Should we worry about microplastics and clear aligners?
Clear aligners are a popular method for delivering orthodontic care. Their use appears to be on the rise. Additionally, they are now being marketed for the treatment of children. Yet, some authors have recently expressed concerns about the impact of microplastics on human health.
This post discusses a new paper examining potential health issues from the rising use of clear aligners. I found this paper interesting and have attempted to summarize its key points.
A team from Greece and Switzerland wrote the paper. The Journal of the World Federation of Orthodontists published the paper. The lead author, Nearchos Panayi, has also published a summary of their paper on his Facebook site.
Nearchos Panayi, Spyridon N. Papageorgiou, George Eliades, Theodore Eliades
JWFO: Volume 13, Issue 6P259-264December 2024
What did they do?
The authors conducted a narrative review, which I will comment on later. I found it challenging to structure a post in my usual format. Therefore, I will highlight the key points they made.
The problem with aligners.
We recommend aligners for addressing the aesthetic issues linked with traditional orthodontic appliances. Yet, as the authors point out, they may not be as biocompatible as those made from stainless steel or ceramic. This distinction is crucial.
“In the light of the combination of plastic and BPA leaching from aligners, should we have second thoughts and consider the effects of plastics into the mouth through ingestion and that other alternative treatment modalities exist?”.
They also emphasize that an argument often made is that there is a risk/benefit ratio for all treatments. However, this reasoning is not valid for aligners, as other treatments, like fixed appliances, do exist.
So what are the health implications?
Aligners are made from thermoplastic polymers, which are non-biodegradable. This adds to the accumulation of plastics in the environment and the potential ingestion of microplastics.
The effects of microplastics are worrying. Their detachment releases tiny plastic particles into the environment and mouth. This release can create significant issues. These include:
- Disruption of gut microbiota
- Respiratory health problems
- Associations with cardiovascular and neurodegenerative diseases
The effects on the environment
The non-biodegradable nature of aligners can influence
- Long-term pollution and environmental contamination
- Marine organisms ingest the microplastics, and this leads to contaminants up the food chain.
Importantly, aligners are classified as medical waste. This limits the usual recycling avenues.
This is a brief summary of the points raised by the authors. Their conclusion was
“Orthodontic professionals should address the issue of microplastic release from aligners and consider transitioning to alternative treatment methods. The emerging evidence highlighting the potential detachment of microplastics from clear aligners underscores the urgency for proactive measures to mitigate human health risks and environmental concerns”.
What did I think?
Firstly, I would like to declare my interest. I have lived most of my life. While I hope for a few more years, I am passionate about the environment. I care deeply about the well-being of future generations. I strive to reduce my plastic use, drive an electric car, follow a plant-based diet, and have rewilded my garden. Given these efforts, I found this paper to be very worrying.
However, let’s first look at the method. This was a narrative review, meaning the authors selected papers to make a point. We need to bear this in mind when we consider the findings. As a result, we can only conclude that the authors have written this paper to make a point. I am happy with this, as this paper could lead to a discussion on the possible harmful effects of aligners. This should then lead to the development of research.
This is a good way ahead, rather than ignoring the potential problem and sticking our heads in the sand. I hope that further research is given priority. I wonder if we should also consider if there are similar concerns with vacuum formed retainers?
Where does this leave us with consent?
This paper also raises the issue of consent. I wonder if we need to inform our patients of the authors’ concerns. This is very relevant when we consider that fixed appliances are relatively inert for the individual and the environment. Should we now be saying this to our patients?
“I can treat you with fixed appliances or aligners. The aligners are less visible. But, they are a source of environmental pollution. They release microplastics that may be linked to potential harm to your health. This does not happen with fixed appliances”.
Finally, I have been accused of being anti-aligner. Perhaps “I see the wood from the trees”?
Let’s chat about this in the comments.
Emeritus Professor of Orthodontics, University of Manchester, UK.
Should this concern extend to Acrylic oral prostheses?
The plastics are much more robust and wear much more slowly BUT the plastic still has to go somewhere and there is really only one path it will follow. It would be ironic to have to go back to porcelain teeth! I wonder if printed teeth are as hard as industrially processed ones- I would think not?
