Comparative evaluation of apical extrusion of bacteria using hand and rotary systems : An in vitro study

AIM: To evaluate the bacteria extruded apically during root canal preparation using two hand and rotary instrumentation techniques. MATERIALS AND METHODS: Eighty freshly extracted mandibular premolars were mounted in bacteria collection apparatus. Root canals were contaminated with the pure culture of Enterococcus fecalis (ATCC 29212) and dried at 37°C for 24 h. Bacteria extruded were collected, incubated in brain heart infusion agar for 24 h at 36°C and the colony forming units (CFU) were counted. STATISTICAL ANALYSIS: The mean number of colony forming units were calculated by One-way ANOVA and comparison between the groups made by multiple comparison (Dunnet D) test. RESULTS: The step-back technique extruded highest number of bacteria in comparison to other hand and rotary Ni–Ti systems. CONCLUSION: Under the limitation of this study all hand and rotary instrumentation techniques extruded bacteria. Among all the instrumentation techniques step-back technique extruded more number of bacteria and K-3 system the least. Further in vivo research in this direction could provide more insight into the biologic factors associated and focus on bacterial species that essentially play a major role in post instrumentation flare-ups.