Cyclic Fatigue Resistance of Glide Path Rotary Files: A Systematic Review of in Vitro Studies

Abstract

The aim of the present systematic review was to perform a qualitative synthesis of in vitro studies that assess the cyclic fatigue resistance of rotary glide path (GP) files of endodontic applications. Systematic electronic searches were performed in the Medline, Embase, Scopus, SciELO, and Web of Science databases on 15 February 2022, and were last updated on 1 April In vitro studies that evaluated and compared the cyclic fatigue resistance of at least one rotary GP file system with another rotary GP file system were included. A total of 25 studies were included in the qualitative synthesis. All studies assessing the difference in the cyclic fatigue resistance between continuous and reciprocating rotation in rotary glide path files found that the latter resulted in a significantly higher cyclic fatigue resistance, as evidenced by a higher number of cycles until fracture and/or time until fracture. Within the limitations of this review and the in vitro nature of the included studies, the results indicate that the cyclic fatigue resistance of rotary GP files may be influenced by several intrinsic factors of the files, such as their taper, cross-sectional design, alloy properties, kinematics, and external factors, such as the curvature and radius at which the file is activated, the irrigation or lubricant used, and the temperature.

Keywords: cyclic fatigue; glide path; patency; rotary files; systematic review.

Figure 1

Systematic flow chart representing the study selection process, based on the PRISMA 2020 flow diagram [18].

Figure 2

Schematic representation of the number of comparisons between files among the included studies. Color key: red (files are compared 6 times), green (files are compared 4 times), blue (files are compared 3 times), yellow (files are compared 2 times), and black (files are compared once).