PETG Orthodontic Aligners Regenerate Force via Thermal Treatment
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Solution Overview
Problem
Orthodontic aligners made from polymers suffer from stress relaxation, leading to inefficient tooth movement due to reduced force application over time, necessitating frequent replacements and increased plastic waste.
Innovation Solution
Polyethylene terephthalate glycol (PETG) co-polymer aligners that regenerate stress forces through thermal energy conversion, maintaining consistent force profiles similar to shape memory materials like nitinol, allowing for predictable and controlled teeth movement with reduced aligner usage and waste.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If polymeric aligners are used for orthodontic treatment, then patient comfort is improved and teeth can be moved, but the aligners become ineffective over time due to stress relaxation of the polymeric material
Solution Approach 1:
The patent applies parameter changes by utilizing the glass transition temperature of polymeric materials. The aligner is thermally treated at temperatures near the glass transition temperature to restore its mechanical properties and force application capability. This temporal parameter change (heating at specific temperature intervals) reverses stress relaxation and restores the aligner's effectiveness without compromising patient comfort.
Solution Approach 2:
The patent implements periodic action through repeated thermal treatment cycles. The aligner undergoes periodic heating at the glass transition temperature to regenerate its force application properties. This periodic thermal stimulus allows the aligner to maintain effectiveness throughout the treatment period by cyclically restoring its mechanical properties.
2Force
If traditional polymeric aligners are used, then initial force application is adequate, but the force diminishes over treatment time requiring frequent aligner replacements and increasing plastic waste
Solution Approach 1:
The patent applies discarding and recovering by thermally treating the used aligner to recover its force application properties. Instead of discarding the aligner after initial use, the polymeric material is heated to the glass transition temperature to restore its mechanical properties, allowing the same aligner to be reused multiple times, thereby reducing plastic waste.
Solution Approach 2:
The aligner performs self-service by regenerating its own force application capability through thermal treatment. The polymeric material inherently possesses the ability to restore its mechanical properties when heated to the glass transition temperature, eliminating the need for replacement and reducing waste.
3Ease of operation
If aligners are made softer for patient comfort, then comfort is improved, but the force applied to move teeth becomes inadequate
Solution Approach 1:
The patent applies dynamics by making the aligner's mechanical properties time-dependent and adjustable. The aligner transitions between soft and stiff states through thermal treatment at the glass transition temperature. This dynamic property change allows the aligner to be soft during wear for comfort, then stiff after thermal treatment for effective force application, optimizing both comfort and effectiveness.
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 PETG co-polymer aligners effectively maintain consistent force application over the treatment period, reducing the number of aligners needed by 30-80% and minimizing plastic waste, while providing predictable and reliable teeth movement with enhanced force retention.
Implementation Method 1
a polymer capable of converting thermal energy into mechanical energy, where the intermolecular interactions in stress relaxed polymers are strengthened or reinforced by converting thermal energy into enthalpic energy
Implementation Method 2
the polymeric aligners due to their viscoelastic nature become ineffective in further moving the position of the teeth over treatment time due to stress relaxation of the aligner materials
Implementation Method 3
the polymeric aligners due to their viscoelastic nature
Implementation Method 4
plastics with elongation at yield higher than 3%, 4% or even 5% are suited as aligners due to their elastic properties
Data Source
AI summary
Aligners having stress force regeneration attributes are described herein. In one variation, a force may be regenerated within the aligner by receiving an aligner within a receptacle post-use by a patient and applying thermal energy to the aligner such that the aligner is maintained at a predetermined temperature for a predetermined period of time.