Effect of body temperature on the cyclic fatigue resistance of the nickel”titanium endodontic instruments: A systematic review and meta-analysis of in vitro studies

Abstract

Aim: The aim of this systematic review was to compare the effect of body temperature (I) on the cyclic fatigue resistance (O) of nickel–titanium (NiTi) endodontic instruments (P) to that of room temperature (C). Methods: The study was registered in the PROSPERO database (CRD42020204286). A systematic search in PubMed, Scopus, Web of Science, Google Scholar, and OpenGrey was conducted in English until December 31, 2021. In vitro studies comparing the cyclic fatigue resistance of NiTi instruments at the body (35°C ± 2°C) and room temperature (20°C–25°C) were included. Eligible studies were evaluated for risk of bias and meta-analyzed to estimate the effects. Results: Twenty-one studies out of 347 met the criteria for inclusion. The meta-analysis included six studies ( n = 215) with comparative study parameters. The overall effect sizes (5.49; 95% confidence interval [CI]: 4.04–6.93) were significantly different ( P < 0.001), indicating that the mean values at room temperature were significantly ( P < 0.001) higher. The effect sizes for full rotary motion (standardized mean difference [SMD]: 4.80; 95% CI: 3.04–6.56) and reciprocating motion (SMD: 6.37; 95% CI: 3.63–9.11) were not significantly different ( P = 0.346). Heterogeneity was high ( I 2 = 94%). Sensitivity analysis revealed that the SMD values were not significantly different ( P > 0.05) from the overall effect size, indicating that none of the studies had an effect on the overall effect size. Conclusions: Within the limitation of the study, the cyclic fatigue resistance of heat-treated NiTi endodontic files is significantly reduced at body temperature when compared to room temperature. Cyclic fatigue testing should be conducted at simulated body temperature.

Evaluation of cyclic and torsional fatigue resistance of several heat‐treated reciprocating nickel–titanium instruments

“…The results of the cyclic fatigue test of RB instruments are consistent with previous studies that showed that WOG present less cyclic fatigue time than RB [19, 20]. Additionally, another previous study [12] demonstrated that there were no significant differences between RB and WOG regarding NCF at simulated body temperature, which is also consistent with our results. The different results among these studies could be related with the different study design, such as the degree of curvature of the artificial canal used and the temperature that cyclic fatigue tests were performed.…”

“…As the failure of instruments is commonly associated with cyclic and torsional fatigue [4,11], and the operating temperature has been shown to influence their performance [4,8,12], the aim of this study was to evaluate the cyclic and torsional resistance of Unicone Plus compared with its predecessor, Unicone, and with two other widely used instruments, Reciproc Blue and Wave One Gold, at simulated body temperature.…”

Evaluation of cyclic fatigue behavior of RACE EVO rotary Files: In-vitro comparative study

“…Also, the experimental test was performed in 37 °C degree similar to the body temperature to mimic the clinical scenario. In addition, several studies found that the NiTi files at simulated body temperature behave less efficiently in terms of cyclic fatigue ( Jamleh et al, 2016 , Alfawaz et al, 2018 , Savitha et al, 2022 ). For a closer simulation of the clinical conditions and the complexity of root canal system, a 60 degree angle of curvature is used in the present study.…”

Impact of pecking amplitude on cyclic fatigue of new nickel–titanium files

“…Thus, it is advisable to conduct cyclic fatigue investigations under conditions simulating body temperature to reproduce the intracanal environment more accurately (Savitha et al, 2022).…”

“…In particular, body temperature adversely affects the cyclic fatigue resistance of NiTi endodontic instruments. Thus, it is advisable to conduct cyclic fatigue investigations under conditions simulating body temperature to reproduce the intracanal environment more accurately (Savitha et al, 2022 ).…”