Objective This study was to explore chromaticity trend by mixing four body shades of VINTAGE A dental porcelain in different ratios under standard firing program. Methods Four body shades were arranged as A1 and A2, A1 and A3, A2 and A3, A3 and A3.5 in sample groups, and A1, A2, A3 and A3.5 in control group. Each sample group was mixed according to the quality proportion of 9∶1, 8∶2, 7∶3, 6∶4 and 5∶5 respectively, and filled into plaster molds. These samples were fired following the manufacturers’instruction, and the thickness was controlled by grinding to 2 mm. The chromatic analysis of these samples was taken through PR-650 spectrum detector. Then recorded the L*, a*, b*, C, H, ΔE value, and calculated datas. Results There was no statistical difference on L* value in each group regardless of quality proportion. Significant difference could be found on L* value among groups, and on a*, b*, C, H value in and among each groups. The higher number of VINTAGE A body shades in the samples, the more deviation of a*-b* coordinate points from linearity. Color differences between neighboring proportions in each group fluctuated around 1.5. Conclusion In the four different groups, the low number body shades resulted in high brightness changes. But within each group, high ratio of the lower number body shade affected little to the brightness. As the number increased, the color turned gradually from yellow to red. L* value made a greater contribution to the chromatic difference than other color parameters that a smallscale fluctuation of L* value may result in visible color changes. In addition, researches on the elementary components and molecule structure of dental porcelain will contribute to further study of the principle of dental porcelain color presence.
