Instrument Design May Influence Bacterial Reduction During Root Canal Preparation

Abstract The aim of this study was to evaluate the bacterial reduction promoted by ProTaper Next and Twisted File by comparing to ProTaper Universal and manual technique. Sixty distobuccal root canals of maxillary molars sterilized with ethylene oxide were contaminated with Enterococcus faecalis broth culture. After incubation for 21 days, bacterial samples were collected and cultured on m-Enterococcus agar plates. The root canals were divided into 4 groups, according to the system used for instrumentation: ProTaper Next, Twisted File, ProTaper Universal, and crown down manual technique. Other 8 uncontaminated root canals were control asepsis. Bacterial samples were collected immediately and 7 days after instrumentation. The bacterial reduction was calculated and then made intragroup analysis by paired t-test and intergroup analysis by ANOVA and Tukey tests, all at 5% significance. All techniques significantly reduced the bacterial number in the root canal (p<0.05). ProTaper Next and Twisted File resulted in more bacterial reduction than ProTaper Universal and manual technique (p<0.05). ProTaper Next and Twisted File were similar (p>0.05). It can be concluded that ProTaper Next and Twisted File promote a higher bacterial reduction than Protaper Universal and manual technique.

摘要 本研究旨在对比ProTaper Next、Twisted File与ProTaper Universal及手工预备技术，评估其根管内细菌减少效果。选取60根经环氧乙烷灭菌的上颌磨牙远中颊根管，采用粪肠球菌（Enterococcus faecalis）肉汤培养液进行污染处理。经21天培养后，采集细菌样本并接种于m-肠球菌琼脂平板上。根据所用根管预备系统将根管分为4组：ProTaper Next组、Twisted File组、ProTaper Universal组及冠向下手工预备技术组。另设8根未污染根管作为无菌对照。分别于根管预备即刻及预备后7天采集细菌样本。计算细菌减少率后，采用配对t检验进行组内分析，采用方差分析（ANOVA）及Tukey检验进行组间分析，所有检验的显著性水准均设定为5%。结果显示，所有预备技术均能显著降低根管内细菌数量（p<0.05）；ProTaper Next与Twisted File的细菌减少效果优于ProTaper Universal及手工预备技术（p<0.05）；且ProTaper Next与Twisted File的细菌减少效果无显著差异（p>0.05）。综上，ProTaper Next与Twisted File的根管内细菌减少效果优于ProTaper Universal及手工预备技术。