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Phase transformation temperatures influence the reduction ratio of fatigue resistance of nickel-titanium reciprocating files at body temperature: an in vitro experimental study
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Walid Nehme, Alfred Naaman, Lola Pedèches, Sylvie Lê, Marie Georgelin-Gurgel, Sang Won Kwak, Hyeon-Cheol Kim, Franck Diemer
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Restor Dent Endod 2025;50(4):e35. Published online November 5, 2025
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DOI: https://doi.org/10.5395/rde.2025.50.e35
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Abstract
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- Objectives
The objective of this study was to evaluate the effects of transformational temperatures on the cyclic fatigue resistance at body temperature of reciprocating file systems: R motion (RM), Procodile Q (PQ), and Reciproc Blue.
Methods Resistance test was done in a custom-made device at room (20°C ± 1°C) and body (37°C ± 1°C) temperatures within a 60° angle of curvature and 5 mm radius of the artificial canal. The time to fracture (TTF) was recorded. The scanning electron microscope observation and differential scanning calorimetry analyses were performed. Two-way analysis of variance and Tukey post-hoc comparison were applied at a significance level of 0.05.
Results The results showed a significant influence of temperature on instrumental breakage, regardless of the file systems (p < 0.05). The TTF is significantly decreased at body temperature (p < 0.05). PQ showed the longest TTF in both temperature conditions (p < 0.05). RM demonstrated a significantly higher TTF reduction ratio compared to the other files (p < 0.05).
Conclusions Within the limitations of this study, the heat-treated files with reciprocating kinetics may have different reduction ratios of the fatigue resistance of the file systems under different temperature conditions. This characteristic is an important point of consideration when clinicians select the file system to reduce potential file fracture.
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