3D Printing Dental Resin Composition for Crack-Resistant Aligners
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Solution Overview
Problem
Cracking occurs during attachment and detachment of orthodontic aligners produced by three-dimensional printing.
Innovation Solution
A three-dimensional printing composition comprising 10 to 80% (meth)acrylate with and without a urethane bond, 3 to 30% polyurethane powder, and 0.01 to 10% photopolymerization initiator, with a viscosity of 200 to 3,000 mPa·s, is used to suppress cracking.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If orthodontic aligners are produced by three-dimensional printing using conventional resin compositions, then manufacturing capability is achieved, but cracks occur during attachment and detachment
Solution Approach 1:
The patent uses a composite resin composition containing both urethane bond-containing (meth)acrylate and urethane bond-free (meth)acrylate in specific proportions (10-80% and 10-80% by mass respectively). This composite approach combines the advantages of both material types: the urethane bond-containing component provides flexibility and crack resistance, while the urethane bond-free component ensures proper viscosity and printability. Additionally, polyurethane powder (3-30% by mass) is incorporated to further enhance flexibility and prevent cracking during clinical use.
Solution Approach 2:
The patent precisely controls the viscosity parameter of the resin composition to be within 200 to 3,000 mPa·s at 23°C using a type B viscometer. This parameter optimization ensures the composition is neither too thick (which would cause printing difficulties) nor too thin (which would compromise structural integrity). The balanced viscosity range allows the material to be properly extruded through three-dimensional printing while maintaining sufficient strength and flexibility to prevent cracking during attachment and detachment.
2Ease of manufacture
If resin composition viscosity is reduced for better printability, then three-dimensional printing ease is improved, but structural integrity and crack resistance deteriorate
Solution Approach 1:
The patent optimizes the viscosity parameter to a specific range (200-3,000 mPa·s) that balances printability and structural integrity. This viscosity control is achieved through careful selection and proportioning of the resin components, ensuring the material flows adequately during printing while maintaining sufficient strength after curing.
Solution Approach 2:
By combining urethane bond-containing (meth)acrylate with urethane bond-free (meth)acrylate and polyurethane powder, the patent creates a composite material where the urethane bond-containing component contributes to flexibility and crack resistance even at optimized printing viscosities, while the urethane bond-free component ensures proper flow characteristics during printing.
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 composition effectively prevents cracking during attachment and detachment of orthodontic aligners, enabling successful production by three-dimensional printing.
Implementation Method 1
0.01 to 10% by mass of a photopolymerization initiator
Data Source
AI summary
The present invention relates to a three-dimensional printing composition containing: 10 to 80% by mass of (meth)acrylate having a urethane bond; 10 to 80% by mass of (meth)acrylate free from a urethane bond; 3 to 30% by mass of a polyurethane powder; and 0.01 to 10% by mass of a photopolymerization initiator, wherein a viscosity of the composition is 200 to 3,000 mPa·s.