Push-out bond strength of bioceramic-based sealers following different irrigation activation techniques

The adhesion of root canal sealers to dentin plays a decisive role in the long-term success of endodontic treatment. Activation of irrigants before obturation has been suggested to enhance sealer penetration and bonding effectiveness. This study aimed to evaluate the effect of different irrigation activation techniques on the push-out bond strength of two bioceramic-based sealers to root dentin.

Eighty extracted human single-rooted teeth were decoronated to a standardized length and instrumented using rotary files with sodium hypochlorite irrigation. Specimens were randomly allocated into four groups according to the irrigation activation technique: conventional needle irrigation (control; lateral side-vented needle), manual dynamic agitation (MDA), EndoActivator, and EDDY (n = 20 each). Each group was further subdivided based on the sealer used-BioRoot RCS or GuttaFlow Bioseal (n = 10 each)-and obturated using the single-cone technique. The roots were sectioned into coronal, middle, and apical thirds, and push-out bond strength was measured using a universal testing machine. Failure modes were analyzed under a stereomicroscope.

A statistically significant regional variation was observed only in the EDDY-BioRoot RCS group, with the highest bond strength recorded in the coronal third (p < 0.05). In intergroup comparisons, significant differences were detected among experimental and control groups in the coronal region (p < 0.001), with the EDDY-BioRoot RCS group demonstrating superior bond strength compared to both activated and non-activated GuttaFlow groups. No statistically significant differences were observed among groups in the middle and apical thirds (p > 0.05). When data were pooled across activation protocols, BioRoot RCS exhibited significantly higher bond strength than GuttaFlow Bioseal in the coronal and middle regions (p < 0.05).

Both the irrigation activation technique and the choice of calcium silicate-based sealer significantly influence push-out bond strength, predominantly in the coronal region. Sonic activation with EDDY in combination with BioRoot RCS yields the most favorable bonding performance. The diminishing effect toward the apical region underscores the need for further optimization of activation strategies to enhance sealer-dentin adhesion throughout the entire root canal system.