In the present study, thirty patients with thirty single rooted teeth were selected. Patients with non-contributory medical history, intact permanent teeth without any previous restoration, with a necrotic or infected pulp as diagnosed clinically and radiographically, with adequate coronal structure for proper isolation, temporization, and restoration will be included. After local anaesthesia administration and rubber dam placement access opening was made and sample S1 was taken (three samples) with paper point after injecting 5 ml normal saline solution. After working length determination and biomechanical preparation till size #40 K-file, post instrumentation sample S2 was collected in the same manner as S1. Then, it was sent to laboratory for processing within 2 hours. After second sampling, the canals were dried and medicaments were applied randomly among 30 patients (15 patients each) with lentulospiral and left in place for 7 days. After 7 days, following medicament  removal, sample S3 was taken. Microbiological samples (S1, S2, S3) were preincubated for 30 minutes and shaken vigorously in a vortex mixture for 60 seconds and then were plated on Brain heart infusion agar and colonies were counted after 24 hours using classic bacterial counting method. 

The results showed that there was significant reduction of bacterial count from stages S1 (after access opening) to S2 (after biomechanical preparation), and S3 (after medicament placement) in both the experimental groups (intracanal medicaments). The percentage reduction was better with Group 2 (silver nanoparticles), however, it was not statistically significant when compared to Group 1 (Calcium hydroxide). 

Within the limitations of this study, it can be concluded that silver nanoparticles showed significant antimicrobial activity and can be used as an effective root canal medicament as an alternative to calcium hydroxide dressing.