Chromatic Study of All-ceramic Restorations: Relative Translucency of 9 All-ceramic Core Materials

Purpose: All-ceramic restorations are widely used in esthetic dentistry. Various materials have been used to improve ceramic core strength, but it is unclear whether they affect the opacity of all-ceramic systems. The aim of this study was to compare the translucency of 9 all-ceramic system core materials at clinically appropriate thickness.Materials and methods: A 360-degree round deep chamfer preparation for the all-ceramic crown was made for a maxillary right first molar tooth as the dental model. Coping of 0.5mm thickness were fabricated by Empress Esthetic (ETC1, EOC1, EO1, EO2), Empress2 (50) (IVOCLAR VIVADENT), Procera AllCeram, Procera AllZirkon (Nobel Biocare), LAVA (3M ESPE), and DentaCAD Systeme (Hint-Els). Abutments were made by black wax and white wax. Spectrophotometric measurements were made by a spectrophotometer. The final color of the central part of the buccal surface was measured and the L*a*b* color space was used to obtain the color values. Contrast ratios were calculated from the luminous reflectance (Y) of the specimens with a black (Yb) and a white (Yw) backing to give Yb⁄Yw with CIE illuminant D65 and 2-degree observer function (0.0=transparent, 1.0=opaque).Results: Contrast ratio in order of most translucent to most opaque were as follows: EO2 .41, EO1 .43, ETC1 .43 , EOC1 .44, Empress2 .50, AllCeram .63, AllZirkon .74, LAVA .76, DentaCAD.80. There was no significant difference(p<.05) between the AllZirkon, LAVA, DentaCAD or ETC1, EOC1, EO1, EO2.Conclusion: Within the limitations of this in-vitro study on 9 all-ceramic core systems, a significant range of translucency was identified across specimen groups.