Comparative Evaluation of Enterococcus faecalis Counts on Different Tapers of Rotary System with Different Irrigating Solutions: An In Vitro Study

Introduction: The conservation of tooth structure and prevention of extrusion of obturating materials have been cited as primary advantages of minimal apical enlargements. The aim of this study is to compare the effects of different rotary file tapers and two irrigating solutions and a combination of two irrigating solutions on E. faecalis counts. In this study, 84 freshly extracted single rooted single canal human premolars were selected and enlarged to ISO #20 K-file. Materials and Methods: The samples were sterilized and inoculated with E. faecalis for 72 hours, divided into six experimental groups, and prepared with #30 nickel-titanium rotary files with 0.04 and 0.06 tapers. Group I was irrigated with 2 mL of 3% sodium hypochlorite, Group 2 was irrigated with 2 mL of 2% chlorhexidine (CHX), and Group 3 was irrigated with 2 mL of a combination of 3% sodium hypochlorite, saline, and 2% CHX irrigation after each file. Cleaning efficacy was evaluated in terms of the reduction of colony forming units. Comparison of the E. faecalis among the groups at 0.04 taper was performed using the Kruskal-Wallis test after establishing normality of variance using the Shapiro-Wilk test. A comparison of the E. faecalis between 0.04 and 0.06 taper within the group was performed using the Mann-Whitney test. Results: Group 1 (3% sodium hypochlorite) and Group 3 (3% sodium hypochlorite + saline + 2% chlorhexidine gluconate) showed no statistically significant difference between the subgroups (0.04 and 0.06 taper), whereas statistically significant difference with E. faecalis was seen with respect to Group 2 between 0.04 and 0.06 taper (2% chlorhexidine gluconate). Conclusion: The study proved the use of sodium hypochlorite, saline, and CHX in combination at both 0.04 taper and 0.06 taper gave better results with no significant change.