目的：探讨0.2 mm咬合干扰不同时间点去除与大鼠咀嚼肌机械痛觉敏感恢复的关系。方法： 选用雄性Sprague-Dawley大鼠（200~220 g），通过在大鼠右上第一磨牙粘固0.2 mm厚金属冠建立咬合干扰模型。实验随机分为对照组（包括空白对照组和假干扰组）和实验组（包括咬合干扰组和2、3、4、5、6 d咬合干扰去除组）， 共8组，每组5只大鼠，分别于建模前1、2、3 d及建模后1、3、5、7、10、14、21、28 d测定大鼠双侧咬肌及颞肌机械刺激反应阈值，并监测建模前1 d及建模后7 d内大鼠体重变化。结果： 空白对照组和假干扰组双侧颞肌和咬肌各时间点机械刺激反应阈值差异无统计学意义。实验组干扰侧和非干扰侧咀嚼肌机械刺激反应阈值差异无统计学意义（P>0.05）；2、3、4、5 d咬合干扰去除组建模后双侧咀嚼肌机械刺激反应阈值出现下降，干扰去除后即出现上升，分别于7、10、14、14 d恢复至假干扰组水平［右侧咬肌机械反应阈值分别为：（137.46±2.08) g，（139.02±2.11) g，（140.40±0.98) g，（138.95±0.98) g］；6 d咬合干扰去除组建模后即出现显著下降，去除咬合干扰后阈值即出现一定升高，14 d后基本稳定，28 d时［右侧咬肌机械反应阈值为(131.24±0.76） g］与假干扰组［右侧咬肌机械反应阈值为(141.34±1.43) g］相比差异仍具有统计学意义（P<0.05）。结论：0.2 mm咬合干扰5 d内去除，大鼠咀嚼肌机械痛觉敏感可完全逆转；0.2 mm咬合干扰6 d去除大鼠咀嚼肌机械痛觉敏感部分逆转，但无法恢复至基线水平；随着刺激时间的延长，即使低咬合干扰也能引起咀嚼肌不可逆的机械痛觉敏感；临床上对于牙体修复造成的咬合干扰应尽早完全消除，避免长期咬合干扰刺激导致不可逆的咀嚼肌机械痛觉敏感。

Objective：To investigate the relationship between the removal time of 0.2 mm occlusal interference and the recovery of masticatory muscle mechanical hyperalgesia in rats.Methods: Forty male Sprague-Dawley rats (200-220 g) were randomly assigned to eight groups, with five rats in each group: (1) na-ve group: these rats were anesthetized and their mouths were forced open for about 5 min (the same duration as the other groups)， but restorations were not applied; (2) sham-occlusal interference control group: bands were bonded to the right maxillary first molars which did not interfere with occlusion; (3)occlusal interference group: 0.2 mm thick crowns were bonded to the right maxillary first molars; (4) 2, 3, 4, 5, and 6 d removal of occlusal interference groups: 0.2 mm thick crowns were bonded to the right maxillary first molars and removed on days 2, 3, 4, 5, and 6. The na-ve group and sham-occlusal interference control group were control groups. The other groups were experimental groups. Bilateral masticatory muscle mechanical withdrawal thresholds were tested on pre-application days 1, 2, and 3, and on postapplication days 1, 3, 5, 7, 10, 14, 21 and 28. The rats were weighed on pre-application day 1 and on post-application days 1, 2, 3, 4, 5, 6, and 7.Results: Between the na-ve group and the sham-occlusal interference control group, there was no significant difference in the masticatory muscle mechanical withdrawal threshold of bilateral temporalis and masseters at each time point. No significant difference was detected between the contralateral side and ipsilateral side in experimental groups (P>0.05). In the 2, 3, 4, and 5 d removal of occlusal interference groups, the masticatory muscle mechanical withdrawal thresholds decreased after occlusal interference and increased after removal of the crowns and recovered to the baseline on days 7, 10, 14, and 14, respectively ［the masticatory muscle mechanical withdrawal thresholds of right masseter muscle were (137.46±2.08) g, (139.02±2.11) g, (140.40±0.98) g, (138.95±0.98) g, respectively］. In the 6 d removal of occlusal interference group, the masticatory muscle mechanical withdrawal threshold increased after removal of the crowns and became stable since day 14. There was a significant difference between the 6 d removal of occlusal interference group and the sham-occlusal interference group on day 28(P<0.05), the masticatory muscle mechanical withdrawal thresholds of right masseter muscle were (131.24±0.76) g and (141.34±1.43) g, respectively. Conclusion: After removal of the 0.2 mm thick crown within 5 days, the mechanical hyperalgesia of the rats could reverse completely. The mechanical hyperalgesia of the rats could only be relieved, but not reverse completely after removal of the 0.2 mm thick crown on day 6. As the time went on, even minor occlusal interference could cause irreversible mechanical hyperalgesia of masticatory muscles. This study suggested that occlusal interference caused by dental treatment should be eliminated as soon as possible, to avoid irreversible orofacial pain.