Plastic waste and aligners

Your clear aligners are destroying the world and the day of the reckoning bears little to no relief. This is an outrageous statement, or is it? Let’s investigate.

Clear aligners like Invisalign® have become the fan-favourite in recent times with the increasing demands for aesthetics overshadowing their deliberate efficacy for treatment. Much of the orthodontic research in the last decade has been dedicated to identifying and developing materials that are able to accentuate cosmetic appeal either by mimicking the natural tooth hue or by blending effortlessly into the tooth substance.

From metal wires cemented onto the frontal surfaces of the teeth to monocrystalline ceramic brackets to virtually transparent aligners, orthodontics has been a revolutionary sphere. Currently, several commercial brands have been erupting in the market with different materials in their aligner composition, each one trying to outperform the other.

But have we considered what this aligner material does to the environment? At the end of the day, it is plastic and it’s not like we don’t already have enough of that desecrating nature. In fact, reports suggest that almost 5.25 trillion pieces of plastic waste are estimated to be in our oceans. This also means that 8 million pieces of plastic waste escape into our oceans every day! What this disturbing fact puts into perspective is the scathing question – what happens to our clear aligners once we discard them? Do they contribute to the world’s already deploring plastic pollution?

Plastic waste in orthodontics

Clear aligners are dispensed to be worn at least 22 hours per day for an average duration of one to two years. When the desired outcomes are achieved and the treatment comes to a screeching halt, there is confusion about what to do with the aligners afterwards.

Orthodontists often recommend patients hold onto their previous set of aligners just in case they lose or break their current ones. But if your treatment is over and you longer need your aligner set, the most common way for you to dispose of them would be in a regular waste bin. However, if we are considering some countries like the U.S. where aligners are not eligible for “routine” recycling, this could pose an issue.

Can clear aligners be recycled?

No, clear aligners are not eligible for recycling mainly because they are classified as contaminated medical waste. But with the total number of consumers for only Invisalign® clear aligners surpassing a whopping 10 million and several other companies producing large volumes of aligners, it is estimated that 25 million aligners typically end up in the general waste landfill each year.

Unfortunately, that is not all. Clear aligners are basically fabricated out of petroleum-derived hydrocarbons – macromolecules which are non-biodegradable and can cause pollution to the environment when burned. As polymers, aligners are classified as Class IIa medical devices which means that the risk of accidentally promoting cross-infection through attempted recycling is high because they were used in the oral cavities of patients and discarded in the common trash.

Invisalign®, in fact, addresses this issue by referring to their product as ‘Medical-grade, high molecular weight, thermoplastic polymers, in either a single layer or multilayer configuration. The thermoplastic polymers are made of a proprietary mixture of co-polyester and polyurethane (TPU).’

This multi-layered polymer is a mix of different plastics and since each type of plastic requires a different mode of recycling, we simply cannot sort them into one recycling method.

What can we do?

An alternative to this problem is to educate clinicians and patients on the importance of collecting aligners after clinical use. The orthodontists can then collect these aligners in a waste container, sanitize them appropriately, and send them to a company for recycling. This would greatly help in preventing the dissemination of infection and in correctly categorizing the material as contaminated and non-biodegradable waste.

Recently, an innovative initiative has allowed for a better disposal system of clear aligners, in a way that they do not end up in a landfill. Spotlight Oral Care is partnering with Terracycle to recycle: ‘Any brand of the dental aligner and its flexible plastic packaging and any brand of plastic aligner case.’

Terracycle is a brand aiming to recycle the ‘non-recyclable’ and is partnering with collectors across 20 countries, diverting waste from landfills and incinerators.

With aligners: ‘Once collected, the dental aligners, flexible plastic packaging and cases are cleaned and melted into hard plastic. This is then remoulded to make new recycled products.’

Billions of tons of plastic have been aggregating in the last decade in trash and litter. This is perhaps the most important period when both the awareness of plastic control and the ironic littering of plastic are at an all-time high. It is important to dispose of clear aligners the best we can so that we can contribute, in our little ways, to minimizing plastic pollution and helping the environment recover.

What is PET-G?

Glycol-modified polyethylene terephthalate (PET-G) is a new generation polyester that possesses many notable properties that would make it the prime candidate for clear aligner fabrication. Not only does it provide good toughness and chemical resistance, but is also durable and resistant to high orthodontic forces.

Where are we with recycling PET-G?

Long story short, researchers have integrated PET-G into the overtly polluted industry of orthodontics because of its unique feature. Even while being a plastic component, PET-G is a 100% recyclable. In fact, PET is the most recycled plastic in the world today and can be identified by its recycling code #1.

PET products have a short lifespan and are immediately transformed into waste. The most adopted methods for PET recycling are chemical recycling by hydrolysis and mechanical blending. Chemical recycling involves the production of terephthalic acid (TPA) and ethylene glycol (EG), to reutilize them for making other synthetic chemicals. However, cost-effectiveness and environmental friendliness make mechanical recycling the most common PET recovery method.

Another interesting trait of PET-G products including clear aligners is that they pose no risk of leaching since the polymer is inert. They are resistant to attack by microorganisms and cannot degrade biologically. Thus, even if they do end up in the landfill space, they will not cause as alarming of damage to the environment as would other plastics.