Color match of a feldspathic ceramic CAD-CAM material for ultrathin laminate veneers as a function of substrate shade, restoration color, and thickness

Abstract

Statement of problem. The final color of a ceramic restoration, especially an ultrathin veneer, is important, but selecting the correct shade is difficult because the substrate can affect the final color of the restoration. Purpose. The purpose of this in vitro study was to investigate the effect of substrate shade and thickness on the final color of ultrathin laminate veneers milled from feldspathic ceramic and to present a straightforward methodology with which a clinician can visualize the effects of substrate color, ceramic thickness, and prefabricated computer-aided design and computer-aided manufacturing (CAD-CAM) block color on the final color of the restoration. Material and methods. All specimens were fabricated by slicing CAD-CAM feldspathic ceramic material with a precision cutter into 12x10-mm slices of approximately 0.35, 0.55, 0.75, and 1.55 mm in thickness with 10 different colors (0M1-1M1-1M2-2M1-2M2-2M3-3M1-3M2-3M3-4M1). As a background substrate, composite resin disks (12x10x2 mm) were fabricated with different shades (0M1 S, 1M1 5, 2M3 S, 3M2 5, 4M3 5, 5M3 S). The CIELab values of the polished surfaces of each specimen were measured on a background (white or simulated foundation) with a spectrophotometer by a single experienced operator, and color differences (AE) were calculated. Mean SD values were calculated and subjected to ANOVA with 2 variables (substrate and ceramic color) (alpha=.05). Results. Combinations of a lighter substrate shade and a lighter value ceramic restoration and of a darker substrate shade and darker value ceramic restoration only changed the final color of the restoration minimally. Conclusions. The final color of a dental restoration is affected by the thickness of the restoration, the substrate color, and the ceramic color. Lighter and darker substrate colors show more color changes, and thin veneers cannot mask the substrate color.