Department of Restorative Dentistry, Endodontics Division, Piracicaba Dental School, State University of Campinas, Piracicaba, SP, Brazil.
J Appl Oral Sci. 2012 Nov-Dec;20(6):661-6. doi: 10.1590/s1678-77572012000600012.
Gram-negative bacteria play an essential role in endodontic infections because they have virulence factors such as endotoxin. Due to its potential cytotoxic activity, special attention has been given to the removal/neutralization of this endotoxin in the root canal system.
The aim of this study was to evaluate the influence of the apical enlargement size (AES) by using rotary instruments on the endotoxin level reduction of dental root canals.
Forty root canals of the mandibular premolar teeth were used. Escherichia coli endotoxin (055: B55) was inoculated into thirty root canals. Ten teeth served as the negative control group. After the incubation period, the first endotoxin samples were collected from the root canals with a sterile/apyrogenic paper point for the analysis of the endotoxin units (EU/mL) present before instrumentation (S1). Specimen instrumentation was performed with the Mtwo rotary system in the sequence 10/.04, 15/.05, 20/.06, 25/.06, 30/.05, 35/.04 and 40/.04. To monitor the effectiveness of increasing apical enlargement on endotoxin removal, the second endotoxin samples were collected from all the root canals after instrumentation with the following instruments: #25/.06--(S2); #30/.05--(S3); # 35/.04--(S4); and #40/.04--(S5). Limulus amebocyte lysate (LAL) was used to quantify the levels of endotoxin. The results were statistically compared by using repeated measures of ANOVA with post hoc Tukey testing.
Increasing levels of endotoxin removal was achieved by large sized apical enlargement: S2 (AES #25/.06)--89.2%, S3 (AES #30/.05)--95.9%, S4 (AES #35/.04)--97.8% and S5 (AES #40/.04)--98.2%. Substantial reduction of endotoxin content was obtained in S4 and S5 compared to S2 (p<0.05), however, the root canal preparation was not able to eliminate the endotoxin.
Under the conditions of this study, it was concluded that the reduction of endotoxin levels of the dental root canals could be predicted by increasing the apical enlargement size.
革兰氏阴性菌在牙髓感染中起着至关重要的作用，因为它们具有内毒素等毒力因子。由于其潜在的细胞毒性活性，人们特别关注在根管系统中去除/中和这种内毒素。
本研究旨在评估使用旋转器械进行根尖扩大尺寸（AES）对根管内内毒素水平降低的影响。
共使用 40 颗下颌前磨牙的根管。将大肠杆菌内毒素（055:B55）接种到 30 个根管中。10 颗牙作为阴性对照组。孵育期后，用无菌/无热源的纸尖从根管中采集第一个内毒素样本，以分析仪器操作前存在的内毒素单位（EU/mL）（S1）。使用 Mtwo 旋转系统按 10/.04、15/.05、20/.06、25/.06、30/.05、35/.04 和 40/.04 的顺序对样本进行仪器操作。为了监测根尖扩大对去除内毒素的效果，在使用以下器械对所有根管进行仪器操作后，从所有根管中采集第二个内毒素样本：#25/.06-（S2）；#30/.05-（S3）；#35/.04-（S4）；和#40/.04-（S5）。使用鲎变形细胞溶解物（LAL）定量内毒素水平。使用重复测量方差分析和事后 Tukey 检验对结果进行统计学比较。
较大的根尖扩大尺寸可实现内毒素去除水平的提高：S2（AES #25/.06）-89.2%，S3（AES #30/.05）-95.9%，S4（AES #35/.04）-97.8%和 S5（AES #40/.04）-98.2%。与 S2 相比，S4 和 S5 对内毒素含量的减少幅度较大（p<0.05），但根管预备不能消除内毒素。
在本研究条件下，可以得出结论，通过增加根尖扩大尺寸可以预测根管内内毒素水平的降低。
