When do you waste unused aligners, and how can you avoid it?

Ten million patients were treated with Invisalign in 2021, and Align Technology is no longer the sole competitor, companies such as Ormco, Straumann and Dentsply Sirona having also entered the clear aligner market.⁶

At the moment, the major aligner companies offer the same system when it comes to the supply chain. They send you as many aligners as you wish and send you more aligners as soon as you request it, within a limited period. In the case of Invisalign aligners, it is limited to five years. Apparently, this policy is fair to the patient and the dentist, since dentists can guarantee a successful treatment regardless of the number of aligners. For instance, in a complex case where I plan 50% distalisation for my patient, I will receive 80 aligners at first, but if after 30 aligners, I see that the aligners do not fit and the strategy is not working, I would have to pause the treatment and order new aligners. It is not easy to predict these undesired situations, but as there are many factors involved, we encounter this problem frequently.

Maybe the misfit is due to the molars not distalising enough or maybe the clinical crowns are too short, the bone is too mineralised, there are micro-collisions between the teeth or the patient has lost motivation and is not wearing the aligners enough. No matter the reason, the strategy is not working, and it does not make sense to continue just to prove that it could. Therefore, I change the strategy and set new goals with my patient. I order new aligners, and I throw away 50 unused aligners. This means that I throw away more aligners than the aligners I have already given to my patient.

This policy of producing more aligners than necessary is not only misaligned with today’s demands related to the environmental crisis and climate change, but also has some disadvantages regarding patient motivation and patient trust. Does it really make sense to produce all the aligners at once? The patient would not even have seen those 50 custom-made aligners.

Has something similar happened to you as well? It probably has, because it has happened to me on many occasions during the nine years I have worked with clear aligners. Everyone who treats complex cases with aligners throws away unused aligners, but not all dentists pay much attention to this.

That was the case for me for my first two years of treating malocclusions with clear aligners—until something happened: one of my patients told me how much she loved her Invisalign aligners but how much waste they created. I did not know what to answer because, before that conversation, I had never thought about it. I care about nature, pollution and climate change, and I use a refillable bottle and a reusable bag, but suddenly I realised the number of unused aligners that we were wasting at work.

That was seven years ago. After that conversation, I started using a strategy I named “divide and conquer”, according to which I ask for the number of aligners that I need for the first ten months or the number that I need to test how good my strategy is or how compliant my patient is.

Aside from reducing the environmental impact of my daily work as an orthodontist, this strategy has several benefits. Patients perceive clear aligners as high-technology devices, and since they are custom-made and expensive, throwing away unused aligners during treatment just because the teeth are not moving as planned is difficult to accept. Ordering the aligners in two phases rather than all at once allows you to adapt the treatment strategy easily without having an awkward conversation with your patient about why the treatment plan is not working and thus why you need to throw away all those valuable aligners and avoids you having to explain to your patient concepts like biological limits and anchorage. You will also not have to convince your patient to pause treatment and wait until the new aligners arrive. Moreover, you will need less space in the office to store your treatment boxes. Why would you want to store aligners that your patient will need only in a year or more? How large is your office storage space? This strategy benefits your patient too, because the expectation of receiving 45 aligners and then 25 more, for example, is different from receiving 70 aligners at once. Of course, if you care about pollution, this way of working is going to have much more impact than using a reusable bag or reusable bottle.

So divide and conquer instead of approving a ClinCheck plan with over 90 aligners. You can ask for the first 30 aligners to test your strategy and patient compliance. If after the first 30 aligners, you see that your treatment strategy is right and everything is working as planned, then you ask for the remaining aligners, without taking new records.

I have been doing this since 2015, and I have been giving this advice to everyone I can, always hoping that someday Align Technology, Ormco and other aligner companies will encourage dentists not to order all the aligners at once and, in doing so, save on production costs. It is not just the plastic of the aligners that is saved, but also all the production scrap, since a printed model must be created for every aligner. It is also about the transportation and the energy it takes to destroy the aligners in the end. Wasting resources is no longer something that can be overlooked in 2022. Why would a company want to overproduce and create waste? Is the latest price increase of Invisalign related to overproduction?

According to the scientific literature and my own experience, there are several situations in which we waste aligners.

This is my list of top ten situations:

1. large sequential movements like distalisation of more than 3 mm;
2. extrusion of the canines or lateral incisors;
3. difficult rotations (mandibular premolars);
4. molar uprighting;
5. poor compliance;
6. excessive overcorrection;
7. dental eruptions in children;
8. small clinical crowns;
9. emergency dental treatments during the aligner treatment; and
10. production defects.

How can you avoid unnecessary refinements and waste at your office?

1. Ask your patient to keep all used aligners, in case he or she has not worn them enough and can then go some aligners back and wear them properly. Let your patient change the aligners every seven days only if he or she has proved that he or she has worn them 20 hours a day (if not, then every 10–14 days).
2. Be realistic with the movements you plan, use auxiliaries that do not require compliance to obtain predictable movements, do pretreatments and reduce the treatment time with aligners. No one wants to wear over 100 aligners.
3. Be careful with overcorrections. Some overcorrection is recommended, but do not think that the more the overcorrection the better the outcome.
4. Prioritise your goals, divide long treatments and ask for a reasonable number of aligners.
5. Do not start the case with erupting canines or premolars. It seems obvious, but sometimes dentists are impatient to start.
6. Spend time analysing your old ClinCheck plans and simulations to avoid repeating the same mistakes.

I have been trying to reduce aligner waste since 2015. Since then, neither Align Technology nor its main competitors have implemented any measures to avoid wasting unused aligners. It is difficult to understand why the companies producing aligners are still not paying attention to this issue. Ironically, all of them claim to care about sustainability; for example, Align Technology has even implemented actions that encourage aligner recycling.^7–9 Recycling is an approach with very little impact and looks more like greenwashing, since the recycled materials cannot be used for aligner production, preventing a circular system. In the best case and with much effort, aligners and their production scrap can only be downcycled. Therefore, recycling is not an option for the aligner industry.

I do not want to criticise the aligner industry, since clear aligners were a game-changer for me and I make my living using them. I just want the aligner industry to see this issue as an opportunity to improve and to be an example for other industries. I challenge the industry to take off its rose-coloured glasses and put on green glasses. Let us start the conversation and all be part of the solutions we need in order to achieve the global goals and the transitions that the Fridays for Future generation deserves.

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