Effect of micrometer-scale metallic fillers on the mechanical and corrosion resistance properties of alternative materials for conservative dentistry.

Abstract

In conservative dentistry, glass-ionomer cements (GICs) have been proposed as substitutes for composite resins. This is because the latter, although widely used over the last 10 yrs, exhibit inadequate physico-chemical properties. Although the performance of a typical commercial GIC is not yet optimal for restorative dentistry, the addition of metallic filler could improve this. In this study, a series of commercially available GICs were incorporated in trial dental amalgams, whose mechanical and calorimetric properties and morphologies, were examined. The metallic component of these amalgams comprised one of three metallic fillers, each including micrometer-scale metal particles of a different shape. The corrosion resistance of the amalgams, in fluids simulating the oral cavity environment, was also studied. The addition of metallic filler to GIC produced a general improvement in mechanical properties. Of particular note were increases in the elastic modulus, up to around sixfold, with the addition of Valiant metallic filler to the GIC Fuji II, and of the stress at break, up to around fourfold, for the New Gen metallic filler/GIC Fuji II amalgam. In these cases, the mechanical properties of dentine were studied. Micrographic observations showed a highly compact structure of the added GICs, thus reflecting a reduction in shrinkage. Calorimetric and dilatometric analyses further confirmed the suitability for applications in preservative dentistry. Finally, with respect to corrosion resistance, the effect of the introduction of the metallic filler was beneficial in samples with low porosity.