Background: Sealers are universally used along with gutta-percha to obturate the root canals in three dimensions. Push-out bond strength is considered appropriate to measure the adhesion capacity of sealers. Aim: To compare the bond strength of recently introduced bioceramic sealer with commonly used sealers and to evaluate the effect of plunger: base orifice size ratio on push-out bond strength. Methods: One hundred mandibular premolars with single canals were decoronated and instrumented up to master apical file F3 Protaper. Specimens were randomly divided into four groups (n=25) based on the sealer used: Group 1-EndoSequence BC Sealer, Group 2-MTA FillApex sealer, Group3-Apexit Plus sealer & Group 4-AH Plus sealer and obturated using cold lateral compaction technique. After two weeks, 1±0.1mm thick slice of each radicular third of specimens was subjected to push-out testing with modified and standardised plunger: base orifice size ratio for each slice and bond strength calculated. Subsequently the slices were observed under stereomicroscope for failure mode analysis. Results: Results showed that AH Plus sealer had the highest overall bond strength followed by EndoSequence BC sealer and MTA FillApex while as Apexit Plus had lowest bond strength. Bond strength of all sealers reduced from coronal to apical direction except in EndoSequence BC sealer which showed better strength in critical apical third. Higher bond strength values were obtained due to modified relation of plunger with base orifice size. Conclusion: Bond strength of all sealers tested except EndoSequence BC reduces in apical direction and is impacted by plunger: base orifice size ratio.

Background: A sealer is required during obturation to fill space between gutta-percha and canal walls. It provides an impervious seal, fills the irregularities and minor discrepancies between the root canal wall and core filling material, and assists in microbial control. Aim: To evaluate the penetration depth and percentage area of a root canal sealer placed by five different techniques using confocal laser scanning microscope (CLSM). In our study we compared ultrasonic, endoactivator (sonic device), lentulospiral (rotary) and master gutta-percha with NiTi spreader in reciprocating hand piece for sealer placement using AH Plus sealer. Methods: Thirty extracted then decoronated and standardised mandibular premolars were prepared by Protaper rotary files up to master apical file F3. Samples were randomly divided into five groups for sealer placement; Group 1, Ultrasonic file; Group 2, Endoactivator; Group 3, Reciprocating hand piece with NiTi spreader; Group 4, Rotary Lentulospiral; Group 5, Master apical gutta-percha .Two root sections from apical and coronal third were analysed for sealer distribution and depth of sealer penetration by confocal microscope, using the ruler tool of the IOB software (Olympus). Results: Results showed that maximum depth and percentage of sealer penetration is shown by Group 1; ultrasonic file and least by Group 5; master apical gutta-percha both at apical as well as coronal levels. Conclusion: Sealer penetration is influenced by placement method and new method of using reciprocating NiTi spreader was comparable to ultrasonic method which showed best sealer penetration and distribution.