光源对天然牙与两种不同金属基底烤瓷冠颜色的影响

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1976 L*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间色异谱指数在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.     

Application of a digital technique in evaluating the reliability of shade guides

There appears to be a need for a reliable method for quantification of tooth colour and analysis of shade. Therefore, the primary objective of this study was to show the applicability of graphic software in colour analysis and secondly to investigate the reliability of commercial shade guides produced by the same manufacturer, using this digital technique. After confirming the reliability and reproducibility of the digital method by using self-assessed coloured images, three shade guides of the same manufacturer were photographed in daylight and in studio environments with a digital camera and saved in tagged image file format (TIFF) format. Colour analysis of each photograph was performed using the Adobe Photoshop 4.0 graphic program. Luminosity, and red, green, blue (L and RGB) values of each shade tab of each shade guide were measured and the data were subjected to statistical analysis using the repeated measure Anova test. The L and RGB values of the images taken in daylight differed significantly from those of the images taken in studio environment (P < 0.05). In both environments, the luminosity and red values of the shade tabs were significantly different from each other (P < 0.05). It was concluded that, when the environmental conditions were kept constant, the Adobe Photoshop 4.0 colour analysis program could be used to analyse the colour of images. On the other hand, the results revealed that the accuracy of shade tabs widely being used in colour matching should be readdressed.     

A2色的天然牙与成品树脂牙的同色异谱效应分析

目的对A2色的天然牙和不同品牌的A2色成品树脂牙在不同光源下的颜色参数进行测量,分析其颜色变化,比较其光谱反射曲线,并分析天然牙和成品树脂牙的同色异谱效应。方法采用PR-650型光谱扫描色度仪测量A2色的天然牙和3种品牌的A2色成品树脂牙在D65光源、A光源、CWF光源和紫外光下的颜色参数L*、a*、b*值和XYZ三刺激值,比较其光谱反射曲线,通过计算特殊同色异谱指数来分析天然牙和成品树脂牙的同色异谱效应。结果A2色的天然牙和成品树脂牙的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。天然牙和成品树脂牙之间、不同品牌的成品树脂牙之间的光谱反射曲线形状有较大区别,但是每条曲线都有3个以上的交叉点和重合处,在特定光源下可以达到颜色匹配,具有同色异谱效应。A2色的天然牙与成品树脂牙之间有较明显的同色异谱效应,天然牙与3种品牌成品树脂牙之间的特殊同色异谱指数在A光源下为3.48、2.52和3.36,在CWF光源下为1.21、1.90和2.79,在紫外光下为1.59、2.07和4.07。不同品牌的A2色成品树脂牙之间的特殊同色异谱指数在A光源下为1.08、0.10和1.01,在CWF光下为1.46、2.23和0.94,在紫外光下为2.55、2.69和4.64。结论光源对天然牙和成品树脂牙的颜色有较大影响,A2色的天然牙与成品树脂牙之间存在较明显的同色异谱效应。