| Background: Glass Ionomer Cement(GIC)is a commonly used filling and restoration material in the oral cavity,which has the characteristics of good biocompatibility,strong adhesion to tooth tissue,and release of fluoride ions to prevent secondary caries.However,compared with other oral materials such as resin and silver amalgam,the lack of mechanical properties of glass ionomer cement and the decline of long-term antibacterial ability limit its application in the clinical field,which often leads to the failure of restorative treatment.Therefore,the modification of the performance of glass ionomer cement has always been one of the research hotspots.With the vigorous development of material science,new materials and new technologies are constantly emerging and attract people’s attention.The development of multinanometer composite system provides a new idea for the modification of glass ionomer cement.Research purposes: In this study,hexagonal boron nitride(h-BN)nanosheets and zinc oxide(Zn O)nanoparticles were used as supports to construct h-BN/Ag and Zn O/Ag,respectively,by in-situ generation of silver(Ag)nanoparticles on their surfaces.Two different nanocomposite systems were added to glass ionomer cements to investigate their effects on mechanical and biological properties.Materials and methods: The structural model of hexagonal boron nitride and silver was constructed and optimized by molecular dynamics software(Material Studio,MS),the molecular dynamics behavior of the two was calculated,the energy change in the formation process of the heterojunction was studied,and the structural model was analyzed.Design principle of h-BN/Ag nanocomposite system.On this basis,we prepared hexagonal boron nitride nanosheets by ball milling method,reduced the silvercontaining precursor salt by ultraviolet irradiation,and controlled the in-situ nucleation and growth of nano-silver on the surface of hexagonal boron nitride nanosheets.Obtained h-BN/Ag nanocomposite material,and by transmission electron microscope(TEM),atomic force microscope(AFM),energy dispersive X-ray spectrum(EDS),Xray diffraction spectrum(XRD),Raman spectrum(Raman),Fu The surface morphology and structural properties of h-BN/Ag composites were studied by characterization methods such as Fourier Transform Infrared Spectroscopy(FTIR).Secondly,the crack evolution inside the glass ionomer cement was explored by finite element analysis,and the ability of the glass ionomer cement to resist vertical loads in the presence of h-BN nanosheet reinforcement phase was proved.Fractions(0.3,0.5,0.7,0.9,1.1 wt.%)of h-BN/Ag nanocomposites were added to glass ionomer cements,and their mechanical and antibacterial properties were evaluated.In addition,we also used EDS,Raman,FTIR,XRD and other testing methods to characterize Zn O/Ag nanocomposites,and Zn O/Ag nanocomposites with different mass fractions(0.3,0.7,1.1,1.5 wt.%)The nanocomposite particles were added to the glass ionomer cement,and the mechanical and biological properties were characterized.Results: The molecular dynamics calculation results show that the adsorption energy of the h-BN/Ag composite system is-140.1kcal/mol,and the two are mainly electrostatic adsorption.TEM and SEM results show that the lateral size of the hexagonal boron nitride nanosheets is about 1 μm,and the thickness is about 4 nm.Ag NPs are distributed on the edge of the surface,and the size is about 2-10 nm.XRD,Raman,FTIR and other characterization results prove the successful preparation of the nanocomposite system.The mechanical properties of h-BN/Ag nanocomposites were improved to varying degrees after adding the glass ionomer cement,and the sample with the addition of 0.9 wt.% showed the best mechanical properties.Compared with the pure sample,its compression The strength,flexural strength,and surface hardness have increased by 76.5%,18.4%,and 66.1% respectively,the antibacterial performance has increased to more than 90%,and the friction performance,solubility,and hydrophilic performance have all been improved.The Zn O/Ag nanocomposite system can also effectively improve the mechanical and antibacterial properties of glass ionomer cements.When the addition amount is 1.1 wt.%,it shows the strongest compressive strength and surface hardness,and the maximum improvement is about94% and 89%.The inhibition rate of Streptococcus mutans can reach 80%.These two works provide new solutions for developing more medical composite nanomaterials with excellent mechanical and antibacterial properties. |
PDF Full Text Request