Effects of three food-simulating liquids on the roughness and hardness of CAD/CAM polymer composites.

Implant-supported frameworks constructed from high-performance polymer CAD/CAM composites are exposed to liquids from the oral environment and routine care maintenance. Therefore, this study investigated the effect of food-simulating liquids (FSLs) on surface properties of three CAD/CAM polymer composite blocks. The composites investigated were (i) a carbon fibre-reinforced composite (CarboCAD 3D dream frame; CC), (ii) a glass fibre-reinforced composite (TRINIA; TR), and (iii) a reinforced PEEK (DentoKeep; PK). The filler contents were determined by thermo-gravimetry. The surface properties were roughness, Vickers hardness (HV), properties measured by Martens force/depth indentation, namely: hardness (HM), modulus (E IT) and creep (C IT). Property measurements were made at baseline on polished specimens and then, where possible, after 1- and 7-days storage at 37 ℃ in three different media: water, 70% ethanol/water and MEK (methyl ethyl ketone). Specimens were selected for light and scanning electron microscopy. Statistical analysis was performed by two-way repeated measures ANOVA, one-way ANOVA, and multiple comparison tests (α = 0.05). The baseline roughness and hardness (HV, HM) and modulus (E IT) correlated approximately with filler content (wt%), with the fibre-reinforced composites being rougher, harder and stiffer than PK. At baseline, roughness (Sa) ranged from 0.202 to 0.268 µm; HV from 23.1 to 36.9; HM from 224.5 to 330.6 N/mm2; E IT : from 6 to 9.8 GPa. After ageing in 70% ethanol and MEK, more pronounced roughness and hardness changes were observed than in water. MEK caused greater deterioration for the FRC than 70% ethanol, while PK specimens showed slight changes in 70% ethanol. Storage media adversely affected the surface and mechanical properties of each CAD/CAM composite. However, during ageing, the reinforced PEEK showed greater relative stability in these properties. Nevertheless, the deterioration may indicate the need for full protection by a veneer material on each surface of an implant-supported framework. [ABSTRACT FROM AUTHOR]