Setting time, mechanical and adhesive properties of magnesium oxide nanoparticles modified glass-ionomer cement

Nanoparticle modifications of glass-ionomer cement are interesting research subjects. This study investigated the effect of MgO nanoparticles on the setting time, compressive and diametral tensile strength, and adhesive properties of glass-ionomer cement. A conventional GIC was modified by the incorporation of MgO nanoparticles at 1%, 2.5%, 5%, and 10% (w/w) ratios with an unmodified GIC used as the control group. The data were analysed using a one-way analysis of variance (ANOVA) and Tukey's HSD test (p <0.05). Although the GICs with 1% and 2.5% MgO nanoparticles were still within the ISO standard range specified for the GIC setting time, increasing the MgO nanoparticle concentration significantly increased the setting time of the tested cement (p <0.05). GICs with 1% MgO nanoparticles had the highest compressive and diametral tensile strength values. Increasing the nanoparticle content from 5% and more significantly decreased the cement strength (p <0.05). The shear bond strength (SBS) of enamel and dentine showed statistically significant differences among the tested groups (p <0.05). However, the addition of MgO nanoparticles up to 5% (w/w) did not have an unfavourable effect on the cement adhesiveness. Although cohesive and mixed type failure modes were more common than adhesive failure modes, no statistically significant associations were found between the failure mode and type of GIC (p > 0.05). Within the limitations of this study, the current findings suggest that modifying GICs by incorporating MgO nanoparticles up to 2.5% (w/w) could be a promising restorative material for clinical dental applications. (C) 2019 The Authors. Published by Elsevier B.V.