Multilayer Ceramic Dental Blank Gradient Coloring Oxides

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Solution Overview

Problem

Existing methods for manufacturing multilayer ceramic blanks for dental restorations fail to achieve a natural tooth appearance, particularly in the translucence and color gradient, as the proportion of coloring oxides decreases from the lowermost to the topmost layer, resulting in an unnatural appearance.

Innovation Solution

The method involves using a first coloring oxide from the group Co, Mn, Ni, Cr in lower proportions in the lowermost layer and higher proportions in the topmost layer, and a second oxide from the group Pr, Er, Fe, Ti, V, Bi, Cu, Tb in greater proportions in the lowermost layer and decreasing proportions in the topmost layer, within a ceramic material matrix that includes zirconium oxide and yttrium oxide, to create a more natural color and translucence gradient.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of manufacture

If the proportion of coloring oxides decreases from the lowermost layer to the topmost layer, then the manufacturing process is simplified, but the natural appearance and translucence of the dental restoration are compromised

Engineering Contradiction:

Improvemanufacturing process simplicityVSAvoidtranslucence and natural appearance

Core Design Contradiction:

Ease of manufactureVSIllumination intensity

Solution Approach 1:

The patent applies local quality by assigning different coloring oxide compositions to different regions of the blank. Specifically, the lowermost layer contains coloring oxides from the first group (Co, Mn, Ni, Cr) at lower proportions, while the topmost layer contains these same oxides at higher proportions. This regional differentiation creates the natural translucence gradient observed in real teeth, with the incisal edges appearing more translucent than the cervical regions.

Inventive Principle:

Principle #3Local quality

Solution Approach 2:

The patent inverts the conventional approach by increasing the proportion of certain coloring oxides (first group: Co, Mn, Ni, Cr) from the lowermost to the topmost layer, rather than decreasing them. This inversion, combined with the complementary decrease of second group oxides (Pr, Er, Fe, Ti, V, Bi, Cu, Tb), creates the desired natural appearance that was not achievable with the traditional single-directional composition gradient.

Inventive Principle:

Principle #13The other way round (Inversion)

2Illumination intensity

If intermediate layers with mixtures of adjacent layer materials are used to achieve continuous transition, then the translucence gradient is improved, but the manufacturing complexity increases

Engineering Contradiction:

Improvecontinuous translucence transitionVSAvoidmanufacturing process complexity

Core Design Contradiction:

Illumination intensityVSDevice complexity

Solution Approach 1:

The patent employs parameter changes by systematically varying the proportions of coloring oxides across different layers. Instead of using complex intermediate mixture layers, the invention achieves continuous transition by adjusting the concentration parameters of specific coloring oxides (first group increasing, second group decreasing) from one layer to the next, creating a smooth gradient effect through controlled compositional parameter variation.

Inventive Principle:

Principle #35Parameter changes

Applied Scientific Principles

This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.

Function Achieved in This Case

This approach results in a dental restoration with a more translucent and tooth-like appearance, especially in the incisal region, closely mimicking the natural appearance of teeth, with improved strength and color intensity through controlled crystal phase stabilization.

Implementation Method 1

as a first coloring oxide as the one coloring oxide at least one oxide from the group Co, Mn, Ni, Cr is used, the proportion of which in the lowermost layer containing the first coloring oxide being lower than that in the topmost layer containing the first coloring oxide

Methodology Applied

Scientific EffectColoring oxide concentration gradient:

Implementation Method 2

at least one oxide from the group Pr, Er, Fe, Ti, V, Bi, Cu, Tb is used as the second coloring oxide, the proportion of which in the lowermost layer containing the second coloring oxide is greater than that in the topmost layer

Methodology Applied

Scientific EffectColoring oxide concentration gradient:

Implementation Method 3

within a ceramic material matrix that includes zirconium oxide and yttrium oxide, to create a more natural color and translucence gradient

Methodology Applied

Scientific EffectCrystal phase stabilization:

Data Source

PatentUS20210290351A1Method for the manufacture of a blank and blank

Publication Date: 2021.09.23 DENTSPLY SIRONA INC

AI summary

The present invention is related to a method for the manufacture of a multilayer blank, having a lowermost layer and a topmost layer, of a ceramic material, where layers of different compositions are introduced layer-by-layer into a mold, compressed and then sintered and where individual layers contain at least one coloring oxide, wherein as a first coloring oxide as the one coloring oxide at least one oxide from the group Co, Mn, Ni, Cr is used, the proportion of which in the lowermost layer containing the first coloring oxide is lower than in the topmost layer containing the first coloring oxide: and at least one oxide from the group Pr, Er, Fe, Ti, V, Bi, Cu, Tb is used as the second coloring oxide, the proportion of which in the lowermost layer containing the second coloring oxide is greater than that in the topmost layer.