Introduction:Three-dimensional obturation of the root canal system is the final objective of root canal therapy. Greater penetration of sealer in root dentine lesser will be the voids at the dentine–sealer interface. Hence, analysis of the dentin/sealer interface allows the determination of a filling technique which could obturate the root canals with least gaps and voids. Therefore, the aim of this study is to compare the depth and percentage of sealer penetration into root dentin using three different root canal sealer placement techniques under confocal laser scanning microscope.Materials and Methods:Thirty single-rooted teeth were selected and prepared. Adseal sealer (Meta Biomed, South Korea) was mixed with Rhodamine B dye and applied using lentulo spiral (Dentsply Maillefer, USA) as Group 1, bidirectional spiral (EZ-Fill– EDS, USA) as Group 2, and ultrasonic endodontic tip (Sonofile– Dentsply Tulsa, USA) as Group 3. Canals were then obturated with gutta-percha. The roots were sectioned at the 3 and 6-mm levels from the apical foramen and examined under confocal laser microscope.Results:Maximum mean depth and percentage of sealer penetration were observed for Group 1 and minimum for Group 3. Furthermore, statistical significant differences among Group 1 and Group 3 were found at 6-mm level and among Group 2 and Group 3 were found at 3-mm level (P < 0.05).Conclusion:The depth and percentage of sealer penetration of sealer are influenced by the type of placement technique and by the root canal level, with penetration decreasing apically. Lentulo spiral has shown better penetration of sealer than the bidirectional file and ultrasonics.