Enamel Anti-Demineralization Effect of Orthodontic Adhesive Containing Bioactive Glass and Graphene Oxide: An In-Vitro Study

Abstract

White spot lesions (WSLs), a side effect of orthodontic treatment, can result in reversible and unaesthetic results. Graphene oxide (GO) with a bioactive glass (BAG) mixture (BAG@GO) was added to Low-Viscosity Transbond XT (LV) in a ratio of 1, 3, and 5%. The composite's characterization and its physical and biological properties were verified with scanning electron microscopy (SEM) and X-ray diffraction (XRD); its microhardness, shear bond strength (SBS), cell viability, and adhesive remnant index (ARI) were also assessed. Efficiency in reducing WSL was evaluated using antibacterial activity of S. mutans. Anti-demineralization was analyzed using a cycle of the acid-base solution. Adhesives with 3 wt.% or 5 wt.% of BAG@GO showed significant increase in microhardness compared with LV. The sample and LV groups showed no significant differences in SBS or ARI. The cell viability test confirmed that none of the sample groups showed higher toxicity compared to the LV group. Antibacterial activity was higher in the 48-h group than in the 24 h group; the 48 h test showed that BAG@GO had a high antibacterial effect, which was more pronounced in 5 wt.% of BAG@GO. Anti-demineralization effect was higher in the BAG@GO-group than in the LV-group; the higher the BAG@GO concentration, the higher the anti-demineralization effect.

Keywords: anti-demineralization; antibacterial effect; bioactive glass; graphene oxide; white spot lesion.

Figure 1

Anti-demineralization length analysis method. (A) Micro-computed tomography (CT) slice of ROI (region of interest) at the center of the lesion perpendicular to the enamel surface. The starting point was the end of the adhesive. Black line: the line of ROI from a reference point on the enamel surface; (B) Histogram in ImageJ. Blue arrow: up to 87% level of gray value from the reference point; red arrow: the distance at the 87% gray value from the reference point.

Figure 2

Characterization of BAG, BAG@GO and GO. (a) XRD of BAG; (b) XRD of BAG@GO; (c) XRD of GO; (d) SEM of BAG; and (e) SEM of BAG@GO.

Figure 3

Microhardness comparison of orthodontic bonding adhesive containing LV and different weight percentages of BAG@GO. The same letters indicate no statistically significant difference between the groups (p < 0.05) by Duncan’s multiple comparison test. Error bars are shown ± standard deviation.

Figure 4

Shear bond strength comparison of orthodontic bonding adhesive containing LV and different weight percentages of BAG@GO. The same letters indicate no statistically significant difference between the groups (p < 0.05) by Duncan’s multiple comparison test. Error bars are shown ± standard deviation.

Figure 5

Cell viability test by HGF cytotoxicity on cured LV and BAG@GO-containing orthodontic bonding adhesive. Cell viability test results after 48 and 72 h are shown. The same letter indicates no statistically significant difference between the groups (p < 0.05) by Duncan’s multiple comparison test. Error bars are shown ± standard deviation.

Figure 6

The difference in antibacterial properties between cured LV and BAG@GO orthodontic bonding pastes at 24 h. The same letter indicates no statistically significant difference between the groups (p < 0.05) by Duncan’s multiple comparison test. Error bars are shown ± standard deviation.

Figure 7

Anti-demineralization length comparison of orthodontic bonding adhesive containing LV and BAG@GO by Image J analysis. The same letter indicates no statistically significant difference between the groups (p < 0.05) by Duncan’s multiple comparison test. Error bars are shown ± standard deviation.

Figure 8

Anti-demineralization point (black arrow) of the LV and BAG@GO orthodontic bonding adhesive via CBCT. (a) LV; (b) 1 wt.% BAG@GO; (c) 3 wt.% BAG@GO; and (d) 5 wt.% BAG@GO.