Evaluation of the effect of different intracanal medicaments on the penetration and bond strength of two bioceramic-based sealers into dentin tubules: A confocal microscopy study

Objective: This study aimed to evaluate the effects of different intracanal medicaments on the dentinal tubule penetration and push-out bond strength of two bioceramic root canal sealers. Materials and Methods: Eighty extracted single-rooted mandibular premolars were included in this study. The samples were assigned to four different medicament groups: control, double antibiotic paste (DAP), 2% chlorhexidine gel, and calcium hydroxide [Ca(OH)₂]. Within each group, the root canals were filled with either NeoSealer Flo or BioRoot RCS, resulting in eight experimental groups (n=10 per group). To enable visualization under the confocal microscope, 0.1% Rhodamine B dye was added to the sealers. Following obturation, each root was carefully sliced into three 2 mm-thick sections representing the coronal, middle, and apical thirds. Sealer penetration was assessed under the confocal microscope, while bond strength was evaluated using the push-out test. The data were analyzed using three-way ANOVA followed by Bonferroni post-hoc tests, with statistical significance set at p<0.05. Results: The findings revealed that the type of medicament, the sealer used, and the section level all had a meaningful impact on both sealer penetration and bond strength (p<0.05). Among the groups, the chlorhexidine gel group consistently showed the lowest values for maximum and average penetration depth, as well as penetration area—and these differences were statistically significant compared to the other medicaments (p<0.001). NeoSealer Flo performed significantly better than BioRoot RCS, offering higher mean penetration (p=0.012) and bond strength (p<0.001). When looking at different root levels, penetration was highest in the coronal section, while bond strength was highest in the apical section (p<0.001 and p=0.012, respectively). The control group showed the highest bond strength overall, whereas the calcium hydroxide group exhibited significantly lower values (p=0.008). Conclusion: The results suggest that the choice of intracanal medicament plays a key role in how well the sealer can penetrate the dentin and bond to the canal walls. NeoSealer Flo showed better performance compared to BioRoot RCS, whereas chlorhexidine gel appeared to interfere with the sealer–dentin interface. Keywords: bioceramic root canal sealer; tubular penetration; bond strength; confocal laser scanning microscopy; intracanal medicament