Color stability and surface roughness of resin based direct and indirect restorative materials

Purpose: This study investigated discoloration and surface roughness (Ra) of resin-based computer aided design (CAD)/computer aided manufacturing (CAM) blocks and direct and indirect resin composites after staining with coffee. Materials & Methods: Using a Teflon mold, 60 disc shaped specimens (8×2 mm2) were fabricated from direct (Estelite Asteria and GrandioSO) and indirect (Gradia Plus) resin composites, and 30 resin CAD/CAM specimens (12×14×2 mm3) were prepared from resin composite CAD/CAM blocks (Vita Enamic, Brilliant Crios, and Cerasmart) (n=10). A contact type profilometer was used to determine the Ra of all 60 polished samples. All specimens were thermocycled between 5 and 55°C for 3000 cycles, and immersed in coffee solution (37°C) for 1 and 7 days. A spectrophotometer was used to determine the color change (∆E00) with the CIEDE2000 formula after the specimens were re-polished. One-way analysis of variance (ANOVA) and Tukey multiple comparison test was performed to analyze the data (p<0.05). Results: The lowest degree of discoloration among the materials tested was found in Vita Enamic resin CAD/CAM block (p<0.001), whereas the highest degree of discoloration was found in the Gradia Plus indirect composite (p<0.001). There was no significant difference was seen between the initial surface roughness values (Ra) among the groups (p=0.249). No significant improvement was observed in the color of the groups except for the Cerasmart resin block after after polishing. Conclusion: Direct resin composites have a higher discoloration potential over resin-based CAD/CAM blocks, whereas they are less prone to discoloration than indirect resin composites