Janardanan Kavitha, Pillai Sreelal Thankappan, Karunakaran Harshakumar
Department of Prosthodontics, Sree Mookambika Institute of Dental Sciences, Kulasekharam, Tamilnadu, India.
Indian J Dent Res. 2012 Nov-Dec;23(6):838. doi: 10.4103/0970-9290.111279.
The final esthetic outcome of a metal-ceramic restoration is influenced by several factors including the type of the underlying metal as well as the brand of the ceramic.
An in vitro study.
The purpose of the in vitro study was to investigate the influence of four types of metal-ceramic alloys and two porcelain systems on the color co-ordinates of the metal-ceramic complex. It also aimed at establishing a color index which correlated the color of the metal-ceramic combination to the yellow-blue axis.
Twenty-four disc-shaped metal specimens of 12 mm × 1 mm were cast from base metal alloys, nickel-chromium (Ni-Cr) (Wiron 99), cobalt-chromium (Co-Cr) (Wirobond C), a palladium (Pd)-rich noble metal alloy (Spartan Plus), and a high noble gold (Au) alloy (Pontostar). These discs were covered with two commercially available feldspathic porcelains (Vita Omega and Shofu Vintage) of A3 shade to a total thickness of 1.2 mm. Each group had six specimens, of which three were coated with Vita Omega and the remaining with Shofu Vintage. Opaque and dentin layers were applied to a standardized thickness of 0.2 mm ± 0.05 mm and 1 mm ± 0.05 mm, respectively onto the metal surface after air abrasion with 50 μm alumina particles. The reflectance spectra were measured with a spectrophotometer and data were recorded in L*, a* and b* coordinates in the CIE Lab Color Order System.
Analysis of variance (ANOVA) and path analysis were the statistical tools employed to analyze the data. A critical difference (CD) value was calculated for each color co-ordinate to make comparisons between each metal-ceramic combination. A color index for each metal-ceramic complex was also calculated from the color co-ordinates obtained.
ANOVA revealed that significant differences existed between the metal-porcelain combination at 0.01 ( P < 0.01) level. The L* value was significantly higher for Au and Co-Cr alloys with Vita Omega porcelain. The a* value was highest for Ni-Cr alloy when combined with Shofu Vintage ceramic. The b* value of Au alloy with Vita Omega porcelain was significantly higher than any other metal-ceramic combination. The color co-ordinates of Pd alloy with both porcelain systems did not show any significant differences. Gold alloy with Vita Omega showed the highest color index value.
The variations in metal-ceramic alloy and porcelain can influence the shade of a metal-ceramic restoration. Color index value was the highest for gold alloy.
金属烤瓷修复体的最终美学效果受多种因素影响，包括底层金属的类型以及陶瓷的品牌。
一项体外研究。
该体外研究的目的是调查四种类型的金属烤瓷合金和两种瓷体系对金属烤瓷复合体颜色坐标的影响。它还旨在建立一个将金属烤瓷组合的颜色与黄蓝轴相关联的颜色指数。
用贱金属合金、镍铬（Ni-Cr）（Wiron 99）、钴铬（Co-Cr）（Wirobond C）、富钯（Pd）贵金属合金（Spartan Plus）和高含金量（Au）合金（Pontostar）铸造24个12mm×1mm的盘状金属标本。这些圆盘覆盖有两种市售的A3色号长石质瓷（Vita Omega和Shofu Vintage），总厚度为1.2mm。每组有六个标本，其中三个涂有Vita Omega，其余涂有Shofu Vintage。在用50μm氧化铝颗粒进行空气研磨后，分别在金属表面以0.2mm±0.05mm和1mm±0.05mm的标准化厚度施加不透明层和牙本质层。用分光光度计测量反射光谱，并在CIE Lab颜色顺序系统中以L*、a和b坐标记录数据。
方差分析（ANOVA）和路径分析是用于分析数据的统计工具。计算每个颜色坐标的临界差值（CD），以便在每种金属烤瓷组合之间进行比较。还根据获得的颜色坐标计算每种金属烤瓷复合体的颜色指数。
方差分析显示，在0.01（P<0.01）水平下，金属与瓷的组合之间存在显著差异。使用Vita Omega瓷时，Au和Co-Cr合金的L值显著更高。Ni-Cr合金与Shofu Vintage陶瓷组合时，a值最高。使用Vita Omega瓷的Au合金的b*值显著高于任何其他金属烤瓷组合。两种瓷体系的Pd合金的颜色坐标均未显示任何显著差异。使用Vita Omega的金合金显示出最高的颜色指数值。
金属烤瓷合金和瓷的变化会影响金属烤瓷修复体的色泽。金合金的颜色指数值最高。
