Aim: To assess the effect of prepared green tea-chitosan microcapsules on the antibacterial efficiency against Enterococcus faecalis, the physical properties, and the sealing ability of resin-based endodontic sealer impregnated with these microcapsules.
Materials and Methods: Green tea extract (GTE) and chitosan solution were prepared, then GTE was dissolved into this solution followed by precipitation of chitosan nanoparticles (CSNPs) loaded with GTE. Microcapsulation of GTE-CSNPs was performed and the solution was prepared (3 % w/v concentration). Characterization of microcapsules was conducted using Fourier-Transform Infrared Spectroscopy (FTIR), Zeta potential, and transmission electron microscope (TEM). The release of GTE at different pH values was evaluated. GTE-CSNPs solution was added to an epoxy resin-based sealer and the antibacterial activity was evaluated via direct contact test. The physical properties of the modified sealer were evaluated according to American Dental Association (ADA) specifications. Sealing ability was evaluated stereomicroscopically. Data were statistically analyzed.
Results: FTIR and Zeta potential ensured the attachment between GTE and Chitosan. The particle size of CSNPs and GTE-CSNPs was around 20 nm, while microcapsules were greater than 1000 nm. A significantly higher percentage of GTE was released at pH 5 than pH 7.4, (𝑃 < 0.001). After sealer modification, the antibacterial evaluation showed significant decrease in optical density (𝑃 < 0.001). Also, the setting time, film thickness and microleakage were significantly decreased, however, the solubility was significantly increased (𝑃 < 0.001) but still within the acceptable limit of ADA specifications.

Conclusions: GTE-Chitosan microcapsule is a proper natural candidate for improvement of sealer's properties.