Ceramic Dental Restoration Core-Shell Sintering for Precise Fit
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Solution Overview
Problem
Existing methods for producing ceramic dental restorations face challenges such as high wear of grinding tools, complex processing times, and risks of deformation or cracking during debinding and sintering, which hinder the production of high-strength, aesthetically sophisticated all-ceramic restorations.
Innovation Solution
A method involving separate additive manufacturing of a core and veneer structures using CAD/CAM, followed by joining and sintering, with slurries containing photopolymerizable monomers and ceramic particles, to achieve precise fit and high strength, while minimizing deformation risks.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If ceramic materials are milled using traditional grinding processes, then precise fit and high strength can be achieved, but the processing time increases significantly and grinding tool wear is high
Solution Approach 1:
The patent replaces traditional mechanical milling and grinding processes with an additive manufacturing process (stereolithography) that builds ceramic restorations layer by layer from liquid photopolymerizable slurry. This substitution eliminates the need for extensive mechanical material removal while achieving precise anatomical fit through digital modeling and controlled layer deposition.
Solution Approach 2:
The patent changes the physical state of ceramic material from solid blocks to liquid photopolymerizable slurry containing ceramic particles. This parameter change enables additive manufacturing where the slurry is selectively cured by light to form green bodies, which are then sintered to achieve final ceramic restorations with precise fit without requiring time-consuming mechanical processing.
2Strength
If traditional milling processes are used for ceramic restorations, then structural integrity can be maintained, but tool wear and processing complexity increase
Solution Approach 1:
The patent replaces complex mechanical milling and grinding operations with additive manufacturing followed by sintering. The green body strength achieved during stereolithography (5-20 MPa) is sufficient for handling and processing, and the subsequent sintering process densifies the structure to achieve final flexural strength of 300-700 MPa, eliminating the need for complex mechanical processing while maintaining structural integrity.
Solution Approach 2:
The patent uses composite materials consisting of ceramic particles dispersed in a photopolymerizable slurry matrix. The organic binder provides green body strength during manufacturing, while the inorganic ceramic particles provide the final mechanical properties after sintering. This composite approach enables complex geometries to be manufactured without requiring complex mechanical processing tools.
3Strength
If debinding and sintering processes are applied to ceramic restorations, then high strength and aesthetic appearance can be achieved, but risks of deformation and cracking increase
Solution Approach 1:
The patent performs preliminary actions to prevent deformation and cracking during debinding and sintering. The green body is designed with controlled porosity and uniform binder distribution to facilitate gradual binder removal. The sintering process uses controlled heating rates and atmosphere to minimize thermal gradients and differential shrinkage between core and veneer structures, preventing deformation and cracking while achieving high strength.
Solution Approach 2:
The patent carefully controls parameter changes during debinding and sintering. The slurry composition is optimized to achieve controlled green body strength and porosity. During sintering, temperature, heating rate, and atmosphere parameters are precisely controlled to match the thermal expansion and shrinkage characteristics of different ceramic materials, minimizing differential stress and deformation risk while achieving the desired flexural strength of 300-700 MPa.
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 produces ceramic dental restorations with high flexural strength and precise fit, reducing the risk of errors and deformation, and enabling a natural tooth-like appearance.
Implementation Method 1
slurries containing photopolymerizable monomers
Implementation Method 2
followed by joining and sintering
Data Source
AI summary
Method for producing an all-ceramic dental restoration with a one-piece core and a shell structure, in which a digital construction model of the dental restoration is constructed, the CAD data set obtained is then divided into at least two separate CAD partial data sets. One partial data set defines the contour of the core structure and a second partial data set defines the contour of the shell structure. A green body of the core structure is produced by the first CAD partial data set and a green body of the shell structure of the restoration is produced by the second CAD partial data set. The core and shell structure are then joined together in the green state. The green body is then subjected to heat treatment to remove the binder and the component is then sintered to obtain the finished dental restoration.