Effect of chitosan and bioactive glass nanoparticles on the push-out bond strength of epoxy resin-based sealer: an in-vitro study

Background This study evaluated the effect of incorporating chitosan nanoparticles (CHSNPs) and/or bioactive glass nanoparticles (BAGNPs) into AH Plus (AHP) on its push-out bond strength (PBS) after 7 and 90 days, with unmodified AHP as the reference formulation and TotalFill BC Sealer (TF) as an additional comparator. Methods A total of 120 straight palatal roots of extracted maxillary molars were prepared to size X4 (40/.06). The specimens were divided into five groups (n = 24 each): AHP, AHP + 10 wt% CHSNPs, AHP + 10 wt% BAGNPs, AHP + 10 wt% CHSNPs + 10 wt% BAGNPs, and TF. Each group was divided into 7- and 90-day storage subgroups (n = 12 each). After cold lateral compaction and storage, PBS was determined in a middle-third slice from each root using a universal testing machine. Data were analyzed using two-way ANOVA and the chi-square test, with the significance level set at P < 0.05. Results Sealer formulation and its interaction with storage period significantly affected PBS ( P < 0.05), whereas the main effect of storage period was not significant ( P > 0.05). At 7 days, all nanoparticle-modified AHP formulations exhibited higher PBS than unmodified AHP and TF ( P < 0.05). After 90 days, AHP and AHP + CHSNPs + BAGNPs exhibited higher PBS than AHP + CHSNPs, and all AHP-based formulations exhibited higher PBS than TF ( P < 0.05). From 7 to 90 days , PBS increased significantly in unmodified AHP and decreased significantly in AHP + CHSNPs ( P < 0.05), whereas no significant storage-related changes were detected in the remaining formulations ( P > 0.05). Conclusions Under the study conditions, CHSNPs and/or BAGNPs enhanced the early PBS of AHP, but their effects after prolonged storage were formulation-dependent. The early benefit was not maintained with CHSNPs alone, whereas BAGNP-containing formulations showed PBS comparable to unmodified AHP after 90 days. Nanoparticle-modified AHP formulations exhibited higher PBS than TF at both storage periods.