Statement of problem

With the different translucency levels and types of computer-aided design and computer-aided manufacturing (CAD-CAM) ceramic materials, choosing the most appropriate CAD-CAM ceramic materials to better reproduce the color appearance of natural teeth can be challenging.

Purpose

The purpose of this in vitro study was to analyze the color differences between natural teeth and milled veneers fabricated with the different types of CAD-CAM ceramic materials.

Material and methods

Ten extracted maxillary central incisor teeth with the A2 shade in the body region were prepared for ceramic veneers. The veneer restorations were designed by using the duplicating method and fabricated from 9 milling blocks (IPS e.max CAD HT/LT, Lava Ultimate CAD HT/LT, VITA SUPRINITY HT/T, IPS Empress CAD HT/LT/Multi) in a dental milling unit (n=10). The bonding surface of the abutment tooth was coated with a thin layer of a separating agent, and the veneer specimen with resin cement was then bonded to the corresponding abutment tooth. A clinical spectrophotometer was used to measure the Commission Internationale de l’Eclairage Lab values of natural teeth, abutment teeth, and milled veneers in the cervical, body, and incisal regions. Color differences between the natural tooth and A2 shade tab (ΔE₁) and between the milled veneer and natural tooth (ΔE₂) were calculated. The ΔE₂ values were compared with the perceptibility threshold (ΔE=2.6) and acceptability threshold (ΔE=5.5). The paired-samples t test, 1-way analysis of covariance, and 2-way ANOVA were used to analyze data (α=.05).

Results

The results of 1-way analysis of covariance showed that ceramic materials significantly affected the a∗ and b∗ values of the milled veneers (P<.001) but did not affect the L∗ values of the milled veneers (P>.05). The results of 2-way ANOVA indicated that the ΔE₂ values were not significantly affected by different CAD-CAM ceramic materials (F=1.560, P=.138), while statistically significant differences were found in the veneer regions (F=6.588, P=.002). The ΔE₂ values ranged from 2.41 to 5.36, less than the clinically acceptable color threshold of 5.5.

Conclusions

The color parameters of milled veneers were affected by the different types of CAD-CAM ceramic materials. The color of the veneer restoration was able to match that of the natural tooth.

中文翻译：

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CAD-CAM陶瓷材料对贴面修复体颜色匹配的影响

问题陈述

由于计算机辅助设计和计算机辅助制造 (CAD-CAM) 陶瓷材料的半透明度级别和类型各不相同，因此选择最合适的 CAD-CAM 陶瓷材料以更好地再现天然牙齿的颜色外观可能具有挑战性。

目的

这项体外研究的目的是分析天然牙齿和用不同类型的 CAD-CAM 陶瓷材料制成的磨削贴面之间的颜色差异。

材料与方法

为陶瓷贴面准备了 10 颗拔出的上颌中切牙，身体区域为 A2 色度。饰面修复体采用复制方法设计，由 9 个铣削块（IPS e.max CAD HT/LT、Lava Ultimate CAD HT/LT、VITA SUPRINITY HT/T、IPS Empress CAD HT/LT/Multi）制成牙科铣床 (n=10)。在基牙的粘接面涂上一层薄薄的分离剂，然后将带有树脂粘固剂的贴面试样粘接到相应的基牙上。使用临床分光光度计测量颈、牙体和切端区域的天然牙、基牙和磨削贴面的国际委员会实验室值。天然牙和 A2 色标之间的色差 (ΔE ₁) 和铣削贴面和天然牙之间的 (ΔE ₂ ) 计算。将ΔE ₂值与感知阈值（ΔE=2.6）和可接受阈值（ΔE=5.5）进行比较。配对样本t检验、1 项协方差分析和 2 项方差分析用于分析数据 (α=.05)。

结果

协方差的单向分析结果表明，陶瓷材料显着影响磨削单板的 a∗ 和 b∗ 值（P <.001），但不影响磨削单板的 L∗ 值（P >.05） . 2-way ANOVA结果表明ΔE ₂值不受不同CAD-CAM陶瓷材料的显着影响（F = 1.560，P = .138），而在贴面区域发现统计学显着差异（F = 6.588，P = .002）。ΔE ₂值的范围为 2.41 至 5.36，小于临床可接受的颜色阈值 5.5。

结论

研磨单板的颜色参数受不同类型的 CAD-CAM 陶瓷材料的影响。贴面修复体的颜色能够与天然牙齿的颜色相匹配。