Statement of problem

High-translucency monolithic multilayer precolored zirconia provides acceptable esthetics and eliminates chipping of the veneering porcelain. However, the color is not always consistent with the standard Vita shade guide, and the color saturation may vary with the thickness of the zirconia.

Purpose

The purpose of this in vitro study was to characterize the effect of thickness on the color accuracy of high-translucency monolithic multilayer precolored zirconia.

Material and methods

Plate-shaped (20×20 mm) Vita A2 shade high-translucency monolithic multilayer precolored zirconia specimens of 3 types (SHT Multilayer, AT Multilayer, and 3D Multilayer) in 4 thicknesses (0.5, 1.0, 1.5, and 2.0 mm) were fabricated (N=120, n=10). A spectrophotometer was used to measure the color attributes (CIELab) against gray or A2 substrates to evaluate the color accuracy based on differences in color (ΔE) (versus the Vita shade guide) and chroma. Statistical analysis was performed by using the Pearson correlation, 2-way ANOVA, and post hoc Scheffé test (α=.05).

Results

Against gray substrates, thickness was significantly positively correlated with all color attributes. Against A2 substrates, L∗ values increased with an increase in thickness; however, a∗, b∗, and chroma values remained stable. Zirconia with a thickness of 1.0 mm exhibited the lowest ΔE, regardless of the type, except for AT Multilayer against A2 substrates, where the lowest ΔE was achieved at 0.5 mm. At thicknesses ≥1.0 mm, the ΔE between the 2 substrates was imperceivable.

Conclusions

Thickness affected the color accuracy of different high-translucency monolithic multilayer precolored zirconia types. It appears that the optimal thickness in terms of color accuracy is 1.0 mm. These results could be used as a reference for the selection and preparation of abutments in clinical applications.

中文翻译：

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不同类型高透明单片多层预着色氧化锆的厚度对颜色准确性的影响：一项体外研究

问题陈述

高透明度整体多层预着色氧化锆提供可接受的美学效果并消除贴面瓷器的碎裂。然而，颜色并不总是与标准的 Vita 色板一致，颜色饱和度可能会随着氧化锆的厚度而变化。

目的

这项体外研究的目的是表征厚度对高半透明单片多层预着色氧化锆颜色准确性的影响。

材料与方法

制备了 4 种厚度（0.5、1.0、1.5 和 2.0 毫米）的 3 种类型（SHT 多层、AT 多层和 3D 多层）的板状（20×20 毫米）Vita A2 色光高半透明单片多层预着色氧化锆试样（N=120，n=10）。使用分光光度计测量灰色或 A2 基材的颜色属性 (CIELab)，以根据颜色 (ΔE)（相对于 Vita 色板）和色度的差异评估颜色准确性。使用 Pearson 相关、2 项方差分析和事后 Scheffé 检验 (α=.05) 进行统计分析。

结果

对于灰色基材，厚度与所有颜色属性显着正相关。对于 A2 基材，L* 值随着厚度的增加而增加；但是，a*、b* 和色度值保持稳定。厚度为 1.0 毫米的氧化锆表现出最低的 ΔE，无论何种类型，除了在 A2 基材上的 AT 多层，其最低的 ΔE 为 0.5 毫米。在厚度 ≥ 1.0 mm 时，无法察觉 2 个基板之间的 ΔE。

结论

厚度影响了不同类型的高半透明单片多层预着色氧化锆的颜色准确度。就颜色精度而言，最佳厚度似乎是 1.0 毫米。这些结果可为临床应用中基台的选择和制备提供参考。