实验性咬合高点诱发头面部疼痛时的肌电分析研究

目的:探讨咬合高点对咀嚼肌肌电活动的影响。方法:在10名个别正常牙合志愿者的右下第一磨牙上赋予牙尖交错位的咬合高点,赋予前以及赋予后第3天利用表面肌电图记录咬肌、颞肌前后束的肌电活动, 并用可视性疼痛示意尺记录受试者的头面颈部疼痛症状。采用秩和检验统计方法比较咬合高点赋予前后肌电活动的变化以及双侧肌电活动的不对称性变化,并进行疼痛症状和肌电活动变化之间的相关性分析。结果:赋予咬合高点后息止位右侧颞肌前束的肌电幅值和积分值显著增加;大力咬合时咬肌、颞肌前后束的肌电幅值和积分值明显减小,同时双侧颞肌前束的肌电活动不对称性指数显著增大(P<0. 05)。受试者出现了不同程度的口颌面痛症状,右侧颞部的疼痛程度与右侧颞肌前束息止位的肌电幅值以及积分值的增加倍数呈正相关(P=0. 001)。结论:赋予实验性咬合高点后干扰侧息止位颞肌前束的紧张度增加,大力咬合时双侧颞肌前束的肌电活动明显不对称,提示了肌电活动的变化与干扰侧颞部疼痛的发生有一定关系。

The electromyographic activity of masseter and temporal muscles in the subjects with oral-facial pain caused by experimental occlusal interference

Objective:To investigate the oral-maxillofacial pain and t he surface electromyographic (EMG) activity of masseter muscles and anterior and posterior portions of temporalis muscles after experimental interference. Methods:A cast onlay of 0.5 mm in height was placed on the right low er first molar and remained for three days in 10 adult volunteers with normal oc clusion and without any symptom of TMD. The oral-maxillofacial pain was continu ously scored on a visual analogue scale(VAS)by the subjects before and after t he placement of the onlay. At the same time, the integral data of surface EMG we re recorded, and then the asymmetry index of the activity of bilateral muscles w as calculated. Results:Three days after the placement of the occ lusal highspot, all the subjects complained oral-maxillofacial pain. 8 of them had headache in right temporal region with VAS value of 1~4; the activity of tem poralis anterior at rest position of mandible was increased significantly (P <0.05) and the amplitude of increased activity was correlated significantly with the VAS value of the pain in temporal region (P=0.001); EMG activity of the tested muscles during clenching was significantly reduced and the asymmetry ind ex of anterior portion of temporalis was increased significantly (P<0.05). Conclusions:Unilateral occlusal trauma may make the ipsolateral anterior temporalis more tenser at rest position and the activity of bilateral a nterior temporalis more unsymmetrical while clenching, which may result in tensi on-type headache.