Pirani Chiara, Ruggeri Oddone, Cirulli Pier Paolo, Pelliccioni Gian Andrea, Gandolfi Maria Giovanna, Prati Carlo
Endodontic Clinical Section (Unit of Odontostomatological Sciences), Department of Biomedical and Neuromotor Sciences, University of Bologna, Bologna, Italy,
Odontology. 2014 Jul;102(2):211-6. doi: 10.1007/s10266-013-0113-6. Epub 2013 Apr 9.
The aim of the study was to evaluate cyclic fatigue resistance of two NiTi instruments and to analyse their surface, fractographic and matrix morphology under ESEM/EDS and optical microscopy. WaveOne Primary and ProTaper Universal F2 brand new instruments were subjected to fatigue testing in an artificial canal with 5.0 mm radius and 60° angle of curvature. Seventy-two instruments were divided into three groups (n = 24), according to the selected kinematics: WaveOne using reciprocation (A); ProTaper using reciprocation (B) or rotation (C). Time to fracture was recorded. Data were analysed with ANOVA and Tukey test. ESEM/EDS analysis was conducted on new files to examine surface characteristics and on fractured fragments to identify the fractographic features. Metallographic analysis was performed with optical microscope on new instruments to evaluate alloy properties. Significant differences were found with Group A, which was statistically more resistant to cyclic fatigue (P < 0.05) than the other groups. Surface analysis of new instruments showed both in WaveOne and ProTaper files the presence of deep milling marks. ESEM fractographic analysis of WaveOne showed multiple crack origins with an area of fatigue propagation wider than ProTaper instruments, in which a single crack origin could be detected. EDS analysis confirmed the equiatomic NiTi composition. Metallographic analysis under optical microscope revealed in WaveOne instruments the presence of nano-crystalline martensitic grains embedded in austenite matrix, presence which could not be found in ProTaper files. WaveOne NiTi files revealed higher resistance to fatigue stress, suggesting extended working time in clinical applications.
本研究的目的是评估两种镍钛器械的抗循环疲劳性能，并在环境扫描电子显微镜/能谱仪（ESEM/EDS）和光学显微镜下分析它们的表面、断口和基体形态。将WaveOne Primary和ProTaper Universal全新器械在半径为5.0 mm、曲率角为60°的人工根管中进行疲劳测试。根据选定的运动方式，将72根器械分为三组（n = 24）：WaveOne使用往复运动（A组）；ProTaper使用往复运动（B组）或旋转运动（C组）。记录断裂时间。数据采用方差分析和Tukey检验进行分析。对新锉进行ESEM/EDS分析以检查表面特征，对断裂碎片进行分析以识别断口特征。用光学显微镜对新器械进行金相分析以评估合金性能。发现A组存在显著差异，与其他组相比，其在统计学上对循环疲劳的抵抗力更强（P < 0.05）。新器械的表面分析显示，WaveOne和ProTaper锉上均存在较深的铣削痕迹。WaveOne的ESEM断口分析显示有多个裂纹起源，其疲劳扩展区域比ProTaper器械更宽，ProTaper器械中可检测到单个裂纹起源。EDS分析证实了等原子镍钛成分。光学显微镜下的金相分析显示，WaveOne器械中存在嵌入奥氏体基体的纳米晶马氏体晶粒，而在ProTaper锉中未发现这种情况。WaveOne镍钛锉显示出对疲劳应力的更高抵抗力，表明在临床应用中工作时间更长。
