计学意义(P < 0.05),下颌偏斜侧的活性最大。与双侧后牙反合患者相比,对照组的 sEMG 活性显著降低(P < 0.05),但仅在 SCM 肌肉中;而在单侧后牙反合患者中未发现这种差异。在 MVC 时,对照组的 SCM 和颈后肌的 sEMG 活性明显低于表现为单侧和双侧后牙反合的患者(P < 0.01)。本研究结果表明,牙合的存在会影响咀嚼肌、颈肌和躯干肌的肌电图活动。