Aim To evaluate ex vivo the effectiveness of single-file instrumentation techniques compared with serial Ni-Ti rotary instrumentation with several irrigation regimens in reducing E.faecalis within root canals.
Methodology A total of 81 extracted human mandibular premolar teeth with a single root canal were infected with E.faecalis before and after canal preparation. Samples were divided randomly into 9 groups, as follows: group 1-A: sterile phosphate-buffered saline+Self-adjusting file, group 1-B: 5% sodium hypochlorite+15% EDTA+Self-adjusting file, group 1-C: 5% sodium hypochlorite+7% maleic acid+ Self-adjusting file, group 2-A: sterile phosphate-buffered saline +Reciproc (R25), group 2-B: 5% sodium hypochlorite+15% EDTA+Reciproc (R25), group 2-C: 5% sodium hypochlorite+7% maleic acid+Reciproc (R25), group 3-A: sterile phosphate-buffered saline+ ProTaper, group 3-B: 5% sodium hypochlorite+15% EDTA+ProTaper, group 3-C: 5% sodium hypochlorite+7% maleic acid+ProTaper. anova was used to analyse statistically the differences in terms of reduction in colony counts between the groups, and Dunn's post hoc test was used for multiple comparisons.
Results All techniques and irrigation regimens significantly reduced the number of bacterial cells in the root canal (P<0.001). Comparisons amongst the groups revealed significant differences between group 1A (sterile phosphate-buffered saline+Self-adjusting file)/group 1B (5% sodium hypochlorite+15% EDTA+Self-adjusting file) (P=0.031), group 1A (sterile phosphate-buffered saline+Self-adjusting file)/group 2C (5% sodium hypochlorite+7% maleic acid+Reciproc) (P=0.003), group 2A (sterile phosphate-buffered saline+Reciproc)/group 3B (5% sodium hypochlorite+15% EDTA + ProTaper) (P=0.036), group 3B (5% sodium hypochlorite+15% EDTA+ProTaper)/group 1A (sterile phosphate-buffered saline+Self-adjusting file) (P<0.001), and group 3C (5% sodium hypochlorite+7% maleic acid+ProTaper)/group 1A (sterile phosphate-buffered saline+Self-adjusting file) (P=0.033).
Conclusions No significant differences in terms of reduction in microbial counts were observed between single-file techniques (SAF and Reciproc) and serial Ni-Ti instrumentation technique (ProTaper) in combination with irrigants.