Endodontic rotary files are cutting instruments used to perform root canal procedures within a tooth interior. Focusing on quantitative fractographic analysis increases necessary, clinical performance understanding of file separation failure. This research employed controlled, dynamic testing to failure of commercial rotary files, analyzing the fractographic, forensic characteristics in relation to Weibull reliability determination, considering: (1) design analysis; (2) stress concentrations; (3) times to failure; (4) number of cycles to failure (NCF). Ex vivo testing included three file designs, each having constant tip size (0.035 mm), taper (0.06 mm/mm), and length (25 mm). Files were individually tested using an electric, torque-controlled handpiece, rotating within a standardized, simulated canal until fracture separation occurred. Fractographic analysis, including critical measurements, was conducted using the scanning electron microscope (SEM) (PhenomProX, PhenomWorld, NL). Weibull statistical analysis established reliability factors per design group. Fractographic analysis identified separation fractures, processing inclusions, flexural-fatigue striations, and stress concentrations at flute pitches. Calculated NCF median values (1277—EE; 899—VB; 713—PI) demonstrated significant statistical differences among groups (p < 0.001). Separated apical fragments yielded statistically significant differences (p ≤ 0.05) for varying file design groups. Weibull moduli among groups were statistically equivalent. Fractographic analysis exposed a presence of multiple failure factors in addition to defect distribution, governing cyclic fatigue failure originating at stress concentration points irrespective of file design. Fractographic analysis indicated that a change in file design, specifically at the working edges, in addition to improved surface finish, has the potential of reducing failures by lowering points of stress concentration and reducing fracture initiating surface cracks.

牙髓旋转锉是用于在牙齿内部执行根管手术的切割器械。专注于定量断层分析增加了对文件分离失败的必要的临床性能理解。本研究采用受控的动态测试对商用旋转锉的失效进行分析，分析与威布尔可靠性确定相关的断口、法医特征，考虑：（1）设计分析；(2) 应力集中；(3) 失败次数；(4) 失效周期数 (NCF)。离体测试包括三种锉刀设计，每一种都具有恒定的尖端尺寸 (0.035 mm)、锥度 (0.06 mm/mm) 和长度 (25 mm)。使用电动扭矩控制手机对锉刀进行单独测试，在标准化的模拟根管内旋转直到发生骨折分离。使用扫描电子显微镜 (SEM) (PhenomProX, PhenomWorld, NL) 进行断口分析，包括关键测量。Weibull 统计分析确定了每个设计组的可靠性因素。断口分析确定了分离裂缝、加工夹杂物、弯曲疲劳条纹和凹槽间距处的应力集中。计算出的 NCF 中值（1277-EE；899-VB；713-PI）表明各组之间存在显着的统计差异（和长笛音高处的应力集中。计算出的 NCF 中值（1277-EE；899-VB；713-PI）表明各组之间存在显着的统计差异（和长笛音高处的应力集中。计算出的 NCF 中值（1277-EE；899-VB；713-PI）表明各组之间存在显着的统计差异（p  < 0.001)。 对于不同的锉刀设计组，分离的根尖碎片产生了统计学上的显着差异 ( p ≤ 0.05)。各组之间的威布尔模量在统计学上是相等的。断口分析揭示了除缺陷分布外还存在多种失效因素，无论文件设计如何，都可以控制源自应力集中点的循环疲劳失效。断口分析表明，锉刀设计的改变，特别是在工作边缘，除了改善表面光洁度，还有可能通过降低应力集中点和减少断裂引发的表面裂纹来减少故障。