Intracanal Bacterial Reduction With NiTi Rotary Versus Hand Instrumentation

Methods: Forty extracted human lower premolar teeth were used. After extirpation the teeth were autoclaved and immersed in broth inoculated with Enterococcus faecalis and incubated for 7 days to allow the infection of the dentinal tubules. The teeth were divided into four experimental groups, each comprising 10 teeth, and instrumented using ProTaper and HeroShaper, as the representatives of NiTi rotary instruments, or with a standardized and a step-back technique. The apical preparation was standardized to a size 30. Irrigation was with saline solution. The canals were sampled before and after instrumentation and samples were cultured on tryptic soy agar. Colony forming units were counted and bacterial reduction in percents was calculated. Statistical analysis was performed using ANOVA and Tukey's HSD test. The significance level was set at 0.05.

Results: All techniques tested significantly reduced the number of bacteria in the root canal. Reduction was at least 97%. However, there was no significant difference between the techniques.

Conclusions: NiTi rotary instrumentation and hand instrumentation with conventional files perform similar and effectively reduce the number of intracanal bacteria.

This study was supported by Gulhane Military Medical Academy Research Center, project number: AR/2004/72.