Department of Restorative Dental Sciences, College of Dentistry, King Saud University, Riyadh, Saudi Arabia.
Department of Restorative Dental Sciences, College of Dentistry, King Saud University, Riyadh, Saudi Arabia.
J Endod. 2018 Oct;44(10):1563-1566. doi: 10.1016/j.joen.2018.07.009. Epub 2018 Aug 25.
We tested the cyclic fatigue resistance of heat-treated instruments immersed in sodium hypochlorite solution under different concentrations and temperature conditions.
Based on the irrigating solution's concentration and temperature, 135 ProTaper Gold (PTG; Dentsply Sirona, York, PA) F2 instruments were divided equally into 9 groups of 15. Cyclic fatigue testing was performed by using a block with artificial canals with a curvature angle of 60°, a curvature radius of 5 mm, and a curvature center 5 mm from the instrument tip. The block was fixed inside a water bath of distilled water, 2.5% sodium hypochlorite (NaOCl), or 5.25% NaOCl. The temperature was preset at 25°C, 37°C, or 60°C. The instrument was rotated at 300 rpm until fracturing occurred. The number of cycles to fracture was calculated, and the fragment length was measured. Fractured surfaces were examined via scanning electron microscopy. NCF data were analyzed statistically via Kruskal-Wallis and Mann-Whitney tests. All statistical analyses were performed using SPSS software Version 22 (IBM Corp, Armonk, NY) at a 5% significance level.
The number of cycles to fracture of the PTG F2 was highest in distilled water at 25°C and lowest in 5.25% NaOCl at 60°C. Changing the irrigating solution from distilled water to NaOCl and increasing the surrounding temperature reduced the fatigue resistance.
NaOCl irrigating solution at different concentrations and temperatures influenced the cyclic fatigue resistance of PTG instruments. Future NiTi instrument failure studies should be conducted under simulated body temperature conditions in commonly used irrigating solutions.
我们测试了在不同浓度和温度条件下浸泡在次氯酸钠溶液中的热处理器械的循环疲劳强度。
根据冲洗液的浓度和温度，将 135 ProTaper Gold（PTG；Dentsply Sirona，约克，宾夕法尼亚州）F2 器械平均分为 9 组，每组 15 个。通过使用带有 60°曲率角、5mm 曲率半径和距器械尖端 5mm 曲率中心的人工管的块进行循环疲劳测试。将块固定在蒸馏水中、2.5%次氯酸钠（NaOCl）或 5.25%NaOCl 的水浴中。预设温度为 25°C、37°C 或 60°C。器械以 300rpm 旋转直至断裂。计算断裂的循环次数，并测量片段长度。通过扫描电子显微镜检查断裂表面。通过 Kruskal-Wallis 和 Mann-Whitney 检验对 NCF 数据进行统计分析。所有统计分析均使用 SPSS 软件版本 22（IBM Corp，Armonk，NY）在 5%的显著水平上进行。
PTG F2 的断裂循环次数在 25°C 的蒸馏水中最高，在 60°C 的 5.25%NaOCl 中最低。将冲洗液从蒸馏水改为 NaOCl 并提高周围温度会降低疲劳强度。
不同浓度和温度的次氯酸钠冲洗液会影响 PTG 器械的循环疲劳强度。未来的 NiTi 器械失效研究应在常用冲洗液的模拟体温条件下进行。
