Microplastic Leakage from Orthodontic Aligners

As aligners become the orthodontic treatment of choice for many patients, emerging research reveals an important concern: microplastic (MP) and nanoplastic (NP) leakage. These invisible by-products of aligner wear may pose health and environmental risks. As clinicians, we have a duty to understand and mitigate these concerns.

Key Evidence in the Literature:

Zecca et al. (2025)

This landmark study compared directly printed aligners (DPA) with thermoformed aligners (TFA) under simulated oral conditions.

• DPA (e.g., Graphy resin) released four times more plastic mass (0.004g/200µl) than TFA (e.g., Invisalign®, 0.001g/200µl).

• DPA produced larger and more numerous plastic particles (203.08 ± 2651.65 µm²) compared to TFA (0.23 ± 27.53 µm²).

• 3D printing methods may increase the risk of microplastic leakage during mastication, signalling a need for design and material optimisation.

Panayi et al. (2024)

A comprehensive review examined aligners’ breakdown under oral forces and temperature changes.

• Showed aligners can degrade into microplastics and even leach chemicals like Bisphenol A (BPA)—an endocrine disruptor.

• Raised concerns about systemic health effects, including gut dysbiosis and chronic inflammation.

• The review also called out improper disposal practices that contribute to plastic pollution in marine environments.

Quinzi et al. (2023)

This study simulated chewing in artificial saliva.

• Found MPs ranging from 5–20 µm detaching from aligners across multiple brands.

• Concluded that material composition heavily influences MP shedding.

Pappalettera et al. (2025)

Examined the effect of repetitive compressive forces (mimicking chewing and swallowing) on aligners.

• All aligners developed microcracks, releasing MPs over time.

• Reinforced the role of mechanical stress in plastic degradation.

Clinical Implications for Orthodontists:

Patient Health Risks: Though long-term effects of oral microplastic exposure are not fully known, early evidence suggests potential systemic impact from ingestion and inhalation—especially in children or prolonged users.

Environmental Responsibility: Discarded aligners contribute to persistent plastic waste. If not properly handled, they break down into microplastics that contaminate water systems and wildlife.

Ethical and Practice Considerations: We must balance clinical outcomes with material safety and environmental stewardship.

Recommendations for Clinical Practice:

1. Material Selection Matters:

• Understand the properties and environmental profiles of the aligners you prescribe.

• Prefer TFA over DPA where clinically appropriate, based on current evidence of lower MP release.

2. Patient Communication:

• Educate patients on safe handling and disposal of aligners.

• Recommend removing aligners while eating and brushing to reduce wear.

3. Collaborate with Industry:

• Encourage manufacturers to develop biodegradable, BPA-free, and low-shedding materials.

• Support innovation in 3D printing processes that minimise plastic release.

Conclusion:

Aligners may offer significant benefits in modern orthodontics, but it is our responsibility to be aware of their hidden biological and environmental impact. Staying informed and advocating for safer materials is no longer optional—it’s part of our ethical duty as healthcare providers.