Bleaching Shaded Zirconia for Dental Shade Gradient
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Solution Overview
Problem
Current methods for achieving a realistic shade gradient in zirconia dental restorations are inconsistent and can reduce the flexural strength of zirconia, leading to warping and unsuitable for multi-unit bridges, as they either require extensive technician expertise or result in reduced mechanical properties.
Innovation Solution
A bleaching liquid comprising metal compounds such as zinc, gallium, and aluminum salts or complexes dissolved in solvents, applied to unsintered shaded zirconia, which maintains the material's strength and allows for customizable shading without acting as a colorant, thereby preventing warping and maintaining the zirconia's mechanical properties.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If coloring liquid is brushed on zirconia surface to generate shade gradient, then aesthetic appearance is improved, but technician expertise requirement and process complexity increase
Solution Approach 1:
Instead of adding color to create gradient, the patent uses bleaching to remove color and create gradient by applying bleaching liquid selectively to areas where lighter shade is desired, inverting the conventional coloring approach
Solution Approach 2:
The patent changes the chemical composition parameters of the zirconia surface by applying bleaching agents (hydrogen peroxide, carbamide peroxide, or chlorine-based compounds) that chemically alter the color properties of the zirconia material
2Illumination intensity
If conventional bleaching liquid (yttrium nitrate) is applied to pre-shaded zirconia, then color gradient is achieved, but flexural strength decreases and warping occurs
Solution Approach 1:
The patent changes the chemical composition by using alternative bleaching agents (hydrogen peroxide, carbamide peroxide, chlorine-based compounds) instead of yttrium nitrate, achieving color modification without the harmful side effects on mechanical properties
Solution Approach 2:
The patent converts the harmful effect of conventional bleaching agents (which cause warping and strength loss) into a beneficial process by selecting bleaching agents that achieve color gradient without compromising mechanical integrity
3Illumination intensity
If multi-layer zirconia blanks are used to create gradient effect, then color gradient is achieved, but manufacturing complexity and equipment requirements increase
Solution Approach 1:
Instead of creating gradient during manufacturing by stacking multiple layers, the patent applies gradient after manufacturing by selective bleaching of the finished or near-finished zirconia restoration
Solution Approach 2:
The patent performs bleaching as a preliminary or intermediate step before final sintering or polishing, allowing gradient creation without complex multi-layer manufacturing 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 solution effectively bleaches shaded zirconia without affecting its flexural strength, ensuring the material's class and usability in multi-unit bridges, while allowing for customizable shading and reducing warping issues.
Implementation Method 1
a liquid for bleaching a shaded dental zirconia, the liquid comprising a metal compound dissolved in a solvent
Data Source
AI summary
Disclosed are compositions and methods for bleaching and optionally coloring a shaded zirconia, particularly mono-chromatic pre-shaded dental zirconia. The compositions and methods are useful in generating a shade gradient in milled dental restorations. The compositions comprise metal salts or complex dissolved in a solvent.