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How do aligners work to move teeth?

How do aligners work to move teeth

New Straight Teeth TV Season 2 episode out now!

In the new episode on the science of teeth straightening, our CEO and co-founder Dr. Aalok Y. Shukla explains everything you need to know about clear aligners and tooth movement. Keep reading to find out how invisible aligners work to move teeth and how to keep your teeth straight for life after treatment!


Let’s dive right in…

#1 History of teeth straightening

#2 How do aligners work to move your teeth

#3 Straight Teeth Direct’s revolutionary A&B aligner system

#4 The three phases of teeth straightening with aligners

#5 Teeth movement after braces


#1 History of teeth straightening

In order to understand the science of orthodontics, it’s important to know that teeth straightening is not new – in fact, it dates back to ancient times.

teeth straightening through time

Orthodontists in ancient Egypt knew that enough constant pressure would result in tooth movement. Among other techniques, finger pressure on individual teeth was used to change their position as desired. This technique is, of course, quite impractical but also demonstrates core physics and biology of tooth movement: it always occurs as a result of consistent pressure. All forms of braces use targeted forces to align your teeth, whether they’re fixed metal braces or invisible aligners.

#2 How aligners work to move your teeth

how do aligners move teeth

To better understand how aligners work, imagine them working like a cartoon animation. Animations are just a sequence of still images (frames) played rapidly in sequence. A moving image is actually made up of many individual frames that differ from each other ever so slightly, creating movement when played one after another. 

Each aligner can be seen as an animation frame that achieves one specific position, about 0.2mm different from the previous aligner. You might think that aligners look like a copy of your current tooth position, but that’s not the case. Each aligner is made from a BPA-free plastic sheet that is heated and vacuum pressed over a custom 3D printed model of your next tooth position, not the current position! Over time (usually about 6-9 months), all these incremental movements amount to an entire smile transformation.

#3 Straight Teeth Direct’s revolutionary A&B aligner system

Traditionally speaking, teeth straightening has never been a comfortable affair, what with uncomfortable wires and brackets to irritate your gums and tongue or trap food. Of course there will be some form of discomfort while straightening teeth, but we developed a unique A and B aligner system that completes each movement stage by helping your teeth make treatment as comfortable as possible:

Revolutionary teeth straightening system

  • A aligners: these are the more flexible of the two and help initiate movement
  • B aligners: complete each movement stage by helping your teeth and surrounding tissues develop support in their new position

Why is this so important? This model allows teeth to move systematically and carefully. After all, there’s no reason they would be prepared for sudden large movements, in fact, this can be quite dangerous and may result in broken wires if performed with fixed braces, causing other dental problems. So, using softer aligners first and taking the transformation step by step prepares both you and your teeth for safe movement. Also, the more rigid B aligners allow teeth and surrounding tissues to stabilise ahead of the next treatment step. 

Now, if the aligners are so comfortable, how would you know that they are working? It’s quite simple: when you first wear a new set of aligners, you should feel some amount of pressure on your teeth and they might be trickier to put in/remove; after about two weeks, they should be easier to put in/remove and you should feel less pressure. This means your teeth have moved, and the aligners are working as designed!

#4 The three phases of teeth straightening with aligners

Did you know there are three phases when it comes to teeth movement with invisible aligners? You can think of it like changing the furniture in a room: you first need to create space by removing old furniture, then you can add new furniture before finally making finishing touches. Teeth straightening is much the same:

  • Expansion – in this phase, space is created by widening the dental arch so that teeth can align without being in each other’s way
  • Alignment – at this stage, the individual teeth are moved to align nicely next to each other in their new positions
  • Fine tuning – this phase completes any last small adjustments to give your new, straight smile its finishing touches


The result of the meticulous planning and implementation described above can be nicely seen in this animation:

teeth straightening simulation

#5 How to keep your teeth straight after braces

The forces created by your jaw, cheek muscles and tongue throughout the day (and night!) cause teeth to misalign in the first place, so unless there is something in place to stop them doing it after treatment, then there is a very high chance that teeth can move again: this is where retainers come into play. Retainers look and feel a lot like aligners, with one key difference: they represent your current tooth position and hold your teeth in place rather than moving them. They are usually worn for 22h a day (like aligners) for up to 2 months after treatment, then every night for up to a year, and then a few days a week following that. 

Some may find that their teeth respond well to stabilisation, while other people have more stubborn teeth that tend to move quickly. Again, this is down to the forces in your mouth and retainers will also wear down over time, making them less effective. For this reason and to ensure they stay hygienic with no bacteria buildup, it’s important to switch to a fresh set roughly every 6 months. That’s why we at Straight Teeth Direct have developed our own Maintainer Plan, a retainer membership with fresh retainers every 6 months so that your smile is protected for life!

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