Aim. To evaluate the cleaning ability of two single-file rotary systems- Self-Adjusting File (SAF) and Wave one (WO) systems in removing the smear layer using sodium hypochlorite (NaOCl) + ethylene diamine tetraacetic acid (EDTA) and NaOCl + Qmix as irrigants at apical one-third of the root canal. Methods. Forty extracted human mandibular premolars were selected and working length was determined. The canal was manually instrumented up to a number 25 size K-file. The roots were divided into the following groups with 10 samples each – Group 1 using SAF: Group 1a- 3% NaOCl + 17% EDTA, Group 1b- 3% NaOCl + Qmix. Group2 using WO: Group 2a- 3% NaOCl + 17% EDTA, Group 2b- 3% NaOCl + Qmix. In the SAF group, the irrigation was performed continuously using the special irrigation apparatus. In the WO group, syringe irrigation was done followed by final irrigant activation using passive ultrasonic irrigation (PUI). The roots were sectioned longitudinally and subjected to scanning electron microscopic (SEM) examination. The amount of smear layer was evaluated using a five score index at the apical third level. Statistical analysis was performed using the Chi-square test. Results. Group 1 (SAF) showed better canal cleanliness at apical third compared to Group 2 (WO) with both irrigant combinations and the results were statistically significant (p<0.05). 3% NaOCl + Qmix was equally as effective as 3% NaOCl + 17% EDTA in removing the smear layer with no significant difference between them. Conclusion. Within the limitation of this study, SAF in combination with 3% NaOCl + Qmix or 3% NaOCl + 17% EDTA should be used for removing smear layer in critical areas of the root canal.

Aim: To compare the effect of smear layer removal with 17% EDTA and Nd:YAG laser on the apical microleakage of two resin based sealers. Materials and Methods: Sixty freshly extracted maxillary central incisor teeth with patent canals were selected. The teeth were debrided and stored in saline for 24 hours before use. The teeth were sectioned at CEJ & cleaning and shaping were done upto 50 size by step back technique. The following groups were analyzed. GROUP 1:  Gutta percha (GP) + AH plus sealer without smear layer removal. GROUP 2:  GP + RC seal sealer without smear layer removal. GROUP 3:  GP + AH plus treated with 17% EDTA. GROUP 4:  GP + RC seal treated with 17% EDTA. GROUP 5:  GP + AH plus treated with Nd:YAG laser. GROUP 6:  GP + RC seal treated with Nd:YAG laser. 8 samples were subjected to dye penetration study for apical microleakage & 2 samples were subjected to SEM in each group to show the effect of smear layer removal by EDTA and laser. The data were analyzed by using ANOVA and TUKEY-HSD test. Results: Groups 1 and 2 showed maximum microleakage , other groups showed lesser microleakage but there was no statistically significant difference between laser and EDTA treated Groups.  Conclusion: EDTA and Nd:YAG laser can be effectively used to  remove smear layer and showed less apical microleakage compared to non-treated groups. Keywords: 17% EDTA, Nd:YAG LASER , AH plus , RC sealer ,  Smear layer.