Microhardness and Wear Resistance of Glass Ionomer Cements Modified by Chitosan and Nano-Hydroxyapatite

Despite the merits of glass ionomer cements (GICs), they suffer from weak mechanical properties such as low wear resistance. In this study, the mechanical properties of GICs after incorporating chitosan and nano-hydroxyapatite was investigated. The samples were prepared in four groups, including non-modified GIGs (NMGIC, n = 5), chitosan incorporated GICs (CHGIC, n = 5), nano-hydroxyapatite incorporated GICs (nanoHAGIC, n = 5), and chitosan/nanohydroxyapatite incorporated GICs (CH/nanoHA/GICs, n = 5). Long-term Vickers microhardness (VH) and wear rate of the samples after immersion in artificial saliva were measured. The results were analysed using one-way ANOVA followed by Scheffé's test (P < 0.05). Moreover, the microstructure of the samples was investigated via scanning electron microscopy. After 1 hour, the VH values of CH/nanoHA/GICs and CH/GICs were greater than nanoHA/GICs and non-modified GICs (p<0.001). However, there were no statistical differences among VH values of all groups after 11 weeks (p>0.05). Based on the wear tests, adding nanoHA or CH to GICs increased their wear rates, while introducing both of them decreased weight loss of GICs. Within the limitations of the present study, introducing both nanoHA and CH to GIC enhances GIC’s microhardness and wear resistance. Consequently, the addition of nanoHA and CH is a promising approach for improving mechanical properties of GICs.