Objective: To establish a two-stage surgical procedure of impacted mandibular third molars (IMTMs) extractions assisted by coronectomy and microimplant anchorage traction and to investigate the influencing factors of root movement and the effects of different traction angles on the clinical outcomes. Methods: Fifty-three IMTM in contact with inferior alveolar nerve (IAN) that underwent tooth extraction in the Peking University School of Stomatology from January 2022 to June 2023 were included, with coronectomy and microimplant anchorage implantation in the first stage of the surgery, root traction was achieved with orthodontic elastic and microimplant anchorages by about 600 g of force, when the IMTM root was detached from IAN, a second surgery was performed to extract the residual root. The basic information of patients and M3M, data on the microimplant anchorage implantation and traction, imaging measurements, and complications were recorded and analyzed. Results: The movement distance of the residual roots was (1.80±0.92) mm, and the duration of traction was (32.9±7.9) d. Multiple linear regression analysis showed that the residual root movement distance was significantly correlated with age, gender, number of roots, traction angle, and depth of the distal bone defect of the second molar (P<0.05). The smaller the traction angle, the more significant the movement of the residual roots (P=0.044). In one case (1.9%, 1/53), the patient experienced abnormal sensation in the lower lip 16 days after traction. Conclusions: The two-stage surgical method of combined coronectomy with rapid traction technique to extract the IMTM allows for rapid movement of the residual root and reduces the risk of IAN injury. The efficiency of root movement can be accelerated by appropriately reducing the traction angle during surgery. The traction effect can be predicted based on indicators such as age, gender, number of roots and depth of distal bone defects of second molar.
目的： 建立牙冠切除术结合支抗钉牵引，分阶段拔除紧邻下颌管的下颌阻生第三磨牙的手术方式，探讨牙根移动的影响因素以及不同牵引夹角对治疗效果的影响。 方法： 前瞻性纳入2022年1月至2023年6月于北京大学口腔医学院·口腔医院口腔颌面外科就诊，下颌阻生第三磨牙紧邻下颌管的患者49例（共53颗下颌阻生第三磨牙）。一期手术行牙冠切除术及牵引钉植入，通过牵引钉及橡皮筋施加约600 g力量牵引，当牙根远离下颌管之后，二期手术取出预留牙根。通过对患者与阻生牙基本信息、牵引钉植入与牵引情况、影像学测量以及并发症情况的比较，评价治疗效果，分析不同牵引角度对治疗效果的影响。 结果： 剩余牙根移动距离为（1.80±0.92）mm，牵引总时长为（32.9±7.9）d，预留牙根移动距离与牵引夹角、年龄、性别、牙根数目和第二磨牙远中骨缺损深度等指标均显著相关（P<0.05）。牵引夹角越小，预留牙根的移动越显著（P=0.044）。1例（1.9%，1/53）患者在牵引过程中出现下唇感觉异常。 结论： 牙冠切除术结合快速牵引技术，分阶段拔除紧邻下颌管的阻生第三磨牙的手术方法，可使预留牙根快速移动，减少下牙槽神经损伤风险。牵引夹角是影响牵引效率的重要因素，术中减小牵引夹角，可加快牙根移动的效率。根据年龄、性别、牙根数目和第二磨牙远中骨缺损深度等指标可以预测牵引效果。.