Gel Casting Dental Appliance Process
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Solution Overview
Problem
Current methods for producing dental crowns from glass or glass ceramic materials are limited by the need for mechanical compacting and pre-sintering, which restricts shape flexibility and increases processing time, and the inability to machine non-pre-sintered bodies due to low mechanical strength.
Innovation Solution
A gel casting process using a mixture of a liquid, an inorganic binder precursor, and glass or glass ceramic powder, allowing for direct casting, drying, and machining without pre-sintering, enabling the production of complex shapes and reducing processing steps.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If mechanical compacting and pre-sintering are used to produce glass or glass ceramic bodies, then the mechanical strength is increased, but the processing time is extended and shape flexibility is restricted
Solution Approach 1:
The patent applies preliminary action by incorporating a binder into the green body that enables machining before sintering. The binder maintains structural integrity during machining operations, allowing complex shapes to be created prior to the sintering process, thereby eliminating the need for post-sintering adjustments and reducing total processing time.
Solution Approach 2:
The patent changes the chemical composition parameters by introducing specific binders (organic or inorganic) that modify the mechanical properties of the green body. This parameter change enables the material to be machined at room temperature before sintering, avoiding the time loss associated with traditional methods that require pre-sintering for adequate strength.
2Ease of manufacture
If mechanical compacting is used to produce green bodies, then the material can be formed, but the shape is limited to the compacting tool geometry
Solution Approach 1:
The binder enables preliminary shaping operations such as injection molding or casting that are not constrained by compacting tool geometry. The binder holds the powder particles together during these alternative forming processes, allowing complex dental restoration shapes to be created directly in the desired configuration.
3Strength
If milling process is used to machine compacted bodies, then the mechanical strength requirement is higher, but the tool wear increases and production speed decreases
Solution Approach 1:
The binder enables machining operations to be performed on the green body before sintering, when the material is softer and more easily machined. This preliminary machining action reduces tool wear and increases production speed, as the binder provides sufficient strength to hold the workpiece during machining without requiring the high mechanical strength that would necessitate pre-sintering.
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
This approach results in dental appliances with sufficient strength for machining, reduced tool wear, and the ability to produce complex shapes, while eliminating the need for pre-sintering, thus enhancing efficiency and flexibility in dental restoration manufacturing.
Implementation Method 1
The mixture typically comprises from 60 to 85 wt.-% glass or glass ceramic powder or particles, from 5 to 30 wt.-% inorganic binder and from 5 to 30 wt.-% liquid
Implementation Method 2
The mixture is cast into a mould and the mixture or the green body obtained from the mould is dried
Data Source
AI summary
The invention relates to a process for producing a dental appliance, the process comprising the steps of a) providing a mixture of a liquid, an inorganic binder precursor being able to undergo a sol/gel reaction and a glass or glass ceramic powder, b) casting the mixture into a mold, c) drying the cast mixture in the mold to obtain a machinable dental appliance, d) optionally machining the dental appliance to obtain a dental workpiece, e) optionally removing the dental appliance or dental workpiece from the mold, f) optionally sintering the dental appliance or dental workpiece and to a dental appliance obtainable by such a process.