Division of Endodontology, Department of Conservative Dentistry, University of Tübingen, Germany.
Int Endod J. 2013 May;46(5):477-82. doi: 10.1111/iej.12015. Epub 2012 Nov 9.
To determine the change in ultrasonic velocity of dentine after the application of 5% NaOCl.
Twenty standardized plano-parallel dentine bars were divided into two groups. Dentine bars were wetted on only one surface. The test group (n = 10) was irrigated with 5% NaOCl, and the control group, (n = 10) with saline. Ultrasonic velocities before and after irrigation were compared to determine the change in the modulus of elasticity. Finally, dentine bars were loaded until failure in a 3-point bending test. Paired t-test and the mean of differences were used to assess the statistical significance between the groups.
The mean ultrasonic velocity decreased by 1.4% after the application of NaOCl; no change was observed for saline. The mean velocity reduction of 49 m s⁻¹ was found to be highly significant (P = 0.004). The ultrasonically derived modulus of elasticity decreased by 2.6% compared to the initial value of 17.8 GPa. However, the observed reduction in elasticity derived from the 3-point bending test was not significant (P = 0.238).
NaOCl reduced the ultrasonic velocity of dentine and the ultrasonically derived modulus of elasticity.
确定应用 5%次氯酸钠后牙本质超声速度的变化。
将 20 个标准化的平面平行牙本质棒分为两组。仅在一个表面润湿牙本质棒。实验组（n=10）用 5%次氯酸钠冲洗，对照组（n=10）用生理盐水冲洗。比较冲洗前后的超声速度，以确定弹性模量的变化。最后，在三点弯曲试验中，将牙本质棒加载至失效。使用配对 t 检验和差值的平均值来评估组间的统计学意义。
应用次氯酸钠后，平均超声速度降低了 1.4%；生理盐水组没有变化。49m/s 的平均速度降低被发现具有高度显著性（P=0.004）。与初始值 17.8GPa 相比，超声弹性模量降低了 2.6%。然而，三点弯曲试验中观察到的弹性降低不具有显著性（P=0.238）。
次氯酸钠降低了牙本质的超声速度和超声弹性模量。
