A comparative in vitro study of Enterococcus faecalis Elimination and Debris Extrusion using Rotary RaCe and Non-Rotary FKG instruments

One of the most important factors in the development of periradicular disease and endodontic failure is infection through the root canal. Apically-extruded debris may be considered a major causative agent of flare-ups and post-instrumentation pain. This in vitro study compared the reduction of intracanal bacteria and the amount of apically extruded debris (AED) using RaCe and FKG systems. Sixty extracted mandibular single-canal premolars were selected for this experimental investigation. 0.5 mm-deep grooves were made around all teeth at a 0.5mm distance from their apices. Sixty vials (7ml) were prepared and preweighed to 0.0001 precision. Each tooth was mounted in a rubber stopper and then fitted into the openings of the vials. All equipment were sterilized by ethylene-oxide and the canals were inoculated with E. faecalis. The samples were then incubated for 24 hours at 37°C in sealed chambers. During canal instrumentation, irrigation was performed with 2 ml normal-saline after each file size. Following preparation, the apical portions of the canals were sampled using sterile paper-points and the bacterial colonies were counted (CFU/ml). The vials were weighed again to obtain the amount of AED. Non-parametric Mann-Whitney U-test was used for statistical analysis. A significant difference was not observed between the RaCe and FKG systems regarding E. faecalis elimination and debris extrusion (P=0.1 and P=0/17, respectively). The two studied systems could not completely eliminate E. faecalis.