The problem with plastics is their very low hardness making them prone to attrition and microplastics leaching. On the other hand acrylic is very hard ,so attrition is very difficult to happen and most of the times acrylic does not cover the occlusal surfaces. If it does friction due to mastication cannot seriously harm the acrylic.
I wonder that the aligner companies do with the trimming waste after manufacture?
By extension this also applies to essix retainers, perhaps not so much the waste issue as the overall number is much less per patient, but the long term wear is bound to produce microplastics which are ingested-we’ve all see retainers worn through on the occlusal surfaces.
I do think we should highlight the single-use plastic waste to our patients, many are very conscious of reducing plastic waste and they may not have thought about this in relation to their treatment.
The other issue is the resin models on which the aligners are made. The volume of waste from the models is huge compared to the aligners.
what about VFM/Essix retainers?- potentially even greater impact as retention is for life
I found this 2023 article from Italy on the topic which compared different clear aligner manufacturers for microplastic leakage in saliva. Disclose: I am an orthodontic as well as the CEO of a marketing agency and have no financial interest or investment in any aligner company. https://pubmed.ncbi.nlm.nih.gov/36603638/
Thanks for recommending my article on microplastics.
Vincenzo Quinzi
We have your article in our references and we use it in all our lectures.
I agree that this issue needs to be considered, given our developing knowledge on microplastics. I wonder if the different types of plastic used by different manufacturers makes a difference. However, in terms of risks to the individual, any orthodontic appliance is in the mouth for a period of a few months to, say, a couple of years. Surely the more significant risk comes from wearing Essix style retainers over a lifetime.
There is similar concern about Nitrous oxide. The truth of the matter though is that medical nitrous oxide is only responsible for less than 0.05% of global warming. So I think we need first some quantitative studies of “how much” microplastics in the enviroment or in our patients before we start discussing this
Super interesting blog topic and lots to process. Talking of environmental pollution, the number one contributor to carbon emissions in dentistry is supposedly from travel. If this is the case, then is there a relevant discussion between 15+ visits to and from a practice compared to potentially half that (until electric cars are more widely adopted)
I am sharing my article on microplastics with you, looking forward to your feedback.
https://doi.org/10.1016/j.scitotenv.2022.161356
Vincenzo Quinzi, Giulia Orilisi, Flavia Vitiello, Valentina Notarstefano, Giuseppe Marzo, Giovanna Orsini
Thanks for this, I will do a post on this, perhaps, early in the new Year.
Thanks Kevin
Our orthodontic adhesives are also polymers that, in their totality, become very fine dust powder in the patients oral cavities when we polish the teeth following Orthodontics treatment . These microplastics are being ingested and inhaled by our patients and our team members despite our use saliva ejectors and high volume suction and PPE. Considering environment concerns, if the waste adhesive dust doesn’t end up in our patients bodies or our bodies it ends up in our immediate environment, in our air, on surfaces, and mostly in our waste water. As orthodontists, I don’t think we can only talk about aligners as the sole source microplastics problem.
I can’t help but think that as a patient takes their aligners in/out 10,12,20 times a day there must be a little plastic shed from the attachments. We like the crisp geometry that aids in tooth movement and freshly placed ones are sharp.
Noticeably absent are the aligner companies, themselves in this discussion. Reminds me of Johnson & Johnson and their baby powder. The argument that generations have used their baby powder with no problems in the end did not hold up. They got hammered in the court room.
The AAO House of Delegates considered a resolution to implement recycling of worn aligners. The FDA classifies those as a class 2 medical device so recycling of medical devices is currently unlawful in this country, even if we are going to melt them down into park benches and back porch decking. The resolution was referred to a committee for further investigation.
