Effects of surface treatments and abutment shades on the final color of high-translucency self-glazed zirconia crowns

Statement of problem. Achieving excellent esthetics with monolithic self-glazed zirconia crowns in anterior teeth is challenging, and the impact of different surface treatments and abutment shades on the final color is unclear. Purpose. The purpose of this in vitro study was to evaluate the effects of different external surface treatments (self-glazed, milled, polished, and glazed), different intaglio surface treatments (milled and airborne-particle abraded), and different abutment shades on the color difference of high translucency self-glazed zirconia crowns. Material and methods. Sixty shade A1 and 60 shade A3 crowns were fabricated with a thickness of 0.80 +/- 0.02 mm and randomly divided into 12 groups (n=10). Different external and intaglio surface treatments were applied. Shade A1 and A3 abutments were made with composite resin. Color was measured with a spectrophotometer and expressed in CIELab coordinates, and color differences (Delta E-00) between specimens and references were calculated. The data were analyzed with ANOVA and the Tukey post hoc test. The impact of different surface treatments and abutment shades on the color difference were compared by using multiple linear regression (alpha=.05). Results. The effects of external surface treatments, intaglio airborne-particle abrasion, and abutment shades on the L*, a*, b* and Delta E-00 values of the final color of the crowns were significantly different (P<.001). Polishing resulted in the greatest Delta E-00 value among all external surface treatments (P<.001). The average Delta E-00 values of all crowns on the A3 abutment were higher than those of all crowns on the A1 abutment (P .001). The influence on the color difference was abutment external surface treatment>intaglio surface treatment. Conclusions. Different surface treatments affected the final color of zirconia crowns, and a greater impact was seen with external surface treatments than with intaglio surface treatments. External polishing resulted in the greatest color difference. The abutment shade had the most effect on the color difference, as the darker the abutment color, the greater the color difference.