Bond strength and dentinal tubule penetration of ready-to-use calcium silicate-based endodontic sealers

Background: The adhesion of endodontic sealers to radicular dentin is essential for the interfacial stability of root canal fillings. However, the bonding behavior, dentinal tubule interaction, and failure patterns of new premixed calcium silicate–based sealers compared with epoxy resin–based sealers remain insufficiently characterized. Purpose: This study compared push-out bond strength, dentinal tubule penetration, and failure patterns of an epoxy resin–based sealer and three premixed calcium silicate–based sealers. Materials and methods: Sixty extracted mandibular premolars were prepared and obturated with the single-cone technique using AH Plus Jet (AHPJ), BioRoot Flow (BRF), ZenSeal (ZS), or EndoCeramic (EC) (n = 12). After 30 days at 37 °C under humidity, roots were sectioned for push-out testing. Failure modes were assessed stereomicroscopically, representative samples by SEM, and additional specimens by CLSM using Rhodamine B–labeled sealers. Data were analyzed using Kruskal–Wallis, ANOVA/Tukey, and χ² tests (α = 0.05). Results: Overall push-out bond strength did not differ among sealers, regardless of root third (p > 0.05). AHPJ, BRF, and EC showed no differences among thirds (p > 0.05), whereas ZS showed higher values in the middle and apical thirds than in the cervical third (p = 0.015 and p < 0.001, respectively). Within thirds, no differences were found cervically or apically (p > 0.05); however, ZS showed higher bond strength than EC in the middle third (p = 0.006). Cohesive failures predominated, with no association between failure mode and sealer type (χ² = 1.93; p = 0.926) or root third (p > 0.05). SEM showed generally continuous interfaces with localized gaps mainly apically. CLSM showed dentinal tubule penetration for all materials, with sealer tags less evident in the apical third. Conclusion: Premixed calcium silicate–based sealers showed dentin bond strength comparable to the epoxy resin–based sealer. All materials penetrated dentinal tubules.