光源对天然牙与两种不同金属基底烤瓷冠颜色的影响

The influence of different illuminants on the color between natural teeth and two types of metal ceramic restorations

目的:研究光源改变后,天然牙与两种金属烤瓷全冠的颜色变化及它们之间是否存在同色异谱现象。方法:采用PR-650分光光度仪对A2色天然牙和A2色金合金、金沉积烤瓷全冠在参照体D65光源与A光源、CWF光源下的颜色参数L、a、b(国际发光照明委员会1976L*a*b*系统)进行测量,比较其光谱反射曲线,同时通过计算特殊同色异谱指数来分析它们的同色异谱效应。结果:A2色天然牙和两种金属烤瓷全冠的L、a、b值随着光源的改变而改变,二者的变化趋势不完全一致,其差异有统计学意义;天然牙和金合金、金沉积烤瓷全冠之间的光谱反射曲线形状有较大区别,不同金属烤瓷全冠之间的光谱反射曲线形状也有一些区别,但是每条曲线都有五个以上的交叉点,在特定光源下可以达到同色,具有同色异谱效应;A2色天然牙与金合金、金沉积金属烤瓷全冠之间同色异谱指数在A光源下为2.03和2.46,在CWF光源下2.84和2.89。结论:光源对天然牙和金合金、金沉积烤瓷全冠的颜色有较大影响,A2色天然牙与两种金属烤瓷全冠之间存在较明显的同色异谱效应。

Objective：To investigate the color difference of natural teeth and two types of metal ceramic restorations when the light source changed. Methods ： According to the CIE L ＊ a ＊ b ＊ color scale , on the condition of illuminants of D65, A and CWF, the color parameter and spectral reflectance curves of natural teeth and two types of metal ceramic restorations of A2 shade were measured with a spectrophotometer （PR-650）. Metameric index was calculated to determine the metameric color differences between natural teeth and two types of metal ceramic restorations. Results：CIE L,a,b values were influenced by the different illuminants in both natural teeth and two types of metal ceramic restorations. The spectral reflectance curves for natural teeth and metal ceramic restorations of A2 shade differed greatly, while there were more than 5 crossing points in each curve. The metameric index between natural teeth and tow types of metal ceramic restorations under illuminant A were 2.03 and 2.46,respectively, 2.84 and 2.89 under illuminant CWF. The metameric index between metal ceramic restorations of different kinds were 1.09 under illuminant A,and 0.40 under CWF. Conclusion：Color differences were found between natural teeth and metal ceramic restorations of A2 shade relative to the different illuminants. The metameric effect between natural teeth and metal ceramic restorations of A2 shade is significant.