Evaluation of color reproduction and translucency of different thicknesses of three newly introduced esthetic dental materials

Abstract

Increased demand for achieving the best esthetics in dentistry has led to an increase in the use of ceramic, hybrid ceramics and tooth-colored composite resin restorations [119]. In particular, the CAD/CAM ceramics have enjoyed growing popularity [120, 121]. The final restoration color may be influenced by the thickness and translucency of the veneer restoration, depending on the amount of light scattering and reflection [122, 123]. In addition, the color of supporting structure or luting agent may also influence the final color of veneer restorations[62, 124]. Therefore, shade selection of thin restorations like laminate veneers is considered a challenge. Porcelain laminate veneer thickness has been reported to range between 0.3 and 1.5 mm[125, 126]. With the introduction of new ceramic materials, the no-preparation thin veneer concept has received more attention and the challenge increased[6]. Three of the new ceramic materials indicated for thin laminate veneers were used in this study, Lava Ultimate from 3M ESPE which is a resin nano-ceramic and according to the manufacturer, it is neither a composite nor a pure ceramic, but a mixture of both and it primarily consists of ceramics. This new CAD/CAM material is made of nano-ceramic particles embedded in a highly polymerized resin matrix (80 % by weight) [83]. Enamic from Vita which combines the properties of ceramic and polymer, it belongs to a new substance class, known as “hybrid-ceramic.” It consists of a hybrid structure with two interpenetrating networks of ceramic and polymer, a so-called double network hybrid (DNH)[81]. And Suprinity also from Vita which is a glass ceramic enriched with zirconia (10 % by weight) reinforced lithium silicate, in order to obtain the world‘s first zirconia reinforced lithium silicate ceramic (ZLS)*, a tough hybrid ceramic. Perception of color involves the participation of three factors, namely, the light source, the object being viewed and the observer viewing the object. In 1978, the CIELAB system defined color in terms of 3 coordinate values (L*, a*, and b*). L* refers to the lightness coordinate and its value ranges from 0(black) to 100(white). The values of a* and b* are the chromaticity coordinates, where a* represents the red (positive value) or green chroma (negative value), while b* represents yellow (positive value) and blue chroma (negative value) [8]. Differences in perceived color (ΔE) can be determined using the CIELAB coordinates. This system is widely used in dental research and is useful for calculating color differences, but not amenable to easy color communication. For color communication, the HSV (hue, saturation, value) system is most commonly used [11, 12].