Objective:

The objective of this study was to evaluate the antimicrobial activity of different power settings of potassium-titanyl-phosphate (KTP) laser in experimentally infected root canals.

Methods:

A total of 119 freshly extracted human single-rooted teeth with mature apices were selected for study. After preparation and sterilization, the specimens were inoculated with 15 µL Enterococcus faecalis for 24 hours at 37°C. The contaminated roots were divided into five experimental groups (1W, 1.5W, 2W, 3W, and 4W KTP laser), one negative control [sodium hypoclorite (NaOCl)] group, and one positive control [sterile saline (SF)] group of 17 teeth each. Before and after applications in the groups, samples retrieved with sterile paper points from the root canal were transferred to tubes containing 5 mL of the brain heart infusion broth. Next, 10 μL of these suspensions were placed at two different sides of the blood agar medium. Bacterial reduction was counted according to the colony-forming units and data were statistically analyzed using the Kruskal–Wallis and Tukey’s tests.

Results:

The maximum decrease occurred in the 2.5% NaOCl (100%±0.00%) group. This decrease was followed by decreases in the following KTP laser groups: 4W (94.26%), 3W (87.98%), 2W (77.43%), SF (68.80%), 1.5W (65.89%), and 1W (52.08%). Statistically, the difference between the 1W KTP laser group and all groups and the difference between the 2.5% NaOCl group and all groups, except the 4W KTP laser group, were found to be significant (p<0.05).

Conclusion:

High-power KTP laser irradiation showed efficient antibacterial activity against E. faecalis.

Keywords: E. faecalis, KTP laser, root canal treatment