Department of Endodontics, São Leopoldo Mandic Dental Research Center, Campinas, São Paulo, Brazil.
Division of Endodontics, Department of Restorative Dentistry, School of Dentistry, University of São Paulo, São Paulo, São Paulo, Brazil.
J Endod. 2017 Dec;43(12):2102-2107. doi: 10.1016/j.joen.2017.07.015. Epub 2017 Oct 21.
The objective of this study was to compare the methods of micro-computed tomography (micro-CT) and cross-sectioning followed by stereomicroscopy in assessing dentinal defects after instrumentation with different mechanized systems.
Forty mesial roots of mandibular molars were scanned and divided into 4 groups (n = 10): Group R, Reciproc; Group PTN, ProTaper Next; Group WOG, WaveOne Gold; Group PDL, ProDesign Logic. After instrumentation, the roots were once again submitted to a micro-CT scan, and then sectioned at 3, 6, and 9 mm from the apex, and assessed for the presence of complete and incomplete dentinal defects under a stereomicroscope. The nonparametric Kruskal-Wallis, Friedman, and Wilcoxon tests were used in the statistical analysis. The study used a significance level of 5%.
The total number of defects observed by cross-sectioning followed by stereomicroscopy was significantly higher than that observed by micro-CT, in all of the experimental groups (P ≤ .05). All of the defects identified in the postoperative period were already present in the corresponding preoperative period. There was no significant difference among the instrumentation systems as to the median numbers of defects, for either cross-sectioning followed by stereomicroscopy or micro-CT, at all the root levels (P > .05). In the micro-CT analysis, no significant difference was found between the median numbers of pre- and postinstrumentation defects, regardless of the instrumentation system (P > .05).
None of the evaluated instrumentation systems led to the formation of new dentin defects. All of the defects identified in the stereomicroscopic analysis were already present before instrumentation, or were absent at both time points in the micro-CT analysis, indicating that the formation of new defects resulted from the sectioning procedure performed before stereomicroscopy and not from instrumentation.
本研究的目的是比较不同机动系统根管预备后使用微计算机断层扫描（micro-CT）和切片后体视显微镜评估牙本质缺陷的方法。
40 颗下颌磨牙近中根被扫描并分为 4 组（n=10）：Reciproc 组（R 组）、ProTaper Next 组（PTN 组）、WaveOne Gold 组（WOG 组）、ProDesign Logic 组（PDL 组）。根管预备后，再次对根进行 micro-CT 扫描，然后从根尖 3、6 和 9mm 处进行切片，在体视显微镜下评估完全性和不完全性牙本质缺陷的存在情况。统计分析采用非参数 Kruskal-Wallis、Friedman 和 Wilcoxon 检验。研究采用 5%的显著性水平。
通过切片后体视显微镜观察到的总缺陷数量明显高于所有实验组 micro-CT 观察到的数量（P≤.05）。在术后期间发现的所有缺陷在相应的术前期间已经存在。在所有根段水平，通过切片后体视显微镜或 micro-CT 评估，各器械系统之间的缺陷中位数数量均无显著差异（P>.05）。在 micro-CT 分析中，无论器械系统如何，器械预备前后的缺陷中位数数量均无显著差异（P>.05）。
评估的器械系统均未导致新的牙本质缺陷形成。体视显微镜分析中发现的所有缺陷在器械预备前已经存在，或者在 micro-CT 分析的两个时间点均不存在，这表明新缺陷的形成是由于在体视显微镜检查前进行的切片程序，而不是器械预备所致。
