Smear layer removal ability and antibacterial activity of endodontic irrigants

Abstract

The aim of this study was to test various alternating sequences of sodium hypochlorite (NaOCl), anolyte solution, and EDTA for their ability to remove the mineralised portion of the smear layer, and to destroy bacteria. Forty-eight single canal teeth were collected and randomly divided into six groups, prepared to working length, sterilized and inoculated with Enterococcus faecalis. The irrigation protocols were as follows: Group 1 (four roots) 3ml sterile distilled water, Group 2 (four roots) 3ml 6% sodium hypochlorite, Group 3 (ten roots) 3ml 6% sodium hypochlorite followed by 3ml 18% EDTA, Group 4 (ten roots) 3ml 6% sodium hypochlorite followed by 5ml anolyte solution, Group 5 (ten roots) 0.5ml 6% sodium hypochlorite followed by 5ml anolyte solution followed by 3ml 18% EDTA and Group 6 (ten roots) 5ml anolyte solution followed by 3ml 18% EDTA. Sterile paper points were inserted into the canals after sterilization, inoculation and irrigation. Standard cultivation techniques were used to count the colony forming units of viable bacteria at each phase. The roots were split longitudinally and prepared for SEM evaluation. Two photomicrographs were randomly taken in the coronal, middle and iv apical thirds of each root and the number of patent dentinal tubules counted. The One-way ANOVA was used for statistical evaluation. The small sample size limited definitive conclusions but the results indicated that the coronal thirds of the roots showed better smear layer removal than the apical thirds, Sodium hypochlorite followed by EDTA showed the best smear layer removal. The various sequences of NaOCl, anolyte solution, and EDTA all had similar antibacterial results.