ANTIBACTERIAL EFFECT OF Er,Cr:YSGG LASER UNDER VARIOUS IRRADIATION CONDITIONS IN ROOT CANALS CONTAMINATED WITH ENTEROCOCCUS FAECALIS

INTRODUCTION: The fundamental aim of endodontic therapy is to completely disinfect the root canal and its three-dimensional tubular network. OBJECTIVES: This in-vitro study compared the antibacterial effect of intracanal irradiation with Er,Cr:YSGG laser in dry condition to laser activated irrigation in root canals contaminated with Enterococcus faecalis.MATERIALS AND METHODS: Twenty-six extracted human single-canaled lower bicuspids were used. Teeth were instrumented and autoclaved, and then three specimens were randomly chosen to serve as negative control. The remaining specimens were inoculated with Enterococcus faecalis for two weeks and then additional three specimens were selected to serve as positive control. The remaining specimens were divided into two equal experimental groups according to the disinfection procedure, Group I: Dry Laser Irradiation, Group II: Laser Activated Irrigation. Bacterial sampling was collected by both paper points and dentin chips from the canal walls and analyzed for the presence of Enterococcus faecalis using culture method. The CFU% reduction of each group was determined in relation to the positive control. RESULTS: For the paper points method of sampling, a statistically significant difference was found between group II (99.60%) and group I (82.50%) (P=0.012). While for the dentin chips method, a statistically significant difference was found between group II (100.00%) and group I (50.00%) (P=0.005).CONCLUSIONS: Er,Cr:YSGG dry laser irradiation is not an alternative but a possible supplement to existing protocols for root canal disinfection. The use of NaOCl together with Er,Cr:YSGG laser activation yields superior disinfecting results.