Detectability of Middle Mesial Canal in Mandibular Molar After Troughing Using Ultrasonics and Magnification: An Ex Vivo Study

Abstract The aim of this study was to evaluate the frequency of the identification of middle mesial (MM) canals in extracted permanent first and second mandibular molars before and after executing a troughing technique with high magnification. Sample consisted of 105 mandibular molars. After gaining access to the pulp chamber and cleaning the chamber floor, root canals were detected in three different stages. The initial location was performed under direct viewing without magnification. In the second stage, a dental operating microscope was employed at 12 magnification. If the MM canal was not observed, a standardized troughing technique was executed with the use of an ultrasonic tip between the mesiobuccal and mesiolingual canals under magnification. Statistical differences in the frequency of MM canals before and after troughing were determined using McNemar’s test, with the significance level set at 5%. No significant increase in the identification of the MM canal was found when comparing observations before (9.52%) and after (12.38%) the troughing technique under high magnification. However, viewing under magnification and the execution of troughing significantly increased the location of the MM canal (12.38%) when compared to viewing without magnification (3.81%) (p<0.01). The troughing technique with the aid of a dental operating microscope significantly improved the identification of MM canals compared to viewing without magnification. Troughing is a safe, minimally invasive procedure that benefits the treatment of mandibular molars.

摘要 本研究旨在评估采用高倍放大技术前后，离体恒下颌第一、第二磨牙近中中间（middle mesial, MM）根管的检出率。研究样本共纳入105颗下颌磨牙。在暴露髓腔并清理髓室底后，分三个阶段开展根管定位：第一阶段在无放大的直视条件下进行初始定位；第二阶段使用牙科手术显微镜（dental operating microscope）以12倍放大倍率开展定位。若未观察到MM根管，则在放大视野下，于近中颊（mesiobuccal）与近中舌（mesiolingual）根管之间采用超声工作尖（ultrasonic tip）实施标准化沟槽制备技术。采用麦克尼马尔检验（McNemar’s test）分析沟槽制备前后MM根管检出率的统计学差异，设定显著性水平为5%。对比高倍放大下沟槽制备前（9.52%）与制备后（12.38%）的MM根管检出率，未发现显著提升。但与无放大直视法的检出率（3.81%）相比，采用高倍放大并实施沟槽制备技术后，MM根管的检出率（12.38%）显著升高（P<0.01）。相较于无放大直视法，借助牙科手术显微镜实施沟槽制备技术可显著提升MM根管的检出率。沟槽制备是一项安全且微创的操作，对下颌磨牙的根管治疗具有积极意义。