Body temperature fatigue behaviour of reciprocating and rotary glide path instruments in sodium hypochlorite solutions alone or combined with etidronate

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

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.

Influence of operator expertise on glide path and root canal preparation of curved root canals with rotary and reciprocating motions

This study intended to help practitioners selecting the appropriate motion according to their level of expertise for glide path and complete root canal preparation of curved canals in terms of instrument fracture and preparation time. A total of 160 curved root canals (angle >30°, radius <6 mm) were allocated randomly to 4 groups: A/B for expert operators and C/D for nonexpert operators. A/C were shaped with rotary and B/D with reciprocating instruments. Preparation time was registered and compared with Kruskal-Wallis non-parametric test and Dunn's post hoc test. Instrument separation was also registered and compared with chi-square test. A fractographic analysis was performed with scanning electron microscopy. The use of reciprocation motions allowed nonexpert operators to avoid instrument breakage during glide path and to prepare root canals faster. Experts were equally effective in rotary/reciprocating root canal shaping and faster with rotary motions than nonexpert operators, who also fractured significantly more rotary instruments.