The chemomechanical preparation of root canal dentin with hand or rotary instruments creates debris and a smear layer. Root canal preparation (RCP) along with irrigants is not effective in cleaning apical portions, and hence, different laser activation systems were used for better cleaning in the apical third. Aim: The aim of this study is to compare the efficacy of erbium: yttrium-aluminum-garnet (Er:YAG) and diode laser irradiation in smear layer removal and dentin permeability after biomechanical preparation using scanning electron microscopic investigation. Material and Methods: Thirty sound single-rooted human teeth were distributed randomly and equally into three groups (n = 10 each) based upon the type of laser irradiation after RCP: Group I (control group) - RCP with ProTaper rotary system using the standard irrigating protocol; Group II - RCP with ProTaper rotary system using the standard irrigating protocol followed by diode laser irradiation; and Group III - RCP with ProTaper rotary system using the standard irrigating protocol followed by Er:YAG laser irradiation. After root sectioning, specimens were dehydrated, then gold plated and observed using a scanning electron microscopy. Then, the smear layer scores were recorded and performed using the statistical analysis. Results: Smear layer removal efficacy of Er:YAG laser was more at coronal, middle, and apical third when compared to Group I and Group II. Debris removal score of Group III (Er:YAG) was better than Group I (17% ethylenediaminetetraacetic acid) and Group II (diode). Conclusion: Er:YAG laser-activated RCP was comparatively efficient in cleaning the smear layer and dentinal tubules opening.
Keywords: 17% ethylenediaminetetraacetic acid; diode laser; erbium:yttrium–aluminum–garnet laser; hand and rotary instruments; root canal preparation; scanning electron microscope; smear layer.