A novel antimicrobial orthodontic band cement with in situ-generated silver nanoparticles

Objective: To develop an antimicrobial orthodontic band cement for the prevention of white spot lesions using a novel process that generates silver nanoparticles (AgNP) in situ. Materials and Methods: Twenty-seven groups of AgNP-loaded Opal Band Cement (OBC) and two control groups were formulated with varying concentrations of additional benzoyl peroxide (0.5, 1.0, 1.5, or 2.0 wt%) and 2,2-(p-Tolylimino) diethanol (0.5 or 1 wt%). Rockwell_15T hardness and near-infrared FTIR were used to assess degree of cure, three-point bending was used to determine modulus and ultimate transverse strength (UTS), and Ag⁺ ion release was measured for up to 4 months in vitro using atomic absorption spectroscopy. Antimicrobial activity against Streptococcus mutans and Lactobacillus acidophilus was tested in vitro by counting colonyforming units for up to 28 days. Biocompatibility was evaluated following ISO specifications 7405 (2008), 10993-3 (2003), 10993-5 (2009), and 10993-10 (2010). Results: Most of the experimental groups had hardness, modulus, and UTS values similar to those of the control group. Ag⁺ ion release was observed for all AgNP-loaded groups for up to 4 months. Increase in Ag loading increased Ag⁺ ion release and in vitro antimicrobial effect. The biocompatibility of the optimal AgNP-loaded OBC was comparable to that of negative controls. Conclusion: A novel antimicrobial orthodontic band cement was developed that has comparable mechanical properties to controls, controlled and sustained Ag⁺ ion release, significant bacterial inhibition in vitro, and excellent biocompatibility.