Capar Ismail Davut, Arslan Hakan, Akcay Merve, Uysal Banu
Department of Endodontics, Faculty of Dentistry, İzmir Katip Çelebi University, İzmir, Turkey.
Department of Endodontics, Faculty of Dentistry, Atatürk University, Erzurum, Turkey.
J Endod. 2014 Sep;40(9):1482-4. doi: 10.1016/j.joen.2014.02.026. Epub 2014 Apr 13.
The aim of the present study was to investigate the incidence of cracks in root dentin after root canal preparation with ProTaper Next (Dentsply Maillefer, Ballaigues, Switzerland), HyFlex (Coltene-Whaledent, Allstetten, Switzerland), and ProTaper Universal (Dentsply Maillefer) rotary instruments.
One-hundred mandibular premolars were selected. Twenty-five teeth were left unprepared and served as a negative control; another 25 teeth were instrumented with the ProTaper Universal system up to size F4 as a positive control, and the remaining 50 teeth were shaped with the following experimental groups with an apical size 40 file: ProTaper Next X4 and HyFlex 40/0.4. After root canal preparation, all of the roots were sectioned perpendicular to the long axis at 2, 4, 6, and 8 mm from the apex, and the sections were then observed under a stereomicroscope. The absence/presence of cracks was recorded, and the data were analyzed with a chi-square test. The significance level was set at P = .05.
No cracks were observed in the negative control group. Vertical root fractures were not observed in any of the groups. The ProTaper Next and HyFlex instruments caused fewer cracks (28%) than the ProTaper Universal instrument (56%) (P < .05). However, there were no significant differences in crack formation between the ProTaper Next and HyFlex groups (P > .05).
Within the limitations of this in vitro study, all of the instrumentation systems used in this study created cracks in the root dentin. The ProTaper Next and HyFlex instruments tended to cause fewer dentinal cracks compared with the ProTaper Universal instrument.
本研究的目的是调查使用ProTaper Next（登士柏迈徕福，瑞士巴拉格）、HyFlex（科伦泰-惠尔登特，瑞士阿尔施泰滕）和ProTaper Universal（登士柏迈徕福）旋转器械进行根管预备后根管牙本质中裂纹的发生率。
选择100颗下颌前磨牙。25颗牙齿未做预备作为阴性对照；另外25颗牙齿用ProTaper Universal系统预备至F4号尺寸作为阳性对照，其余50颗牙齿用以下实验组以40号根尖锉进行预备：ProTaper Next X4和HyFlex 40/0.4。根管预备后，所有牙根在距根尖2、4、6和8毫米处垂直于长轴进行切片，然后在体视显微镜下观察切片。记录裂纹的有无，并采用卡方检验分析数据。显著性水平设定为P = 0.05。
阴性对照组未观察到裂纹。所有组均未观察到垂直根折。ProTaper Next和HyFlex器械导致的裂纹（28%）比ProTaper Universal器械（56%）少（P < 0.05）。然而，ProTaper Next组和HyFlex组之间在裂纹形成方面无显著差异（P > 0.05）。
在本体外研究的局限性内，本研究中使用的所有预备系统均在根管牙本质中产生了裂纹。与ProTaper Universal器械相比，ProTaper Next和HyFlex器械导致的牙本质裂纹较少。
