Machinable Dental Bulk Block with Gradient Crystalline Phases
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Solution Overview
Problem
Current dental crown materials, such as lithium disilicate crystallized glass, have poor workability due to coarse crystalline phases, leading to material shrinkage and complexity in manufacturing, and fail to replicate the multi-gradation transmittance and color tones of natural teeth, making them unsuitable for efficient chairside production and aesthetically pleasing restorations.
Innovation Solution
A machinable dental bulk block made of a functionally graded material with a gradient of lithium disilicate and lithium phosphate crystalline phases, heat-treated with a temperature gradient to achieve varying particle sizes and transmittance values, allowing for improved mechanical strength and aesthetic replication of natural teeth without the need for additional CAD/CAM operations beyond cutting.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If lithium disilicate crystallized glass is used to increase mechanical strength, then strength is improved, but workability deteriorates due to coarse crystalline phases
Solution Approach 1:
The patent applies local quality by creating a functionally graded material where the crystalline phase composition varies through the depth of the bulk block. The surface region contains fine crystals for aesthetics and workability, while the interior contains coarse crystals for strength, allowing each region to optimize its local properties for its specific function.
Solution Approach 2:
The patent uses parameter changes by controlling the temperature gradient during heat treatment to transform the crystalline phase structure. By varying the temperature parameter through the depth of the material, different crystalline phases are formed at different depths, achieving both fine surface crystals and coarse interior crystals from a single homogeneous starting material.
2Strength
If thermal treatment is applied to change crystalline phase for increased strength, then mechanical strength is improved, but manufacturing complexity increases and dimension accuracy deteriorates due to material shrinkage
Solution Approach 1:
The patent merges multiple functions into a single heat treatment process. By applying a temperature gradient during one continuous heating process, the patent simultaneously achieves crystalline phase transformation, dimensional stabilization, and aesthetic surface finish without requiring separate treatment steps for each property.
Solution Approach 2:
The patent performs preliminary crystallization at the surface region before final cooling, creating a fine crystal structure that locks in the desired dimensions and shape. This preliminary action at the surface prevents subsequent shrinkage and maintains dimensional accuracy while the interior continues to transform to its final strong crystalline phase.
3Strength
If conventional heat treatment is used to produce lithium disilicate crystallized glass, then mechanical strength is improved, but aesthetic properties deteriorate due to coarse crystal phase
Solution Approach 1:
The patent applies local quality by creating a functionally graded material where the crystalline phase composition varies through the depth of the bulk block. The surface region contains fine crystals for aesthetics and workability, while the interior contains coarse crystals for strength, allowing each region to optimize its local properties for its specific function.
Solution Approach 2:
The patent transitions from uniform heat treatment to gradient heat treatment, adding the dimension of spatial variation in temperature. This creates a depth-dependent crystalline structure where the surface layer develops fine crystals for aesthetics while the interior develops coarse crystals for strength, resolving the contradiction between appearance and mechanical properties.
4Productivity
If chairside production is pursued to reduce treatment time, then productivity is improved, but manufacturing precision deteriorates due to material shrinkage from thermal treatment
Solution Approach 1:
The patent performs preliminary crystallization at the surface region before final cooling, creating a fine crystal structure that locks in the desired dimensions and shape. This preliminary action at the surface prevents subsequent shrinkage and maintains dimensional accuracy while the interior continues to transform to its final strong crystalline phase.
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 enables the production of artificial teeth with multi-gradation transmittance and physical properties similar to natural teeth, enhancing reproducibility and structural stability while reducing manufacturing time and complexity, and allowing for natural-colored restorations with improved force distribution and machining efficiency.
Implementation Method 1
heat-treated with a temperature gradient to achieve varying particle sizes and transmittance values
Implementation Method 2
A machinable dental bulk block made of a functionally graded material with a gradient of lithium disilicate and lithium phosphate crystalline phases
Data Source
AI summary
Disclosed is a machinable dental bulk block that is a glass ceramic block including an amorphous glass matrix and crystalline phases introduced into the matrix. A major crystalline phase is lithium disilicate and a minor crystalline phase is lithium phosphate. The dental block is made of a functionally gradient material in which the major crystalline phase exhibits a gradient of particle sizes in a depth direction of the dental block and which has no interface at a point where the gradient of particle sizes of the major crystalline phase changes. The dental bulk block is useful for production of a dental prosthesis (artificial tooth) similar to a natural tooth. The dental bulk block can reduce time and the number of processing steps to manufacture a dental prosthesis and provides improved structural stability through good force distribution obtained by functionally graded mechanical properties.