3種類のNiTi歯内療法用器具の繰返し疲労抵抗性および相変態挙動に及ぼす温度の影響

Effect of Temperature on the Cyclic Fatigue Resistance and Phase Transformation Behavior of Three Different NiTi Endodontic Instruments.

抄録

本研究の目的は，相変態挙動を解析し，異なる温度がファイルの破壊強度に及ぼす影響を評価することである．方法 合計108本のファイルを用い，HyFlex EDM，VDW.ROTATE，TruNatomyの3種類の温度（+4℃，+35℃，+60℃）で繰返し疲労試験を行った．さらに、破断片の長さを測定した。正規分布しないデータを群別に比較するために、Kruskal-Wallis検定を用いた。比較にはMann-Whitney U検定を行った。P値＜0.05を統計的に有意とみなした。結果 すべてのファイルで温度が上昇するにつれて、破断までのサイクル数（NCF）は減少した。NCFは、4℃と60℃のROTATEと35℃のHyFlex EDMで有意に高かった。結論 すべてのヤスリの繰返し疲労に対する耐性は、温度が上昇するにつれて著しく低下した。

Background This study aims to analyze the phase transformation behavior and evaluate the effect of different temperatures on the fracture strength of files. Methodology A total of 108 files were used, and cyclic fatigue tests were performed on HyFlex EDM, VDW.ROTATE, and TruNatomy at three different temperatures (+4°C, +35°C, and +60°C) The time to fracture of files was measured, and the number of cycles was calculated. In addition, the fractured fragment lengths were measured. The Kruskal-Wallis test was used to compare the data that were not normally distributed according to groups. The Mann-Whitney U test was performed for comparisons. P-values <0.05 were considered statistically significant. Results As the temperature increased for all files, the number of cycles to fracture (NCF) decreased. NCF was significantly higher for ROTATE at 4°C and 60°C and HyFlex EDM at 35°C. Conclusions The resistance to cyclic fatigue in all files decreased significantly as the temperature increased.