Desenvolvimento e caracterização de cimento ionômero de vidro modificado por nanomateriais

Abstract

Glass ionomer cement (GIC) has unique properties that enable versatile clinical applications, including adhesion to tooth structure, fluoride release, and biocompatibility. However, its mechanical limitations restrict its indication for definitive restorations. In this context, nanomaterials can provide mechanical reinforcement, improve esthetics, and induce antimicrobial and therapeutic effects. In particular, graphitic nitrogenated graphene (g-C₃N₄), silver phosphate (Ag₃PO₄), and nanostructured clinker show great potential as reinforcements for high-strength composites, preserving good mechanical properties and enhancing antimicrobial activity. The objective of this study was to develop and characterize GICs modified with nanomaterials: (i) g-C₃N₄; (ii) Ag₃PO₄; and (iii) nanostructured clinker. The commercial GIC powder (Ketac Molar Easy Mix, 3M-ESPE) was modified differently for each nanomaterial: (i) 0.5%, 1%, and 1.5% g-C₃N₄; (ii) 4%, 6%, and 8% Ag₃PO₄; and (iii) 0.001%, 0.005%, 0.01%, 0.1%, 0.3%, and 0.5% nanostructured clinker. Scanning electron microscopy, energy dispersive spectroscopy, Raman spectroscopy, X-ray diffraction, and thermogravimetric analysis were used for characterization. Performance tests included compressive and flexural strength, elastic modulus, Vickers microhardness, surface roughness, color stability, fluoride release, cell viability, free radical production, and microbiological evaluation, following recommended standards. Statistical analysis used one-way ANOVA followed by Tukey's post hoc test to compare more than two groups, and Kruskal-Wallis with Dunn's post hoc test when appropriate. For evaluations at different time points of the same sample, repeated-measures ANOVA (or Friedmann's test when indicated) with Tukey's or Dunn's post hoc test was applied. The software used was GraphPad Prism 8 (La Jolla, CA, USA); the significance level was p < 0.05. Results showed that GIC modified with g-C₃N₄, Ag₃PO₄, or nanostructured clinker presented the desired mechanical reinforcement, with gradual improvement as their respective concentrations increased. In a compartmentalized manner it was concluded that: (i) the incorporation of g-C₃N₄ into the GIFC promoted significant improvements in mechanical properties, especially compressive and flexural strength, without compromising fluoride release or biocompatibility, evidenced by low cytotoxicity and reduced cellular oxidative stress. Furthermore, the modified material demonstrated selective antibacterial activity against S. mitis; (ii) the enrichment of Ag₃PO₄ into the GIFC significantly improved compressive strength, fluoride release, and antimicrobial inhibition, without compromising properties such as flexural strength, elastic modulus, roughness, and microhardness; (iii) the modification of the GIC with nanostructured clinker proved to be an effective approach for enhancing its mechanical, biological, and functional properties, without compromising its biocompatibility or surface stability.