Contrast Ratio and Masking Ability of Three Ceramic Veneering Materials

Abstract

Masking severely discolored dentitions is one of the indications for the use of ceramic veneers. IPS e.max Press and Vita VM7 had significantly higher contrast ratios and masking abilities than Nobel Rondo Press Alumina: Solo. However, none of the materials tested was able to completely mask the black background. SUMMARYStatement of the Problem: Porcelain veneer materials are translucent and are therefore affected by their thickness as well as the color of the underlying substructure, which limits their masking ability and compromises the esthetic result in heavily stained teeth.Purpose: The purpose of this study was to compare the contrast ratio (CR) and masking ability of three different veneering ceramics with two thicknesses by measuring the color differences over white and black backgrounds. Correlations between CR and masking ability of these veneering ceramics were evaluated.Methods and Materials: A total of 30 discshaped specimens (12 mm diameter 3 1.0 mm or 1.5 mm) were fabricated in shade A2 from three types of all-ceramic systems: IPS e.max Press (IPSe; Ivoclar Vivadent, Schaan, Liechtensein), Vita VM7 (VM7; VITA Zahnfabrik, Bad Sä ckingen, Germany), and Nobel Rondo Press Alumina: Solo (NRPA; Nobel Biocare, Zü richFlughafen, Switzerland). The CR, defined as the ratio of illuminance (Y) of the test material when placed on the black background (Yb) to the illuminance of the same material when placed over a white background (Yw), was determined (CR=Yb/Yw). The color (CIE L*a*b*) and Y of each specimen were measured over standard white and black tiles using a spectrophotometer (ColorEye 7000 A, Model C6, GretagMacbeth, New Windsor, NY, USA). Masking abilities of the specimens were determined by measuring the color difference (DE) over white and black backgrounds. Both CR and DE data were analyzed using two-way analysis of variance (ANOVA). One-way AN-OVA was used to compare the mean values of CR across the three materials followed by the Duncan multiple comparison test. The Results: CR values of NRPA were significantly less than those of IPSe and VM7, and the CR of IPSe was higher than that of VM7. Furthermore, CR increased as the thickness of the discs increased to 1.5 mm for all three materials. Mean DE values were significantly higher with 1.0-mm-thick discs than with 1.5-mm discs. Among the three materials it was observed that NRPA had the highest DE when compared with IPSe or VM7, whereas the DE of the latter two were not significantly different from one another. There was a strong linear correlation between CR and masking ability.Conclusion: CR and masking ability are affected by the type as well as the thickness of the ceramic used. IPSe and VM7 are similar in their masking abilities, whereas NRPA had the lowest masking ability. NRPA was the most translucent, followed by VM7; IPSe was the most opaque. None of the materials tested was able to completely mask the black background. It is therefore recommended that the type of ceramic should be chosen according to each clinical situation.

Shade of Resin‐Based Luting Agents and Final Color of Porcelain Veneers

“…Use of dentin porcelain may yield a more opaque aspect, reducing the influence of the dental substrate; however, the final appearance of the restoration might become less aesthetic. These results are in agreement with previous studies which confirm that low value substrates and more translucent ceramic systems result in higher color changes of the restorations …”

Relative Translucency of a Multilayered Ultratranslucent Zirconia Material

“…16 Translucency parameter is based on differential colorimetric assessment of materials on white and black backgrounds and is generated according to the international CIE L*a*b* color scale. 12,17 The coordinate L* corresponds to lightness, while a* and b* define hue. The coordinate a* represents greenness (−a*) and redness (+a*), while b* corresponds to yellowness (+b*) and blueness (−b*).…”

“…9 Two parameters are used to evaluate the translucency and opacity of esthetic restorative materials: Absolute translucency (T%) representing the percentage of total light transmittance and relative translucency indicating the masking ability. [10][11][12] Absolute translucency is usually assessed using radiometers or spectrophotometers that measure the total light transmitted through a specimen along with the scattered light. Intensity of transmitted and scattered lights is compared with that of the light source…”

Influence of Resin Cements on Color Stability of Different Ceramic Systems

“…Resin cements may mask the underlying color and modify the final color of the restoration; therefore, controlling and balancing its opacity and color parameters is key to achieve good final aesthetic outcomes (13).…”