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Inside Dentistry
September 2016
Volume 12, Issue 9
Peer-Reviewed

When the dental technician knows the shade of the underlying tooth preparation, compensatory shading and die fabrication techniques can be employed to account for the combination of the translucency of the restorative material and the underlying influence of the stump (prepared tooth). Failure to provide that information can lead to a restoration that is either too light or too gray when in place. Even though the clinician selected the correct shade (hue and chroma), the more sensitive observer’s eye will find the restoration unacceptable.

All-ceramic restorations commonly do not match the natural dentition accurately. Some all-ceramic restorations look too bright in comparison to the natural dentition. When this happens, it is said that the restoration is too high in value compared to the natural dentition and not an accurate shade match. What about a restoration that appears too gray? This would be an example of a restoration that is lower in value than the natural dentition. An interesting observation the author has made is that a patient will accept a crown that is higher in value when compared with the natural dentition more often than they will accept one that is too low. The perception is that higher value (brighter/whiter) looks better and that lower value (darker) looks worse. That being said, the goal should be a very accurate shade match, every time.

Why do all-ceramic restorations not match perfectly every time? The value of an all-ceramic restoration can be affected by the color of the preparation underneath (stump shade). With all-ceramic material, light passes through its surface and bounces off the underlying preparation, allowing more or less of that underlying stump color to show through the restorative material depending on translucency, which possibly affects the value by either lowering it (too dark or gray) or raising it (too bright or light).

Conclusion

It is critical to find the right balance between translucency and shade/color considerations to create a realistic restoration that will match well with the patient’s natural dentition. The overarching goal is to match the restoration perfectly every time to ensure that the patient is satisfied.

References

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6. Jiang L, Liao Y, Wan Q, Li W. Effects of sintering temperature and particle size on the translucency of zirconium dioxide dental ceramic. J Mater Sci Mater Med. 2011;22(11):2429-2435.

7. Anselmi-Tamburini U, Woolman JN, Munir ZA. Transparent nanometric cubic and tetragonal zirconia obtained by high-pressure pulsed electric current sintering. Adv Funct Mater. 2007;17(16):3267-3273.

8. Casolco SR, Xu J, Garay JE. Transparent/translucent polycrystalline nanostructured yttria stabilized zirconia with varying colors. Scripta Materialia. 2008; 58(6):516-519.

9. Zhang Y. Making yttria-stabilized tetragonal zirconia translucent. Dent Mater. 2014;30(10): 1195-1203.

10. Williamson SJ, Cummins HZ. Light and Color in Nature and Art. New York, NY: John Wiley and Sons; 1983:173.

About the Author

Gregg A. Helvey, DDS, MAGD, CDT
Adjunct Associate Professor
Virginia Commonwealth University School of Dentistry
Richmond, Virginia
Private Practice
Middleburg, Virginia

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