In Vitro Evaluation of Intracanal Bacterial Reduction Using Two Different Instrumentation Techniques and Irrigation Regimens

Abstract

BACKGROUND Enterococcus faecalis, a facultative anaerobic Gram-positive coccus is involved in the endodontic failures. The bacterial elimination from the infected root canal is often achieved by mechanical cleaning and shaping along with irrigants. This study compares the intracanal bacterial reduction using two instrumentation techniques and irrigation regimens. METHODS 50 extracted human mandibular bicuspid teeth with single canal were decoronated at cemento-enamel junction and pulpectomy done. Working length determined and apical foramen sealed with acrylic resin and specimens autoclaved at 121 0 centigrade for 20 minutes. Samples were divided in to six groups. Group I-Hand instrumentation with 0.9% saline irrigant; Group II-Hand instrumentation with 5% sodium hypochlorite as irrigant; Group III-Rotary instrumentation with 0.9% saline irrigant; Group IV-Rotary instrumentation with 5% sodium hypochlorite as irrigant; Group V-Control-Only saline irrigation; Group VI-Samples taken immediately after sterilization. Sterilized teeth infected with E. faecalis and incubated for one day at 37 0 centigrade. Samples were collected from the canals before and after instrumentation and irrigation. The colony forming units were then counted and transformed to log numbers and analysed statistically. RESULTS The reduction in number of colony-forming units was statistically significant. Statistical analysis reveals bacterial reduction in the following order GIV>GIII>GII>GI>GV. CONCLUSION Bacterial reduction is higher with greater taper (0.06 mm/mm) instrumentation and it is enhanced with the use of 5% sodium hypochlorite compared to 0.9% saline solution.