Zirconia Mill Blank Stabilizer Gradient for Dental Translucency
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Solution Overview
Problem
Current zirconia mill blanks for dental cutting and machining lack the ability to impart translucency and color gradation similar to a natural tooth, especially in applications requiring high aesthetic properties, due to visible boundaries between layers and insufficient material properties.
Innovation Solution
A zirconia mill blank with a specific stabilizer concentration gradient, where the difference between maximum and minimum stabilizer concentrations (ΔSPmax) is controlled to achieve gradual translucency and color gradation, allowing for natural tooth-like appearance without the need for special equipment, using a structured composition and impregnating solutions to enhance properties.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If multiple layers with different stabilizer content and colorant content are used to create translucency gradation, then translucency gradation is achieved, but visible boundaries between layers appear and aesthetic property deteriorates
Solution Approach 1:
The patent applies local quality by creating a continuous gradient of stabilizer concentration throughout the zirconia mill blank. Instead of discrete layers, the stabilizer concentration varies continuously from one region to another, with each local region having a specific stabilizer concentration that determines its translucency. This continuous variation eliminates abrupt boundaries while maintaining translucency gradation, directly resolving the contradiction between achieving translucency variation and avoiding visible boundaries.
Solution Approach 2:
The patent employs parameter changes by systematically varying the stabilizer concentration as a continuous parameter throughout the material. The stabilizer concentration is controlled to follow a specific gradient profile (with maximum difference ΔSPmax less than 0.5 between adjacent measurement points), transforming the material's optical properties continuously. This approach replaces the discrete layer structure with a continuous parameter variation, eliminating visible boundaries while preserving translucency gradation.
2Illumination intensity
If stabilizer concentration difference (SPmax-SPmin) is increased to enhance translucency variation, then translucency gradation is improved, but maximum stabilizer concentration difference (ΔSPmax) increases causing visible boundaries
Solution Approach 1:
The patent resolves this contradiction by carefully controlling the stabilizer concentration parameter throughout the material. It allows the overall difference (SPmax-SPmin) to be sufficient for achieving translucency gradation (0.3 or more), while simultaneously constraining the local maximum difference (ΔSPmax) between adjacent points to be less than 0.5. This dual control of parameter variation ensures both adequate translucency variation and smooth transitions without visible boundaries.
Solution Approach 2:
The patent applies dynamics by creating a gradual, continuous transition of stabilizer concentration rather than abrupt changes. The stabilizer concentration profile is designed to vary smoothly through the material, with the rate of change controlled at each location. This dynamic approach allows the material to exhibit translucency gradation while maintaining local uniformity, preventing visible boundaries even as overall variation increases.
Data Source
AI summary
To provide a zirconia mill blank for dental cutting and machining that can impart translucency gradation and color gradation similar to a natural tooth to a zirconia perfect sintered body without the need for special equipment.To provide a zirconia mill blank for dental cutting and machining comprisingtwo opposing surfaces and a side surface between the two opposing surfaces, whereinthe side surface has a rectangular shape in a side view of the zirconia mill blank for dental cutting and machining, andin a case in whichone of the two opposing surfaces is defined as surface A,the other surface of the two opposing surfaces is defined as surface B,a surface which is parallel to the surface A and is located at a position of 1.0 mm to 1.5 mm from the surface A toward the surface B in a direction parallel to the side surface is defined as surface C,points which are set to having 0.5 mm of distance on the straight line in the direction parallel to the side surface from the surface C toward the surface B in the area from the surface C to the surface B are defined as point P(1), point P(2), to point P(n) in the order from the surface C,a stabilizer concentration (mol %) at each point is defined as SP(1), SP(2), to SP(n) (n≥((shortest distance (mm) between the surface C and the surface B)−2)/0.5),the maximum value of the stabilizer concentration (mol %) is defined as SPmax,the minimum value of the stabilizer concentration (mol %) is defined as SPmin, andthe maximum value of ASP(m) defined by the following formula is defined as ΔSPmax,the zirconia mill blank for dental cutting and machining has a portion where the value of “SPmax−Spmin” which is a difference between the SPmax and the SPmin is 0.3 or more, and the ΔSPmax is less than 0.5.ΔSP(m)=<semantics definitionURL="">❘<annotation encoding="Mathematica">"\[LeftBracketingBar]"</annotation></semantics>SP(m)-SP(m+1)<semantics definitionURL="">❘<annotation encoding="Mathematica">"\[RightBracketingBar]"</annotation></semantics>(m=1,2,… n-1)