Color Masking Ability of Lithium Disilicate Ceramic for Titanium Alloy Implant Abutments

Abstract

The aim was to assess the acceptable thickness of monolithic Lithium Disilicate (LD) ceramic in masking of Titanium (Ti) implant abutment by comparison to Zirconium (Zr) crowns through color matching. Forty LD and 10 Zr copings (control) using Hot-pressing and CAD-CAM techniques were fabricated. A standard Ti abutment (Straumann, ITI, Basel, Switzerland) was used as foundation substrate. LD crowns were divided into different thickness [1.0 mm (n = 10), 1.2 mm (n = 10), 1.5 mm (n = 10) and 1.8 mm (n = 10)] and 10 Zr copings (control) had 0.5 mm thickness. Different crown materials and crown thicknesses resulted in 5 study groups designated as Zr-Ti-0.5, LD-Ti1.0, LD-Ti-1.2, LD-Ti-1.5 and LD-Ti-1.8. Specimens were cemented to Ti abutments and using a spectrophotometer the difference of color for specimen and controls was determined by comparing ΔL, Δa and Δb (CIELab color system) and an overall ΔE. These were statistically compared using analysis of variance and Tukey post hoc multiple comparisons. Among LD specimens with Ti abutments, lowest color difference was achieved for LD-Ti-1.8 (2.3 ± 0.31) and the highest color difference was for LD-Ti-1.0 (4.93 ± 0.45). The lowest ΔE was recorded for Zr copings (control), which was lower than (p < 0 01) LD crowns of 1.0 and 1.2 mm thickness. LD crown thickness had a significant effect on ΔE (color difference) on Ti abutments. Masking of Ti abutments by 1.5 mm LD crowns was comparable to Zr specimens (control). Lithium disilicate crown of 1.5 mm thickness showed statistically comparable color stability to 0.5 mm Zr copings on Ti implant abutments.