Preparation And Properties Study Of Glass Ionomer Cements /Fluorinated Graphene Composites

Objective.The aim of this study was to evaluate the mechanical properties,wear resistance,Fluoride ion releasing,solubility and antibacterial properties of glass ionomer cements(GICs)/fluorinated graphene(FG),to provide experiment evidences for follow-up clinical application.Materials and methods.FG with bright white color was prepared using graphene oxide by a hydrothermal reaction.Four experimental groups was prepared by adding FG to the traditional GICs powder with four different weight ratios(0.5 wt%,1 wt%,2 wt% and 4 wt%)using mechanical blending and ultrasonic treatment.The Vickers microhardness of all the specimens was measured by a Vicker microhardness tester.Compressive and flexural strength of each experimental and control group materials were investigated using a universal testing machine.For tribological properties of the composites,specimens of each group were investigated by UMT-2 friction tester.Fluoride ion releasing was measured by fluoride ion selective electrode methods for 126 days.The solubility was measured under the artificial saliva environment for 1,30,90 days.The antibacterial effect of GICs/FG composites on selected bacteria(Staphylococci aureus and Streptococcus mutans)was tested with pellicle sticking method.Results.The prepared GICs/FG composites with white color were successfully fabricated by mechanical blending and ultrasonic treatment.1)Characterization of FG: TEM at low magnification shows a thin and transparent 2D nanostructure of FG with lateral dimensions in range between 200 nm and 2 ?m.Similar to graphene,FG shows wrinkled surface.TEM at high magnification shows that FG has oneycomblike structure.Raman spectra shows that FG has a more disorder microstructures than GO.XPS shows that the content of F in FG was 35.75%.2)Characterization of GICs/FG composites: SEM shows FG was dispersed uniformly in the cement.3)Mechanical performance: The Vickers microhardness and compressive strength of GICs/FG composites were enhanced with the increase of FG content.When the content of FG was 2 wt%,the VHN and CS of the composites were increased by 60.81% and 59.56% compared to the pure GICs.4)Tribological performance: The COF of the GICs/FG composites decreased significantly with the increase of FG content compared to unreinforced GICs.When the content of FG was 4 wt%,the average COF and wear rate were decreased by 20.8% and 61.59%?5)Fluoride ion releasing measurement and solubility: Fluoride ion accumulating releasing shows no remarkable change between the groups and the solubility of the GICs/FG composites were decreased(except for the GICs/FG(4 wt%)).6)Antibacterial activity: The colony count against S.aureus and S.mutans decreased with the increase of the content of FG.And the antibacterial rate of S.mutans can be up to 85.27% when the FG content was 4 wt%.Conclusion.FG with white color was successfully prepared by hydrothermal reaction of GO and hydrofluoric acid.Mechanical blending was able to prepare GICs/FG composites and FG was dispersed uniformly in the GICs.Significant improvement on mechanical properties of GICs has been found with the addition of FG(the VHN and CS were enhanced with the increase of FG content).The COF and volume wear rate of GICs/FG composites decreased significantly.Fluoride ion accumulating releasing showed no remarkable change and the dissolving-resistance ability of the GICs/FG composites were improved except for the GICs/FG(4 wt%).In addition,GICs/FG composites showed superior performance of killing S.mutans and S.aureus.We believe GICs/FG composite materials would be a new avenue for the application of dental restoration.