Influence of accelerated ageing on the physical properties of CAD/CAM restorative materials

Abstract

This study aims to investigate the influence of thermocycling on the physical properties of different CAD/CAM restorative materials and assess their ability to maintain energy dissipation capacities and damping effects. The results of a 3-point bending test were used to calculate flexural strength (FS), modulus of elasticity (ME), modulus of toughness (MT) and elastic recovery (ER) for three ceramic, twelve composite and five polymer-based materials. Specimens (n = 10, 4.0 × 1.5 × 17.0mm3) were loaded until rupture after water storage (24h; 37.0 ± 1.0°C) or thermocycling (5000cycles; 5-55°C). Statistical data analysis was performed using parametric statistics (p = 0.05). Thermocycling had no significant influence on any investigated properties of ceramic materials (p > 0.05). Hybrid composites showed significant differences between water storage and thermocycling (p < 0.05), with the exception of FS of Tetric CAD. Similarly, ME with AMBARINO High-Class, CERASMART, Tetric CAD and Vita Enamic and MT and ER with Paradigm and Tetric CAD were not affected. For polymer-based materials, significant differences were found with the exceptions of FS (PEEK-OPTIMA, Telio CAD), ME (M-PM Disc, PEEK-OPTIMA, Telio CAD, Vita CAD-Temp), MT (Telio CAD) and ER (Telio CAD). The material properties of composite and polymer-based CAD/CAM materials were susceptible to degradation processes induced by thermocycling. Only Telio CAD and Tetric CAD showed no significant effects like all ceramic materials, thus preserving their inherent ability to elastically and plastically dissipate energy. A careful material selection is advisable when planning CAD/CAM restorations as remarkable differences may exist in the durability of physical characteristics through the impact of water.