Methods: Test specimens with commercially-available opaque porcelains used for PFM restoration were prepared using a 17x10mm-mold, fired according to manufacturers' firing schedules, ground to 0.1mm thickness, and measured for visible-light transmission using a spectrophotometer (U-4000, HITACHI). Central incisor crown models were fabricated using commercially-available dental porcelains used for PFM crown(A3-shade), with dentin porcelain built up in varied thicknesses (0.4, 0.6, 0.8, 1.0, 1.2mm) and fired, and shades of the obtained crown restorations were measured with a noncontact color-measuring device (DCCM, Shofu) to calculate color difference from a VITA shade guide.
Results: Visible-light transmissions of each opaque porcelain were: 0.45% (Vintage MP), 1.99% (Product-A), and 5.94% (Product-B). Color differences between each central incisor crown model fabricated with Vintage MP dental porcelain and VITA Classical shade guide were font ΔE(0.4):3.0, ΔE(0.6):2.4, ΔE(0.8):3.0, ΔE(1.0):2.7, and ΔE(1.2):4.0.
Conclusion: Shades of central incisor crown models fabricated with Vintage MP were lighter and brighter than the VITA Classical shade guide. Vintage MP exhibited stable shades regardless of the thickness of the dentin porcelain build-up layer.