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<p>In the present research, the cyclic fatigue resistance (CFR) of four pediatric nickel-titanium (NiTi) rotary files (Orodeka, Yirui M3, Baofeng and C-Root) was compared under simulated body temperature conditions. The instruments were tested in a simulated curved root canal (60° curvature, radius 5&#xa0;mm) at 35 ± 1&#xa0;°C. Measurements included the number of cycles to failure (NCF) and fragment length. The data were analyzed with the help of the Kruskal–Wallis test, whereas the fracture surfaces were scrutinized with the help of scanning electron microscopy (SEM) to determine what caused the failure. In addition, differential scanning calorimetry (DSC) and lateral SEM observations were conducted. There were significant differences in the NCF between the groups (<i>P</i> &lt; 0.001). The highest cyclic fatigue resistance was shown by the Orodeka system (median NCF: 336.68; IQR: 233.5–415.2), followed by Yirui M3 (median: 291.32; IQR: 228.3–334.8), Baofeng (median: 228.14; IQR: 193.7–301.3) and, finally, C-Root (median: 166.60; IQR: 110.4–200.5). Subsequent post hoc tests revealed that Orodeka and Yirui M3 had significantly higher NCF scores than C-Root (<i>P</i> &lt; 0.001) and that Orodeka performed significantly better than Baofeng (<i>P</i> = 0.030). The difference among fragment lengths was not statistically significant (4.5–4.6&#xa0;mm, <i>P</i> &gt; 0.05). SEM examination verified the presence of fatigue cracks and ductile fracture properties with fatigue striations and dimples in all groups. DSC analysis revealed that Orodeka remained mostly in the highly flexible martensitic phase, and lateral SEM revealed severe machining defects on the surfaces of the Baofeng and C-Root files. In conclusion, there are significant differences in the CFR among the tested files because of the different metallurgical properties and cross-sectional designs across the files. Although all the systems can be used in pediatrics, the Orodeka system showed the best cyclic fatigue resistance under simulated body temperature. The regular replacement of instruments is still needed to ensure clinical safety.</p>

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Evaluation of the cyclic fatigue resistance of four specialist nickel-titanium files for primary teeth under simulated body temperature

  • 期刊论文

  • 出版模式：

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  • 发表日期：

    2026年4月29日

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  • Yuan Sun,
  • Xiao-mei Hou,
  • Wen-xin Chen,
  • Shi-yan Huang,
  • Yu Yan,
  • Yi-wen Xu,
  • Chang Yu,
  • Yan Zhao

摘要

In the present research, the cyclic fatigue resistance (CFR) of four pediatric nickel-titanium (NiTi) rotary files (Orodeka, Yirui M3, Baofeng and C-Root) was compared under simulated body temperature conditions. The instruments were tested in a simulated curved root canal (60° curvature, radius 5 mm) at 35 ± 1 °C. Measurements included the number of cycles to failure (NCF) and fragment length. The data were analyzed with the help of the Kruskal–Wallis test, whereas the fracture surfaces were scrutinized with the help of scanning electron microscopy (SEM) to determine what caused the failure. In addition, differential scanning calorimetry (DSC) and lateral SEM observations were conducted. There were significant differences in the NCF between the groups (P < 0.001). The highest cyclic fatigue resistance was shown by the Orodeka system (median NCF: 336.68; IQR: 233.5–415.2), followed by Yirui M3 (median: 291.32; IQR: 228.3–334.8), Baofeng (median: 228.14; IQR: 193.7–301.3) and, finally, C-Root (median: 166.60; IQR: 110.4–200.5). Subsequent post hoc tests revealed that Orodeka and Yirui M3 had significantly higher NCF scores than C-Root (P < 0.001) and that Orodeka performed significantly better than Baofeng (P = 0.030). The difference among fragment lengths was not statistically significant (4.5–4.6 mm, P > 0.05). SEM examination verified the presence of fatigue cracks and ductile fracture properties with fatigue striations and dimples in all groups. DSC analysis revealed that Orodeka remained mostly in the highly flexible martensitic phase, and lateral SEM revealed severe machining defects on the surfaces of the Baofeng and C-Root files. In conclusion, there are significant differences in the CFR among the tested files because of the different metallurgical properties and cross-sectional designs across the files. Although all the systems can be used in pediatrics, the Orodeka system showed the best cyclic fatigue resistance under simulated body temperature. The regular replacement of instruments is still needed to ensure clinical safety.