Takeuchi Tamiyo, Arima Taro, Ernberg Malin, Yamaguchi Taihiko, Ohata Noboru, Svensson Peter
Department of Crown and Bridge Prosthodontics, Graduate School of Dental Medicine, Hokkaido University, Sapporo, Japan.
Headache. 2015 Mar;55(3):381-94. doi: 10.1111/head.12528. Epub 2015 Mar 7.
The traditional view contends bruxism, such as tooth grinding/clenching, is part of the etiology of temporomandibular disorders (TMD) including some subtypes of headaches. The purpose of this study is to investigate if a low-level but long-lasting tooth-clenching task initiates TMD symptoms/signs.
Eighteen healthy participants (mean age ± SD, 24.0 ± 4.3 years) performed and repeated an experimental 2-hour tooth-clenching task at 10% maximal voluntary occlusal bite force at incisors (11.1 ± 4.6 N) for three consecutive days (Days 1-3). Pain and cardiovascular parameters were estimated during the experiment.
The task evoked pain in the masseter/temporalis muscles and temporomandibular joint after 40.0 ± 18.0 minutes with a peak intensity of 1.6 ± 0.4 on 0-10 numerical rating scale (NRS) after 105.0 ± 5.0 minutes (Day 1). On Day 2 and Day 3, pain had disappeared but the tasks, again, evoked pain with similar intensities. The onset and peak levels of pain were not different between the experimental days (P = .977). However, the area under the curve of pain NRS in the masseter on Day 2 and Day 3 were smaller than that on Day 1 (P = .006). Cardiovascular parameters changed during the task but not during the days.
Prolonged, low-level tooth clenching evoked short-lived pain like TMD. This intervention study proposes that tooth clenching alone is insufficient to initiate longer lasting and self-perpetuating symptoms of TMD, which may require other risk factors.
传统观点认为磨牙症，如牙齿研磨/咬紧，是颞下颌关节紊乱病（TMD）病因的一部分，其中包括某些类型的头痛。本研究的目的是调查低强度但持续时间长的牙齿咬紧任务是否会引发TMD症状/体征。
18名健康参与者（平均年龄±标准差，24.0±4.3岁）以门牙最大自主咬合力量的10%（11.1±4.6 N）进行并重复一项为期2小时的实验性牙齿咬紧任务，连续进行三天（第1 - 3天）。在实验过程中评估疼痛和心血管参数。
任务开始40.0±18.0分钟后，咬肌/颞肌和颞下颌关节出现疼痛，在第1天105.0±5.0分钟时疼痛强度达到峰值，在0 - 10数字评分量表（NRS）上为1.6±0.4。在第2天和第3天，疼痛消失，但任务再次引发了强度相似的疼痛。实验各天之间疼痛的发作和峰值水平无差异（P = 0.977）。然而，第2天和第3天咬肌疼痛NRS曲线下面积小于第1天（P = 0.006）。任务期间心血管参数发生变化，但在各天之间未发生变化。
长时间、低强度的牙齿咬紧会引发类似TMD的短暂疼痛。这项干预研究表明，仅牙齿咬紧不足以引发TMD更持久且会自我持续的症状，可能还需要其他风险因素。
