Thesis (M.Sc.) - Cairo University - Faculty of Oral and Dental Medicine - Department of Endodontics

Aim: This study was conducted to evaluate the effect of chitosan nanoparticles (CNPs), CNPs/EDTA (1:1), and EDTA as final irrigants on the push-out bond strength and nanoleakage of different root canal sealers. Methodology: Sixty extracted human, single-rooted mandibular premolars were prepared using ProTaper Next rotary system with 2.5% NaOCl irrigation. The specimens were randomly distributed into three groups according to the final irrigating solution; Group 1: 0.2% CNPs, Group 2: 0.2% CNPs/17% EDTA (1:1), and Group 3: 17% EDTA. A standardized volume of 5 ml of each chelating solution was used for 3 min. Each group was divided into two subgroups based on the tested sealer; AH Plus resin sealer and Sure-Seal Root bioceramic sealer. For assessment of the push-out bond strength, roots were sectioned horizontally to obtain 2 mm-thick discs from the coronal, middle and apical thirds, then discs were subjected to a compressive load via the universal testing machine followed by assessment of the failure pattern using stereomicroscope. Nanoleakage evaluation was done using a modified silver staining technique with ammoniacal silver nitrate tracer solution. Teeth were sectioned longitudinally and examined using scanning electron microscope (SEM) .Results: AH Plus had a significantly higher bond strength compared to Sure-Seal bioceramic sealer in the three groups (p < 0.05). There was no significant difference in AH Plus bond strength among the three groups. On the other hand, Sure-Seal bioceramic sealer displayed a significantly higher bond strength in the CNPs group (p = 0.02). AH Plus showed a significantly higher bond strength at the coronal third compared to Sure-Seal bioceramic sealer (p < 0.05) with no significant difference between them in the middle third

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