Home/News/The Color of Zirconia All-Ceramic Dentures – Color Matching
Zirconia all-ceramic restorations are widely used in denture restoration due to their excellent mechanical properties, biocompatibility, and aesthetic effects. Compared with traditional porcelain-fused-to-metal crowns, the color characteristics of zirconia ceramics make them closer to natural teeth, providing patients with both aesthetic and natural restoration effects, greatly meeting the demands of modern oral aesthetics.With the increasing demand for aesthetic dentures among the public, color is one of the most important performance indicators for zirconia dentures. During the fabrication process of dentures, understanding color, comparing colors, and achieving precise color matching are particularly important. Among them, the color matching of denture restorations and professional dental shade guides are crucial for determining the color of dentures. This article briefly introduces dental shade guides, including their classification, naming, related definitions, and color-matching techniques.
一、 Understanding Shade Guides
Shade guides consist of a series of color chips with specific color parameters, which simulate the common color range of natural teeth. By comparing the color chips of the shade guide with natural teeth and observing the differences between them, the appropriate color for zirconia all-ceramic dentures can be initially determined.
The Vita Classic shade guide is primarily based on hue, with four main color series: A, B, C, and D. Each hue is further divided into 3 to 5 gradients based on lightness and chroma, totaling 16 shades, each corresponding to a different color tendency.
| A colour scheme |
red——brown |
A1、A2、A3、A3.5、A4 |
| B colour scheme |
red——yellow |
B1、B2、B3、B4 |
| C colour scheme |
grey |
C1、C2、C3、C4 |
| D colour scheme |
red——grey |
D2、D3、D4 |
Due to the limited color range, low accuracy of color matching, and lack of scientificity and fixed rules in the Vita Classical 16-color shade guide, the Vita 3D shade guide was introduced based on the Vita Classic shade guide. The 3D shade guide has a broader color range, fully considering the three-dimensional effects of color: lightness, saturation, and hue. The distribution of the shade tabs is more reasonable, and the color-matching process is simple, fast, reliable, and systematic.
The Vita 3D-Master shade guide is an improved version of the 16-shade guide based on colorimetry and color theory. It is first divided into 5 groups according to lightness, and then each group is further classified into 1, 1.5, 2, 2.5, and 3 levels based on saturation. Finally, it is divided into three groups according to hue: L (yellowish), M (normal), and R (reddish). This shade system is in harmony with the colorimetric system of the naked eye, and the shade-matching sequence is more scientific. The color distribution of this shade guide is reasonable and the intervals are equal. Therefore, intermediate colors can be expressed by simple addition, and two adjacent porcelain powders can be mixed in a 1:1 ratio to obtain them. This makes more tooth colors reflected on the shade guide.
The Vita Classical 16-color shade guide and the Vita 3D-Master shade guide are both mainly used in dental clinical practice for matching and determining the color of teeth, providing color references for dental restoration and other treatments, helping dentists and technicians select appropriate material colors to achieve better aesthetic restoration results. Moreover, in some cases, they can be used interchangeably to more comprehensively cover the range of tooth colors.
In the naming of color codes, the left number on the color code represents the brightness (Value) group; the middle English letters represent the color value (Hue), and the right number represents the saturation. For example: 2L1.5 = second group of brightness / hue / 1.5 saturation.
The colors of natural teeth are rich and diverse, and there are subtle differences among different individuals. If the color values of zirconia all-ceramic dentures can precisely match the natural teeth of patients, it can significantly enhance the naturalness of the dentures. The luminance (L*) of the color value determines the brightness of the denture. An appropriate luminance makes the denture visually consistent with the adjacent natural teeth, avoiding the awkwardness of being too bright or too dark. The chromaticity parameters a* (red-green axis) and b* (yellow-blue axis) further fine-tune the color tendency, ensuring that the color of the denture matches the red-yellow or blue-green tones of the natural teeth.
In 1976, the International Commission on Illumination (CIE) officially confirmed an imaginary three-dimensional spherical structure to represent colors. This structure ingeniously simplifies the color of teeth into three parameter values: luminance, saturation, and hue. Among them, luminance represents the brightness of the color, saturation reflects the concentration of the color, and hue is represented by the angles in the diagram. This three-dimensional sphere encompasses all the colors in the world, like a universe of colors. When we delve deeper, we will find that the vertical axis represents luminance, the horizontal axis represents concentration (i.e., saturation), and the angles in the diagram precisely depict hue.
二、The Three-Dimensional Effect of Color Chips
To understand luminance, one can imagine it based on a black-and-white photo without saturation or hue. A black-and-white photo only has black and white, as well as small ranges of gray and gray-black. White has the highest luminance because it can fully reflect light, while black has the lowest luminance because it absorbs all light. Additionally, various grays are finely divided into several gradients due to the different proportions of light absorption and reflection, and these gradients precisely represent different luminance levels.
Saturation is an indicator for measuring the depth of color, reflecting the intensity of the tooth color, that is, the degree of its brightness and dullness. Saturation determines the purity and vividness of the color. By measuring and adjusting the saturation, the depth of the tooth color can be effectively changed, thereby influencing the overall aesthetic effect.
The color values help us accurately represent the color of teeth. The color range of teeth is extensive, including seven basic colors such as red, orange, yellow, green, blue, indigo and purple.
三、 Colorimetry Technique Using Vita 3D-Master Color Chart
1. To determine the brightness, the brightness levels on the color chart are divided into 5 groups from the brightest on the left (the first group) to the darkest on the right (the fifth group), with the brightness of all color marks in the same group being consistent. First, select a darker natural light source and place the 3D color chart next to the teeth. Start observing from the group with the greatest contrast in brightness to the teeth, select the brightness group that is most similar to the brightness of the contrasting tooth, and then record the selected group (1, 2, 3, 4, 5). It is worth noting that the colorimetry results under different light conditions are different, so the correct light source is very important for choosing the correct brightness.
2.Determine the saturation. From the selected brightness groups, take the middle color scale group “M” and turn it on. Then, place it close to the tooth surface. From the perspective of comparing saturation, select the closest color scale (light – medium – dark). Then, record the selected saturation (1, 2, 3), or the intermediate degree (1.5, 2.5). Here, 1 – the lowest saturation and the highest brightness; 4 – the highest saturation and the lowest brightness.
3.Determine the color value. The range of natural tooth color values is from bright yellow, pale yellow to brownish red. The following letters can be found on the color comparison chart, and they contain the following meanings:
L = The left group = Yellow
M = The middle group = No obvious yellow or brownish red
R = The right group = Brownish red
Pay attention to whether the tooth part has obvious yellow or brownish red. If not, choose the M middle group, and then record the selected color value (L, M, R).
The application of the color comparison chart in zirconia all-ceramic dentures is essentially to achieve a high degree of uniformity in color and texture between the restoration and natural teeth through standardized color comparison tools. It not only meets patients’ aesthetic needs but also ensures the professionalism and accuracy of the restoration treatment. It is a key link connecting clinical diagnosis, patient needs, and denture processing, and plays an irreplaceable role in improving the quality of oral restoration.
Dezime Ceramic, as a professional manufacturer of zirconia all-ceramic denture materials, has been dedicated to the color research of zirconia ceramic block dentures for a long time, continuously improving the understanding of all-ceramic denture colors and technical application, to ensure the accuracy and stability of the color of zirconia ceramic blocks.
If you have any questions related to the color of zirconia all-ceramic dentures, please feel free to call for product technical communication. Dezime Ceramic, your trusted expert in zirconia materials!
