How Does Invisalign Work? – Behind the Science & Process

Ever wondered ‘how does Invisalign work’?

Invisalign is an unbelievable system. The process involves you placing thin plastic aligners in your mouth for a few months, and at the end of it, you’re rewarded with straight teeth and a beautiful smile. But this seamless straightening procedure doesn’t happen by chance. Invisalign was the first clear aligner on the market back in 1997. Over that time it’s spent millions of pounds learning how teeth react to their system and then perfecting the process to the present day.

how does invisalign work

If you’d like to know how Invisalign has mastered the art of clear aligners and become the world’s leading provider you’re in the right place. This article is split into two parts, both explained in easy to understand language. In the first part, you’ll find out about the process of undergoing  Invisalign, including the steps involved. In part two,  you’ll discover the science behind how Invisalign moves your teeth.

So how does Invisalign work? Without further ado, let’s find out.

Briefly, what is Invisalign?

Invisalign is a type of orthodontic treatment using clear aligners to move your teeth instead of traditional train track braces.

Part 1) The process – how Invisalign works

the invisalign lab

Before you start Invisalign you’ll need a consultation with your dentist. At this appointment, your dentist will assess if you’re suitable for the treatment and take photographs. This is the perfect opportunity to ask any questions you may have about how Invisalign works.

Your dentist will take X-rays, then moulds or scans of your teeth to map their starting positions. If everything looks good then we proceed with a ‘Clinicheck’.  The Clinicheck is a cool piece of kit. It’s a computer simulation which shows you the final position of your teeth so you know exactly what they’ll look like. Once your smile has been designed and you’re happy we accept the treatment with one simple click of the mouse.

This click orders the aligners directly from the US with no human interaction. Once that button is pressed the aligners are automatically manufactured and you’re on the way to beautifully straight teeth!

It’s treatment time…

The Invisalign aligners arrive within 2 weeks.

Once your dentist has the aligners you’ll come in for the fitting appointment. The dentist will check they fit well and may need to do some ‘IPR’ or fit ‘attachments’ (these are explained in the science part so don’t worry about it now).

You’ll change each aligner every 1-2 weeks depending on your dentist’s instructions. Each one is kept in 22 hours per day, removing only to eat, drink and brush. The longer the Invisalign aligner is in your mouth the quicker your teeth move.

Sometimes you get to your last aligner and your teeth aren’t exactly as the Clinicheck showed. This is nothing to worry about and is normal. If this is the case you’ll need a ‘refinement’ stage which may consist of several more aligners. These are provided at no extra cost.

The Invisalign process can be completed in as little as 3 months depending on how much tooth movement is required.

Once your teeth are straight and you’re thrilled to bits you’ll need ‘retainers’. These stop your teeth moving back to how they were and preserve your perfect teeth.

Part 2) The science – how Invisalign works

science of how invisalign works

How teeth move with Invisalign

As you know by now, Invisalign uses clear plastic aligning trays to move the teeth.

It can do this by tipping or pivoting them, rotating them, pushing them into your gum or pulling them further out.

The series of trays differ in shape. So tray number 1 will look like your teeth now, but your final tray will look straight. Those in between get you closer and closer to your final desired shape. Each tray is 0.25 mm different, so for every 4 trays your teeth have moved 1 mm. If your dentist recommends changing them every week that’s only 1 month for 1 mm of improvement. That’s why Invisalign is a short term choice compared with traditional orthodontic braces.

The bone has to remodel

Your teeth need to move to straighten, but how do you move teeth through solid bone? Let me explain.

The roots of your teeth are set in bone, but between the bone and the root is a ligament. This is called the periodontal ligament and is like a cushion. This is why if you wobble your teeth there’s about 2mm movement.

The periodontal ligament has busy cells inside it. Some remove the bone in the direction the tooth is moving, and some add new bone in the space the tooth has moved out of. The process of remodelling is started by pressure exerted from the trays pushing your teeth. You may even find when you wobble your teeth during Invisalign they’ll feel even looser and this is completely normal.

When you’ve finished the treatment it takes time for the bone to harden the whole way around the teeth. Immediate retention after teeth straightening is paramount for this reason.


Invisalign attachments are small buttons of composite material stuck to the fronts on your teeth. This is added in the same way as a white filling but there’s no drilling or injections. The white filling is the same shade as your teeth and is hardly noticeable.

These attachments are used as a lever to move your teeth. They are in different positions and angles. The trays lock into the attachments and push against them to aid tooth movement.

At the end of your treatment, the attachments are removed without a trace.


IPR stands for ‘interproximal reduction’.

In English, it’s reshaping the sides of your teeth to create some space to straighten them. It’s normally used in crowded mouths where we’re short of space.

Retention is needed afterwards

Retention is the final step of your Invisalign treatment.

Once your teeth are straight we have to ‘retain’ their position, as they have a tendency to drift back or relapse.

I’ve written a detailed article about retention after Invisalign if you wanted to find out more, but the key thing to remember is that retention is for life. As long as you want straight teeth you’ll need to wear some sort of retainer.

Final thoughts

Invisalign has now completed over 6 million cases! That’s a lot of patients treated and subsequent research and development.

They’ve also put a tremendous amount of money into understanding the science of how Invisalign works and then perfecting the process and the system.

For this reason, Invisalign is miles ahead of the competition and the number 1 system out there.

If you’re looking for Invisalign Bournemouth then get in touch with us and we’ll hook you up.