Bennett Jeffery, Chung Kwok-Hung, Fong Hanson, Johnson James, Paranjpe Avina
Department of Endodontics, University of Washington, Seattle.
Department of Restorative Dentistry, University of Washington, Seattle.
J Clin Exp Dent. 2017 Jul 1;9(7):e879-e885. doi: 10.4317/jced.54049. eCollection 2017 Jul.
Many new rotary files systems have been introduced, however, limited research has been conducted related to the surface irregularities of these files and if these have any effects on the files themselves. Hence, the aim of the present study was to analyze surface irregularities of the ProTaper® Universal rotary files (PTU) and the ProTaper Next™ rotary files (PTN) before and after instrumentation in curved canals. The main objective was to investigate the nature of these irregularities and how they might influence the use and fracture of rotary files during root-canal treatments.
The files were examined pre-operatively using a stereomicroscope and scanning electron microscopy(SEM) to analyze surface imperfections and the presence of particles. Mesial roots of forty extracted mandibular molars were selected. Each instrument was used to prepare one of the mesial canals. The files were then rinsed with alcohol, and autoclaved and analyzed again.
Of the 80 files used in this study, five files fractured, five files unwound and seven files were curved or bent and they all belonged to the PTU group. Irregularities and debris could be visualized with the SEM on both unused PTU and PTN files. Most of the debris was found associated with deeper milling grooves and defects on the surface of the metal. Surface analysis of the files that were used and sterilized were performed and the SEM images demonstrated organic debris, metal flash, and crack formation and initiation of fractures for both file types. All files showed machining grooves, metal flash, debris, and defects on cutting edges.
These irregularities appear to be critical in the accumulation of debris and initiation of fatigue and crack propagation within the NiTi alloy. The accumulation of debris could be a concern due to the potential exchange of organic debris between patients. ProTaper® Universal, ProTaper Next™, surface characteristics, SEM.
许多新型旋转锉系统已被引入，然而，关于这些锉的表面不规则性以及它们是否对锉本身有任何影响的研究却很有限。因此，本研究的目的是分析ProTaper®通用旋转锉（PTU）和ProTaper Next™旋转锉（PTN）在弯曲根管预备前后的表面不规则性。主要目的是研究这些不规则性的性质以及它们在根管治疗过程中如何影响旋转锉的使用和折断。
术前使用体视显微镜和扫描电子显微镜（SEM）检查锉，以分析表面缺陷和颗粒的存在情况。选取40颗拔除的下颌磨牙的近中根。每支器械用于预备其中一条近中根管。然后将锉用酒精冲洗，高压灭菌后再次进行分析。
在本研究中使用的80支锉中，有5支锉折断，5支锉松解，7支锉弯曲，它们均属于PTU组。在未使用的PTU和PTN锉上均可通过SEM观察到不规则性和碎屑。大多数碎屑与金属表面较深的铣削凹槽和缺陷有关。对已使用并灭菌的锉进行表面分析，SEM图像显示两种锉均有有机碎屑、金属飞边、裂纹形成和骨折起始。所有锉均显示出加工凹槽、金属飞边、碎屑和切削刃上的缺陷。
这些不规则性似乎在碎屑堆积以及镍钛合金内疲劳和裂纹扩展的起始中起关键作用。由于患者之间可能存在有机碎屑的交换，碎屑的堆积可能是一个问题。ProTaper®通用型、ProTaper Next™、表面特征、扫描电子显微镜
