Translucent Zirconia Composition for Natural-Looking Front Dentures
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Solution Overview
Problem
Existing zirconia sintered bodies used as dental materials lack the aesthetic and mechanical properties required for front tooth dentures, such as translucency and color tone similar to natural teeth, and require costly special sintering methods like pressure sintering.
Innovation Solution
A zirconia sintered body composition containing specific amounts of yttria, erbium, iron oxide, and cobalt oxide, along with controlled relative density and crystallite size, is produced through a simple pressureless sintering process, achieving the desired aesthetics and strength without additional coatings.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If a zirconia sintered body is used as a front tooth denture, then aesthetics (translucency and color tone) are improved, but strength is deteriorated
Solution Approach 1:
The patent applies parameter changes by precisely controlling the yttria content (3.5-5.5 mol%) and adding specific metal elements (Fe, Co, Ni) in controlled amounts. This optimization of compositional parameters achieves the right balance between translucency and strength, allowing the zirconia to maintain both aesthetic properties and mechanical strength suitable for front tooth dentures
2Illumination intensity
If porcelain is laminated on the surface of zirconia to adjust color tone, then aesthetics are improved, but device complexity is worsened
Solution Approach 1:
The patent extracts the color adjustment function from the separate porcelain layer and integrates it directly into the zirconia material itself by adding metal elements (Fe, Co, Ni). This eliminates the need for additional porcelain lamination, simplifying the structure while achieving natural tooth-like color tone
Solution Approach 2:
The patent merges the color adjustment function (previously requiring separate porcelain layer) with the zirconia base material by incorporating metal elements during sintering. This combination creates a monolithic structure that provides both structural integrity and aesthetic color tone without layered complexity
3Illumination intensity
If special sintering methods (pressure sintering, HIP, SPS) are used to achieve high translucency, then translucency is improved, but manufacturing cost is worsened
Solution Approach 1:
The patent applies self-service by formulating a zirconia composition that achieves high translucency and density through conventional atmospheric pressure sintering alone, without requiring external pressure assistance (HIP, SPS, or pressure sintering). The specific compositional parameters enable the material to self-densify effectively under standard sintering conditions, eliminating costly specialized equipment requirements
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 zirconia sintered body achieves translucency and color tone equivalent to natural teeth, suitable for front tooth dentures, while eliminating the need for costly special sintering methods.
Implementation Method 1
Zirconia sintered bodies, in which yttria is solid-solved as a stabilizer
Implementation Method 2
translucent zirconia sintered body having a color tone equivalent to that of a natural front tooth
Implementation Method 3
a zirconia sintered body obtained by pressure sintering using hot isostatic pressing
Data Source
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AI summary
An object of the present invention is to provide a zirconia sintered body suitable as a front tooth denture having aesthetics equivalent to those of a natural front tooth and strength. Another object of the present invention is to provide a zirconia sintered body having a color tone equivalent to the color tone guides of various natural teeth and having the same aesthetics as a natural front tooth. The present invention provides a colored translucent zirconia sintered body comprising zirconia containing greater than 4.0 mol% and not greater than 6.5 mol% of yttria, less than 0.25 mol% of erbia, less than 2,000 ppm of iron oxide in terms of Fe2O3, less than 0.01 wt.% of cobalt oxide in terms of CoO, and less than 0.1 wt.% of alumina; the zirconia sintered body having a relative density of not less than 99.90%, a total light transmittance of not less than 25% and less than 40% for light having a wavelength of 600 nm at a sample thickness of 1.0 mm, and a strength of not less than 500 MPa.