Bactericidal effect of KTP laser irradiation against Enterococcus faecalis compared with gaseous ozone: an ex vivo study

Objective The objective of this study was to evaluate the antimicrobial activity of potassium-titanyl-phosphate (KTP) laser and gaseous ozone in experimentally infected root canals. Study design Eighty single-rooted teeth with straight canals were selected. After preparation and sterilization, the specimens were inoculated with 10 μL Enterococcus faecalis for 24 hours at 37°C. The contaminated roots were divided into 2 experimental groups, 1 negative control group, and 1 positive control group of 20 teeth each: Group 1, KTP laser group; Group 2, gaseous ozone group; Group 3, sodium hypochlorite group (NaOCl) (negative control); and Group 4, saline group (positive control). Sterile paper points used to sample bacteria from the root canals were transferred to tubes containing 5 mL of brain heart infusion broth. Then 10-μL suspension was inoculated onto blood agar plates. The colonies of bacteria were counted and data were analyzed statistically using Kruskal-Wallis 1-way analysis of variance and Mann-Whitney U tests. Results There were statistically significant differences between all groups ( P < .05). The saline group had the highest number of remaining microorganisms. Complete sterilization was achieved in the 2.5% NaOCl group. The KTP laser and gaseous ozone did not completely sterilize the root canals. Conclusion Both KTP laser and gaseous ozone have a significant antibacterial effect on infected root canals, with the gaseous ozone being more effective than the KTP laser. However, 2.5% NaOCl was superior in its antimicrobial abilities compared with KTP laser and gaseous ozone.