Bactericidal effect of Nd

Abstract

It is difficult to eliminate biofilms with routine endodontic techniques which depend on chemo-mechanical debridement. Furthermore, biofilms are very resistant to host defense and antimicrobial agents. It might be possible to eliminate biofilms remaining in the root canals of infected teeth with the use of lasers which can penetrate into the root canals. In the present study the bactericidal effect of Nd:YAG laser on biofilms of Enterococcus faecalis, which is the most common microorganism isolated from the root canals of endodontically treated teeth with refractory periradicular infections in comparison with 1% sodium hypochlorite solution was evaluated. Materials and methods: The root canals of 60 freshly extracted maxillary central incisors were chemo-mechanically prepared and after elimination of the smear layer, the teeth were sterilized. Then E. faecalis biofilms were formed within the root canals. The root canals were evaluated under SEM after 6 weeks to confirm biofilm formation. Then the teeth were randomly divided into 4 groups of 15. Group 1 samples did not undergo any interventions to serve as controls. Group 2 samples underwent a 3-W laser beam for 10 seconds. The root canals in group 3 were irrigated with 1% sodium hypochlorite for 15 minutes and then irradiated with a 3-W laser beam for 10 seconds. The root canals in group 4 were irrigated with 1% sodium hypochlorite for 15 minutes. Dentin chips were collected from the root canal walls and weighed. Then the chips were used to prepare a suspension. The classic CFU counting technique was used to determine remaining bacterial counts. Results: The bacterial counts in groups undergoing 3-W laser beam and 1% sodium hypochlorite irrigations had decreased to 54% and 2.39%, respectively. In the group undergoing 3-W laser beam plus 1% sodium hypochlorite solution no bacterial growth was observed. There were no significant differences between the control and laser groups (P>0.05). Conclusion: Based on the results of the present study, the effect of Nd:YAG laser beam on E. faecalis biofilm is less than that of sodium hypochlorite solution. A combination of laser and sodium hypochlorite results in a complete elimination of E. faecalis biofilm.