Dental Modeling Material Thermal Expansion Control
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Solution Overview
Problem
Conventional materials used in dental modeling for investment casting processes often result in cracks and defects due to thermal expansion issues, as they do not exhibit the same melting behavior as waxes, leading to stress on the investment material and subsequent cracking.
Innovation Solution
Radically polymerizable compositions containing a radically polymerizable monomer, an initiator for radical polymerization, and an inert component such as phthalates or polyethylene glycols, which control thermal expansion and prevent cracking by allowing for expansion without residue.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If alternative materials (curable resins, plastic-wax hybrid discs) are used instead of pure waxes for dental modeling, then productivity and ease of manufacture are improved, but the materials expand thermally during heating without flowing out, exerting pressure on the investment material and causing cracks and defects
Solution Approach 1:
The patent modifies the thermal behavior parameters of the modeling material by formulating a composition that undergoes controlled softening and melting at specific temperature ranges. The material transitions from a rigid state to a flowable state, allowing it to expand and then flow out of the investment material without causing cracks, thus resolving the contradiction between productivity and manufacturing precision.
Solution Approach 2:
The patent uses a composite material system consisting of a polymer matrix combined with specific additives and fillers that provide the desired melting and flowing characteristics. This composite approach allows the material to exhibit both the structural integrity needed for accurate modeling and the thermal behavior necessary to prevent investment material cracking, thereby achieving both high productivity and manufacturing precision.
2Reliability
If materials with large thermal expansion are used to allow for expansion during heating, then the risk of cracking is reduced, but the accuracy and precision of the final dental restoration deteriorates
Solution Approach 1:
The patent exploits phase transitions of the modeling material during heating. The material undergoes a controlled phase change from solid to semi-fluid state at specific temperature ranges, allowing it to accommodate thermal expansion through flow rather than stress accumulation. This phase transition mechanism enables the material to expand without cracking the investment material while maintaining the accuracy of the final restoration through controlled deformation.
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 materials achieve low maximum linear thermal expansion, reducing the risk of defects and ensuring crack-free molds with high accuracy and precision, suitable for producing dental restorations like inlays, crowns, and bridges.
Implementation Method 1
radically polymerizable compositions which contain (a) at least one radically polymerizable monomer, (b) at least one initiator for the radical polymerization
Implementation Method 2
They expand thermally during the setting/curing of the investment material and the temperature rise associated therewith as well as during the subsequent heating, however do not flow out of the mould but are primarily removed therefrom by thermal decomposition
Data Source
AI summary
Modelling material which contains (a) at least one radically polymerizable monomer, (b) at least one initiator for the radical polymerization and (c) at least one inert component. The inert component (c) is selected from phthalates, polyethylene glycols (PEG), polypropylene glycols (PPG), PEG-PPG copolymers, glycerol derivatives, ethoxylated or propoxylated glycerol, ethylenediamine tetrakispropoxylates and ethylenediamine tetrakisethoxylates. The material is suitable in particular for the production of models of dental restorations for investment casting processes.