Influence of calcium hydroxide/nano-chitosan as intracanal medication on push-out bond strength of epoxy resin and bioceramic sealers: an ex-vivo study

BACKGROUND: The present study aimed to evaluate the impact of intracanal medicaments-calcium hydroxide (CH) and calcium hydroxide/nano-chitosan (CH/NC)-on the push-out bond strength (POBS) of AH Plus (AHP) and NeoSEALER Flo (NSF). METHODS: Nano-chitosan (NC) characterization was done using transmission electron microscopy (TEM), dynamic light scattering (DLS) and zeta potential analysis. Sixty extracted maxillary central incisors were instrumented up to X5 (50/0.06). Based on intracanal medicament used, specimens were allocated into three groups (n = 20): Group I; no intracanal medicament (control), Group II; (CH), and Group III; (CH/NC). Intracanal medicaments were removed after one week of incubation. Each group was subdivided based on sealer used (n = 10): subgroup A (AHP) and subgroup B (NSF). Obturation was performed with cold lateral compaction. After one week of incubation, roots were sectioned and a universal testing machine was used to evaluate POBS. Three-way ANOVA and Chi-square tests were conducted at 0.05 significance level. RESULTS: TEM showed mostly spherical NC particles with diameters less than 50 nm. DLS analysis revealed a hydrodynamic Z-average diameter of 62.4 nm with a polydispersity index of 0.195. Zeta potential analysis demonstrated a positive surface charge of + 47.57 mV. The "medication" factor, "medication/sealer", "medication/root level" and "sealer/root level" interactions significantly affected POBS (P < 0.05). Neither "sealer" nor "root level" factors significantly affected POBS (P > 0.05). Pooled POBS data revealed that: IA and IB subgroups were significantly higher than IIA, IIB, IIIA and IIIB subgroups (P < 0.05). Regarding failure mode, tested subgroups showed no significant difference (P > 0.05). CONCLUSIONS: Under the conditions of this study, prior application of CH or CH/NC reduced POBS for both sealers compared with controls. The addition of NC to CH did not provide a statistically significant improvement in POBS compared to CH alone. Overall, AHP and NSF demonstrated comparable POBS to root canal dentin.