The influence of printing angle on color and translucency of 3D printed resins for dental restorations

Objectives: To evaluate the influence of printing orientation on color and translucency of 3D printing restorative resins. Methods: Four 3D printing resin systems in the available shades (DFT-Detax Freeprint Temp- A1, A2,A3; FPFormlabs Permanent Crown- A2,A3,B1,C2; FT- Formlabs Temporary CB- A2,A3,B1,C2; GCT-GC TemporaryLight, Medium) were evaluated. Three samples (10x10x1.2 mm) from each material were printed at two different printing orientations (0 degrees and 90 degrees) and polished to 1.00 +/- 0,01 mm of thickness. Spectral reflectance was measured against black background using a calibrated spectroradiometer, CIE D65 standard illuminant and the 45 degrees/0 degrees geometry. Color and translucency differences were evaluated using CIEDE2000 metric (AE00) and 50:50% perceptibility (PT00 and TPT00) and acceptability (AT00 and TAT00) thresholds. Results: In general, color changes due to printing orientation at (0 degrees and 90 degrees) were mainly produced by AL* or AC* . AE00 were above PT00 for all DFT shades, FP-B1, FP-C2, FT-A2 and FT-B1. Only for DFT-1, AE00 was above AT00. ARTP00 values were above TPT00 for DFT-A1, DFT-A3, FP-B1 and FT-B1, but lower than TAT00. The direction of the changes in translucency (ARTP00) depends on the material and shade. Significance: The selection of building orientation (0 degrees and 90 degrees) for the 3D printed resins influence the visual color and translucency and therefore their esthetic appearance. These aspects should be considered when printing dental restorations using the evaluated materials.