The evaluation of the mechanical characteristics of the synthesized glass-ionomer cements (GICs): the effect of hydroxyapatite and fluorapatite nanoparticles and glass powders

The goal of this research is to examine the influence that incorporation of synthesized hydroxyapatite (HA) and fluorapatite (FA) nanoparticles has on the synthesis and mechanical characteristics of glass-ionomer cements (GICs). In this research, HA and FA nanoparticles were synthesized through wet-chemical precipitation method. The obtained inorganic nanoparticles were evaluated with XRD, SEM, TEM, and STA analyses. The glass powder of the GIC (G 1 and G 2 ) were synthesized with two different formulations, and in addition, the polymer of GIC, acrylic-itaconic copolymer, was prepared in this research. The synthesized GIC components were appraised employing XRD and STA (for glass component) and FTIR and H-NMR (for polymer component). HA and FA nanoparticles were then added into the powder component (G 1 and G 2 ) at 5% and 8 wt%, and unblended powder was utilized as a control. Compressive strength (CS) and diametral tensile strength (DTS) before and after 1, 7, and 28 days of storage in distilled water were investigated utilizing a universal testing machine. Surface microhardness after 1 and 7 days of storage in distilled water was measured utilizing Vickers microhardness tester. Also, setting and working time was determined as specified in the ASTM standard. The obtained results showed that the calcined HA and FA nanoparticles have an ellipsoid-like morphology, and their mean crystallite sizes were measured as 24 and 30 nm, respectively. The mechanical results of the modified GICs, following the addition of HA and FA (5 and 8 wt%) into the glass ionomer cement and 28 days storage in distilled water, exhibited statistically higher CS (64–70 and 66–72 MPa, respectively). Also, higher DTS was observed, at about 7.5–10.5 and 8.5–12 MPa, respectively. The microhardness of the GICs containing HA and FA nanoparticles (5 wt%) increased by 6.5 and 14%, respectively. In addition, the working time and setting time by adding the 5 wt% nanoparticles reduced about 12 and 19% for HA and 13.5 and 18% for FA, respectively. Finally, it can be concluded that the synthesized GICs containing HA and FA nanoparticles provide enhanced mechanical properties to restorative dental materials.