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Thermoplastic clear dental aligners under cyclic compression loading: A mechanical performance analysis using
Claudia Barile1, Claudia Cianci1, Vimalathithan Paramsamy Kannan1
1Dipartimento di Meccanica, Matematica e Management, Politecnico di Bari, Bari, Italy.
Journal of the Mechanical Behavior of Biomedical Materials
|February 4, 2024
Summary
This study evaluated clear aligner performance using Acoustic Emission (AE) testing. Thermoformed PET-g aligners demonstrated stable energy absorption, potentially matching Invisalign
Area of Science:
- Materials Science
- Biomedical Engineering
- Acoustics
Background:
- Clear aligners are widely used in orthodontics, but their material performance and degradation under cyclic loading are not fully understood.
- Assessing the durability of thermoplastic materials used in clear aligners is crucial for predicting their functional lifespan.
- The Acoustic Emission (AE) technique offers a non-destructive method to monitor material damage evolution in real-time.
Purpose of the Study:
- To analyze the performance and damage evolution of clear aligners made from different thermoplastic materials under cyclic compression.
- To evaluate the effectiveness of the Acoustic Emission (AE) technique in identifying damage stages and sources in clear aligners.
- To compare the mechanical properties and durability of thermoformed PET-g and polyurethane (PU) aligners, including additively manufactured PU.
Main Methods:
- Three types of clear aligners were tested: thermoformed PET-g, thermoformed PU, and additively manufactured PU.
- Cyclic compression tests were conducted to simulate 22,500 simulated swallows.
- The Acoustic Emission (AE) technique, utilizing time-domain and frequency-based parameters, was employed to monitor damage.
- Machine learning algorithms were applied to AE data for damage state identification.
- Microscopy was used to validate AE findings on material damage.
Main Results:
- Thermoformed PET-g aligners exhibited stable energy absorption (around 4 Nmm) throughout the cyclic testing.
- PU-based aligners initially showed higher energy absorption (around 7 Nmm) but decreased after 12,500 cycles.
- AE analysis, particularly frequency-based parameters, successfully identified damage initiation, evolution, and distinct damage sources.
- Microscopy confirmed the damage states detected by the AE technique.
Conclusions:
- Thermoformed PET-g aligners show potential to meet the performance requirements for clear aligner dentistry, comparable to additively manufactured PU aligners like Invisalign.
- The AE technique is a valuable tool for monitoring clear aligner degradation and predicting the onset of functional loss.
- Understanding material-specific damage mechanisms is key to optimizing the design and longevity of thermoplastic orthodontic devices.
Keywords:
Acoustic EmissionClear dental alignersCyclic testInvisalignOptical microscopyOrthodontic forcesMore Related Videos
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