Surface roughness and color change of methacrylate and ormocer-based direct composite versus indirect CAD/CAM composite blocks

Abstract

Objectives

To assess the color stability and surface roughness of resin-free and resin-based nanohybrid composites after immersion in various staining media.

Methods

A resin-free ormocer composite, Admira fusion (Voco, Germany), and a methacrylate resin composite, Grandio (Voco, Germany), were used for direct composite restorations with 30 discs per material formed using a Split Teflon mold (10 mm × 2 mm). Grandio Bloc (Voco, Germany) universal indirect CAD/CAM block specimens (n = 30) were sliced to a thickness of 2 mm with a precision saw. Each material was divided into 3 groups (n = 10 each) based on the immersion solution. Specimens were soaked in coffee (Turkish coffee, Baja, Saudi Arabia), cola (Coca-Cola Co., USA), and artificial saliva. Color was evaluated before staining and after 30 days of staining using a spectrophotometer. Color change (ΔE*) was measured using the system of CIE L*a*b*. Surface roughness was determined using a stylus profilometer and represented using Atomic Force Microscopy before and after immersion in the staining solutions.

Results

After immersion in the staining solutions for 30 days, the color values of all the composites changed. Group A (coffee) had the greatest effect (ΔE > 5), and indirect Grandio blocs caused the greatest color change. The surface roughness values increased, particularly in group B (Coca-Cola), for all the tested materials after 30 days. Direct Grandio had a significantly higher roughness than the other materials (p < 0.001).

Conclusion

Immersion in coffee resulted in considerable color change, while immersion in cola had the greatest negative impact on surface roughness in all tested restorative materials. The nanohybrid ormocer did not provide better surface integrity than conventional methacrylate-based nanohybrid composites.