Assessment of Shear Bond Strength and Cytotoxicity of Orthodontic Adhesive with Addition of Silver Nanoparticles in Varying Concentrations

Prolonged treatment with fixed orthodontic appliances tend to compromise oral hygiene maintenance in patients, increasing their susceptibility to white spot lesions and caries. Incorporating silver nanoparticles into adhesives and orthodontic appliances is known to improve its antimicrobial properties. The aim of the present study was to assess and compare the bond strength of orthodontic adhesive when Silver Nanoparticles were added in varying concentrations and also to assess their cytotoxicity on periodontal ligament fibroblasts. Various concentrations of silver nanoparticles (1%, 5%, 10%w/w) were incorporated into Transbond XT composite adhesive and their shear bond strength and cytotoxicity were compared to a control group. Brackets were bonded to extracted premolar teeth and shear bond strength was assessed using Instron Universal Testing Machine. The viability of periodontal ligament fibroblasts was assessed after incubating with the experimental composite for 24 hours and 1 week using MTT assay. There was a decrease in the shear bond strength when 1% and 5% of silver nanoparticles were incorporated into the adhesive.However, it was within the clinically recommended range for bonding brackets. When the concentration was increased to 10%, the SBS was not acceptable for orthodontic bonding. The composite incorporated with silver nanoparticles was cytotoxic to fibroblasts at all concentrations at both time intervals. The shear bond of orthodontic adhesive with nanosilver is comparable to plain transbond XT in low concentrations, however, the addition of silver nanoparticles seems to increase the time-bound cytotoxicity of orthodontic adhesive.