Antibacterial Activity of Silver Nanoparticles Incorporated in Acrylic Resin - An In vitro Study

Background: Self cure acrylic resin is a polymer widely used in dentistry for fabrication of orthodontic appliance, the provisional prosthesis, denture relining etc., However, it does not possess any inherent antibacterial property. Hence, various antibacterial agents have been added to resin and tested for the antibacterial activity. Aims: The aim of this study was to investigate the antibacterial effect of silver nanoparticles incorporated into the resin matrix over a period. Materials and Methods: The samples were divided into two groups, study and control. For control group, self-cure resin was polymerized in cylindrical molds of 9 mm diameter -3 mm height. For study group, silver nanoparticles were added to monomer liquid in the concentration of 0.06% (0.6 mg/ml) and polymerized in similar molds. Agar diffusion assay was used to test for anti-bacterial activity of both groups against a cariogenic strain of Streptococcus mutans. The antibacterial activity was tested at 1, 7, 15 and 30 days time period. The readings were recorded and analyzed using unpaired t-test. Results: The control group showed no zone of growth inhibition on agar plates. While study group (containing 0.06% silver nanoparticles) showed zone of growth inhibition around the acrylic tablets placed in agar plates. The zone of growth inhibition decreased over time. On day 30, no zone of growth inhibition was seen in study group. Conclusion: When silver nanoparticles are added to the resin liquid in 0.06% concentration, the resin matrix shows antibacterial property without affecting its compressive strength. The antibacterial effect gradually decreased with time, as silver particles are released from the resin matrix.