Efficacy of Three Irrigation Agitation Techniques on Bacterial Elimination: A Microbiologic and Microscopic Evaluation SIBEL KOC ¸ AK, 1 MUSTAFA MURAT KOC ¸ AK, 1 BARAN CAN SAG ˘ LAM, 1 AND ELIF AKTAS ¸ 2 1 Faculty of Dentistry, Department of Endodontics, Bu ¨lent Ecevit University, Zonguldak, Turkey 2 Faculty of Medicine, Department of Microbiology, Bu ¨lent Ecevit University, Zonguldak, Turkey Summary: The aim of this study was to compare in vitro reduction of Enterococcus faecalis by using three agitation methods. Fifty-five mandibular premolar teeth were used. The root canals were prepared by using ProTaper instruments to size F4. Fresh bacterial suspensions were inoculated into each canal and the teeth were incubated at 37˚C under aerobic conditions for 3 weeks. The specimens in negative control group were not contaminated and the teeth in positive control receive no further instrumentation or irrigation after contamination. The contaminated teeth were divided into three experimental groups and two control groups. The experimental groups were as follows according to agitation of NaOCl irrigation solution; group 1, the brush-covered NaviTip FX needle; group 2, EndoVac apical negative pressure irrigation system; and group 3, self-adjusting file (SAF). Following the final irrigation, samples obtained with sterile #40 H-file from teeth and the file used were placed into sterile microcentrifuge tubes. After the incubation period, bacterial colony numbers were noted as CFU/ml. Three teeths were randomly selected from each group for scanning electron microscope evaluation. The three groups were compared with the Kruskal–Wallis test. Compar- isons between three groups were made with the Mann– Whitney U-test with Bonferroni correction. SAF was significantly effective in elimination of E. faecalis when compared to EndoVac (p < 0.05). There was no difference between NaviTip FX needle and other two methods (p > 0.05). In conclusion, agitation of NaOCl with SAF for 2 min may be an effective alternative approach. SCANNING 36:512–516, 2014. © 2014 Wiley Periodicals, Inc. Key words: bacterial elimination, irrigation agitation, scanning electron microscopy Introduction Microorganisms are main factors of pulpal and periapical inflammation (Oliveira et al., 2007). The elimination of bacteria from the root canal was recommended for the success of root canal treatment and dentists used a combination of mechanical instrumentation, various irrigation solutions, and anti- bacterial medicaments (Gorduysus et al., 2011). How- ever, bacteria can remain within the canal system even after all treatment procedures (Molander et al., ’98). The pathogenicity of facultative bacteria in endodon- tic infections is well documented (Sundqvist et al., ’98). Among the facultative bacteria, Enterococcus faecalis (E. faecalis) is one of the most dominant micro- organisms in post-treatment apical periodontitis and a possible cause of failure of root canal treatment (Gomes et al., ’96). To improve root canal disinfection, researchers have introduced alternative procedures to standard therapies, including syringe irrigation with needles (Cameron, ’95), brush-covered needles (Goel and Tewari, 2009), ultrasonic irrigation (Goel and Tewari, 2009), manual dynamic activation (Gu et al., 2009), and aspiration/irrigation systems such as the EndoVac system (Miranda et al., 2013). NaviTip FX needles have brushes on their tips. The brushes increase the mechanical debridement by active scrubbing of canal walls. They agitate the irrigating solution to enhance the chemical action (Gu et al., 2009). EndoVac is a negative pressure irrigation system that delivers irrigants into the apical portion of the canal. It is designed to optimize the removal of the smear layer and minimize the extrusion of solution through the apical foramen (Nielsen and Baumgartner, 2007). The SAF, a new nickel–titanium file system, adapts itself Contract grant sponsor: Research Foundation of Bu ¨lent Ecevit University. Conflict of interest: none. Address for reprints: Mustafa Murat Koc ¸ak, Faculty of Dentistry, Department of Endodontics, Bu ¨lent Ecevit University, Zonguldak, Turkey. E-mail: mmuratkocak@yahoo.com Received 29 January 2014; Accepted with revision 17 April 2014 DOI: 10.1002/sca.21147 Published online 9 May 2014 in Wiley Online Library (wileyonlinelibrary.com). SCANNING VOL. 36, 512–516 (2014) © 2014 Wiley Periodicals, Inc.