Color Stability and Roughness of a 3D-Printed Denture Base Resin

Objectives: The aim of this study was to evaluate the influence of printing parameters on the surface roughness and color stability of a 3D-printed denture base resin after immersion in coffee over time.
Methods: Disc-shaped specimens (10 x 1.2 mm, priZma 3D Bio Denture, N=72) were printed using Liquid Crystal Display, LCD or Digital Light Processing, DLP at 0°, 45°, or 90°. Color differences (ΔE2000) were calculated using the CIEDE2000 formula. Ra (µm) and ΔE2000 were measured at baseline and 1-, 3-, 6-, 12-, 24-, 36-month simulated periods of coffee consumption. For ΔE2000, Generalized Estimating Equations (GEE) were performed with post hoc Bonferroni tests for multiple comparisons of means. The perceptibility and acceptability thresholds of color change was set at PT/AT: ΔE00= 1.7/4.1. For Ra, a three-way mixed-model ANOVA was used. All analyses were performed with α=.05.
Results: Unacceptable color values were observed in the groups printed in DLP at 3- and 6-month periods of immersion in coffee. For LCD, the color change was clinically unacceptable only at the 3-month period. Regardless of the system, at the 3-month period of immersion in coffee, clinically unacceptable color changes were observed in the groups printed at 0°, 45° and 90° (ΔE00 ≥ 4.1). For specimens printed at 45°, Ra increased significantly from the 3-month period (0.22 ± 0.19 µm) and remained similar until the 3-year (0.29 ± 0.21 µm), irrespective of the system.
Conclusions: DLP resulted in greater color change than LCD in all periods, except at 12 and 36 months when they were similar, regardless of the printing angle. The 3-month period of immersion in coffee is critical, resulting in higher roughness at 45°, irrespective of the system, and clinically unacceptable color change values, irrespective of the system or printing angle. LCD should be indicated for printing denture bases.