Moriya Paulo Takeji, de Carvalho Kleber Kildare Teodoro, Kishen Anil, Souza Erick M, Versiani Marco A
Private Practice, São Paulo, Brazil.
Department of Endodontics, Núcleo de Estudos Odontológicos (NEO), São Paulo, Brazil.
Int Endod J. 2023 Nov;56(11):1399-1411. doi: 10.1111/iej.13961. Epub 2023 Aug 11.
The aim of this study is to compare the stress produced on the internal walls of simulated canals by nine rotary and four reciprocating systems.
Sixty-five isotropic transparent blocks containing a 60° curved and tapered simulated canal were selected and distributed into 13 groups (n = 5) according to the preparation system: BioRace, HyFlex EDM, iRaCe, Mtwo, One RECI, ProTaper Next, RaCe EVO, Reciproc, Reciproc Blue, R-Motion, VDW.ROTATE, XP-Endo Rise Shaper, and XP-Endo Shaper. Each resin block was mounted in a vice and a digital camera recorded the entire sequence of each preparation system through a circular polariscope set for dark field analysis. The video frames when each instrument reached the end of the coronal, middle, and apical thirds of the canal were extracted from the recordings and analysed by two independent observers regarding the stress generated on the canal walls using a semi-quantitative evaluation on a 0-5 scale. Intra- and inter-observer agreement were subjected to the Cohen's Kappa coefficient test, whilst the experimental results were compared using Kruskal-Wallis test post hoc pairwise comparisons with Bonferroni correction (α = 5%).
The inter- and intra-observer agreement were 0.98 and 1, respectively. Most instruments demonstrated acceptable performance (scores ≤ 2) in all thirds. Other instruments, such as the HyFlex EDM 25.12 (coronal and middle thirds), Reciproc Blue R25 and Reciproc R25 (coronal and apical thirds), R-Motion 30.04 (apical third), and VDW.ROTATE 20.05 (apical third) showed scores higher than 3. Statistical analysis revealed a significant difference amongst the tested systems at the coronal, middle, and apical thirds (p < .05).
None of the canal instrumentation protocols were stress-free, showing varying levels of stress concentrations. Various factors seemed to influence the magnitude of stress and its distribution pattern on the canal walls. Overall, instruments characterized by a larger taper, lower speed, reciprocating motion, and made of heat-treated NiTi alloy exhibited higher patterns of stress distribution.
本研究旨在比较九种旋转系统和四种往复运动系统对模拟根管内壁产生的应力。
选取65个各向同性透明块，每个透明块包含一个60°弯曲且呈锥形的模拟根管，并根据预备系统将其分为13组（n = 5）：BioRace、HyFlex EDM、iRaCe、Mtwo、One RECI、ProTaper Next、RaCe EVO、Reciproc、Reciproc Blue、R-Motion、VDW.ROTATE、XP-Endo Rise Shaper和XP-Endo Shaper。将每个树脂块固定在虎钳中，一台数码相机通过设置用于暗场分析的圆偏振光镜记录每个预备系统的整个操作过程。从记录中提取每种器械到达根管冠部、中部和根尖三分之一处末端时的视频帧，由两名独立观察者使用0 - 5级半定量评估法分析根管壁上产生的应力。观察者间和观察者内的一致性采用Cohen's Kappa系数检验，同时使用Kruskal-Wallis检验及事后两两比较和Bonferroni校正（α = 5%）对实验结果进行比较。
观察者间和观察者内的一致性分别为0.98和1。大多数器械在所有三分之一处均表现出可接受的性能（评分≤2）。其他器械，如HyFlex EDM 25.12（冠部和中部三分之一处）、Reciproc Blue R25和Reciproc R25（冠部和根尖三分之一处）、R-Motion 30.04（根尖三分之一处）以及VDW.ROTATE 20.05（根尖三分之一处）的评分高于3。统计分析显示，在冠部、中部和根尖三分之一处，测试系统之间存在显著差异（p < 0.05）。
没有一种根管预备方案是无应力的，均表现出不同程度的应力集中。各种因素似乎会影响根管壁上应力的大小及其分布模式。总体而言，具有较大锥度、较低速度、往复运动且由热处理镍钛合金制成的器械表现出更高的应力分布模式。
