Translucency Assessment of Metal-Ceramic Crowns and All-Ceramic Crowns

Objectives: The purpose of the study was to compare translucency of different ceramic systems : ceramic veneers and cores used in metal-ceramic and all-ceramic crowns at clinical relevant thicknesses.
Methods: Different ceramic materials were tested. Porcelain veneers specimens : GC Initial IQ Dentin feldspathic veneer (DFV), IPS e.max Ceram Dentin (ECD), GC Initial Zr-FS Dentin (ZD) ; ceramic cores specimens : IPS e.max Press core (EPC), Metoxit TZP Zirconia core (MZC) ; veneered ceramic cores specimens : IPS e.max Press core with IPS e.max Ceram Dentin (EPC/ECD) and Metoxit Zirconia core with GC Initial Zr-FS Dentin (MZC/ZD) were prepared following the manufacturers’ instructions into predetermined thicknesses. The shade was set to A3.
Translucency was evaluated by the measurement (n=10) of direct transmittance (T) between 300nm and 900nm with a transmission spectrophotometer (SpectroVis, Vernier, Oregon, US). Statistical analysis was carried out with non parametric rank tests : Kruskal Wallis and U de Mann Whitney (p<0.05).
Results: Differences in transmittance were found among porcelain veneers specimens : DFV (2.1mm) T=20.98±0.4, ECD (2.1mm) T=19.16±0.63, ZD (2.1mm) T=15.8±0.21 (p<0.05) ; among ceramic cores : EPC (0.5mm) T=51.47±0.45 MZC T=43.94±0.38 (p<0.05); and veneered ceramic cores : EPC/ECD (0.5mm and 1.5mm) T=20.94±0.18 and MZC/ZD (0.5mm and 1.5mm) T=15.42±0.22 (p<0.05).
Conclusions: Translucency of dental porcelain was influenced by the ceramic type. All-ceramic cores evaluated in the present study were translucent. However, EPC was more translucent than MZC. Feldspathic veneer porcelain (DFV) used in metal-ceramic crowns showed the best degree of translucency.