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

Objectives: The objective of this study was to evaluate flexural strength and staining property 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 1.0-mm thickness for colorimetric measurement (n=3). Three point bending tests were performed after polishing with silicon carbide paper until #2,000 grid and storing in distilled water at 37 °C for 7 days. Colorimetric test specimens were polished with the silicon carbide paper until #4,000 grid and finished with buffing. 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 (△E*_ab) was measured by a color difference meter (CR241, Konica Minolta) after 1, 2, 3, 7, 14 and 28 days, and calculated by △E*_ab=(△a²+△b²+△L²)^1/2. These data were analyzed using two-way ANOVA followed by Tukey’s multiple comparison test (α=0.05).
Results: The flexural strength before stored water was not significantly different between each material, and that of KAPB showed the highest (263.3 MPa), and significantly higher compared with EPB (242.4 MPa) after stored water. Color difference of KZR3 after 1 day showed the lowest (0.43), and that of EPB showed the highest (1.20). Color difference of C300 after 28 days showed the lowest (1.30), and that of EPB showed the highest (2.96).
Conclusions: The results of this study suggested that the mechanical and physical properties were difference between each hybrid resin composite.