Department of Operative Dentistry and Endodontics, Guanghua School of Stomatology, Sun Yat-sen University, Guangzhou, China.
Dent Mater. 2010 Jun;26(6):514-23. doi: 10.1016/j.dental.2010.01.009. Epub 2010 Feb 23.
This study evaluated the effects of different NaOCl concentrations and contact times on removal of the organic phase from mineralized dentin with and without the adjunctive use of EDTA, and the effect of NaOCl concentrations on canal wall erosion after the use of EDTA as the final active irrigant.
Dentin powders were immersed in 5.25% or 1.3% NaOCl for different contact periods and then rinsed with 17% EDTA for 2 min. Before and after the use of 17% EDTA as the final rinse, the NaOCl-treated dentin powders were examined using ATR-FT-IR spectroscopy to analyze the relative loss of organic and inorganic components. Scanning (SEM) and transmission electron microscopy (TEM) were used to examine the erosion of instrumented canal walls irrigated with 5.25% NaOCl/EDTA or 1.3% NaOCl/EDTA.
Compared with 1.3% NaOCl, less intact collagen remained within the subsurface of the mineralized dentin powder after the use of 5.25% NaOCl, irrespective of subsequent rinsing with 17% EDTA. Canal wall erosion was apparent only under SEM when root canals were irrigated 5.25% NaOCl followed by 17% EDTA. Under TEM examination, subsurface erosion extended 10-15 microm beneath the sealer-bonded dentin surface after the use of 5.25% NaOCl for 20 min.
The superficial destructive effect of NaOCl on mineralized dentin is irreversible and is present irrespective of whether EDTA is subsequently employed as the final active irrigant. The EDTA removes the collagen-depleted apatite phase to expose the underlying cause of destruction that is morphologically perceived as canal wall erosion.
本研究评估了不同次氯酸钠浓度和接触时间对含有和不含有 EDTA 辅助剂的矿化牙本质中有机相去除效果的影响，以及 EDTA 作为最终活性冲洗剂使用后次氯酸钠浓度对根管壁侵蚀的影响。
将牙本质粉末浸泡在 5.25%或 1.3%次氯酸钠中不同的接触时间，然后用 17% EDTA 冲洗 2 分钟。在使用 17% EDTA 作为最终冲洗液前后，使用衰减全反射傅里叶变换红外光谱（ATR-FT-IR）分析技术对处理过的牙本质粉末进行分析，以分析有机和无机成分的相对损失。使用扫描电子显微镜（SEM）和透射电子显微镜（TEM）观察使用 5.25% NaOCl/EDTA 或 1.3% NaOCl/EDTA 冲洗的器械化根管壁的侵蚀情况。
与 1.3% NaOCl 相比，使用 5.25% NaOCl 后，矿化牙本质粉末的亚表面残留的完整胶原更少，无论随后是否用 17% EDTA 冲洗。只有在使用 5.25% NaOCl 冲洗后再用 17% EDTA 冲洗时，SEM 下才能观察到根管壁明显侵蚀。在 TEM 检查下，使用 5.25% NaOCl 处理 20 分钟后，牙本质表面下的牙本质表面下侵蚀扩展到 10-15μm。
次氯酸钠对矿化牙本质的表面破坏性影响是不可逆的，无论随后是否使用 EDTA 作为最终活性冲洗剂。EDTA 去除了脱胶原的磷灰石相，暴露出形态上被认为是根管壁侵蚀的根本原因。
