Marending M, Luder H U, Brunner T J, Knecht S, Stark W J, Zehnder M
Division of Endodontology, Department of Preventive Dentistry, Periodontology, and Cariology, University of Zürich Center of Dental Medicine, Zürich, Switzerland.
Int Endod J. 2007 Oct;40(10):786-93. doi: 10.1111/j.1365-2591.2007.01287.x. Epub 2007 Aug 14.
To investigate the mechanical, chemical and structural alterations of human root dentine following exposure to ascending sodium hypochlorite concentrations.
Three-point bending tests were carried out on standardized root dentine bars (n = 8 per group, sectioned from sound extracted human third molar teeth) to evaluate their flexural strength and modulus of elasticity after immersion in 5 mL of water (control), 1% NaOCl, 5% NaOCl or 9% NaOCl at 37 degrees C for 1 h. Additional dentine specimens were studied using microelemental analysis, light microscopy following bulk staining with basic fuchsin, and scanning electron microscopy (SEM). Numerical data were compared using one-way ANOVA. Bonferroni's correction was applied for multiple testing.
Immersion in 1% NaOCl did not cause a significant drop in elastic modulus or flexural strength values in comparison to water, whilst immersion in 5% and 9% hypochlorite reduced these values by half (P < 0.05). Both, carbon and nitrogen contents of the specimens were significantly (P < 0.05) reduced by 5% and 9% NaOCl, whilst 1% NaOCl had no such effect. Exposure to 5% NaOCl rendered the superficial 80-100 mum of the intertubular dentine permeable to basic fuchsin. Three-dimensional SEM reconstructions of partly demineralized specimens showed NaOCl concentration-dependent matrix deterioration. Backscattered electron micrographs revealed that hypochlorite at any of the tested concentrations left the inorganic dentine components intact.
The current data link the concentration-dependent hypochlorite effect on the mechanical dentine properties with the dissolution of organic dentine components.
研究人牙根牙本质在接触不同浓度次氯酸钠后的力学、化学和结构变化。
对标准化的牙根牙本质条（每组8个，从完好拔除的人第三磨牙上截取）进行三点弯曲试验，以评估其在37℃下于5mL水（对照）、1%次氯酸钠、5%次氯酸钠或9%次氯酸钠中浸泡1小时后的抗弯强度和弹性模量。使用微量元素分析、碱性品红整体染色后的光学显微镜以及扫描电子显微镜（SEM）对额外的牙本质标本进行研究。使用单因素方差分析比较数值数据。采用Bonferroni校正进行多重检验。
与水相比，浸泡在1%次氯酸钠中并未导致弹性模量或抗弯强度值显著下降，而浸泡在5%和9%次氯酸钠中会使这些值减半（P<0.05）。5%和9%次氯酸钠使标本中的碳和氮含量均显著降低（P<0.05），而1%次氯酸钠则无此作用。暴露于5%次氯酸钠使管间牙本质表面80-100μm可被碱性品红渗透。部分脱矿标本的三维SEM重建显示次氯酸钠浓度依赖性的基质降解。背散射电子显微镜图像显示，任何测试浓度的次氯酸钠均使牙本质无机成分保持完整。
目前的数据将次氯酸钠对牙本质力学性能的浓度依赖性影响与牙本质有机成分的溶解联系起来。
