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

中文翻译：

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咖啡热循环对研磨和 3D 打印最终修复材料的颜色和半透明度的影响

目前还缺乏对 3D 打印最终树脂的颜色和半透明度特性以及咖啡热循环对这些特性的影响的研究。这项体外研究的目的是研究咖啡热循环对用于最终修复的研磨和 3D 打印材料的颜色和半透明度参数的影响。3 个铣削的板状标本 (12×12×1 mm)（IPS e.max CAD (LDS)、Vita Enamic (PICN)、Cerasmart (RNC)）和两个 3D 打印的标本（VarseoSmile Crown (VSP)、永久牙冠（VarseoSmile Crown (VSP)） PC））被制造（n=12）。在 10 000 次咖啡热循环之前和之后，用分光光度计测量亮度 (L*)、红绿 (a*) 和黄蓝 (b*) 参数。使用CIEDE2000公式计算相对半透明度参数（RTP）和颜色变化。评估了可染色性（ΔE）和半透明度差异（ΔRTP）。使用 Kruskal-Wallis、Mann-Whitney U 和 Wilcoxon 检验对数据进行分析。使用Spearman相关性检验来分析ΔE和ΔRTP值（α=.05）。材料类型和咖啡热循环显着影响两个测量周期的评估参数 (=.001)。咖啡热循环降低了 L* 和 RTP 值，同时增加了 a* 和 b* 值 (=.001)。最高的 ΔE 值出现在 VSP 和 PC 中，它们在统计上相似 (=.291)，而最高的 | ΔRTP | 观察到 VSP 值 (=.001)。最低的 ΔE 和 | ΔRTP | 在 LDS (=.001) 中找到了值。ΔE 和 | 之间存在正相关关系。ΔRTP| 值（=.590，=.01）。咖啡热循环后，所有测试材料均表现出变暗、泛黄和不透明的外观，但这些材料的颜色和半透明度的变化仍处于临床可接受的阈值 (AT=1.81) 内。