Effects of Niobium Oxide Addition on the Mechanical Properties of Glass Ionomer Cement

Abstract

Aiming at inadequate mechanical properties of Glass ionomer cement (GIC) commonly used in dental clinic, commercial and melt quenched GIC powders as control groups, homemade GIC powder was prepared by sol–gel route and modified by Nb2O5. The GIC samples were characterized by X-ray Diffraction (XRD), particle size analysis, Scanning Electron Microscope (SEM) and Fourier Transform Infrared (FT-IR). The compressive strength, Vickers hardness, working and net setting time were tested. The data was analyzed by one-way ANOVA. The XRD results showed that commercial, melt quenched and sol gel GIC powders were similar amorphous. D90 of three GIC powders and Nb2O5 powder were 26 μm, 17 μm, 29 μm and 19 μm respectively. 5% Nb2O5-GIC exhibited the highest values of compressive strength and Vickers hardness, which were 112.93 Mpa, 139.48 MPa and 142.25 MPa respectively, increased 19.11%, 30.56% and 16.51% (P <0.05); the Vickers hardness were 35.15 MPa, 36.23 MPa and 37.62 MPa, increased 18.03%, 29.95% and 16.32% (P <0.05) compared to those of unmodified GICs as well. There was no significant change of the FT-IR characteristic peaks of modified GIC. The working time of three kinds of GIC were 4'58 ", 3'28" and 4'10 ", the net setting time were 5'16", 3'15 "and 4'38" (standard is 1.5-6 minutes). It was concluded that the dispersion stiffened effect of niobium oxide could improve the mechanical properties of the filling GIC without affecting the clinical operating performance.