Souza Erick Miranda, Calixto Amanda Martins, Lima Camila Nara E, Pappen Fernanda Geraldo, De-Deus Gustavo
Department of Dentistry II, Federal University of Maranhão, São Luis, Brazil.
Private Practice, São Luis, Brazil.
J Endod. 2014 Oct;40(10):1600-3. doi: 10.1016/j.joen.2014.02.028. Epub 2014 Apr 25.
Stabilizing sodium hypochlorite (NaOCl) at an alkaline pH is proposed to increase solution stability and tissue dissolution ability; however, a reduction on the flexural strength of dentin discs has been found to be a side effect. This study sought to determine whether a stabilized alkaline NaOCl reduces the fracture resistance of root canal-treated bovine teeth after root canal preparation compared with a neutral solution counterpart.
The 4 anterior incisors were removed from 20 mandibular bovine jaws, and each 1 was randomly assigned to 1 of 4 groups (20 teeth each). Teeth were prepared with a sequence of 6 K-type files. The following experimental groups received a different irrigation regimen: G1: distilled water (negative control), G2: 5% NaOCl at a pH of 7.2, and G3: 5% NaOCl at a pH of 12.8; in the positive control group (G4), teeth remained untreated. The time of contact and volume of solution were carefully standardized. After bone and periodontal ligament simulation, teeth were subjected to a fracture resistance test.
A significant difference was observed among the 4 groups tested (analysis of variance, P < .05). The 5% NaOCl groups (G2 and G3) presented significantly lower resistance to fracture than the control (G1 and G4) (Tukey test, P < .05). Both NaOCl solutions similarly reduced the fracture resistance at approximately 30% (Tukey test, P > .05). No differences were observed between positive and negative control groups (Tukey test, P > .05).
Stabilized alkaline and neutral NaOCl solutions similarly reduced the fracture resistance of root canal-treated bovine teeth by about 30%.
有人提出在碱性pH值下稳定次氯酸钠（NaOCl）可提高溶液稳定性和组织溶解能力；然而，已发现牙本质盘的抗弯强度降低是一种副作用。本研究旨在确定与中性溶液相比，稳定的碱性NaOCl在根管预备后是否会降低根管治疗的牛牙的抗折性。
从20个下颌牛颌骨中取出4颗前牙，每颗随机分配到4组中的1组（每组20颗牙）。用一系列6根K型锉对牙齿进行预备。以下实验组接受不同的冲洗方案：G1：蒸馏水（阴性对照），G2：pH值为7.2的5% NaOCl，G3：pH值为12.8的5% NaOCl；在阳性对照组（G4）中，牙齿未进行处理。仔细规范接触时间和溶液体积。在模拟骨和牙周韧带后，对牙齿进行抗折性测试。
在测试的4组之间观察到显著差异（方差分析，P <.05）。5% NaOCl组（G2和G3）的抗折性明显低于对照组（G1和G4）（Tukey检验，P <.05）。两种NaOCl溶液同样使抗折性降低约30%（Tukey检验，P >.05）。阳性和阴性对照组之间未观察到差异（Tukey检验，P >.05）。
稳定的碱性和中性NaOCl溶液同样使根管治疗的牛牙的抗折性降低约30%。
