Predicting porcelain thickness required for dental shade matches

Statement of problem. Production of a ceramic dental restoration that matches a target shade is dependent on porcelain thickness. Even when adequate porcelain thickness exists, clinical shade matches are difficult to achieve. Purpose. This study predicted the thickness of dentin porcelain required to obtain a clinical shade match (less than or equal to 3 Delta E units) for a variety of dental porcelain systems and shades. Material and methods. Three all-ceramic crown systems (Empress, Inceram-Alumina, Inceram-Spinell) and 2 metal ceramic systems (Vintage, VMK-95) were evaluated, each in shades A1, A3, and C2. Five specimens of each porcelain, of each shade, were fabricated at thicknesses of 1.0, 1.2, 1.5, and 2.0 mm. CIE-LAB coordinates were recorded for each specimen, and for the midgingival third of corresponding shade tabs with a Minolta CR-321 colorimeter. Results. Seventy percent of the color difference between specimen and shade tab was due to high L* (Munsell value) in the specimens. At thicknesses of less than or equal to 2.0 mm of dentin porcelain, the all-ceramic systems exhibited more shade matches than the metal ceramic systems. Conclusion. Specimens made from semi-translucent all-ceramic systems exhibited clinical shade matches that were superior to those made with the metal ceramic systems. Increasing thickness of the semi-translucent systems from 1.0 to 2.0 mm did not improve shade matching.