Objective To evaluate the optical data of the different sites of the gold-platinum alloys substructures covered by four different all-ceramic crowns, as well as the color difference between the crowns and target tab by using a digital dental spectrophotometer. Methods Ten gold-platinum alloy substructures were made and were respectively tested on four different groups of all-ceramic crowns(Procera aluminia, Procera zirconia, Lava zirconia, and IPS E.max glass-ceramic lithium disilicate-reinforced monolithic crown). The color data of the cervical, body, incisal sites of the specimens were recorded and analyzed by a spectrophotometer. The L*, a*, b* values were measured again after veneered application. The color difference between the substructures covered by all-ceramic crowns and target A2 dentine shade tab was evaluated. Results The L* values of the substructures can be increased by all four groups of all-ceramic copings and were higher than that of the A2 tab, but a* values were decreased and lower than A2 tab. The b* values showed inconsistent tendency of change. A statistical difference was found among four groups of copings. After veneered application, the L* values of all the copings declined and were lower than that of the control group. The values of a* and b* increased significantly, but the a* of the specimens was lower than that of the control. When compared with A2 dentine shade tab, the ΔΕ of the crowns was small, but the color difference was still clinically perceptible by human eyes. Conclusion Four ceramic crowns, made up of just coping and dentine porcelain, effectively promoted the color of the alloy www.gjkqyxzz.cn substructures, but the lightness and hue were lower than the target A2. The color difference between the specimens and target was clinically acceptable, but noticeable. Thus, veneering porcelain with lower color saturation and high translucency is needed.
