Aligners: how clear orthodontic trays work

What are aligners?

Aligners are clear, paper-thin, removable plastic trays that correct misaligned teeth. They are produced as a series of trays made individually for each patient. Aligners mean one thing above all else: a comfortable way to straighten your teeth without the people around you even noticing. The trays come out for eating and dental care, so there are no restrictions on what you can eat or how you brush.

There are several aligner providers, with different prices and different technologies behind them. We will walk you through the differences.

What types of aligners are there?

The first clear-aligner treatment was brought to market by Invisalign. For many years, Invisalign held the sole patent on clear orthodontic trays. When the patent expired in 2006, a wave of new companies entered the market with their own versions. But aligners from different providers vary widely in what they can do, in quality, in fit and in comfort.

Because many of the new companies lacked the know-how to replicate Invisalign's orthodontic trays, they limited their concept to cosmetic aligners. Cosmetic aligners are designed only for mild corrections of the front 6 to 8 teeth. In most cases, however, straightening is a little more complex — some teeth need a stronger movement or rotation, or the whole bite needs correcting. That is where cosmetic trays reach their limits.

Invisalign, on the other hand, can also handle complex tooth movements and correct a misaligned bite, just like fixed braces. More than 660 patents continue to protect Invisalign technology. The attachments in particular — small composite dots that act like anchors and make tooth movement more effective — are patented in both shape and function, and they enable a whole different level of treatment results.

How do aligners work?

With most providers, an aligner treatment starts with a digital impression of the teeth. The full set of teeth is scanned, a computer simulation is built, and treatment planning starts from there. Some providers still use a tray filled with impression material to take a mold of the jaw. The do-it-yourself providers in particular have patients take an impression at home and mail it in.

Caution: the association of orthodontists does not recommend this approach. It is important that a provider examines your teeth and their health before any aligner therapy starts — and continues to check in regularly while it is underway.

Once the impression has been taken in the office, the plastic trays are produced individually for each patient. The patient then receives the full set of aligners and switches to the next pair every 1 to 2 weeks on their own. Each switch moves the teeth a little further until they reach the desired position at the end of treatment.

How long do you have to wear aligners?

Most aligners are worn 18 to 22 hours a day and come out only for meals and brushing. The more disciplined you are about wear time, the better the result. They are comfortable, barely visible and easy to live with. The first visible changes appear within a few weeks. Every patient receives an individual treatment plan, and depending on the severity of the case an aligner therapy can run anywhere from 3 months to 3 years.

What can aligners correct?

As mentioned, there are two types of aligners: cosmetic and orthodontic. Cosmetic trays can handle mild crowding and minor rotations of the front teeth in the upper and lower jaw. They reach their limits when the back teeth or the bite need correcting.

Orthodontic aligners can correct crowding, overbite, underbite, crossbite, edge-to-edge bite, open bite and gaps. There are only a few very severe cases that Invisalign cannot treat.

Note: not every provider achieves the same results with Invisalign therapy. Experience with the Invisalign system goes hand in hand with successfully treating complex cases. That is why Invisalign providers are ranked by the number of cases they complete each year and receive a provider status accordingly.

What are the advantages of aligners?

Aligner therapy has many advantages over traditional braces. Overall, it is more pleasant and more comfortable. The metal brackets and wires of fixed braces can cause cuts and sores inside the mouth — issues that almost never happen with clear plastic trays. Patients also report that the pressure on the teeth is barely noticeable compared to traditional braces. Because you switch trays yourself every two weeks at the latest, the movement happens more gradually and with less discomfort.

The clear trays are very discreet and do not interfere with work or daily life. Eating is easier too — no food getting caught in brackets. In general there are no food restrictions, because the trays come out and you eat whatever you want. Brushing and overall dental hygiene are also far easier with aligner therapy.

The biggest advantage, though, is the aesthetics. With clear trays, the people around you barely notice the treatment, so you can work toward your dream smile discreetly. That said, treatment with clear aligners does demand discipline from the patient: wear time has to be kept up if the treatment is going to succeed.

How do you care for aligners?

Aligners should be cleaned on both sides before every use with lukewarm water, a small amount of toothpaste and a soft toothbrush. Liquid soap also works. Do not clean them with hot water, because the trays can warp. Denture cleaners and mouthwash can attack the plastic surface and are not recommended. Cleaning crystals made specifically for aligners are well suited for a deeper clean.

Whenever you take the aligners out, put them straight into their case. That keeps bacteria off the surface and makes it far less likely you will lose them.

What happens after aligner therapy?

After aligner treatment is complete, a retainer is needed so the teeth can settle into their new position. There are many retention options, but the two most popular are bonded wire retainers and night-time clear retainers. Each has its pros and cons. A bonded wire retainer holds the teeth in place 24 hours a day, because it is fixed to the inside of the teeth with a special adhesive. The downside is that dental hygiene becomes a bit more involved. A night retainer, on the other hand, places no limits on your brushing routine — but it requires discipline and should not be neglected.