Influence of Silica Fumes on Compressive Strength and Wear Properties of Glass Ionomer Cement in Dentistry

BACKGROUND Glass ionomer cements (GIC) are an interesting restorative option due to their biocompatibility. However, it has limitations that challenge its survival in oral environment due its porous set matrix influencing the properties of the cement. This study was conducted to evaluate the influence of the addition of varying concentrations of silica fumes (SF) on the properties of GIC by field emission scanning electron microscopy [FESEM] and energy-dispersive spectroscopy [EDX]. The final set matrix of GIC remains porous, compromising the mechanical properties, limiting its extended use clinically. Incorporation of silica fumes, a pozzolan, as an additive in GIC serves as a potential filler by increasing its compressive strength and reducing wear properties. METHODS The cement was divided into 5 groups based on the absence or presence of varying concentrations (0.5, 1, 1.5, 2 %) of silica fumes; conventional glass ionomer group (CG) (I) and 0.5, 1, 1.5, 2 silica fumes incorporated glass ionomer cement (SG) (II, III, IV & V) respectively. Compressive strength and wear resistance were subjected to Universal Testing Machine and Pin on Tribometer respectively. The microstructure and the elemental composition of prepared specimens of all the groups were evaluated using FESEM and EDX. Data obtained was analysed using Statistical Package for the Social Sciences (SPSS) V22.0 (IBM, USA) followed by one-way analysis of variance (ANOVA) and post hoc Tukey test (P < 0.05). RESULTS Except 0.5SG, increased compressive strength and decreased wear of glass ionomer material was observed as the concentration of silica fumes increased. Of all the concentrations, 2SG had significantly increased compressive strength (221.62 ± 22.84 MPa) compared to CG (167.38 ± 36.94 MPa) (P < 0.05). Significantly increased resistance to wear was noted in 2SG (11.80 ± 2.58 µm) compared to CG (20.40 ± 2.07 µm) (P < 0.05). The set matrix of silica fumes modified GIC showed minimal / absence of pores with dispersion of crystalline particles as the concentration of SF increased. EDX revealed similar constitution of minerals but, varied with increased concentration of silica fumes. CONCLUSIONS 2 % silica fumes incorporated glass ionomer cement (2SG) enhanced the properties of conventional glass ionomer cement. KEY WORDS Compressive Strength, EDX, Field Emission Scanning Electron Microscope, Glass Ionomer Cement, Silica Fumes, Pozzolan