Evaluation of microplastic release from orthodontic clear aligner – A spectroscopic study

Objectives: The purpose of this study was to assess how mechanical friction caused microplastics (MPs) to be released from clear aligners in simulated oral environments. The study’s objectives were to compare MP release between friction-exposed and control samples, which characterize the MPs using Raman Microspectroscopy (RMS) and Scanning Electron Microscopy (SEM) clear aligners are made of different types of polymers, such as polyethylene terephthalate (PET), polyurethane (PU), or polycarbonate (PC). These polymers are susceptible to a number of mechanical and environmental conditions that can break them down into smaller pieces known as secondary MPs. MPs are synthetic polymer fibers or particles with a diameter ranging from 1 to 5000 μm. Identifying the original components of MPs and their possible effects on the environment and human health is difficult since they can also absorb other contaminants. Material and Methods: Clear aligners were immersed in artificial saliva and subjected to mechanical friction using a linear reciprocating tribometer for durations of 3 h, 5 h, 7 h, and 7 days. MPs released were isolated and analyzed using RMS to identify their chemical composition and SEM to characterize their size and morphology. Control samples were stored in artificial saliva without friction exposure. Results: The study found that mechanical friction significantly increased MP release from clear aligners, with particles as small as 5 μm detected. The quantity of MPs released increased with exposure time, reaching the highest levels after 7 days. Control samples without friction showed no detectable MP release, confirming mechanical stress as the primary factor. Conclusion: Prolonged use of clear aligners results in the release of MPs due to mechanical friction, posing potential risks to oral health and the environment. The findings highlight the need for biocompatible and sustainable materials to minimize microplastic pollution and its associated impacts.