抄録
Three types of shade A system of dentin porcelain VITA for layering (2 D, 3 D, and 3.5 D) and 5 types of enamel porcelain (N, 1 E, 2 E, 3 E, and 4 E) in the layering method, in which more emphasis is put on cosmetic appearance, were evaluated. The thickness of the porcelain was varied and color tone in the abutment teeth color sample was changed, i.e., natural teeth (A 2, A 3, and A 3.5), 2 types of gold alloy and palladium alloy (Au and Pd) as casting metal core, and discolored teeth influenced the color tone of IPS EMPRESS crown. The conclusion were as follows:
1. Lightness difference When the ratio of the thickness of dentin and enamel samples was varied within the range of 1.5 mm (two-thickness samples), the lightness difference tended to decrease when thickness of the dentin sample was increased, while no interruption of color tone was observed.
2. Color difference
1) The smaller the shade number was, the higher the color difference was between Au and Pd samples and natural tooth color sample, and the color difference decreased when the dentin sample was thicker. Almost all two-thickness samples showed the value of 1.2 or more, i.e., within the criterion for color difference, and it was evaluated as “detectably different.”
2) In the color difference between discolored tooth sample and natural tooth color sample, the smaller the shade number was, the higher the color difference was. The color difference decreased as dentin sample became thicker. In all of the two-thickness samples, the value was 1.2 or more, thus falling within the criterion for color difference in the present study. Some of the two-thickness samples showed a color difference of 3.3 or more. Thus some samples were evaluated as “extremely different.”
