J Oral Facial Pain Headache. 2014 Spring;28(2):159-64. doi: 10.11607/ofph.1210.
To investigate the association between experimental tooth clenching and the release of β-endorphin in patients with myofascial temporomandibular disorders (M-TMD) and healthy subjects.
Fifteen M-TMD patients and 15 healthy subjects were included and assigned an experimental tooth-clenching task. Venous blood was collected and pain intensity was noted on a visual analog scale. The masseter pressure pain threshold (PPT) was assessed 2 hours before the clenching task and immediately after. A mixed-model analysis of variance was used for statistical analyses.
Significant main effects for time and group were observed for pain intensity and PPT, with significantly lower mean values of pain intensity (P < .001) and PPT (P < .01) after the clenching task compared with baseline. M-TMD patients had significantly higher pain intensity (P < .001) and significantly lower PPT (P < .05) than healthy subjects. No significant time or group effects were observed for the level of β-endorphin. Neither pain intensity nor PPT correlated significantly with β-endorphin levels.
This experimental tooth-clenching task was not associated with significant alterations in β-endorphin levels over time, but with mechanical hyperalgesia and low to moderate levels of pain in healthy subjects and M-TMD patients, respectively. More research is required to understand the role of the β-endorphinergic system in the etiology of M-TMD.
探讨实验性磨牙症与咀嚼肌筋膜颞下颌紊乱（M-TMD）患者和健康受试者β-内啡肽释放之间的关系。
纳入 15 名 M-TMD 患者和 15 名健康受试者，并进行实验性磨牙任务。采集静脉血，用视觉模拟评分法记录疼痛强度。在磨牙任务前 2 小时和立即后评估咬肌压力痛阈值（PPT）。采用混合模型方差分析进行统计分析。
疼痛强度和 PPT 均观察到时间和组的显著主效应，磨牙任务后疼痛强度（P<0.001）和 PPT（P<0.01）的平均值明显低于基线。M-TMD 患者的疼痛强度（P<0.001）显著高于健康受试者，而 PPT（P<0.05）显著低于健康受试者。β-内啡肽水平无显著的时间或组效应。疼痛强度和 PPT 均与β-内啡肽水平无显著相关性。
本实验性磨牙任务与β-内啡肽水平的时间变化无显著相关性，但与健康受试者和 M-TMD 患者的机械性痛觉过敏和低至中度疼痛相关。需要进一步研究来了解β-内啡肽能系统在 M-TMD 病因中的作用。
