Chitosan nanoparticles used via different irrigation techniques: Syringe and laser activated irrigation via Er: YAG laser on smear layer and pushout bond strength: An In Vitro SEM assessment.

Objectives: To quantify the efficacy of final canal disinfectants, ethylene-diamine-tetraacetic acid (EDTA) Chitosan nanoparticles (CHNPs) used via different irrigation techniques, i.e., Syringe irrigation (SI), laser-activated irrigation (LAI) on smear layer (SL), and push-out bond strength (POBS) of root canal filling material to dentin. Methodology: The present in vitro study was approved by the ethical committee of King Saud University and completed in three months (April 10 to July 10, 2025). Forty-four fully matured, single-rooted human mandibular premolars were selected. After confirming the working length, the root canal procedure was initiated, and the canal was shaped. The teeth were arbitrarily distributed into four distinct cohorts based on final disinfection protocols (n=11): Group-IA: (EDTA-SI), Group-IIA: (CHNPs+ SI), Group-IB: (EDTA-LAI), and Group-IIB: (CHNPs-LAI). Scanning Electron Microscopy (SEM) assessed SL removing efficiency. Root canal filling was performed on ten samples. The POBS and modes of failure were evaluated quantitatively with a universal testing machine and a stereomicroscope. ANOVA and Tukey post hoc test were used to analyze data, p<0.05. Results: The Cervical third of Group-IIB (NaOCl + CHNPs-LAI) presented the maximum SL removal (12.36±0.56 MPa) and maximum POBS (12.36±0.56 MPa) of GFP. However, the apical section of Group-I (NaOCl + EDTA-SI) samples revealed the lowest SL removal (3.55±0.42) and minimum POBS (6.43±0.42 MPa). Conclusion: Chitosan nanoparticles activated with laser as a final root canal disinfectant presented better SL removal and bond strength of AH plus sealer to the canal dentin.