Effect of aging on mechanical and antibacterial properties of fluorinated graphene reinforced glass ionomer: In vitro study

Abstract

ObjectivesThis study: 1) aims to test the mechanical and antibacterial properties of fluorinated graphene strengthened glass ionomer materials (FG/GICs); 2) aims to investigate the effects of thermo-cycling on (FG/GICs). Materials and methodsFluorinated graphene (FG) with bright white color was prepared from fluorinated graphite (SIGMA Aldrich), using modified Hummer's method, to be added to conventional glass ionomer cements (GICs). In addition to a control group (group 1), experimentally modified GICs were prepared by adding FG to the conventional glass ionomer powder with three different weight ratios; (group 2, 1 wt %; group 3, 2.5 wt %; and group 4, 5 wt %) using mechanical blending method. Experimental groups of the specimens (n = 240) were divided, for each concentration (n = 120) half of the specimens were subjected to thermo-cycling. Hardness, compressive strength, and antibacterial activity of (FG/GICs) were measured with and without thermo-cycling. Compressive strength was measured by a universal testing machine, hardness was measured using a Vickers micro-hardness tester, and antibacterial effects against staphylococcus aureus and streptococcus mutans were tested by the pellicle sticking method. For statistical analysis, numerical data were explored for normality and variance homogeneity using Shapiro-Wilk and Leven's tests respectively. ResultsThe prepared (FG/GICs) showed an increase in hardness in group 4 (p < 0.001). Groups 3 and 4 gave the highest compressive strength values with no significant difference between them (p < 0.001). Groups 2, 3, and 4 showed improved antibacterial activity with no statistical difference between them (p > 0.001). Results after thermo-cycling showed significantly decreased hardness, and compressive strength values (p < 0.001), however, the results of antibacterial activity against streptococcus mutans showed no statistical difference after thermo-cycling (group 2, p = 0.05; group 3, p = 0.18; group 4, p = 0.26). The same results were observed for antibacterial activity against staphylococcus aureus (p = 0.92, p = 0.14, and p = 0.48 respectively). ConclusionFG can be considered a promising additive to GICs to promote its anti-cariogenic effects, however, these antibacterial effects are only useful in the short term, as aging adversely affected their mechanical properties. The 2.5 wt % FG/GICs is suggested to be the most encouraging, as after aging, it represented the highest compressive strength among all groups, while its hardness values were at least comparable to that of conventional glass ionomer. Clinical significanceFG/GICs can be considered an anti-cariogenic restoration in temporary restorative interventions, as in certain cases in deciduous teeth where considerable esthetics may be required, especially those with difficult moisture control, where neither resin composite restorations nor amalgam restorations will be indicated. It can also be used for patients with high caries index or in atraumatic restorative treatment (ART) in low-income countries.