Effect of yellow anodization of titanium on the shade of lithium disilicate ceramic with different thicknesses

Statement of problem. The color of the titanium abutment can affect the shade of the definitive restoration. Methods such as anodic oxidation, which changes the gray color of implant abutment to yellow, have been advocated to mask the unesthetic gray color of the abutment. However, whether a yellow anodized titanium abutment can prevent discoloration of translucent ceramic restorations is uncertain. Purpose. The purpose of this in vitro study was to evaluate the effect of the yellow anodization of titanium on the shade of lithium disilicate ceramic with different thicknesses by using CIEDE 2000 formulas. Material and methods. Sixty grade V titanium backgrounds were fabricated and divided into 2 test groups (n=30): group A was anodized to a yellow color, and group U was unanodized. Each group was subdivided into 3 subgroups (n=10) according to the thickness of the lithium disilicate ceramic cemented over it: subgroup 1 with 1-mm-thick lithium disilicate, subgroup 1.5 with 1.5-mm-thick lithium disilicate, and subgroup 2 with 2-mm-thick lithium disilicate. Each titanium background was cemented to its corresponding lithium disilicate block by using translucent resin cement. For the control group, 5-mm-thick lithium disilicate specimens were fabricated. Color measurements of the specimens were made with a spectrophotometer, and differences were calculated by using CIEDE 2000 formulas (Delta E-00). Comparisons between the 2 study groups were done by using independent samples t test. Two-way ANOVA was used to assess the effect of anodization and thickness on Delta E-00 with calculation of adjusted means and 95% confidence intervals (alpha=.05). Results. Statistically significant differences were found among the mean values between yellow anodized and unanodized groups in all ceramic thicknesses (P<.001 for 1 mm, P<.001 for 1.5 mm, and P<.046 for 2 mm). Yellow anodization of titanium and increasing the ceramic thickness from 1 to 2 mm decreased the Delta E-00 values. Conclusions. The restoration shade appeared to be improved by titanium anodization to a yellow color and by increasing the thickness of the machinable high-translucent lithium disilicate.