Comparison of residual E. faecalis counts after root canal preparation with hand files and rotary Flexmaster files with 4% taper

The main objective of root canal therapy is to eliminate the contents and internal irritants from the root canal and achieve a complete seal of the root canal system. Despite mechanical preparation, always some organic tissues and bacteria remain in the root canal. The aim of this study was to compare the amount of residual Enterococcus faecalis after root canal preparation with hand files and rotary Flexmaster files with 4% taper.
Thirty-four extracted human anterior teeth were divided into two experimental (n=12) and two control (positive and negative) (n=5) groups in this in vitro study. All the samples were initially prepared with #30 K-files, rinsed and sterilized in an autoclave. The root canals were contaminated with Enterococcus faecalis. The root canals in groups 1 and 2 were prepared with rotaryFlexmaster and hand files, respectively; in the positive control group the bacteria were cultured without filing and in the negative control group the bacteria were not cultured. Then the root canal debris was transferred into microtubes and incubated. The residual bacterial CFUs were determined after 24 hours of growth in bile esculin agar medium. Data were analyzed with one-way ANOVA at α=0.05.
The difference between groups 1 (K-files) and 2 (rotaryFlexmaster) was significant (p value = 0.001); the differences between groups 1 and 2 on one hand and the positive and negative control groups on the other hand were significant, too (p value = 0.001).
Intra-canal Enterococcus faecalis counts decreased significantly after preparation of the root canals with rotary files.