Antimicrobial Efficacy of Silver Nanoparticles Incorporated in an Orthodontic Adhesive: An Animal Study

This study assessed the antimicrobial efficacy of silver nanoparticles (AgNPs) incorporated in Transbond XT orthodontic adhesive used in rats.Transbond XT orthodontic adhesive containing 0%, 1%, 5% and 10% AgNPs was experimentally produced. Twenty-eight male Wistar rats were randomly divided into four groups (n=7) of control (0% AgNPs), 1% AgNPs, 5% AgNPs and 10% AgNPs. After anesthetizing the rats, one drop (10 μm) of the adhesive was applied on the central incisor, and light-cured for 20 s. Transbond XT composite (1×1×1 mm) was also applied. Another 10-μm drop was applied over it, and light-cured for 40 s. Biofilm test was carried out, and the number of colony forming units (CFUs) of Streptococcus sanguinis (S. sanguinis), Streptococcus mutans (S. mutans) and Lactobacillus acidophilus (L. acidophilus) in the saliva of rats was counted at baseline and 24 h after the application of adhesive. The data were analyzed using one-way ANOVA and Tukey's test.In presence of 5% and 10% AgNPs, S. sanguinis and L. acidophilus counts were significantly lower than those in the control and 1% AgNP groups (P<0.05). The S. mutans colony count was significantly lower in presence of all concentrations of AgNPs compared with the control group (P<0.05). The S. mutans colony count in 10% AgNP group was significantly lower than that in 1% and 5% AgNP groups (P<0.05).Silver nanoparticles have dose-dependent antimicrobial effects; 5% concentration is the minimum concentration of AGNPs with optimal antimicrobial efficacy against all strains evaluated in this study.