Study On The Preparation,Structure And Properties Of Basalt Fiber Reinforced Glass Ionomer Cement

As a potential dental restoration material,glass ionomer cement,GIC for short,is widely used in dental defect repair,cavity filling,and pit and fissure sealing,etc.,but it is limited to non-stress bearing areas of teeth because of its poor mechanical strength.In order to improve its mechanical strength and expand its clinical use in the oral cavity,the basalt fiber,BF for short,exhibiting excellent comprehensive performance and being green,environmental protection,non-toxic and harmless to human,was chose to reinforce GIC,and the effects of BF length,BF content and various surficial modifying groups on the mechanical properties,fracture morphology,water-aging resistance properties,water sorption and solubility of the BF reinforced GIC were studied.It not only has important clinical significance to broaden the application of GIC dental repair materials,but also has important scientific research value to promote the research and development and application of new dental repair materials.All the results of this study were listed as below:（1）The strengthen modification of GIC using BF with 1 mm and 2 mm of length and3wt.%,5wt.%,7wt.%,9wt.%of content were prepared.The BF-GIC with 2 mm,7wt.%BF showed the best mechanical properties.Compared with GIC,the flexural strength,compressive strength and fracture toughness of BF-GIC increased by 58.5%,50.5%,226.3%,respectively,while the flexural modulus showed no obvious change.The water-aging resistance of BF-GIC was worse than that of GIC;GIC spline exhibited the characteristics of brittle fracture,BF-GIC exhibited ductile fracture characteristics,and there was a certain bonding between BF and GIC,while the bonding between the two disappeared after 1-month water immersion;The water sorption of BF-GIC was significantly higher than that of GIC while the solubility of BF-GIC and GIC was similar.（2）The surface modification of BF with 1%,3%,5%and 7%mass fraction ofγ-aminopropyl triethoxy silane,APS for short,were done and the APS-BF with various APS content were prepared and the structures were confirmed by FT-IR,XPS,SEM and TG analysis.The APS-BF-GIC prepared by 5%APS-BF showed the best mechanical properties,the flexural strength and fracture toughness were increased by 33.7%and 42.7%comparing to BF-GIC while the flexural modulus and the compressive strength did not show significant difference;The water-aging resistance of APS-BF-GIC was better than that of BF-GIC;APS-BF showed a better adhesion between GIC than BF,and after 1-month water immersion,the bonding between APS-BF and GIC weakened while did not disappeared;APS-BF-GIC showed similar water sorption with BF-GIC,and the solubility of APS-BF-GIC slightly decreased compared to BF-GIC.（3）The APS-BF surface was modified by the reaction of-NH₂ on the surface with isophorone diisocyanate and ethylenediamine in turn and the DIEDA-BF modified by various generation of straight-chain DIEDA with ureido group and-NH₂ was prepared and the structures were confirmed by XPS,SEM and TG analysis.The DIEDA-BF-GIC prepared by DIEDA-BF-G₁ showed the best mechanical properties,the flexural strength and fracture toughness were increased by 26.5%and 27.1%comparing to APS-BF-GIC while the flexural modulus and the compressive strength did not show obvious change;The water-aging resistance of DIEDA-BF-GIC was better than that of APS-BF-GIC;The bonding between DIEDA-BF and GIC was stronger than that between APS-BF and GIC,and after 1-month water immersion,the bonding between the two was weakened but still stronger than that between APS-BF and GIC;DIEDA-BF-GIC showed slightly decreased water sorption than APS-BF-GIC and the solubility of DIEDA-BF-GIC decreased compared to APS-BF-GIC.（4）The APS-BF was modified by carrying out the Michael addition reaction of the-NH₂to methyl acrylate and the amination reaction of ester group to ethylenediamine in turn and the PAMAM-BF modified by various generation of dendritic PAMAM with amide groups and-NH₂ was prepared and the structures were confirmed by FT-IR,XPS,SEM and TG analysis.The PAMAM-BF-GIC with PAMAM-BF-G₁ showed the best mechanical properties,the flexural strength and fracture toughness were increased by 37.3%and 43.5%comparing to APS-BF-GIC while the flexural modulus and the compressive strength were basically the same without significant difference;The water-aging resistance of PAMAM-BF-GIC was better than that of APS-BF-GIC;There was a stronger bonding between PAMAM-BF and GIC and after 1-month water immersion,the bonding between the two was still good;The water sorption and solubility of PAMAM-BF-GIC were comparable to APS-BF-GIC.（5）The order from good to bad for the comprehensive performance of the enhanced GIC is as follows:PAMAM-BF-GIC>DIEDA-BF-GIC>APS-BF-GIC>BF-GIC.Among them,the flexural strength of PAMAM-BF-GIC has reached the strength requirement of dental occlusal repair materials（not less than 80MPa）specified in ISO 4049:2019,and the flexural strength of APS-BF-GIC and DIEDA-BF-GIC have reached the strength requirement of resin-based restorative materials（not less than 50 MPa）specified in ISO 4049:2019.Moreover,the fracture toughnesses of the 4 kinds of enhanced GIC were similar to that of the tooth.