###### Abstract  
This study compared the push-out bond strength and adaptation of the recently developed AH Plus bioceramic (AHP-Bio) root canal sealer with Bioceramic Endosequence (BC) and AH Plus (AHP) sealers when exposed to simulated body fluid for inducing bioactivity. Cross-section discs of 1 mm thick slices from obutrated root canals were prepared and either kept dry or immersed in serum for 30 days. All discs were evaluated using scanning electron microscopy (SEM) and then subjected to a push-out test. The failure modes were also determined. The data were statistically analyzed using an ANOVA test at \(p<0.05\). In both environments, the BC sealer recorded the greatest bond strength, while the AHP-Bio sealer recorded the lowest mean values. However, bond strength was significantly improved after immersion in serum (\(p<0.001\)). The chi-square test and [PERSON]'s exact test revealed a significant difference in failure mode among the tested groups at \(p<0.001\). The predominant failure mode was cohesive failure in both bioceramic sealers, with the greatest value for AHP-Bio (70%), and adhesive failure for AHP/gutta-percha (60%, 80%) in both environments. SEM revealed good dentin adaptation of the three sealers, with marked decreases in gaps at the bioceramic/dentin interface after immersion in serum. In conclusion, although BC exhibited greater push-out bond strength than AHP-Bio, the latter achieved good displacement resistance that increased when the sealer was exposed to simulated body fluid (serum). AHP Plus bioceramic sealer; push-out bond strength of root canal sealers; bioactivity; displacement resistance; BC Endosequence; AH Plus +
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by increasing the adaptability at the sealer/dentin contact [8]. However, AHP does not demonstrate bioactivity and has been shown to fail to form an apatite layer [9]. Bioceramic Endosequence (BC) has been extensively used since 2009 because of its biological and bioactivity characteristics [9; 10]. As a premixed, injectable paste composed of calcium silicate, calcium phosphate, calcium hydroxide and zirconium oxide [9; 11; 12], BC is a hydraulic cement that uses the fluid inside the dentinal tubules to harden [10; 11]. Although it has superior antibacterial, biocompatibility, tissue inductivity, bioactivity and flowability properties [9; 10; 13], the high solubility of BC is its main drawback compared with epoxy resin sealers [11; 14]. To improve the performance of bioceramic sealers, the manufacturer Dentsply Sirona launched a new type of AHP bioceramic (AHP-Bio) root canal sealer containing both bioactive bioceramic compounds and AHP resin particles [15]. AHP-Bio is a premixed injectable paste composed of tricalcium silicate, dimethyl sulfoxide, lithium carbonate, zirconium oxide and thickening agents. Similar to all bioceramics, AHP-Bio is a hydrophilic sealer that solidifies in the presence of a moist environment [15; 16]. As claimed by the manufacturer, this new sealer offers adequate adhesion and bioactivity when the sealer contact simulates tissue fluids [15; 16]. The manufacturer also reports that AHP-Bio has improved solubility [15]. Good adhesion and adaptation are important properties for root canal obturation, which depends mainly on the sealer. The assessment of interfacial bond strength between the sealer and radicular dentin is clinically relevant to the adhesive quality of the root canal sealer. Push-out bond strength is regarded as a significant diagnostic factor for evaluating sealer/dentin adhesion [17]. Scanning electron microscopy is the best method to evaluate the adaptation of root canal obturation. It is effective for detecting the degree of sealer penetration within dentinal tubules, the formation of tag-like structures and the presence or absence of voids at the sealer/dentin interface that compromise the degree of adaptation, and can be responsible for easy obturation displacement [18]. There is a lack of information about the adhesion ability of the AHP-Bio sealer to radicular dentin.