Comparison of effectiveness of Reciproc, Wave One, Protaper, and One Shape rotary instruments in reduction of bacterial load in root canals

Aim: To compare the effectiveness of Reciproc, Wave One, Protaper, and One Shape rotary instruments in reduction of E. faecalis in root canals. Methodology: In this in-vitro study, after initial stages of canal enlargement and irrigation, a suspension containing Entrococcus faecalis was inoculated into the root canals of 84 extracted single-canal premolars. The samples (apart from 2 positive and 2 negative controls) were randomly assigned into 4 groups according to rotary instruments used: Reciproc, Wave One, One Shape, Protaper. Each group was then subdivided to 2 groups based on irrigating solutions of normal saline and NaOCl. After instrumentation, the root canals were filled with brain-heart infusion (BHI) broth. Finally bacterial colony forming units (CFU) were counted. Results: Reduction in number of bacterial colonies before and after instrumentation and irrigation was not significantly different in different rotary instrument systems (P=0.128, F=1.955). However, NaOCl was more effective in reduction of bacterial load compared to normal saline (P<0.001, F=15.528). Conclusions: All rotary instruments used in the study are effective in reduction of the bacterial load.