This study is aimed at comparing the efficacy of heat softening and ultrasonic removal of root-end gutta-percha during retrograde preparation for root apical microsurgery. Recently extracted single-rooted premolars () were prepared with standardized endodontically treated and root-end resection and then randomly divided into four groups that received root-end cavity preparation using four different instruments: a diamond-coated ultrasonic tip (AS3D; SACTEON, Paris, France), AS3D with the modified plugger of cordless heat carrier (MSE; B&L Biotech, Bala Cynwyd, PA, USA), stainless steel ultrasonic tip (Jetip-2; B&L Biotech, Bala Cynwyd, PA, USA), or Jetip-2 with MSE. The time required for root-end preparation was recorded. The root apex samples were examined by scanning electron microscopy to assess root surface microcracks and marginal integrity. The remnants of gutta-percha on the cavity walls were evaluated using a stereomicroscope. Statistical analysis was performed using Student’s -test and Wilcoxon rank-sum test (). Usage of MSE with Jetip-2 significantly reduced preparation time from to (), the number of microcracks from 42 to 13 (), and the remnants of gutta-percha from 80% to 20% (). Similar results were observed for AS3D with MSE. The heat softening of MSE was effective in cleaning gutta-percha, thus greatly improving the efficiency of the root-end preparation, thereby producing a root-end cavity with fewer microcracks and better marginal integrity.

中文翻译：

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根端牙胶热软化与超声去除对牙髓显微手术根端准备质量的影响

本研究旨在比较根尖显微手术逆行准备过程中热软化和超声去除根端牙胶的效果。最近拔除的单根前磨牙（)采用标准化的牙髓治疗和根端切除进行制备，然后随机分为四组，使用四种不同的器械进行根端腔制备：金刚石涂层超声尖端 (AS3D; SACTEON, Paris, France)，AS3D 与改进的无线热载体堵塞器（MSE；B&L Biotech，Bala Cynwyd，PA，USA）、不锈钢超声波尖端（Jetip-2；B&L Biotech，Bala Cynwyd，PA，USA）或带有 MSE 的 Jetip-2。记录根端准备所需的时间。通过扫描电子显微镜检查根尖样品以评估根表面微裂纹和边缘完整性。使用立体显微镜评估空腔壁上的古塔胶残留物。使用Student's进行统计分析-检验和 Wilcoxon 秩和检验 (）。将 MSE 与 Jetip-2 一起使用显着减少了从至(),微裂纹数从 42 到 13 ()，而古塔胶的残留量从 80% 增加到 20% (）。对于具有 MSE 的 AS3D，也观察到了类似的结果。MSE的热软化对牙胶的清洁效果显着，从而大大提高了根端制备的效率，从而产生了具有更少微裂纹和更好边缘完整性的根端空腔。