An in vitro evaluation of the effects of nanoparticles on shear bond strength and antimicrobial properties of orthodontic adhesives: A systematic review and meta-analysis study

Introduction > Biofilm accumulation around orthodontic brackets and composite is a common complication of orthodontic treatment. Objective > A systematic review and meta-analysis were done to find out whether the association of nanoparticles with the orthodontic adhesives compromises its properties and whether there are exceptional nanoparticles exhibiting excellent antimicrobial potential against cariogenic bacteria along with remarkable mechanical properties. Materials and methods > Electronic databases were searched using the following keywords; orthodontic or orthodontics and antimicrobial or antibacterial and adhesive and nanoparticles and shear bond strength. Thirteen studies were included and meta-analysis was performed. Results > The results indicated no drastic changes in mechanical properties (0.812, 95% CI [0.750, 0.861], P = 0.000). The Ag-HA, Cur, Cur-ZnO, and TiO2 in concentration >= 1% showed a statistically significant difference, where the control groups had higher shear bond strength. Nine studies assessed the antimicrobial properties of nanoparticles. 1 wt% Cu and 5 wt% TiO2 not only did not affect shear bond strength but also showed more antimicrobial activity against Streptococcus mutans. The analysis demonstrated the absence of heterogeneity (Q value = 44.014; df (Q) = 12; and I-2 = 72.736) in shear bond strength of orthodontic adhesives with nanoparticles, with low risk of bias. Conclusions > Adding <= 5 wt% antimicrobial nanoparticles to an orthodontic adhesive is less conducive to microbial growth than unmodified adhesive and does not influence bracket-enamel bond strength.