Mechanical reduction of the bacterial population in the root canal by three instrumentation techniques

The in vitro reduction of the bacterial population in the root canal by the mechanical action of instrumentation and irrigation was evaluated. Root ca nals inoculated with a Enterococcus faecalis suspension were instrumented u sing hand Nitiflex files, Greater Taper (GT) files, and Profile 0.06 taper Series 29 rotary instruments. Irrigation was performed using sterile saline solution. Root canals were sampled before and after instrumentation. In th e group of the Nitiflex files, samples were also taken after each file size . After serial dilution, samples were plated onto Mitis-Salivarius agar, an d the colony forming units grown were counted. All techniques and instrumen ts tested were able to reduce significantly the number of bacterial cells i n the root canal. Instrumentation to a Nitiflex #30 was significantly more effective than GT files. There were no significant differences when compari ng the effects of the Profile instrument #5 with either the GT files or the Nitiflex #30, Enlargement to a Nitiflex #40 was significantly more effecti ve in eliminating bacteria when compared with the other techniques and inst ruments tested (p < 0.05), The results of this study showed that the instru mentation and irrigation can mechanically remove more than 90% of bacterial cells from the root canal,