Lithium Silicate Glass-Ceramic Dental Prosthesis Casting
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Solution Overview
Problem
Current methods for producing dental prostheses based on lithium silicate glass or lithium silicate glass-ceramic are complex and require improved manufacturing techniques for reproducibility and simplified processes using manageable starting materials.
Innovation Solution
A method involving melting a powder mixture with specific compositions, producing spherical or lens-shaped glass particles, and casting them into a negative mold, followed by heat treatments to crystallize lithium metasilicate or disilicate phases, using centrifugal casting or vacuum die-casting techniques to produce dental prostheses with controlled viscosity and additives.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If cylindrical pellets are produced and grouted in a muffle, then dental prostheses can be produced using a proven method, but the manufacturing process remains complex and lacks reproducibility
Solution Approach 1:
The patent applies parameter changes by precisely controlling the composition ranges of glass forming oxides (SiO2: 50-70%, Li2O: 5-25%, B2O3: 1-5%, P2O5: 1-10%) and network modifying oxides (Al2O3: 0.5-10%, K2O: 0.5-10%, Na2O: 0.5-5%, CaO: 0.5-5%, MgO: 0.5-5%) to achieve reproducible casting properties. The viscosity is controlled within 4-80 dPa·s at casting temperature, and crystallization is achieved through specific heat treatment parameters (600-760°C for 20-120 minutes), transforming the process from complex pellet grouting to a controlled casting method with consistent results.
Solution Approach 2:
The patent extracts the essential casting properties from the complex pellet grouting process by identifying and isolating the key parameters: glass composition ranges, viscosity control (4-80 dPa·s), and crystallization conditions. This extraction simplifies the manufacturing process to a controlled casting method while maintaining reliability, removing the need for complex pellet preparation and grouting procedures.
2Strength
If glass particles are produced with specific composition ranges, then mechanical properties such as bending strength and translucency are achieved, but the number of compositional parameters increases
Solution Approach 1:
The patent manages compositional complexity through defined parameter ranges rather than fixed values. Glass forming oxides are controlled within specific ranges (SiO2: 50-70%, Li2O: 5-25%, B2O3: 1-5%, P2O5: 1-10%) and network modifying oxides (Al2O3: 0.5-10%, K2O: 0.5-10%, Na2O: 0.5-5%, CaO: 0.5-5%, MgO: 0.5-5%). This parameter range approach provides flexibility in composition while ensuring the mechanical properties (bending strength and translucency) are consistently achieved through the controlled casting and crystallization process.
3Productivity
If centrifugal casting or vacuum die-casting is used, then manufacturing efficiency is improved, but control of melt viscosity becomes more critical
Solution Approach 1:
The patent addresses viscosity control by specifying a narrow range of 4-80 dPa·s at casting temperature for both centrifugal casting and vacuum die-casting methods. This controlled viscosity range ensures proper fill of the mold cavity and eliminates defects, allowing the use of efficient casting methods while maintaining manufacturing precision. The viscosity parameter serves as a critical control point that enables high productivity without sacrificing quality.
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 simplifies the production of dental prostheses, ensuring reproducibility and handling of starting materials, achieving desired mechanical properties such as bending strength and translucency, while reducing internal stress and manufacturing complexity.
Implementation Method 1
crystallizing lithium metasilicate as main crystalline phase from the solidified melt by employing a first heat treatment at a temperature between 600° C. and 760° C. over a time between 20 min and 120 min
Implementation Method 2
producing spherical or lens-shaped glass particles solidified from the melt
Data Source
AI summary
A method for producing a dental prosthesis based on lithium silicate glass or lithium silicate glass-ceramic, including the steps of: melting a powder mixture containing at least SiO2, Li2O, Al2O3; producing spherical, lens-shaped or rod-shaped glass particles solidified from the melt; portioning the glass particles and filling them into a crucible; melting the glass particles in the crucible and setting a viscosity v, wherein 4 dPa·s≤v≤80 dPa·s; casting the thus produced melt into a negative mold which is enclosed by an embedding compound and corresponds to the dental prosthesis and; solidifying the melt in the negative mold, and crystallizing lithium metasilicate and/or lithium disilicate from the solidified melt.