The effect of ytterbium fluoride and barium sulphate nanoparticles on the reactivity and strength of a glass-ionomer cement

Abstract

Objectives While clinical advantages of glass-ionomers include fluoride release and radiopacity, disadvantages include low strength, slow initial setting times and opacity. The addition of nanoparticles, in particular those containing fluoride and cross-linkable ions, may mitigate the disadvantages while further improving the advantages. This investigation evaluated the effects of the addition of ytterbium fluoride (YbF 3) and barium sulphate (BaSO 4) on the strength and reactivity of a commercial glass-ionomer cement. Methods YbF 3 and BaSO 4 nanoparticles were incorporated into the powder component of Riva SC (SDI Ltd., Bayswater, Australia) at 1, 2, 5, 10, 15, and 25% by weight. Capsules were assembled at a powder:liquid ratio of 2.9:1, activated and mixed, and the resultant pastes evaluated for working time, initial setting time, 24-h surface hardness and 24-h compressive strength. Results Working and initial setting times were reduced with the addition of YbF 3. Addition of BaSO 4 at low concentrations reduced working and initial setting times, but further addition delayed the setting reaction. Compressive strength decreased with the addition of either YbF 3 or BaSO 4, while surface hardness was slightly but insignificantly higher at 1–2% nanoparticles and then decreased with increasing nanoparticle concentrations. Significance Nanoparticles modified the setting characteristics, strength and surface hardness of a commercial glass-ionomer cement, and may be useful for refining the handling characteristics of these materials. Further improvements in powder blending may result in more significant improvements in mechanical properties.