Evaluation of er:Yag laser combined with nd:Yag laser's bactericidal effect against enterococcus faecalis biofilm in curved root canals

The aim of this study was to evaluate Er:YAG laser combined with Nd:YAG laser's bactericidal effect against Enterococcus Faecalis biofilm in curved root canals. In our study 65 human permanent maxillary molar and mandibular molar teeth were used. So that the tilt was included for the purposes of research work in changing teeth 15 to 30 degrees, the other teeth were eliminated. Crowns and roots of the teeth were separated and root length were determined to be 12-14 mm. ProTaper root canal instruments were used for preparing root canals. The smear layer, which was produced by preparation, was removed by 10 ml 17% EDTA, 10 ml 5% NaOCl solutions and 10 ml distilled water irrigation. Thereafter specimens were sterilized by autoclaving 121°C for 20 minutes. 5 root canals samples, which were inoculated with sterile BHI, were used for determining sterilization of working conditions. The roots were randomly divided into 5 test groups (n=10) and 1 control group (n=10). All roots were infected for 3 weeks with E. faecalis (ATCC 29212) strain. No treatment was applied to samples of control group. Treatment protocols applied in the experimental groups; Group 1: 5% NaOCl; Group 2: Saline and Er:YAG laser; Group 3: %5 NaOCl and Er:YAG laser; Group 4: %2 CHX and Er:YAG laser and Group 5: Saline, Er:YAG laser and Nd:YAG laser. Each root canals were irrigated with 1 ml physiologic saline to colllect microbiologic samples from root canals. Dentine chips were created using in sequence #20 K-file and #20 H-file, sterile paper points will be held in root canals for 60 seconds to collect dentin chips. Samples, which was collecting root canals, transferred to sterile centrifuge tubes containing 1 ml sterile saline. The received samples were sent to microbiology laboratory for evaluation of quantitative changes in microorganisms. After the microbiological evaluation CFU were enumerated for every root canal sample, the data was analyzed statistically. As a result of analysis performed, 5% NaOCl, %5 NaOCl and Er:YAG laser and %2 CHX and Er:YAG laser groups were found to be the most efficient antibacterial effect againts E. faecalis biofilm. Saline and Er:YAG laser and Saline, Er:YAG laser and Nd:YAG laser groups were found to show inefficient antibacterial characteristics even if they were slightly better than control group. Additionally, it was concluded using of 5% NaOCI with Er:YAG laser activation did not improve antibacterial efficacy with respect to using of 5% NaOCI alone on curved root canals. It was concluded there is a need further studies to determine the antibacterial effectiveness of PIPS system alone or along with Nd:YAG laser (Twinlight Endodontic Treatments) on curved root canals. Keywords: Curved root canals, E. faecalis, Er:YAG laser, Nd:YAG laser, Root canal disinfection