Synthesis of an experimental resin-based adhesive with the addition of silver nanoparticles

Abstract

Objective: To synthesize and characterize in vitro an experimental resin-based adhesive system modified with different concentrations of biogenic silver nanoparticles (nAg).

Methods: The adhesive was synthesized from bis-GMA, HEMA, and a conventional photoinitiator, incorporating nAg dissolved in acetone at 96 and 192 µg/mL. Cohesive strength (tensile test, n=10/group), microshear bond strength to dentin (n=10/group), and degree of conversion (FTIR-ATR) were evaluated. nAg distribution was analyzed by confocal Raman microscopy and X-ray diffraction. Biocompatibility was assessed via MTT assay in 3T3 fibroblasts (24 and 48 h), and antimicrobial activity against S. mutans via agar diffusion with colorimetric staining.

Results: nAg incorporation did not alter cohesive strength or dentin bond strength (p>0.05). Degree of conversion decreased significantly with nAg (67.1% control vs. 48.7% and 41.1%; p=0.002). Cell viability was lower at the higher concentration at 24 h (p=0.009), with no differences at 48 h (p=0.935). Raman analysis confirmed homogeneous nAg distribution without detectable agglomerates. Inhibition of S. mutans growth was observed, more pronounced at 192 µg/mL than at 96 µg/mL; the adhesive without nAg showed no antimicrobial activity.

Conclusions: Biogenic nAg incorporation preserved mechanical and adhesive properties, maintained biocompatibility comparable to the control at 48 h, and showed a dose-dependent inhibitory effect against S. mutans. The reduction in degree of conversion indicates the need to optimize the formulation.