Remineralization Property of an Orthodontic Primer Containing a Bioactive Glass with Silver and Zinc

Abstract

White spot lesions (WSLs) are irreversible damages in orthodontic treatment due to excessive etching or demineralization by microorganisms. In this study, we conducted a mechanical and cell viability test to examine the antibacterial properties of 0.2% and 1% bioactive glass (BAG) and silver-doped and zinc-doped BAGs in a primer and evaluated their clinical applicability to prevent WSLs. The microhardness statistically significantly increased in the adhesive-containing BAG, while the other samples showed no statistically significant difference compared with the control group. The shear bond strength of all samples increased compared with that of the control group. The cell viability of the control and sample groups was similar within 24 h, but decreased slightly over 48 h. All samples showed antibacterial properties. Regarding remineralization property, the group containing 0.2% of the samples showed remineralization properties compared with the control group, but was not statistically significant; further, the group containing 1% of the samples showed a significant difference compared with the control group. Among them, the orthodontic bonding primer containing 1% silver-doped BAG showed the highest remineralization property. The new orthodontic bonding primer used in this study showed an antimicrobial effect, chemical remineralization effect, and WSL prevention as well as clinically applicable properties, both physically and biologically.

Keywords: bioactive glass; remineralization; silver-doped BAG; white spot lesion; zinc-doped BAG.

Figure 1

The SEM images of the (a) BAG; (b) BAG@Ag1 and (c) BAG@Zn5; (d) XRDpattern of BAG.

Figure 2

Comparison of the microhardness of the BAG and ion-doped BAG orthodontic bonding primer. Error bars indicate the ± standard deviation. The same letters indicate that the p-value is not significantly different (p < 0.05). p < 0.05 using Duncan’s Multiple Range Test (n = 5).

Figure 3

Comparison of the shear bond strength of the BAG and ion-doped BAG orthodontic bonding primer. Error bars indicate the ± standard deviation. The same letters indicate that the p-value is not significantly different (p < 0.05). p < 0.05 using Duncan’s Multiple Range Test (n = 5).

Figure 4

Images of tooth surface after shear bond strength test. (a) Control; (b) BAG 0.2%; (c) BAG 1.0%; (d) BAG@Ag1 0.2%; (e) BAG@Ag1 1.0%; (f) BAG@Zn5 0.2%; (g) BAG@Zn5 1.0%.

Figure 5

Cell viability test by Human gingival fibroblasts (HGF) cytotoxicity on the cured BAG and ion (silver or zinc)-doped BAG orthodontic bonding primer. (a) Cell viability test after 24 h; (b) Cell viability test after 48 h; (c) Cell viability test after 72 h. Viability is measured using MTT((3-(4,5-Dimethylthiazol-2-yl)-2,5-Diphenyltetrazolium Bromide) absorbance on 620 nm. Duncan’s Multiple Range Test (n = 3). The same letters indicate that the p-value is not significantly different (p < 0.05). Error bars indicate the ± standard deviation.

Figure 5

Cell viability test by Human gingival fibroblasts (HGF) cytotoxicity on the cured BAG and ion (silver or zinc)-doped BAG orthodontic bonding primer. (a) Cell viability test after 24 h; (b) Cell viability test after 48 h; (c) Cell viability test after 72 h. Viability is measured using MTT((3-(4,5-Dimethylthiazol-2-yl)-2,5-Diphenyltetrazolium Bromide) absorbance on 620 nm. Duncan’s Multiple Range Test (n = 3). The same letters indicate that the p-value is not significantly different (p < 0.05). Error bars indicate the ± standard deviation.

Figure 6

Comparison remineralization length of the BAG and ion (silver or zinc)-doped BAG orthodontic bonding primer using the ImageJ analysis. Duncan’s Multiple Range Test (n = 9). The same letters indicate that the p-values are not significantly different (p < 0.05). Error bars indicate the ± standard deviation.

Figure 7

Remineralization point of the BAG and ion (silver or zinc)-doped BAG orthodontic bonding primer via CBCT. (a) Control; (b) BAG 0.2%; (c) BAG 1.0%; (d) BAG@Ag1 0.2%; (e) BAG@Ag1 1.0%; (f) BAG@Zn5 0.2%; and (g) BAG@Zn5 1.0%.

Figure 8

Remineralization length analysis method. (a) Micro CT (computer tomography) slice of the region of interest at the center of the lesion perpendicular to the enamel surface, red arrow: Perforated landmark for a reference point, blue line: line of interest region from reference point on enamel surface; (b) Histogram in ImageJ. Green arrow: up to 87% level of gray value from the reference point, orange arrow: the distance at the 87% gray value from reference point.