Effect of tooth brushing simulation on the surface properties of various resin-matrix computer-aided design/computer-aided manufacturing ceramics.

Abstract

The purpose was to investigate the alterations in surface properties of different resin-matrix CAD/CAM ceramics following tooth brushing simulation (TBS) and compare them with a direct resin composite and a glass ceramic CAD/CAM material. Four resin-based CAD/CAM restoratives (Brilliant Crios-BR, Lava™ Ultimate-LV, Grandio Blocs-GR and Shofu Block HC-SH), a leucite-reinforced glass ceramic (IPS Empress® CAD-EC) and a resin composite (Filtek™ Z250-FZ) for direct restorations were tested. In particular, surface loss, hardness, roughness and morphology were investigated utilizing confocal microscopy, scanning electron microscopy and nanoindentation tester. TBS was conducted for 4 × 15 min on the surface of the samples and then the changes in their surface properties were evaluated. After TBS, all the experimental groups exhibited surface loss to different extent. FZ and BR presented the highest surface loss, while EC and GR the lowest (p < 0.05). Regarding surface roughness, all the tested materials exhibited increase after TBS (p < 0.05), except LV (p = 0.099). EC presented the lowest Sa values, while FZ and BR the highest (p < 0.05). Changes in surface morphology were in compliance with the results of surface roughness and also surface hardness was correlated with surface loss. The tested resin-matrix CAD/CAM ceramic restorative materials showed a competent behavior against abrasive forces applied during TBS. Surface loss and roughness changes were material dependent and superior compared to a resin composite for direct restorations, while in comparison with a leucite-reinforced glass ceramic exhibited inferior properties. Tooth brushing affected differently the surface of the tested restorative materials. However, the abrasive wear that was induced was negligible. Clinical studies are necessary to ascertain if there is clinical significance of these surface alterations that may demand repair of such restorations.