Orthodontic adhesive doped with nano-graphene oxide: physico-mechanical and antimicrobial properties

In fixed orthodontics, formation of white spot lesions, enamel demineralization, and tooth decay around appliances are common complications which mar the outcome.

The aims of this study were the determination of the shear bond strength (SBS) and adhesive remnant index (ARI) of orthodontic adhesive doped with N-GO, as well as the assessment of antimicrobial activities of the modified orthodontic adhesive against Streptococcus mutans.

N-GO was characterized by a scanning electron microscope (SEM), Fourier transformation infrared (FTIR), X-ray diffraction (XRD), and Zeta potential. The SBS and ARI of modified orthodontics adhesive containing different concentrations of N-GO (0, 1, 2, 5, and 10 wt%) were then measured. The influences of adding N-GO on antimicrobial properties of orthodontic adhesive were determined against S. mutans by disc agar diffusion (DAD) testing and biofilm formation inhibition assay.

The SEM, FTIR, XRD, and Zeta potential analysis indicated the successful synthesis of N-GO. Orthodontics adhesive doped with 5 wt% N-GO showed the highest concentration of N-GO and SBS value (21.71±7.45 MPa, p<0.05) simultaneously with no significant differences in adhesive remnant index compared with the control group. SBS in the 1, 2, and 5% N-GO were significantly higher than that in 10% N-GO (p=0.025, p=0.036, p=0.041, respectively). The disinfection ability of the modified orthodontic adhesive doped with N-GO against S. mutans in the DAD and biofilm formation inhibition assays were positively associated with increased in N-GO concentrations (p<0.05). However, the 5 and 10 wt% N-GO showed a statistically significant decrease the CFU/mL of the test microorganisms in biofilm structures (p<0.05).

It could be concluded that 5 wt% of N-GO can be considered as an orthodontic adhesive additive to reduce the microbial count and biofilm with no adverse effect on SBS and ARI.