1 Associate professor, Department of orthodontics, Hamadan University of Medical Sciences, Hamadan, Iran

2 Assistant professor, Iran polymer and petrochemical institute, Tehran, Iran

3 Assistant professor, Department of Orthodontics, Ardebil dental school, Ardebil, Iran



Background and aim: Present in-vitro study was designed to evaluate the effect of nanosilver incorporation on antibacterial properties and Bracket Bond Strength (BBS) of orthodontic composite resin. 
Materials and methods: A light curing composite resin was mixed with metallic nanosilver to obtain final concentrations of 0%, 0.5%, 1% and 2.5% (wt/wt). Scanning electron microscopy (TESCAN, VEGA II, XMU, Czech Republic) was used to confirm the uniform distribution of nanoparticles in resin matrix. Thirty disk type specimens (4.0 × 1.0mm) were prepared for each group. Antibacterial activity was determined by evaluation of bacterial growth in suspension media versus growth in direct contact with specimens. BBS and bond failure interface (ARI) were evaluated and compared between the specimens. Bacterial activity of control group compared with the group with maximum antibacterial activity. 
Results: There were no significant differences in bacterial growth in any specimens in suspension media (P=0.623). The results of second method (direct contact) showed significant differences between all groups (P<0.001). Specimens with maximum antibacterial activity (containing 1% nanosilver) and control group had no significant difference in the BBS (P=0.455). ARI was completely identical in these two groups. 
Conclusions: Nanosilver containing composite could confer surface antibacterial activity without significant difference on BBS and ARI.