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 (YbF₃) and barium sulphate (BaSO₄) on the strength and reactivity of a commercial glass-ionomer cement.

Methods

YbF₃ and BaSO₄ 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 YbF₃. Addition of BaSO₄ at low concentrations reduced working and initial setting times, but further addition delayed the setting reaction. Compressive strength decreased with the addition of either YbF₃ or BaSO₄, 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.

Keywords: Polyalkenoate cement, Compressive strength, Working time, Setting time, Reactive fluoride glass, Nanoparticle, Radiopacity, Glass-ionomer