Influence of implant abutment material on the color of different ceramic crown systems

Abstract

Statement of problem. Ceramics are widely used for anterior restorations; however, clinical color reproduction still constitutes a challenge particularly when the ceramic crowns are used on titanium implant abutments. Purpose. The purpose of this in vitro study was to investigate the effect of implant abutment material on the color of different ceramic material systems. Material and methods. Forty disks (11x1.5 mm, shade A2) were fabricated from medium-opacity (mo) and high-translucency (ht) lithium disilicate (IPS e.max) blocks, an aluminous ceramic (VITA In-Ceram Alumina), and a zirconia (Zirkonzahn) ceramic system. Disks were fabricated to represent 3 different implant abutments (zirconia, gold-palladium, and titanium) and dentin (composite resin, A2 shade) as background (11x2 mm). Disk-shaped composite resin specimens in A2 shade were fabricated to represent the cement layer. The color measurements of ceramic specimens were made on composite resin abutment materials using a spectrophotometer. CIELab color coordinates were recorded, and the color coordinates measured on composite resin background served as the control group. Color differences (Delta E-00) between the control and test groups were calculated. The data were analyzed with 2-way analysis of variance (ANOVA) and compared with the Tukey HSD test (alpha=.05). Results. The ceramics system, abutment material, and their interaction were significant for Delta E-00 values (P<.001). Clinically unacceptable results (Delta E-00>2.25) were observed for lithium disilicate ceramics on titanium abutments (2.46-2.50). The Delta E-00 values of lithium disilicate ceramics for gold- palladium and titanium abutments were significantly higher than for other groups (P<.05). Conclusion. The color results (Delta E-00 > 2.25) of an implant-supported lithium disilicate ceramic restoration may be clinically unacceptable if it is fabricated over a titanium abutment. Zirconia may be a more suitable abutment material for implant-supported ceramic restorations.