Evaluation of antibacterial and mechanical features of dental adhesives containing colloidal gold nanoparticles

Abstract

In this study, colloidal gold nanoparticles (NPs) with sizes less than 20 nm were added to the dentin adhesive in various concentrations to achieve favorable antibacterial properties. The effect of gold NPs on mechanical, antibacterial, and cytotoxicity features of adhesive was evaluated systematically. It was shown that the addition of gold NPs at the concentration of 5X (i) increased flexural strength of dentin tooth adhesive by 75%, (ii) increased the micro-shear bond strength by 60%, and (iii) increased the tensile diameter strength of adhesive by 65% compared to the based adhesive. Multiscale modeling was used to simulate and calculate stress and strain distribution around the nanoparticles and within the adhesive matrix. Antibacterial properties of adhesives containing gold NPs were examined using disk diffusion and the pour plate methods. The results showed that adhesive with the 5X concentration of gold NPs had a bacterial growth inhibition zone with a diameter of 2 mm is in the disk diffusion method which indicates the antibacterial characteristics of adhesive at this concentration. Also, the antibacterial effect of adhesive-containing NPs was observed in the pour plate method and the reduction of bacterial growth is increased by the addition of nanoparticles. The cytotoxicity of NPs is examined in pure form and combination with dental adhesive using the MTT assay. The results showed that pure gold NPs have shown no toxicity for the growth of cells and the incorporation of gold NPs has increased the cell viability in the base adhesive.