Department of Surgery, Medicine, Dentistry and Morphological Sciences with Transplant Surgery, Oncology and Regenerative Medicine Relevance (CHIMOMO), University of Modena and Reggio Emilia, Modena, Italy.
Department of Engineering "Enzo Ferrari" (DIEF), University of Modena and Reggio Emilia, Modena, Italy.
Int Endod J. 2020 Feb;53(2):250-264. doi: 10.1111/iej.13214. Epub 2019 Sep 27.
To compare the mechanical properties and metallurgic features of new and used Reciproc Blue and Reciproc instruments.
A total of 120 R25 Reciproc Blue and R25 Reciproc instruments were used. The morphological, chemical, mechanical, thermal and phase composition characteristics of new and ex vivo used files were investigated by scanning electron microscopy (FEG-SEM) with energy dispersive X-ray spectroscopy (EDS), focused ion beam analysis (FIB), micro-Raman spectroscopy, FEG-SEM metallography, X-ray diffraction (XRD), differential scanning calorimetry (DSC) and indentation tests. Usage-induce degradation was evaluated. Ten new and ten used instruments per type were run until fracture occurred in a stainless steel artificial canal (60° angle of curvature, 4-mm radius). Time to fracture and the length of the fractured fragment were recorded. Torque and angle of rotation at failure of ten new and ten used instruments for each type were measured according to ISO 3630-1. The fracture surface of each fragment was examined. Two-way analyses of variance was used to analyse the data statistically (α-level 0.05).
SEM analysis revealed microcracks near the tip on both files after ex vivo usage tests. FIB imaging and micro-Raman spectroscopy confirmed the presence of an oxide layer on the Reciproc Blue surface. There was no thinning of the coating after use. XRD revealed a reduction of martensite and R-phase in Reciproc Blue after use. DSC analysis revealed different transformation temperatures for the instruments analysed. Reciproc Blue was significantly more flexible than Reciproc for both new and used samples (P < 0.05), and they were significantly more resistant to cyclic fatigue than Reciproc (P < 0.05). Ex vivo usage reduced the fatigue resistance of both files. Torsional resistance of Reciproc and Reciproc Blue was not reduced by simulated use (P > 0.05).
The thermal treatment of Reciproc Blue was associated with a finer structure with smaller grains than Reciproc, which increased its fracture resistance and was also responsible for its reduced hardness and lower elastic modulus. Both files were safe during ex vivo usage in severely curved canals.
比较新型和使用过的 Reciproc Blue 和 Reciproc 器械的机械性能和冶金特性。
共使用 120 个 R25 Reciproc Blue 和 R25 Reciproc 器械。通过扫描电子显微镜（FEG-SEM）结合能谱分析（EDS）、聚焦离子束分析（FIB）、微拉曼光谱、FEG-SEM 金相学、X 射线衍射（XRD）、差示扫描量热法（DSC）和压痕试验研究新的和离体使用后的器械的形态、化学、机械、热和相组成特性。评估使用引起的降解。每型各取 10 个新器械和 10 个使用过的器械，在不锈钢人工管（60°曲率角，4mm 半径）中直至器械断裂。记录断裂时间和断裂碎片的长度。根据 ISO 3630-1 测量每种器械的 10 个新器械和 10 个使用过的器械的断裂扭矩和断裂时的旋转角度。检查每个碎片的断裂表面。采用双向方差分析对数据进行统计学分析（α水平 0.05）。
SEM 分析显示，离体使用后，两种器械的尖端附近都有微裂纹。FIB 成像和微拉曼光谱证实 Reciproc Blue 表面存在氧化层。使用后涂层没有变薄。XRD 显示 Reciproc Blue 中的马氏体和 R 相在使用后减少。DSC 分析显示分析器械的相变温度不同。新型和使用过的 Reciproc Blue 都比 Reciproc 更柔韧（P<0.05），而且它们比 Reciproc 更能抵抗循环疲劳（P<0.05）。离体使用降低了两种器械的抗疲劳性。模拟使用并没有降低 Reciproc 和 Reciproc Blue 的扭转阻力（P>0.05）。
Reciproc Blue 的热处理与 Reciproc 相比晶粒更小，结构更细，这提高了它的断裂阻力，也导致其硬度降低，弹性模量降低。在严重弯曲的根管中离体使用时，两种器械都是安全的。
