Characterization of a new material based on silver nanoclusters synthesized in polymethacrylic acid for the infiltration of dental structures affected by caries

Abstract

Objective: To characterize the physical and biological properties of a solution of silver nanoclusters (AgNCls) synthesized in polymethacrylic acid (PMAA) for the infiltration of dental structures affected by caries. Materials and methods: AgNCls were synthesized in PMAA via photoreduction of AgNO₃. The physical properties evaluated were: color change (measured by spectrophotometer), shear bond strength (SBS) of glass ionomer cement (GIC) to demineralized dentin, surface hardness (measured using the Vickers hardness test), and penetration depth of silver ions (tracked using scanning electron microscopy with energy-dispersive X-ray spectroscopy [SEM-EDS]). Biological properties included antibacterial activity (minimum inhibitory concentration [MIC], minimum bactericidal concentration [MBC], and colony-forming unit [CFU] count) against Streptococcus mutans and Lactobacillus acidophilus, and cytotoxicity in pulp cells (using the MTT assay). Silver diamine fluoride (SDF) at 38% was used as a reference, and specific statistical analyses were performed. Results: Surfaces treated with AgNCls in PMAA exhibited color stability and high microhardness and SBS values for the GIC. A consistent presence of silver was detected throughout the entire depth of the lesion. The antibacterial effect was significant against CIM and CBM, starting at dilutions of 1.25% and 2.5%, respectively. Cell viability remained high, ranging from 92% to 89% (from 24 to 72 h). Conclusions: The AgNCls solution in PMAA did not cause staining, improved the SBS of the GIC, restored surface hardness, exhibited acceptable cytotoxicity, and demonstrated an excellent antibacterial effect, with silver ions penetrating the full depth of the lesion in dental structures affected by caries.