Dental Bulk Block With Crystal Gradient for Strength and Milling
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Solution Overview
Problem
Conventional dental materials face challenges in achieving high strength, aesthetic appearance, and processability, with limitations in direct mechanical processing due to large crystal phases, and require secondary heat treatments that affect dimensional accuracy and increase economic burden.
Innovation Solution
A method for manufacturing a dental bulk block with a crystalline size gradient and functional properties, using a glass composition that includes lithium disilicate and silicate phases, heat-treated with a temperature gradient to achieve multi-gradation of transmittance and mechanical properties similar to natural teeth.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If conventional lithium disilicate crystallized glass is used to achieve high strength, then strength is improved, but processability deteriorates due to large crystal phase size
Solution Approach 1:
The patent applies local quality by creating a functionally gradient material where the crystal phase size varies through the depth of the bulk block. The surface region contains fine crystal phases (5-50 μm) for good processability and aesthetics, while the inner region contains coarse crystal phases (50-200 μm) for high strength. This spatial variation in crystal size allows each region to optimize its local properties for its specific function.
Solution Approach 2:
The patent transitions from uniform material properties to dimensionally varied properties by introducing a depth-dependent crystal phase size gradient. This dimensional variation allows the material to simultaneously exhibit different characteristics at different depths, resolving the contradiction between surface processability and bulk strength.
2Strength
If secondary heat treatment is performed to form lithium disilicate crystal phase for high strength, then strength is improved, but manufacturing complexity increases due to additional process steps
Solution Approach 1:
The patent applies preliminary action by forming the desired functionally gradient crystal phase structure during the initial heat treatment process. The heat treatment is designed to create different crystal phases at different depths simultaneously, eliminating the need for subsequent secondary heat treatment to form lithium disilicate. This preliminary structuring achieves both strength and processability in a single process.
Solution Approach 2:
The patent merges the functions of creating strength-enhancing crystal phases and ensuring processability into a single heat treatment process. Instead of separate steps for forming different crystal phases, the process combines these functions by controlling heat treatment parameters to generate the gradient structure in one operation.
3Strength
If secondary heat treatment is performed to increase strength, then strength is improved, but manufacturing time increases due to additional heat treatment process
Solution Approach 1:
The patent performs the crystal phase formation action preliminarily during the first heat treatment process. The heat treatment parameters are optimized to create the functionally gradient structure with appropriate crystal phases for strength in the inner region and processability in the surface region, eliminating the need for time-consuming secondary heat treatment.
Solution Approach 2:
The patent skips the secondary heat treatment step entirely by designing a heat treatment process that directly produces the desired gradient crystal phase structure. This rushing through of the process achieves the strength enhancement without the time delay of additional heat treatment cycles.
4Strength
If conventional lithium disilicate crystallized glass is used to achieve high strength, then strength is improved, but aesthetic appearance deteriorates due to coarse crystal phase
Solution Approach 1:
The patent applies local quality by creating a functionally gradient material where the crystal phase size varies through the depth of the bulk block. The surface region contains fine crystal phases (5-50 μm) for good processability and aesthetics, while the inner region contains coarse crystal phases (50-200 μm) for high strength. This spatial variation in crystal size allows each region to optimize its local properties for its specific function.
5Strength
If heat treatment process is performed to form lithium disilicate crystal phase, then strength is improved, but dimensional accuracy deteriorates due to shrinkage
Solution Approach 1:
The patent performs the crystal phase formation action preliminarily during the first heat treatment process. The heat treatment parameters are optimized to create the functionally gradient structure with appropriate crystal phases for strength in the inner region and processability in the surface region, eliminating the need for subsequent secondary heat treatment that would cause additional shrinkage and dimensional 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
The method allows for efficient CAD/CAM processing, reducing manufacturing time and ensuring structural stability by emulating natural tooth characteristics without additional processes, enhancing aesthetic and mechanical properties.
Implementation Method 1
a method of manufacturing a block having a predetermined shape using a glass composition; and heat treating the block
Implementation Method 2
2 to 6 wt% of P 2 O 5 serving as a nucleation agent
Implementation Method 3
heat treating the block so as to ensure a temperature gradient in a depth direction of the block
Data Source
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AI summary
Disclosed is a dental bulk block for grinding processing. The dental bulk block includes a crystalloid, which includes lithium disilicate as a main crystal phase and silicate as a sub-crystal phase, and hyaline as a remainder. The dental bulk block is a functionally gradient material having a crystalline size gradient with respect to a depth thereof and having no interface at a change point of a crystalline size gradient value. The dental bulk block is useful for manufacturing an artificial dental prosthesis that is similar to natural teeth. Accordingly, the time and process for manufacturing the artificial dental prosthesis are shortened, and structural stability is increased in terms of dispersion of force due to gradient functionalization of mechanical properties.