Synergistic effect of nanosilver fluoride with L-arginine on remineralization of early carious lesions

Abstract

The synergistic effect of nanosilver fluoride (NSF) with L-arginine on early carious lesions was evaluated. NSF was synthesized from chitosan, acetic acid, silver nitrate, sodium borohydride, and sodium fluoride. NSF + Arg was synthesized by adding L-arginine. After demineralization the enamel slabs from extracted molar, remineralization agents were applied by randomly dividing them into five groups (n = 15): sodium fluoride varnish (NaF), silver diamine fluoride (SDF), NSF, NSF + Arg, and control. The surface microhardness (SMH), remineralization effects using microcomputed tomography and color changes using a spectrophotometer were measured before and after pH cycling. SMH was analyzed by Kruskal-Wallis test with Dunn's test. Remineralization effects, and color changes were analyzed using the one-way analysis of variance with Duncan's test; p-value < 0.05 was considered significant. SMH recovered to similar levels in all groups (p > 0.05), except in the control group after pH cycling. The NSF + Arg and SDF groups showed a higher remineralization than the NaF and NSF groups (p < 0.05). SDF caused the largest discoloration (p < 0.05). The other groups showed no difference in discoloration. NSF + Arg could be an alternative to SDF given its ability to remineralize early caries lesions without discoloration.

Keywords: Early carious lesions; L-arginine; Nano silver fluoride; Remineralization; Silver diamine fluoride.

Fig. 1

Transmission electron microscopy images and histogram distributions of AgNPs in NSF and NSF + Arg solutions. (a–c) NSF solution, scaled at 50, 20, and 10 nm, respectively. (d) Particle size distribution of AgNPs in the NSF solution, (e–g) NSF + Arg solution, scaled at 50, 20, and 10 nm, respectively. (h) Particle size distribution of AgNPs in the NSF + Arg solution. AgNPs, silver nanoparticles; NSF, nanosilver fluoride, (i) Visual appearances of synthesized aqueous solution of NSF (left) and NSF + Arg (right).

Fig. 2

SEM images of the enamel surface morphology after pH cycling. Loss of surface integrity and high surface porosities are shown in (a) demineralized enamel surface and (b) control group (deionized water). The remineralized samples reveal less microporosity and a relatively smooth surface (c), SDF (d), NaF varnish (e), NSF (f), NSF + Arg. AgNPs, silver nanoparticles; NSF, nanosilver fluoride, SEM, scanning electron microscope.

Fig. 3

Representative micro-CT images of the enamel specimens. MD at postdemineralization (T₁), and post pH cycling (T₂). CT, computed tomography, MD, mineral density.

Fig. 4

Enamel specimens after the application of remineralization agents followed by pH cycling.

Fig. 5

Schematic illustration of the specimen preparation procedure.