A Comparison of Apical Bacterial Extrusion in Manual, ProTaper Rotary, and One Shape Rotary Instrumentation Techniques

• Apical extrusion is an inherent limitation associated with cleaning and shaping of root canals.
• Many factors affect apical extrusion such as, instrumentation technique, instrument type, instrument size, and so on.
• Manual step-back technique extrudes more bacteria than the engine-driven systems.
• ProTaper rotary extruded significantly more bacteria than One Shape rotary system.
• One Shape single-file system presents an attractive economic approach to prepare canals in minimal time with conventional endodontic motors, while minimizing apical extrusion.

IntroductionApical 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, multiple-file continuous rotary system (ProTaper) and single-file continuous rotary system (One Shape).MethodsForty-two human mandibular premolars were inoculated with Enterococcus faecalis by using a bacterial extrusion model. The teeth were divided into 3 experimental groups (n = 12) and 1 control group (n = 6). The root canals of experimental groups were instrumented according to the manufacturers' instructions by using manual technique, ProTaper rotary system, or One Shape rotary system. Sterilized saline was used as an irrigant, and bacterial extrusion was quantified as colony-forming units/milliliter. The results obtained were statistically analyzed by using one-way analysis of variance for intergroup comparison and post hoc Tukey test for pair-wise comparison. The level for accepting statistical significance was set at P < .05.ResultsAll the instrumentation techniques resulted in bacterial extrusion, with manual step-back technique exhibiting significantly more bacterial extrusion than the engine-driven systems. Of the 2 engine-driven systems, ProTaper rotary extruded significantly more bacteria than One Shape rotary system (P < .05).ConclusionsThe engine-driven nickel-titanium systems were associated with less apical extrusion. The instrument design may play a role in amount of extrusion.