Opaque Zirconia Crown Coating for Selective Inner-Surface Masking
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Solution Overview
Problem
Existing methods struggle to impart opacity selectively to specific portions of zirconia dental prostheses without compromising strength or transparency, particularly when using zirconia with high yttrium content for improved transparency, and existing coloring methods can degrade sintering properties.
Innovation Solution
An opaque imparting liquid containing water-soluble aluminum and/or lanthanum compounds, water, and organic solvents is applied to the inner surface of zirconia prostheses, adjusting opacity without coloring, using specific ratios to maintain strength and transparency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If zirconia with high yttrium content (5-6 mol%) is used to improve optical transparency, then transparency is improved, but bending strength decreases and breakage occurs
Solution Approach 1:
The patent applies different yttrium oxide content to different regions of the zirconia blank. The incisal part uses high yttrium content (5-6 mol%) for transparency, while the cervical part uses lower yttrium content (3-4 mol%) for strength. This regional differentiation allows each area to have optimal properties for its specific function.
Solution Approach 2:
The patent creates a composite zirconia structure by superimposing multiple zirconia powders with different yttrium oxide content and color tones. This composite approach combines the transparency benefits of high-yttrium zirconia with the strength benefits of low-yttrium zirconia in a single prosthesis device.
2Strength
If zirconia with low yttrium content (3-4 mol%) is used to maintain strength, then bending strength is sufficient, but optical transparency is insufficient
Solution Approach 1:
The patent assigns lower yttrium content (3-4 mol%) to the cervical portion of the zirconia blank where structural strength is critical for bridge support, while reserving higher transparency regions for the incisal portion where aesthetics are prioritized.
Solution Approach 2:
The multilayered composite structure allows the lower-yttrium layers to provide structural integrity while higher-yttrium layers provide transparency, achieving both requirements simultaneously in different regions of the same prosthesis.
3Illumination intensity
If conventional coloring methods are used to mask discolored teeth, then aesthetic property is improved, but sintering properties deteriorate and strength decreases
Solution Approach 1:
The patent changes the chemical composition parameters by incorporating specific metal oxides (0.1-5 wt% iron oxide, 0.1-5 wt% erbium oxide, 0.1-5 wt% cobalt oxide) that provide coloring functionality without adversely affecting sintering behavior, unlike conventional coloring methods.
Solution Approach 2:
The patent uses composite zirconia powders that combine the base zirconia material with small controlled amounts of coloring oxides, creating a material that achieves aesthetic goals while maintaining sintering properties and mechanical strength.
4Illumination intensity
If multilayered structure with different color tones is created to reproduce natural tooth gradation, then aesthetic property is improved, but manufacturing complexity increases
Solution Approach 1:
The patent pre-mixes zirconia powders with different color tones and yttrium oxide content into homogeneous composite powders before shaping, allowing the multilayered structure to be formed in a single pressing operation rather than requiring multiple sequential coating and sintering steps.
Solution Approach 2:
The use of composite zirconia powders with built-in color and transparency gradients allows a single pressing step to produce the multilayered aesthetic effect, significantly simplifying manufacturing compared to conventional multi-step coating processes.
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
The method effectively imparts opacity to desired areas of zirconia prostheses, enhancing aesthetic properties by masking discolored teeth and maintaining structural integrity.
Implementation Method 1
applying an opaque imparting liquid only to an inner surface of a prosthesis device cut and machined from a dental zirconia for cutting and machining
Implementation Method 2
the opaque imparting liquid contains (a) 10 to 39 wt.% of a water-soluble aluminum compound and/or a water-soluble lanthanum compound
Data Source
AI summary
To provide a liquid material which can only adjust transparency by applying on a part of a zirconia crown having high transparency, without coloring. The present invention provides an opaque imparting liquid used for a prosthesis device cut and machined from a dental zirconia for cutting and machining, comprising; (a) 10 to 39 wt.% of a water-soluble aluminum compound and/or a water-soluble lanthanum compound, (b) 60 to 89 wt.% of water, and (c) 1 to 20 wt.% of an organic solvent.