Çelik Gül, Özdemir Kısacık Feyza, Yılmaz Emir Faruk, Mersinlioğlu Arife, Ertuğrul İhsan Furkan, Orhan Hikmet
Faculty of Dentistry, Endodontics, Suleyman Demirel University, Isparta, Turkey.
Vefa Oral and Tooth Health Center, Afyonkarahisar, Turkey.
PeerJ. 2019 Aug 19;7:e7419. doi: 10.7717/peerj.7419. eCollection 2019.
Dentistry has undergone an evolution in endodontics practice caused by the advancement of rotary techniques for root canal preparation and their subsequent incorporation into the teaching of dentistry undergraduates. This research aimed to evaluate the shaping ability of third-year dental students as their first experience in rotary instrumentation using ProTaper Universal (PTU) and ProTaper Next (PTN) (Dentsply Maillefer) rotary instruments in simulated curved canals.
Forty students instrumented 200 simulated canals with a 40° curvature in resin blocks according to the manufacturer's instructions with PTU and 39 students and 195 canals with PTN files. The canals were prepared at a speed of 300 rpm using a 16:1 reduction hand-piece powered by an electric motor (Xsmart; Dentsply Maillefer). The final apical preparation was set to F2 for the PTU and X2 for the PTN group. The change in canal curvature was evaluated based on Schneider technique using the AutoCAD 2007 software on post-digital photographs. The incidence of instrument fracture and deformation, the incidence of ledge, the change in working length (WL), and the working time were noted. The data were analyzed with Student's -test and Chi-Square test at a significance level of 0.05 using SPSS.
PTN maintained the original canal curvature better, resulting in fewer fractures and ledges, and shaped the canals faster than the PTU ( < 0.05). The mean curves of the resin canals after the instrumentation for the PTU and PTN groups were 24.03° ± 3.14° and 25.64° ± 2.72°, respectively. Thirty-three (17.4%) PTU and 18 (9.3%) PTN files fractured ( < 0.05). Nine (4.5%) PTU and 2 (2.6%) PTN deformed ( > 0.05). The change in WL after instrumentation was 0.97 mm ± 0.95 mm in PTU and 0.96 mm ± 0.80 mm in PTN ( < 0.05). The mean times were 627 s ± 18 s for PTU and 379 s ± 18 s for PTN ( < 0.000).
PTN can be recommended in severely curved root canals in terms of maintenance of the original canal curvature, superior instrument fracture and fewer ledges. Even if training before preparation provides an acceptable level of canal shaping for preclinical students, the use of NiTi rotary instruments should be included in the undergraduate dental curriculum, contributing to an increase in the quality of root canal shaping and, consequently, to an improvement of the clinical experience of students.
由于根管预备旋转技术的进步及其随后被纳入牙科本科生教学中，牙科学的牙髓治疗实践发生了演变。本研究旨在评估牙科三年级学生在模拟弯曲根管中首次使用ProTaper Universal（PTU）和ProTaper Next（PTN）（登士柏迈福）旋转器械进行旋转器械操作的成形能力。
40名学生按照制造商的说明，使用PTU在树脂块中预备200条曲率为40°的模拟根管，39名学生使用PTN锉预备195条根管。使用由电动马达驱动的16:1减速手机（Xsmart；登士柏迈福）以300转/分钟的速度预备根管。PTU组的最终根尖预备设定为F2，PTN组设定为X2。使用AutoCAD 2007软件，基于施奈德技术在数字照片上评估根管曲率的变化。记录器械折断和变形的发生率、台阶的发生率、工作长度（WL）的变化以及工作时间。使用SPSS在显著性水平为0.05时进行学生t检验和卡方检验分析数据。
PTN能更好地保持原始根管曲率，导致折断和台阶更少，并且比PTU更快地完成根管成形（P<0.05）。PTU组和PTN组预备后树脂根管的平均曲率分别为24.03°±3.14°和25.64°±2.72°%。33支（17.4%）PTU和18支（9.3%）PTN锉折断（P<0.05）。9支（4.5%）PTU和2支（2.6%）PTN变形（P>0.05）。PTU组预备后WL的变化为0.97mm±0.95mm，PTN组为0.96mm±0.80mm（P<0.05）。PTU组的平均时间为627秒±18秒，PTN组为379秒±18秒（P <0.000）。
就保持原始根管曲率、器械折断率低和台阶少而言，在严重弯曲的根管中可推荐使用PTN。即使在预备前的训练为临床前学生提供了可接受的根管成形水平，镍钛旋转器械的使用也应纳入牙科本科课程，有助于提高根管成形质量，从而改善学生的临床经验。
