Color Changes in New Generation of CAD/CAM Polymers

Objectives: Most of restorative materials for gingiva imitation and artificial teeth can be fabricated in Computer-Aided-Designed/Computer-Aided-Manufacturing (CAD/CAM) technology which implies standardized manufacturing processes and restoration reproducibility. CAD/CAM high-density dental polymers provide good precision in fitting and better mechanical properties in comparison to conventional ones. Also, due to lower porosity and more compact surfaces, they provide better optical properties. However, color changes with staining solutions have not been investigated.
The aim of this study is to compare color changes of different polymers after immersion in staining solutions.
Methods: Specimens were made of two CAD/CAM polymers: Vivodent CAD (Ivoclar Vivadent), IvoBase CAD (Ivoclar Vivadent), and one conventional acrylate, ProBase Hot (Ivoclar Vivadent). From each group, 5 specimens (10x10 mm) were made. Manufacturing and polishing was in accordance with the manufacturer's instructions. The samples were submerged in wine, coffee and distilled water for 67 hours. The color was measured before and after staining with VITA Easyshade V. CIEDE2000 formula was applied and T test and ANOVA for statistical difference (p<0.05).
Results: ΔE formula showed that CAD/CAM polymers stained more in wine and coffee but less in water compared to conventional acrylate (table 1). Comparison within staining solution groups, showed significant difference between materials when staining with wine and water, while there was no difference in staining with coffee. In the wine group, the significant difference was between IvoBase CAD and ProBase Hot (p=0.0028), and between Vivodent CAD and ProBase Hot (p=0.0001). Similarly, in the water group, the significant difference was between Vivodent CAD and ProBase Hot (p=0.0001) and between IvoBase CAD and ProBase Hot (p=0.0001). ANOVA test showed statistical difference between groups (p= 0.003).
Conclusions: Differences in color changes between CAD/CAM and conventional polymers are significant. Further investigations in terms of polymers porosity and absorption are needed in order to determine nature of those differences.