Effect of cement color and tooth-shaded background on the final color of lithium disilicate and zirconia-reinforced lithium silicate ceramics: An in vitro study.

Abstract

To evaluate the translucency and effects of different cement colors on the final shade of lithium disilicate ceramics (LDS) and zirconia-reinforced lithium silicate ceramics (ZLS) over an A1 and A3 tooth-shaded background. Eighty-eight rectangular-shaped specimens were sliced from LDS and ZLS blocks. The final thickness of the specimens was set at 0.8 ± 0.01 mm. Spectrophotometric measurements for the translucency were taken against black and white backgrounds. Composite resin tooth-shaded background disks were fabricated in two shades (A1 and A3), as were resin cement disks (opaque and translucent) (n = 11). Next, the ceramic specimens and tooth-shaded backgrounds were connected with glycerin, and baseline measurements were taken. These measurements were used as a reference. Then, the ceramic specimens, cement specimens, and tooth-shaded backgrounds were connected together with glycerin, and a second set of measurements was taken. The CIEDE2000 (ΔE00 ) color formula was used to calculate the translucency and color differences. A Mann-Whitney U test was also performed for the translucency, and a three-way ANOVA (analysis of variance) test was performed for the ΔE00 values (α = .05). The LDS and ZLS groups had similar translucency (P = .055). The ΔE00 values of the specimens were significantly affected by the cement color and tooth-shaded backgrounds in the LDS and ZLS groups (P < .05). Using the opaque cement color resulted in statistically significant differences against the light and dark (A1 and A3) tooth-shaded backgrounds in both the LDS and ZLS groups (P = .022 and P = .006). The material type did not affect the translucency or final color. However, the cement color did affect the final shade when thin ceramic restorations were used. It should be noted that the cement color and tooth-shaded background used may change the final color of thin high translucency ceramic restorations that contain lithium disilicate and zirconia-reinforced lithium silicate.