Study on Characteristics of High Toughness Hybrid Resin for CAD/CAM

Objectives: The objective of this study was to evaluate flexural strength and staining properties of high toughness hybrid resin composite for CAD/CAM.
Methods: The high toughness hybrid resin composites for CAD/CAM used in this study were Cerasmart 300 (C300; GC), Estelite P Block (EPB; Tokuyama Dental), Katana Avencia P Block (KAPB; Kuraray Noritake Dental) and KZR-CAD HR 3 (KZR3; Yamakin). The specimens were prepared with size of 1.2 mm x 4.0 mm x 14.0 mm for three-points bending test (n=10), and size of 12.0 mm diameter and 1.0 mm thickness for colorimetric measurement (n=3). After polishing with the silicon carbide paper until #2,000 grid, three-points bending test and colorimetric test were performed. After stored in distilled water at 37 °C for 7 days, bending test was performed. Staining solution of colorimetric measurement was used a coffee solution. The specimens were immersed into coffee solution at 37 °C. The value of color difference (ΔE*ab) was measured by a color difference meter (CR241, Konica Minolta) after 1, 2, 3, 7, 14 and 28 days, and then calculated by ΔE*ab=(Δa²+Δb²+ΔL²)^1/2. These data were analyzed using one-way ANOVA followed by Tukey’s multiple comparison test (α=0.05).
Results: Flexural strength of KAPB before stored water showed highest (292.5 MPa). After water immersion, that of KAPB showed highest (263.3 MPa), and significantly higher compared with EPB (242.4 MPa). Color difference of KZR3 after 1 day showed lowest (0.43), and that of EPB showed highest (1.20). Color difference of C300 after 28 days showed lowest (1.30), and that of EPB showed highest (2.96).
Conclusions: The results of this study suggested that mechanical and physical properties were difference between each hybrid resin composite for CAD/CAM.