eng Oriental Scientific Publishing Company Biomedical and Pharmacology Journal 0974-6242 2021-12-30 14 4 2173 2182 10.13005/bpj/2315 41459 article Sachin Metkari 1 Dinesh Rao 2 Kulvindersingh Banga 1 Conservative Dentistry and Endodontics Nair Hospital Dental College, Dr.A.L.Nair Road, Opposite Maratha Mandir, Mumbai Central, Mumbai-400008, Maharashtra, India. Maharashtra University of Health Sciences, Nashik (M.U.H.S., Nashik) Department of Pediatric Dentistry, Pacific Dental College and Hospital, PAHER University Udaipur-313001, Rajasthan, India. Conservative Dentistry and Endodontics Nair Hospital Dental College, Dr.A.L.Nair Road, Opposite Maratha Mandir, Mumbai Central, Mumbai-400008, Maharashtra, India. Background: Periapical extrusion of debris, irrigating solution and microorganism are the major contributing factors for flare-ups during root canal therapy. The aim of this ex vivo study was to evaluate the effect of different types of instrumentation in combination with different irrigation methods on apical bacterial expulsion. Material and Methods: Three hundred and ten extracted human permanent teeth were infected with Enterococcus faecalis. After incubation at 37°C for 24 h, three hundred teeth were instrumented with three different instrumentations using two irrigation methods. The remaining ten teeth were used as negative and positive control groups, in which no inoculation was done and no instrumentation was carried out respectively. Three hundred teeth were equally divided in three groups (n = 100), in which instrumentation was performed  using a protaper universal rotary file (group 1), WaveOne reciprocating file (group 2) and a flexiCON rotary file (group 3). In each group, 50 samples were irrigated with conventional needle irrigation, and 50 samples were irrigated with the endoVac irrigation method. During instrumentation, apically extruded bacteria were collected in an Eppendorf tube. Microbiological samples were taken from the Eppendorf tube and incubated for 24h, and colony-forming units were counted. The data collected were statistically analysed. Results: The group 2 showed highest bacterial extrusion using conventional irrigation while group 3 showed lowest using endovac irrigation system. Conclusion: FlexiCON rotary instrumentation with the endoVac irrigation system produced significantly less bacterial extrusion than the other techniques. https://biomedpharmajournal.org/vol14no4/effect-of-different-instrumentation-and-irrigation-methods-on-apical-microbial-extrusion-an-ex-vivo-study/ Bacterial Extrusion Flare-Up Irrigation