
Apical extrusion of irrigants and debris is an inherent limitation associated with cleaning and shaping of root canals and has been studied extensively because of its clinical relevance as a cause of flare-ups. Many factors affect the amount of extruded intracanal materials. The purpose of this study was to assess the bacterial extrusion by using manual, Mtwo NiTi rotary system and V(variable) taper rotary instrumentation techniques. Thirty six human mandibular premolars were inoculated with Enterococcus faecalis. The teeth were divided into 3 experimental groups (n=10) and 1 control group (n=6). The root canals of experimental groups were instrumented according to the manufacturers’ instructions by using manual technique, Mtwo NiTi rotary system and V (variable) taper rotary instruments .Sterilized saline was used as an irrigant and bacterial extrusion was quantified as colony-forming units/milliliter. Results obtained were statistically analysed with suitable statistical test.