J Oral Facial Pain Headache. 2015 Winter;29(1):31-40. doi: 10.11607/ofph.1268.
To test the hypothesis that experimental pain in the masseter muscle or temporomandibular joint (TMJ) will decrease the anterior maximum voluntary bite force (MVBF) and jaw muscle activity in relation to the perceived effort.
Sixteen volunteers participated in two experimental sessions. Participants were injected with 0.2 mL of monosodium glutamate (1.0 M) into either the masseter muscle or TMJ. The MVBF and corresponding electromyographic (EMG) activity of the masseter, anterior temporalis, and digastric muscles were recorded 10 times at an interval of 2 minutes before and after injection. Pain was measured using a visual analog scale and McGill Pain Questionnaire. In addition, participants were asked how they perceived the interference of pain on their biting performance. The data analysis included a two-way analysis of variance model and t test.
There was no significant difference in peak pain intensity (P = .066) and duration of pain (P = .608) between painful muscle and TMJ injections, but TMJ injection produced a significantly larger area under the curve (P = .005) and a significantly higher pain rating index (P = .030). Pain in the muscle (P = .421) and TMJ (P = .057) did not significantly change the MVBF from baseline levels. The EMG activity also did not differ significantly from baseline levels during muscle pain. However, there was a significant increase (P = .028) in the EMG activity of the anterior temporalis and a significant decrease (P = .010) in the EMG activity of the anterior digastric muscle compared to baseline during TMJ pain. Subject-based reports also revealed that in the majority of cases (62.5%), pain did not interfere with the MVBF task.
Experimental pain from either masseter muscle or TMJ did not affect the MVBF, in accordance with the subject-based reports. Jaw muscle activity, except for EMG activity of the anterior temporalis and anterior digastric muscles during TMJ pain, also remained unaffected by pain. The findings suggest that it is not pain in itself but rather how pain is perceived that may lead to adaptation of motor function, supporting an integrated pain adaptation model.
验证以下假说，即实验性咀嚼肌或颞下颌关节疼痛会降低前牙最大自主咬合力（MVBF）和与感知用力相关的咀嚼肌活动。
16 名志愿者参加了两个实验环节。参与者的咀嚼肌或颞下颌关节分别注射 0.2 毫升 1.0M 谷氨酸单钠。在注射前后 10 次，每隔 2 分钟记录 10 次咀嚼肌、前颞肌和二腹肌的 MVBF 和相应的肌电图（EMG）活动。疼痛采用视觉模拟量表和 McGill 疼痛问卷进行评估。此外，参与者被要求描述他们对疼痛对咀嚼功能的干扰的感知。数据分析采用双因素方差分析模型和 t 检验。
肌内和颞下颌关节注射的峰值疼痛强度（P =.066）和疼痛持续时间（P =.608）无显著差异，但颞下颌关节注射的曲线下面积（P =.005）和疼痛评分指数（P =.030）显著更高。肌内疼痛（P =.421）和颞下颌关节疼痛（P =.057）并未显著改变 MVBF 与基线水平的差异。EMG 活动在肌内疼痛期间也与基线水平无显著差异。然而，在颞下颌关节疼痛期间，前颞肌的 EMG 活动显著增加（P =.028），前二腹肌的 EMG 活动显著降低（P =.010），与基线水平相比。基于个体的报告也显示，在大多数情况下（62.5%），疼痛并未干扰 MVBF 任务。
与基于个体的报告一致，来自咀嚼肌或颞下颌关节的实验性疼痛并未影响 MVBF。除了颞下颌关节疼痛期间的前颞肌和前二腹肌 EMG 活动外，咀嚼肌活动也不受疼痛影响。这些发现表明，可能不是疼痛本身，而是对疼痛的感知，导致运动功能的适应，支持综合疼痛适应模型。
