Evaluation of antimicrobial efficacy of laser and ozone against in root canal disinfection

The aim of this study was to evaluate the antimicrobial efficacy of laser and ozone against Enterococcus faecalis (E. faecalis) in root canal disinfection. In our study, 132 human root with single canal (permanent mandibular premolars) were used. The teeth were kept in sterile saline solution at 4 degrees until the study was performed. Crowns and roots of the teeth were separated and root length were set as 16±1 mm. The working length was adjusted 1 mm back from the apical foramen. Reciproc rotary instruments were used for instrumentation. The smear layer, which was produced by preparation, was removed by 10 ml 17% EDTA, 10 ml 2,5% NaOCl solutions and 10 ml distilled water irrigation. Dried with sterile paper cones. Thereafter specimens were sterilized by autoclaving the specimens at 121°C for 20 minutes. Roots were randomly divided into 11 groups (n =10). All groups were incubated with E. faecalis (ATCC 29212) strain for 24 hours in a 37°C. The treatment protocols applied in the experimental groups are as follows; Group 1: 2,5% NaOCL (5 ml); Group 2: 2% CHX (5ml); Group 3: 2,5% NaOCl (5 ml)+laser (PIPS) (3x20 sec); Group 4: 2% CHX (5 ml)+laser (PIPS) (3x20 sec); Group 5: ozone; Group 6: 2,5% NaOCl (5 ml)+ozone (24 sec); Group 7: 2% CHX (5 ml)+ozone (24 sec); Group 8: 2,5% NaOCl (5 ml)+EndoActivator (60 sec); Group 9: 2% CHX (5ml)+EndoActivator (60 sec); Group 10: Control group; Group 11: Sterility control group. After disinfection protocols, 5 ml of 0,9% sterile saline solution was applied to collect microbiological samples from root canals. Sterile paper cones were placed in root canals for 60 seconds and transferred to eppendurf tubes with neutralizing solutions. The samples were sent to the microbiology laboratory to evaluate the change in the number of microorganisms. After microbiological evaluation, colony forming units (CFU) were counted from each specimen and the obtained data were evaluated statistically. Samples were also evaluated by scanning electron microscopy (SEM). After microbiological evaluation, colony forming units (CFU) were counted for each channel sample and the obtained data were transferred to SPSS 20.0 computer program and evaluated statistically by one-way Anova (p <0.05) test. Samples of each group were also examined by scanning electron microscopy (SEM) (JEOL_JSM 5200 Tokyo, Japan) and photographed for evaluation of bacterial accumulation and surface properties. As a result of statistical analysis, 2,5% NaOCl+laser group (Group 3) showed the most effective antibacterial properties against E. faecalis and complete elimination was achieved. The difference between CFU / ml values in the 2% CHX + laser (Group 4), 2,5% NaOCl + ozone (Group 6) and 2,5% NaOCl + EndoActivator (Group 8) groups was not statistically significant (p = 0.56 and p = 0.855). In the SEM analysis of the study, it was observed that after the laser application, a very irregular structure was formed due to the laser light and the smear layer in the root canals was removed. Laser removal of the smear layer from the root canal walls is considered to be an important advantage of the technique. With in the limitations of these results, it was concluded that 2,5% NaOCI activation by Er:YAG laser increase the antibacterial effect when used alone. Application of ozone and EndoActivator in combination with the respective irrigant agents may be an alternative of choice to laser but more studies are needed on this subject. Keywords: Enterococcus faecalis; Laser İnduced Activation; Ozone, EndoActivator.