Developing a biocompatible and antibacterial silver-nanoparticles solution for dental use

Abstract

Objectives: Silver composites such as silver diamine fluoride (SDF) are effective antibacterial agent but they stain caries black. This study aimed to synthesize a biocompatible silver nanoparticles (AgNPs) solution with antibacterial properties and does not stain caries lesion. Methods: The solution containing new AgNPs were prepared using silver nitrate, epigallocatechin-3-gallate (EGCG) as reducing agent and chitosan as dispersant. The AgNPs were characterized by transmission electron microscopy (TEM) and ultraviolet-visible spectrophotometry (UV–vis). Its antibacterial properties were evaluated by minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) against Streptococcus mutans using spectrophotometric microdilution method and agar dilution method. Chitosan and silver diamine fluoride (SDF) were used for comparison. The MTT (3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide) assay was used to study cytotoxicity of AgNPs and SDF against mouse osteoblast precursor cell (MC3T3-e1). Their half maximal inhibitory concentration (IC50) were measured. The staining property was assessed by measuring the colour of AgNPs-treated and SDF-treated demineralised dentine using CIELAB system. Total colour change (ΔE) was calculated and ΔE>3.7 would be visible. Results: TEM and UV-vis showed formation of a homogeneous spherical AgNPs, with mean diameter of 38nm. The MIC for the AgNPs, chitosan and SDF were 31.28±1.19µg/mL 182.29±63.79µg/mL and 40.31±5.1µg/mL (p<0.001, AgNPs < SDF < chitosan). The MBC for the AgNPs, chitosan and SDF were 59.44±1.14µg/mL, 572.91±127.58µg/mL and 86.62±6.7µg/mL (p<0.001, AgNPs < SDF < chitosan). The IC50 of the AgNPs and SDF were 32.44±2.13 and 35.06±0.56 (p=0.015). ΔE of AgNPs-treated dentine was 3.59±0.69 and SDF-treated dentine was 38.54±12.92 (p=0.04). Conclusions: A biocompatible silver nanoparticles solution with antibacterial properties was developed. It did not stain caries lesion and could be used as an alternative for silver composites in controlling bacteria in caries lesion.