This simple plastic has the makings of a Pandora’s Box.
https://pubmed.ncbi.nlm.nih.gov/38884540/
Tommaso
Elastics are entirely different compared to aligners. Aligners cover the surfaces of the teeth. Masticatory forces create friction and aligner attrition 20h a day for 1 to 2 years and aligners are renewed every week. According to studies one forth of patients are bruxists with all the consequences on the aligner integrity. It is proved that aligner insertion and removal creates an environment of monomer and especially BPA or BPs release due to the friction between aligner and attachment. In addition the aligner itself which is much softer compared to attachments leaches microplastics. Elastics do not interfere with occlusion ,they might release plastics but (which actually is not plastic but latex) but the size of them is big and it goes to the toilet. Aligners according to the in vitro study by Quinzi release microplastics. There is no comparison between aligners and any other plastic material in the mouth. In addition speaking about risk and benefit ratio, we don’t have something else apart elastics while for aligners we do have, fixed appliances
Aligners are the thermoformed but also directly printed
Is there a future heightened teratogenic risk for females with orthodontic plastics absorbed into the ovum/gametes and any heightened risk to fetal development with aligner and retainer microplastics in the in situ circulation during fetal development?
I’m glad you posted on this. I was just wondering this weekend about this very subject. I have invested a lot of time working on my ability to produce the best results with clear aligners, and I was wondering at what point they will stop being used due to microplastics.
This is interesting in terms of quantity. Aligners are going to pollute the environment more than vacuum formed retainers in terms of quantity, but the retainers are will produce longer individual exposure. I suppose the question is whether there is an acceptable limit.
Bottled water and plastic food packaging are likely a bigger concern, but effects may be compounded when everything we use is leaching microplastics into our bodies and our environments.
How would it be possible to actually study or quantify the amount of microplastic ingested during the course of aligner treatment or many years of nighttime retainer wear. Is it worse than dental composite restorations or the chemicals that could leach from the adhesives holding a bonded retainer in place?
Aren’t aligners and vacuum formed retainers more or less the same thing? We have been using VFR’s for Decades, well at least many years!
I think everyone here is using elastics in sagittal corrections, and not only, therefore please read this
https://pubs.acs.org/doi/epdf/10.1021/envhealth.3c00051?ref=article_openPDF
And this is not a narrative review. New research fields need to be considered in using plastics/silicons in orthodontics.
I’ve a conflict of interest since I’m an Invisalign speaker
Thanks, I will have a look at this as well.
According to estimates, Invisalign produces a significant amount of plastic waste EACH YEAR with around 25 MILLION dental aligners ending up in landfills, contributing to the overall plastic waste problem due to the high volume of users and disposable nature of the aligners.
are microplastics released from conventional bonding materials?
The answer is yes – there are concerns about microplastics from resin-based composite materials, as well as the leaching of chemicals. My colleagues at the University of Sheffield in the UK are researching this (Mulligan S et al Resin-based composite materials: elution and pollution https://doi.org/10.1038/s41415-022-4241-7). Glass ionomer cement contains inert glasses and may be better for the environment, but realistically only those containing resin are strong enough for bonding orthodontic attachments (Benson et al 2019 https://doi.org/10.1016/j.ajodo.2018.09.005).
Very interesting article! I have thought about this myself and am concerned about it
However, correct me if I’m wrong. Isn’t prof O’Brien a fan a of VFM? Isn’t it the same things?
Kevin, an electric car……..
Every action we take has consequences. We just may not know what they are for a long, long time.
I got a diesel when the government were saying they were better than petrol……
First of all, I would like to thank you for this article, which addresses an essential and often overlooked topic in the field of orthodontics. As an orthodontist, I am particularly sensitive to the issues raised regarding aligners, especially their potential health impact and their contribution to plastic pollution.
To dig deeper, I personally tried to learn more about the carbon footprint of aligner production by reaching out directly to companies like Invisalign, Spark, and others. Unfortunately, I did not receive any responses.
I believe it would be highly beneficial if professors or respected figures in orthodontics took a serious interest in this matter. For example, a comparative study on the carbon footprint of aligners versus traditional fixed appliances could provide valuable data to guide our reflections and move our practices toward more sustainable solutions.
Once again, thank you for shedding light on these crucial issues. I hope this helps spark further discussions.
Dear Professor O,Brien
Thanks for reviewing our article.
It seems we share the same concerns. I am trying to decrease the aligners in my office(doing only in office).
Research is needed and we are already preparing!!
Thank you for your valuable contribution to our profession.