Antibacterial Effects of Nd:YAG Laser Irradiation within Root Canal Dentin

ABSTRACT The microbial flora of the root canal dentin can cause failures in the conventional treatment of infected root canals if it cannot be sufficiently removed by preparation and chemical disinfection of the root canal. The aim of this study is to examine the bactericidal effects of neodymium:y ttriumaluminum garnet (Nd:YAG) laser irradiation in the depth of the root canal dentin. Following sterilization, longitudinal section dentin slices of different thicknesses (100–1000 μm) were inoculated on one side with 4 μl of a Streptococcus mutans suspension. The opposite sides of the dentin slices were then irradiated four times for 10–20 sec (according to the sample area) using the Nd:YAG laser at a setting of 1.5 W, 15 pps with a 200 μm glass fiber from an angle of about 5°. The bacteria were then removed from the dentin using vibration and plated out on culture dishes that were selective for Streptococcus mutans. When compared with untreated control slices, counting of the colonies revealed a highly sign...