Department of Operative Dentistry and Endodontics, Guanghua School of Stomatology, Sun Yat-sen University, Guangzhou, China.
J Endod. 2010 Jan;36(1):105-9. doi: 10.1016/j.joen.2009.10.020.
This study tested the null hypothesis that there is no difference between the use of 1.3% NaOCl/17% ethylenediaminetetraacetic acid (EDTA) and 5.25% NaOCl/17% EDTA irrigation regimens on the collagen degradation and flexural strength reduction in mineralized dentin.
Dentin powder and mineralized dentin sections were immersed in 1.3% or 5.25% NaOCl for 10-240 minutes and then rinsed with 17% EDTA as the final irrigant for 2 minutes. Untreated mineralized dentin powder/sections served as controls in the respective experiments. Dentin powders were examined by using Fourier transform infrared (FT-IR) spectroscopy to analyze their relative subsurface intact collagen content with the apatite/collagen ratio. Hydrated dentin sections were subjected to 3-point flexure under water for determining their flexural strengths.
Collagen degradation was significantly increased and the flexural strength of mineralized dentin was significantly reduced after the use of 5.25% NaOCl as the initial irrigant for more than 1 hour (P < .05). Conversely, changes were insignificant when 1.3% NaOCl was used as the initial irrigant for up to 4 hours (Kruskal-Wallis analysis of variance, n = 10, P < .05).
The null hypothesis was rejected. The deleterious effects attributed to the use of NaOCl on dentin are concentration-dependent and time-dependent and are not associated with the demineralization caused by the use of EDTA as the final active irrigant.
本研究旨在验证以下假设，即使用 1.3%次氯酸钠/17%乙二胺四乙酸（EDTA）和 5.25%次氯酸钠/17%EDTA 冲洗方案对矿化牙本质的胶原降解和挠曲强度的影响没有差异。
将牙本质粉末和矿化牙本质切片浸入 1.3%或 5.25%次氯酸钠中 10-240 分钟，然后用 17%EDTA 作为最后冲洗液冲洗 2 分钟。未处理的矿化牙本质粉末/切片在各自的实验中作为对照。使用傅里叶变换红外（FT-IR）光谱法分析牙本质粉末的相对亚表面完整胶原含量及其与磷灰石/胶原的比值。将水合牙本质切片置于水下进行三点挠曲试验，以确定其挠曲强度。
使用 5.25%次氯酸钠作为初始冲洗液超过 1 小时后，牙本质的胶原降解明显增加，矿化牙本质的挠曲强度明显降低（P<0.05）。相反，当使用 1.3%次氯酸钠作为初始冲洗液时，在 4 小时内变化不显著（Kruskal-Wallis 方差分析，n=10，P<0.05）。
该假设被拒绝。次氯酸钠对牙本质的有害影响与浓度和时间有关，与使用 EDTA 作为最后活性冲洗液引起的脱矿无关。
