Effect of coffee thermocycling on the color and translucency of milled and 3D printed definitive restoration materials.

Statement Of Problem: Research on the color and translucency properties of 3-dimensionally (3D) printed definitive resins and the effect of coffee thermocycling on these properties is lacking.

Purpose: The purpose of this in vitro study was to investigate the effect of coffee thermocycling on the color and translucency parameters of the milled and 3D printed materials used for definitive restorations.

Material And Methods: Plate-shaped specimens (12×12×1 mm) of 3 milled (IPS e.max CAD (LDS), Vita Enamic (PICN), Cerasmart (RNC)) and two 3D printed (VarseoSmile Crown (VSP), Permanent Crown (PC)) were fabricated (n=12). The brightness (L*), red-green (a*), and yellow-blue (b*) parameters were measured with a spectrophotometer before and after 10 000 coffee thermocycles. The relative translucency parameters (RTP) and color change were calculated using the CIEDE2000 formula. Stainability (ΔE) and translucency differences (ΔRTP) were evaluated. Data were analyzed with the Kruskal-Wallis, Mann-Whitney U, and Wilcoxon tests. The Spearman correlation test was used to analyze the ΔE and ΔRTP values (α=.05).

Results: The type of material and coffee thermocycling significantly affected the evaluated parameters at both measurement periods (P=.001). Coffee thermocycling decreased the L* and RTP values while increasing the a* and b* values (P=.001). The highest ΔE values were found in VSP and PC, which were statistically similar (P=.291), while the highest | ΔRTP | values were observed for VSP (P=.001). The lowest ΔE and | ΔRTP | values were found in LDS (P=.001). A positive relationship was found between the ΔE and | ΔRTP| values (R=.590, P=.01).

Conclusions: After coffee thermocycling, all tested materials exhibited a darkened, yellowish, and opaque appearance, although the alterations in color and translucency remained within clinically acceptable thresholds (AT=1.81) for these materials.