Ghisi Alexandre Corrêa, Kopper Patrícia Maria Poli, Baldasso Flávia E R, Stürmer Caroline P, Rossi-Fedele Giampiero, Steier Liviu, Figueiredo José Antonio Poli de, Morgental Renata Dornelles, Vier-Pelisser Fabiana Vieira
Department of Endodontics, School of Dentistry, PUCRS - Pontifical Catholic University of Rio Grande do Sul, Porto Alegre, Brazil.
Department of Conservative Dentistry, School of Dentistry, UFRGS -Federal University of Rio Grande do Sul, Porto Alegre, Brazil.
Braz Dent J. 2014 Sep-Oct;25(5):420-4. doi: 10.1590/0103-6440201300129.
The present study aimed to evaluate the influence of the following irrigating solutions on the microhardness of root canal dentin: 2% sodium hypochlorite (2NaOCl), 5% sodium hypochlorite (5NaOCl), super-oxidized water (400 ppm Sterilox - Sx) and 17% EDTA (E). Eighty roots from bovine incisors were randomly divided into 8 groups (n=10): 2NaOCl, 5NaOCl, Sx, and 2NaOCl + E, 5NaOCl + E, Sx + E (associated with E as final irrigant for 5 min), E solely and distilled water (dH2O) as the negative control. Root canal preparation was performed by hand instruments, using one of the irrigation protocols for 30 min. Then, 5 mm of the cervical root third were cut out from each sample and subjected to the Vickers microhardness test, at two points, one at approximately 500-1000 µm from the root canal lumen (distance 1), and the other at approximately 500-1000 µm from the external root surface (distance 2). Data were analyzed by Wilcoxon and Kruskal-Wallis tests at 5% significance level. Microhardness values at distance 1 were significantly lower than those at distance 2 for all groups, except 5NaOCl and 5NaOCl + E groups (p>0.05). EDTA showed the lowest microhardness values. However, no statistically significant difference was detected among groups at distance 1 and EDTA was significantly different only from Sx at distance 2. In conclusion, all tested solutions showed lower microhardness at the most superficial root canal dentin layer compared to the one found near the external root surface, except 5NaOCl and 5NaOCl + E; EDTA promoted lower microhardness values in comparison to Sterilox at this site.
2%次氯酸钠（2NaOCl）、5%次氯酸钠（5NaOCl）、超氧化水（400 ppm Sterilox - Sx）和17%乙二胺四乙酸（E）。将80颗牛切牙的牙根随机分为8组（n = 10）：2NaOCl组、5NaOCl组、Sx组、2NaOCl + E组、5NaOCl + E组、Sx + E组（联合E作为最终冲洗液5分钟）、单纯E组和蒸馏水（dH2O）作为阴性对照组。使用手动器械进行根管预备，采用其中一种冲洗方案冲洗30分钟。然后，从每个样本中切下颈段牙根的三分之一5 mm，并在两个点进行维氏显微硬度测试，一个点距离根管腔约500 - 1000 µm（距离1），另一个点距离牙根外表面约500 - 1000 µm（距离2）。采用Wilcoxon检验和Kruskal - Wallis检验在5%显著性水平下分析数据。除5NaOCl组和5NaOCl + E组外（p>0.05），所有组在距离1处的显微硬度值均显著低于距离2处。乙二胺四乙酸显示出最低的显微硬度值。然而，在距离1处各实验组之间未检测到统计学显著差异，且在距离2处乙二胺四乙酸仅与Sx有显著差异。总之，除5NaOCl和5NaOCl + E组外，所有测试溶液在根管牙本质最表层的显微硬度均低于牙根外表面附近的显微硬度；在此部位，与Sterilox相比，乙二胺四乙酸使显微硬度值更低。
