3D Printable Resin Composition for Tough Orthodontic Aligners
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Solution Overview
Problem
Existing 3D printing resins for orthodontic aligners are too brittle and prone to fracture in a moist environment, leading to potential health risks and treatment interruptions, while high viscosity resins complicate the printing process and post-curing.
Innovation Solution
A printable composition comprising a high viscosity polymerizable component admixed with a temporary solvent to maintain material properties and printability, using a method that includes selective curing and solvent removal.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If existing 3D printing resins with high crosslinking are used, then mechanical strength is improved, but brittleness increases and elongation decreases
Solution Approach 1:
The patent uses a composite resin system combining thermosetting and thermoplastic polymers. The thermosetting polymer (e.g., epoxy or polyester) provides high crosslinking density and mechanical strength, while the thermoplastic polymer (e.g., polycarbonate or polyethylene terephthalate) contributes ductility, elongation, and fracture toughness. This composite approach allows the material to achieve both high strength and resistance to brittleness, enabling reliable oral appliances that can withstand masticatory forces without fracturing.
2Reliability
If polymerizable components with less crosslinking and higher elongation are used, then resilience is improved, but strength is lost when immersed in water
Solution Approach 1:
The dual-polymer composite system addresses water degradation by combining polymers with complementary properties. The thermosetting polymer forms a highly crosslinked network that maintains structural integrity and strength in aqueous environments, while the thermoplastic polymer provides the necessary elongation and resilience. The synergistic interaction between the two polymer phases ensures that the composite retains both mechanical strength and resilience when immersed in water, making it suitable for oral applications.
Solution Approach 2:
The patent modifies the chemical composition parameters of the resin by incorporating specific ratios of thermosetting to thermoplastic polymers, along with controlled amounts of crosslinking agents and initiators. By adjusting these compositional parameters, the material achieves an optimal balance between water resistance and resilience, allowing the appliance to maintain its mechanical properties in the oral environment.
3Strength
If high viscosity polymerizable component is used, then mechanical properties are improved, but printability deteriorates
Solution Approach 1:
The patent controls the viscosity of the polymerizable composition by adjusting the molecular weight and structure of the polymer components, adding appropriate solvents or diluents, and optimizing the ratio of viscous to less viscous components. This parameter optimization ensures the resin has sufficiently low viscosity for effective pumping and deposition through 3D printing nozzles, while still achieving the desired mechanical properties after curing. The composition is formulated to flow easily during printing but set properly once deposited.
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 provides resilient orthodontic appliances with enhanced mechanical properties and ease of printing, without significant swelling in water or saliva, ensuring reliable treatment.
Implementation Method 1
selectively curing the printable composition to form an article representing the shape of the three-dimensional object
Implementation Method 2
By admixing the high viscosity resin with elevated levels of a temporary and removable solvent, the material properties of the polymerizable component can be retained in a cured article without sacrificing the printability of the resin
Implementation Method 3
removing a substantial amount of the temporary solvent from the article
Data Source
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AI summary
The present disclosure provides a method for building a three-dimensional object using a printable composition including high viscosity polymerizable components. The method includes the steps of a) providing a printable composition comprising a high viscosity polymerizable component and a temporary solvent; b) selectively curing the printable composition to form an article representing the shape of the three-dimensional object; and c) removing a substantial amount of the temporary solvent from the article. The method is particularly well suited to making an orthodontic clear tray aligner. Also disclosed are a variety of printable compositions including high viscosity polymerizable components, such as polyurethane methacrylates, and temporary solvents.