Evaluation of dentinal tubule penetration of a novel nano calcium hydroxide–zinc oxide intracanal medicament: An in vitro pilot study

Background Residual microorganisms within dentinal tubules remain a key factor in persistent endodontic infections. Therefore, the ability of intracanal medicaments to effectively penetrate these tubules is critical for post-endodontic treatment success and effective long-term prognosis. Aim To evaluate and compare the dentinal tubule penetration capabilities of a novel nano calcium hydroxide–zinc oxide (NCAL + ZnO) formulation with conventional calcium hydroxide (RC CAL) and triple antibiotic paste (TAP) using confocal laser scanning microscopy (CLSM). Materials and methods Forty-five extracted single-rooted human teeth were biomechanically prepared using standardized protocols and randomly allocated into three groups (n = 15). Medicaments were labelled with rhodamine B and placed into root canals. Samples were sectioned at coronal, middle, and apical thirds and analyzed using CLSM. Penetration depth (μm) was measured and analyzed using one-way ANOVA and Tukey post hoc test (p < 0.05). Results RC CAL demonstrated the greatest penetration depths in the coronal and middle thirds, while NCAL + ZnO was the only material showing penetration in the apical third. All intergroup differences were statistically significant (p < 0.001). Conclusion The novel nano Ca(OH) 2 –ZnO formulation showed a distinct advantage in apical penetration, suggesting potential clinical relevance for improving disinfection in anatomically challenging apical regions.