Effect of aging on optical behavior and color of 3D printing resin-based dental restorative materials

To evaluate the influence of aging on color and optical properties of 3D printing resin-based dental restorative materials.

Four 3D printing resin-based dental restorative materials (DFT- Detax Freeprint Temp; FT- Formlabs Temporary CB; FP- Formlabs Permanent Crown; and GCT- GC TempPrint) were evaluated. The structures were printed using digital light processing (DLP) (DFT and GCT groups) and stereolithography (SLA) (FT and FP groups) technologies. Samples (10 × 10 × 1 mm; n = 3) were printed in light (L) and medium (M) shades and at 0° and 90° and then polished to a thickness of 1.00 ± 0.01 mm with silicon carbide (SiC) sandpapers under water cooling. Artificial aging followed the ISO 4892-2 standard. 1) Color differences were evaluated using CIEDE2000 and perceptibility and acceptability thresholds (PT₀₀ and AT₀₀), 2) spectral reflectance (R%) and transmittance (T%) were measured and scattering (S) and absorption (K) coefficients, light reflectivity (RI), infinite optical thickness (X∞) pre- and post-aging were calculated using Kubelka-Munk method and Root Mean Square Error (RMSE) and Goodness of Fit (GFC) were used as performance optical behavior.

1) All 3D-printed dental resins evaluated, irrespectively of the printed angles, showed mean ΔE₀₀ values above AT₀₀ (_.ΔE₀₀>1.8), and FT-M and FP-M showed the least color changes among the evaluated materials, 2) GFC<0.999 and RMSE >2 % values were found between pre and post aging for R%, T%, S, K, RI and X∞ properties.

This study showed poor spectral match and comparative spectral values of R%, T%, S, K, RI and X∞ between after and before aging, resulting in unacceptable color changes. Printing orientation does not influence the change of the optical behavior of the evaluated materials after aging.

Aging causes significant changes on the spectral optical behavior for the 3D-printed resin-based restorative materials studied, resulting in clinically unacceptable color changes.