Insight 91 — One Shade, Two Values: Why A1 Is Not the Same in IPS e.max and Zirconia

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Clinical Explanation

One thing I have seen many times in clinical work is that a crown's value does not depend only on the shade we write on the lab prescription; the type of ceramic also has a large effect on it. If we choose shade A1 for a tooth and make the crown once in e.max and once in zirconia, the zirconia crown is usually lighter and has a higher value, while e.max shows a lower value in the same shade.

The reason is that A1 is not one fixed color for every material. Each manufacturer tries to bring the color of its own material close to the VITA shade tab, but the result is not the same for every material, and two materials with the same shade name can have different colors.

In zirconia this difference leans toward higher value and lower chroma, meaning the crown comes out lighter and less saturated than we expect. This is especially noticeable when the zirconia crown sits next to another restoration or a natural tooth.

In e.max the issue is mostly translucency. e.max lets more light pass through it, so the color of the prepared tooth under the crown (stump shade), the color of the cement and the darkness inside the mouth have more effect on the final color, and the crown looks darker. For the same reason the difference is smaller on a light prepared tooth and larger on a dark tooth or a metal abutment.

Of course, not all zirconias are alike. The newer generations, which are more translucent and multilayer, differ from older zirconias, and there is a lot of variation between brands too. So this point is a general tendency, not a fixed rule.

In practice it is better not to see the shade separately from the material. When we order zirconia, we should allow for the crown turning out lighter, and when we make e.max, we should count the color of the prepared tooth and the cement as part of the final color.

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