الفهرس 
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Abstract
The aim of this study was to assess the effect of addition of silver nanoparticles on the solubility, sealing ability and antibacterial effect of three different root canal sealers (AD Seal, MTA Fillapex and GuttaFlow 2).
For evaluation of solubility, sixty molds with 15 mm diameter and 3 mm thickness were fabricated. They were divided into six groups (n=10) according to the type of sealer used. They were filled with the freshly mixed sealers and left to allow the sealers to fully set.
Each sample weighted initially three time and the average weight was recorded (Wo). After this, samples were immersed in 20 ml deionized water at 1,7,14 and 28 days. After each immersion period, samples were removed, rinsed with distilled water, dried with blotted paper, placed in an incubator at 37oC for 48 hours until they become dry and reweighted. Each sample weighted three times and the average weight was recorded (Wf1, Wf7, Wf14 and Wf28). Assessment of solubility was made through the equation:
Solubility (%) = (W0 – WF / W0) x100
For evaluation of sealing ability, the fluid filtration method was applied. Sixty mandibular premolars with single root canals were instrumented to apical size #50. At the stage of obturation, they were divided into six groups (n=10) according to the sealer used. All roots were obturated using cold lateral technique.
The assessment of sealing ability was used by monitoring the distance the air bubble moved in a specific time.
For evaluating the antibacterial effect, the direct contact test was applied. The endodontic sealers were put in sterile polyethylene tubes. About 18 mg of each sealer were weighed and placed in a tube. Sealers then covered with 400 micro-L of Brain Heart Infusion (BHI) broth and 100 micro-L of bacterial suspension. As a negative control, same amount of sealer and culture media and 100 micro-L of saline solution (without bacterial suspension) was used. As a positive control, same amount of culture media and 100 micro-L of bacterial suspension without any sealer was used.
The same procedure was made again after 1 hour. After 1 min, 1 hour, the bacterial survival in each tube was evaluated by 10-fold serial dilutions up to 10-7, and three aliquots of 20 micro-L from each dilution were cultured on BHI agar plates. Plates were then incubated for 24 hours at 37o C and the CFU/mL were counted.