Fatigue failure of NiTi endodontic files: scoping review

Introduction: Nickel-Titanium (NiTi) endodontic files are made of hyperelastic material with shape memory. However, these files suffer a sudden fracture during the endodontic treatment, which is considered an unfavorable prognosis. Many studies have been conducted to establish fatigue resistance focused on file brands and determine which is better. Although the most common failure mechanisms have been established for motorized endodontic files, the information is scattered, making it difficult to develop clear research trends. Methods: a scoping review was carried out using Scopus, Dimensions.ai, Web of Science, and Science Direct databases to answer screening questions related to the predominant fracture mechanism in NiTi files, test types, and equipment used for experimentation and to identify the most active authors.Results: using the general search terms, 432 research papers were found, of which 75 were finally selected after eliminating duplicates and applying exclusion criteria. Conclusions: typical failure mechanisms for rotatory and reciprocating files were identified based on the panoramic review and bibliometric indicators. Also, the standard mechanical tests for endodontic files and the characteristics of their assemblies were summarized. The most active authors in the area and their nationality were tagged. Finally, gaps for future research are proposed to generate a comprehensive knowledge of NiTi file failure.