title: Comparative evaluation of apical extrusion of bacteria using hand and rotary systems : An in vitro study.
abstract: OBJECTIVE
  To evaluate the bacteria extruded apically during root canal preparation using two hand and rotary instrumentation techniques.
  
  
  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.
  
  
  METHODS
  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.
  
  
  CONCLUSIONS
  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.
authors.affiliation: Department of Conservative Dentistry and Endodontics, Sharad Pawar Dental College, Sawangi (Meghe), Wardha, Maharashtra, India.
authors.forename: Sheetal B
authors.initials: SB
authors.lastname: Ghivari
authors.forename: Girish C
authors.initials: GC
authors.lastname: Kubasad
authors.forename: Preethi
authors.initials: P
authors.lastname: Deshpande