Comparative study of apical extrusion of intracanal bacteria using different instruments and techniques : in vitro study

Background : To compare the number of bacteria extruded apically from extracted teeth after canal instrumentation using the nickel-titanium instruments (both Hand & Rotary ProTaper) and hand Stainless Steel instruments. Methodology : sixty extracted single-rooted human teeth were used. Access opening was prepared and root canals were then contaminated with a suspension of Enterococcus faecalis. The contaminated roots were divided into three experimental groups of 20 teeth. Group 1, Rotary ProTaper group : the root canals were instrumented using Rotary ProTaper instruments. Group 2, Hand ProTaper group : the root canals were instrumented using Hand ProTaper instruments. Group 3, Hand Stainless Steel instruments group : the root canals were instrumented using Hand Stainless Steel instruments. Bacteria extruded from the apical foramen during instrumentation were collected into vials. The microbiological samples from the vials were incubated in culture media for 24 h. Colonies of bacteria were counted and the results were given as number of colony-forming units. The data obtained were analysed using the one-way ANOVA analysis of variance and ttests p value 0.05 as the level for statistical significance. Results : There was no significant difference to the number of extruded bacteria between the Rotary & Hand (P>0.05 Non significant) but there was significant difference between Rotary & Hand ProTaper and Hand Stainless Steel instruments (P < 0.05). Conclusions : Hand Stainless Steel instruments extruded more bacteria apically than Rotary & Hand ProTaper.