Effect of Er:YAG laser treatment on the root canal walls of human teeth: an SEM study

The purposes of the study were to observe the morphological changes on root canal walls after instrumentation and irrigation, and assess the efficacy of conventional cleansing procedures and the effectiveness of Er:YAG laser in removing debris and smear layer from the root canal walls. Thirty-six endodontically treated human mandibular incisor teeth with single root canals were bisected longitudinally and divided into three groups of 12 teeth. Group 1 (G1) was left unlased as a control. The teeth of group 2 (G2 and group 3 (G3) were irradiated by Er:YAG laser (laser parameters were set at 1 W, 100 mJ/pulse and 10 Hz) for 3 s and 5 s. The teeth were prepared for scanning electron microscope study. Control specimens showed debris and heavy smear layer obscuring the dentinal tubules at all levels in the canals. The root canal walls irradiated by Er:YAG laser were free of debris, with an evaporated smear layer and open dentinal tubules. These results suggested that Er:YAG laser irradiation had an efficient cleaning effect on the prepared root canal walls.