Synergistic Effect of Nano Silver Fluoride (NSF) with L-Arginine on Remineralization of Early Carious Lesions: an in Vitro Study

Abstract

Although different dental anticarious agents have been introduced over the years. The prevalence of dental caries remains prevalent worldwide. Therefore, effective alternative approaches to the existing ones are still needed. The aim of the study was to investigate and compare the remineralizing and staining effects of nano silver fluoride with L-arginine (NSF+ Arg) on artificially demineralized permanent enamel lesions with other experimental groups, including nano silver fluoride (NSF), silver diamine fluoride (SDF), and sodium fluoride varnish (NaF). NSF and NSF + Arg formulations were prepared and characterized with transmission electron microscopy (TEM) and particle size analysis. Demineralized human enamel specimens were allocated randomly to five groups of 15 specimens each. Group I received a topical application of a 2.5 % NaF Varnish (FluoriMax, Elevate Oral Care, West Palm Beach, FL, USA). Group II received a topical application of a 12% SDF (Dengen Dental, Bahadurgarh, Haryana, India). Group III received a topical application of NSF solution (lab made). Group IV received a topical application of NSF + Arg solution (lab made). Group V received deionized water that served as a control group. After applying the test materials, all the specimens underwent a 10-day pH-cycling model. The surface morphology, color parameters, mineral density, and surface microhardness (SMH) were assessed on each enamel specimen using scanning electron microscopy (SEM), digital spectrophotometry, micro-computed tomography (micro-CT), and Vickers microhardness tester, respectively. TEM analysis of both NSF + Arg and NSF formulations revealed relatively mono-dispersed spherical silver nanoparticles with diameters ranging from 3 to 18 nm. SEM examination showed the smoothest enamel surface in the NSF + Arg group and the roughest in the control group. Among the tested groups, only the group treated with SDF (Group II) exhibited a significant black staining of enamel specimens, as indicated by a higher ΔE value (57.84 ± 1.84). In contrast, the remaining groups (I, III, IV, and V) demonstrated lower ΔE values (3.18 ± 1.56, 3.94 ± 1.35, 3.60 ± 1.17, 2.27 ± 0.52), respectively. The %SMH for groups I, II, III, IV, and V showed an increase of 30.6%, 37.7%, 28.1%, 41.8%, and 1.6%, respectively, with no statistically significant differences among the tested groups except for the control group. Among the experimental groups, NSF + Arg exhibited the highest mineral gains and % remineralization, but there were no statistically significant differences. In conclusion, judging by our results, the NSF + Arg formulation could serve as an alternative approach to SDF. This is due to its ability to remineralize early carious lesions without causing black staining.