Influence of intracanal medicaments on dentinal tubule penetration and bond strength of bioceramic sealers: a confocal laser scanning microscopy and push-out study

BACKGROUND: To evaluate the effects of commonly used intracanal medicaments on the dentinal tubule penetration and push-out bond strength of two bioceramic sealers. METHODS: Eighty extracted single-rooted mandibular premolars were instrumented using sodium hypochlorite and ethylenediaminetetraacetic acid. The specimens were randomly assigned to four groups (n = 20): no medicament, double antibiotic paste, 2% chlorhexidine gel, and calcium hydroxide. After 14 days, medicaments were removed and samples were subdivided according to the sealer used (NeoSealer Flo or BioRoot RCS) labeled with Rhodamine B (n = 10). Sections from the coronal, middle, and apical thirds were analyzed using confocal laser scanning microscopy to evaluate penetration parameters. Push-out bond strength was also measured. Statistical analysis was performed using appropriate tests with a significance level set at p < 0.05. RESULTS: Compared with the other medicaments, 2% chlorhexidine gel produced significantly lower penetration values (p < 0.001). NeoSealer Flo demonstrated greater dentinal tubule penetration and bond strength than BioRoot RCS (p = 0.012 and p < 0.001). Penetration was highest in the coronal third, whereas bond strength was greatest in the apical third. The control group presented the highest bond strength, whereas calcium hydroxide significantly reduced the dislodgement resistance (p = 0.008). Greater dentinal tubule penetration did not consistently correspond to higher push-out bond strength. CONCLUSIONS: Intracanal medicaments significantly influence the dentinal tubule penetration and bond strength of bioceramic sealers. However, greater tubular penetration does not necessarily correspond to improved dislodgement resistance. These findings suggest that sealer-dentin interaction may depend more on interfacial adaptation and chemical interaction than on penetration depth alone, with potential implications for material selection in endodontic treatment.