Influence of Gold Nanoparticle Incorporation Into Glass Ionomer Cement on Fibroblast Metabolic Activity, Surface Roughness and Hardness.

Objective: To assess the influence of gold nanoparticle (AuNP) liquid-phase modification of glass ionomer cement (GIC) on fibroblast metabolic activity, alongside its effects on surface hardness and roughness, in an exploratory pilot in vitro study. Methods: GIC specimens were prepared using liquid mixtures containing 25% and 50% AuNP suspension within the liquid phase alongside an unmodified control. The exact AuNP concentration in the final set cement was not determined, and direct structural characterisation of nanoparticle incorporation was not performed. Cell viability was evaluated using the MTT assay at 24 and 72 h and data were analysed using the Kruskal-Wallis test followed by Dunn's post hoc test. Surface hardness and surface roughness data were analysed using the Mann-Whitney Results: At 24 h, the unmodified GIC group showed a mean cell viability of 3.86% ± 2.1%, while both experimental groups exhibited higher values: 15.32% ± 10.7% for the 25% AuNP-GIC group and 14.93% ± 12.6% for the 50% AuNP-GIC group. After 72 h, the 50% AuNP-GIC group maintained the highest cell viability: 8.63% ± 1.6%, which was significantly higher than the unmodified GIC group: 4.71% ± 2.6% ( Conclusion: Within the limitations of this exploratory pilot in vitro study, the 50% AuNP-containing liquid formulation showed the most favourable overall findings, being associated with less severe reduction in fibroblast metabolic activity than the unmodified control, improved surface smoothness and no significant difference in hardness. However, these findings should be interpreted cautiously, and further biological and physicochemical characterisation studies are required before any conclusions can be drawn regarding compatibility or clinical applicability. Significance: In this preliminary in vitro study, AuNP-containing liquid formulations used during GIC preparation were associated with less severe reduction in metabolic activity than unmodified GIC, together with reduced surface roughness. However, these findings should not be interpreted as evidence of acceptable cytocompatibility, and direct incorporation of nanoparticles into the final set cement was not confirmed. Further studies incorporating human oral cell models, complementary biological assays and physicochemical characterisation are needed before biological or clinical relevance can be established.