Comparison of masking properties of monolithic CAD/CAM ceramics on different tooth colors

The aim of this study is to evaluate translucency parameter and masking ability of nine different monolithic CAD/CAM ceramics with light transmittance which were placed on different colored substructures. In the study, substructure specimens 12 mm x 12 mm x 2.5 mm were prepared from composite resin-based material to mimic 9 different abutment tooth colors. In the study, squared shaped specimens, (12 mm x 12 mm) and 1.5 mm in thickness were prepared from 9 different monolithic CAD/CAM ceramic blocks [feldspathic (C), leucite (Emp), lithium disilicate (e.max), zirconia reinforced lithium silicate (VS), resin nanoceramic (LU), polymer infiltrated ceramic (VE), nanoparticle resin hybrid (GC), monolithic zirconia (TZI) and composite resin(TC)] (n=10). Mechanical polishing was applied to one surface of the ceramic specimens Mechanical polishing was applied to one surface of the ceramic specimens. Color parameters were measured from the polished surface of the specimens on a white and black background, and the translucency parameter (TP) was calculated. A translucent dual polymerized self-adhesive resin cement was prepared in 0.2 mm thickness. In order to evaluate the masking properties, optical gel was applied between the substructures (ND2), the cement layer, and the ceramic specimen The first measurements of L, a, b, C, and H parameters were made with a spectrophotometer. After measuring the color parameters of each ceramic material on the other different colored resin-based composite substructures, the color difference was calculated with the CIEDE2000 formula and the masking ability was determined. One-way ANOVA test was used for evaluating the TP values. Games-Howell test was used for pairwaise comparisons among the ceramic type groups. The color change values of the experimental groups were analyzed with two-way ANOVA. Tukey HSD test was used for multiple comparisons to determine which ceramic type * substructure type interaction (the combined effect of ceramic type and substructure type) created the difference. The translucency values of all monolithic CAD/CAM materials used in the study are found from high to low, respectively, TC, LU, Emp, C =GC, e.max, VS, VE and TZI. The color difference values of TZI, VS and VE on the other infrastructures except for ND9 were found to be as ∆E00, which is below the acceptable threshold value. These materials showed high masking properties compared to other ceramics. It was determined that all the materials used in the study masked the ND1 and ND3 colored substructures, but other ceramics except TZI, VS and VE could not mask the ND6 substructures. The ND9 colored background, which represents the metallic infrastructure color, could not be masked by any of the monolithic CAD/CAM ceramics used in the study.