摘要：

目的： 探讨伸长第三磨牙拔除前后对颞下颌关节功能、咀嚼肌肌电活动及关节间隙的影响。方法： 选取2024年4月至2025年2月就诊于新疆医科大学第一附属医院口腔颌面外科门诊的伸长第三磨牙患者24例，其中单侧伸长者14例、双侧伸长者10例。比较患者拔除伸长第三磨牙前和拔牙后3个月的最大张口度、下颌边缘运动（前伸、侧方、后退）、关节区压痛阈值、双侧颞肌前束（temporal anterior muscle，TA）和咬肌（masseter muscle，MM）的表面肌电（surface electromyography，sEMG）平均幅值、咀嚼肌不对称指数（asymmetry index，AsI）及双侧颞下颌关节间隙（前间隙、上间隙、后间隙）的变化。结果： 拔牙后3个月，患者最大张口度增大，上颌伸长组下颌前伸及后退运动范围增大，下颌伸长组下颌前伸运动范围增大；单侧及双侧伸长组双侧关节区压痛阈值均较拔牙前升高（均P<0.05）。单侧伸长第三磨牙患者拔牙前伸长侧TA sEMG平均幅值显著高于非伸长侧，拔牙后两侧TA、MM sEMG平均幅值差异无统计学意义（P>0.05）。与拔牙前比较，拔牙后单侧伸长患者伸长侧与非伸长侧TA、MM sEMG平均幅值均升高，且双侧TA的AsI较拔牙前降低；双侧伸长患者拔牙前后双侧TA和MM sEMG平均幅值及AsI差异均无统计学意义（P>0.05）。单侧伸长患者拔牙后双侧颞下颌关节前间隙较拔牙前减小、后间隙增大（均P<0.05）。双侧伸长患者拔牙前后前间隙和上间隙差异均无统计学意义（P>0.05）。结论： 单侧第三磨牙伸长可以导致咀嚼肌肌电活动不对称、颞下颌关节前间隙增大及后间隙变小，拔除伸长第三磨牙可有效改善上述异常。

关键词: 伸长第三磨牙, 颞下颌关节, 咀嚼肌表面肌电, 锥形束CT, 关节间隙

Abstract:

Objective: To investigate the effects of elongated third molars on the temporomandibular joint function, masticatory muscle electromyographic activity, and joint space. Methods: A total of 24 patients with elongated third molars who attended the outpatient clinic of the Department of Oral and Maxillofacial Surgery at the First Affiliated Hospital of Xinjiang Medical University from April 2024 to February 2025 were selected. Among them, 14 had unilateral elongation and 10 had bilateral elongation. The following parameters were compared before and 3 months after the extraction of the elongated third molars: Maximum mouth opening, range of mandibular border movements (protrusion, lateral movement, retrusion), tenderness threshold of the temporomandibular joint area, mean amplitude of surface electromyography (sEMG) of the bilateral anterior temporalis (TA) and masseter muscles (MM), asymmetry index (AsI) of the masticatory muscles, and bilateral temporomandibular joint space (anterior, superior, and posterior joint spaces). Results: Three months after tooth extraction, the patients' maximum mouth opening increased. In the maxillary elongation group, the range of mandibular protrusion and retrusion increased, while in the mandibular elongation group, the range of mandibular protrusion increased. The tenderness threshold of the bilateral TMJ area in both the unilateral and bilateral elongation groups was higher than that before extraction (all P<0.05). In patients with unilateral elongated third molars, the mean sEMG amplitudes of the TA on the elongated side were significantly higher than that on the non-elongated side before extraction. After extraction, there was no statistically significant difference in the mean sEMG amplitude of the TA and MM between the two sides (P>0.05). Compared with before extraction, the mean sEMG amplitudes of the TA and MM on both the elongated and non-elongated sides increased after extraction in patients with unilateral elongation, and the AsI of the bilateral TA decreased. In patients with bilateral elongation, there were no statistically significant differences in the mean sEMG amplitudes and AsI of the bilateral TA and MM before and after extraction (P>0.05). In patients with unilateral elongation, the anterior joint space of the bilateral TMJ decreased and the posterior joint space increased after extraction compared with that before extraction (all P<0.05). In patients with bilateral elongation, there were no statistically significant differences in the anterior and superior joint spaces before and after extraction (P>0.05). Conclusion: Unilateral elongation of the third molar can lead to asymmetry in the electromyographic activity of the masticatory muscles, an increase in the anterior joint space, and a decrease in the posterior joint space of the TMJ. Extraction of the elongated third molar can effectively improve these abnormalities.

Key words: elongated third molar, temporomandibular joint, surface electromyography of the masticatory muscles, cone beam CT, joint space

中图分类号: 

• 伸长第三磨牙

• 颞下颌关节

• 咀嚼肌表面肌电

• 锥形束CT

• 关节间隙

• elongated third molar

• temporomandibular joint

• surface electromyography of the masticatory muscles

• cone beam CT

• joint space