Effect of ultrasonic activation on the intratubular penetration and pushout bond strength of five different endodontic sealers to root canal dentin – An in vitro study

Aim: The objective of the study was to assess and compare the effect of ultrasonic activation (UA) on intratubular penetration and pushout bond strength (POBS) to root canal dentin of five distinct endodontic sealers. Methods: One hundred extracted human single-rooted teeth were decoronated and standardized to 16 mm root length. After instrumentation with WaveOne Gold #45.06, the samples were divided into five groups (n = 20 each) according to sealer type: AH26, Pulp Canal Sealer (PCS), BioRoot RCS (BRS), MTA Fillapex (MTAF), and Nanoseal-S, and further subdivided into ultrasonic and nonultrasonic activation groups. Sealers were mixed with Rhodamine B dye for visualization. UA was performed using a noncutting tip, followed by obturation with WaveOne Gold gutta-percha and lateral condensation. The samples were transversely sectioned at two specific levels: 8 mm and 12 mm from the apex. Middle-third slices were analyzed under confocal laser scanning microscopy for sealer penetration, whereas coronal-third slices were subjected to POBS testing. Results: UA significantly improved both sealer penetration and bond strength (P < 0.05). BRS (73.10 µm) showed the greatest penetration, followed by AH26 (68.80 µm), with the least in PCS (48.10 µm). MTAF (55.80 µm) and Nanoseal-S (54.40 µm) demonstrated comparable penetration. For bond strength, AH26 (41.5 MPa) and BRS (39.4 MPa) performed similarly and were superior to MTAF (20.6 MPa) and Nanoseal-S (21.4 MPa), whereas PCS showed the lowest value (10.8 MPa). Conclusion: UA improved the intratubular penetration and POBS of all tested sealers. BRS showed the highest penetration, whereas AH26 and BRS exhibited superior bond strength. PCS demonstrated the weakest performance in both parameters.