Sayin Taner Cem, Serper Ahmet, Cehreli Zafer C, Otlu Harika G
Department of Endodontics, Nova Southeastern University, College of Dental Medicine, Fort Lauderdale, FL 33328, USA.
Oral Surg Oral Med Oral Pathol Oral Radiol Endod. 2007 Sep;104(3):418-24. doi: 10.1016/j.tripleo.2007.03.021.
The purpose of this study was to evaluate the effect of single and combined use of ethylenediamine tetra acetic acid (EDTA), ethylene glycol bis [b-aminoethylether] N,N,N',N'-tetraacetic acid (EGTA), EDTA plus Cetavlon (EDTAC), tetracycline-HCl, and NaOCl on the microhardness of root canal dentin.
The crowns of 30 single-rooted human teeth were discarded at the cementoenamel junction and the roots were bisected longitudinally to obtain root halves (N = 60). The specimens were embedded in autopolymerizing acrylic resin, leaving the root canal dentin exposed. Dentin surfaces were prepared for microhardness test by grinding and polishing. The reference microhardness values of untreated specimens were recorded using a Vicker's microhardness tester at the apical, midroot, and cervical levels of the root canal. Thereafter, the specimens treated with single (test solution only) or combined (test solution, followed by 2.5% NaOCl) versions of the irrigants for 5 minutes. Posttreatment microhardness values were obtained as with initial ones. Statistical comparisons between the test groups and among single and combined treatments were carried out using 2-way ANOVA with repeated measures (P =.05). Comparisons within each group with respect to application regions were made with Friedman's nonparametric 2-way analysis of variance at the same level of significance.
All treatment regimens except distilled water significantly decreased the microhardness of the root canal dentin (P < . 05). The single and combined use of EDTA decreased the microhardness of the root canal dentin significantly more than all other treatment regimens (P < .05). Compared with their single-treatment versions, all combined treatment regimens decreased the mean microhardness values significantly (P < .05). A comparison of single and combined treatment regimens revealed significant decreases only for EDTA and EDTA + NaOCl in the coronal region and for EDTAC and EDTAC + NaOCl in the apical and middle regions of the root canal (P < .05).
The use of EDTA alone or prior to NaOCl resulted in the maximum decrease in dentin microhardness. The softening effect of subsequent NaOCl treatment was both material and region dependent. However, for combined treatment regimens, subsequent use of NaOCl levels the statistical differences between the regional microhardness values obtained after treatment with EGTA, EDTAC, and tetracycline-HCl.
本研究旨在评估单独及联合使用乙二胺四乙酸（EDTA）、乙二醇双[β-氨基乙醚]N,N,N',N'-四乙酸（EGTA）、EDTA加西他氯铵（EDTAC）、盐酸四环素及次氯酸钠（NaOCl）对根管牙本质显微硬度的影响。
将30颗单根人牙的牙冠在牙骨质牙釉质界处截除，牙根纵剖为两半（N = 60）。将标本嵌入自凝丙烯酸树脂中，使根管牙本质暴露。通过打磨和抛光制备牙本质表面以进行显微硬度测试。使用维氏显微硬度测试仪在根管的根尖、根中及颈段记录未处理标本的参考显微硬度值。此后，将标本用单一（仅测试溶液）或联合（测试溶液，随后用2.5% NaOCl）冲洗剂处理5分钟。处理后的显微硬度值测量方法与初始时相同。使用重复测量的双向方差分析对测试组之间以及单一和联合处理之间进行统计学比较（P = 0.05）。在相同显著性水平下，使用弗里德曼非参数双向方差分析对每组内不同应用区域进行比较。
除蒸馏水外，所有处理方案均显著降低了根管牙本质的显微硬度（P < 0.05）。EDTA单独及联合使用比所有其他处理方案更显著地降低了根管牙本质的显微硬度（P < 0.05）。与单一处理版本相比，所有联合处理方案均显著降低了平均显微硬度值（P < 0.05）。单一和联合处理方案的比较显示，仅在根管的冠部区域，EDTA和EDTA + NaOCl，以及在根尖和中部区域，EDTAC和EDTAC + NaOCl导致显著降低（P < 0.05）。
单独使用EDTA或在NaOCl之前使用会导致牙本质显微硬度最大程度降低。随后NaOCl处理的软化效果既取决于材料也取决于区域。然而，对于联合处理方案，随后使用NaOCl使在EGTA、EDTAC和盐酸四环素处理后获得的区域显微硬度值之间的统计学差异趋于均衡。
