Comparative analysis of heat impacts on bond strength and failure modes of calcium silicate- and epoxy resin-based sealers

A hermetic seal is essential for successful root canal therapy. Sealers fill the interface between gutta-percha and dentin, improving adaptation and sealing ability. This study aimed to evaluate the effect of heat on the push-out bond strength and failure modes of calcium silicate- and epoxy resin-based sealers.

Thirty-two extracted human premolars with single straight canals were prepared and randomly assigned to two sealer groups (AH Plus, NeoSEALER Flo). Each group was further subdivided based on obturation technique: cold lateral condensation (CLC) or warm vertical compaction (WVC). Root slices from the coronal, middle, and apical thirds were subjected to a push-out test. Failure modes were classified as adhesive, cohesive, or mixed under stereomicroscopy. Data were analyzed using three-way ANOVA and multinomial mixed models with significance set at p < 0.05.

NeoSEALER Flo showed significantly higher bond strength than AH Plus across all root levels and techniques (p < 0.001). Heat application during WVC reduced the bond strength of AH Plus but had no effect on NeoSEALER Flo. In both sealers, the apical third exhibited the highest bond strength, followed by the middle and coronal thirds. Failure analysis revealed predominantly cohesive failures for NeoSEALER Flo, while AH Plus showed more adhesive and mixed failures under heat application.

NeoSEALER Flo provided superior bond strength and stability regardless of obturation technique. Heat negatively influenced AH Plus but not NeoSEALER Flo, supporting the clinical advantages of calcium silicate-based sealers.

The findings of this in vitro study suggest that calcium silicate-based sealers may provide improved bond strength and stability compared to epoxy resin-based sealers under different obturation techniques. However, further clinical studies are required to confirm these results under in vivo conditions.