How Invisalign Actually Works — and Who It Genuinely Suits

Invisalign is, without much competition, the thing patients ask me about most. It gets googled constantly, and there’s a lot of marketing around it, so I want to do something simple here: explain in plain terms how it actually works, what the parts of the process are, and — just as importantly — which cases it suits well and which it doesn’t.

This is the fourth piece in my BDS Dental series. I plan every Invisalign case I treat myself, going back and forth on the plan until I’m satisfied, so what follows is how it looks from the inside.

How it moves teeth

At its heart, Invisalign works by applying a gentle pushing motion to your teeth, in a controlled, customised way.

It starts with a 3D scan of your teeth, which is uploaded to the Invisalign system. Then I sit down and plan the case — deciding which teeth need to move and where, what I’m trying to achieve, and which teeth need attachments. I write all of that down, a technician produces a proposed plan, and I work through it with them, usually several times, before I’m happy to proceed. (I wrote more about why that back-and-forth matters in an earlier piece in this series — the plan should never be accepted blindly.)

Once the plan is agreed, a series of customised aligners is made. You wear each one and change to the next on a schedule — for most patients weekly, though for more complex movements I’ll often ask for every two weeks. Each aligner moves the teeth by a small, deliberate amount — roughly 0.2 of a millimetre per aligner. Small steps, many times over, add up to a big change.

Attachments and elastics, explained

Two things often confuse patients, so let me clear them up.

Attachments are small bumps of tooth-coloured filling material bonded onto certain teeth. They’re not decorative and they’re not random — they give the aligner something to grip, so that particular tooth movements become more efficient and more effective. Some movements simply work better with an attachment helping the aligner do its job. They’re temporary and come off at the end.

Elastics come into some treatments too — small bands the patient wears for more complex movements, usually to help correct the way the upper and lower teeth relate. Not everyone needs them, but where the bite needs work as well as the alignment, they often play a part.

Refinements: the bit nobody mentions in the adverts

Here’s something patients are often surprised to hear, and I’d rather they heard it from me upfront. Teeth don’t always move exactly the way the simulation predicts. Some movements are inherently less predictable than others, and a tooth can fall behind the plan. When that happens, we take a fresh scan towards the end and produce refinement aligners — additional aligners to tidy the case up and finish it properly.

This is normal. For my more complicated cases, I’d say around 90% need some refinement at the end. It’s not a sign anything has gone wrong — it’s the system working as it should, accounting for the fact that real teeth in real mouths don’t follow a computer model to the millimetre. As the technology keeps improving, the amount of refinement needed is gradually reducing. And how well a patient wears their aligners makes a real difference too — which brings me to the honest caveat.

Who Invisalign suits

Invisalign is genuinely excellent for a good range of problems. It works very well for crowding, for expansion cases, and for open bites — where the front teeth don’t quite meet. It’s good when you need to push the upper teeth back to create a little space, or tuck in front teeth that are protruding slightly, particularly where there’s room to do so (for instance if the wisdom teeth are absent or being removed as part of the plan).

It’s more difficult for deep bite cases, where the upper teeth heavily overlap the lower ones — not impossible, but harder. And there are limits: you can’t necessarily do everything with aligners that you can with fixed train-track braces. An honest specialist will tell you when fixed braces are the better tool for your particular case.

But the single biggest factor is you. With a committed patient who wears the aligners as instructed, it’s genuinely remarkable what can be achieved — I’ve treated some quite complicated bites this way. Aligners only work while they’re in your mouth, so compliance isn’t a detail; it’s the engine of the whole thing.

The real advantages

For the right case, the appeal is obvious. Aligners are far more discreet than fixed braces. They’re removable, so you can keep your teeth properly clean, you don’t have to change your diet, and you’re not worried about breaking a bracket. For adults juggling work and a social life, that all makes treatment far more livable — which is exactly why almost all of my adult patients choose aligners over fixed braces, and honestly, I’d want the same.

A quick note for completeness: I’ve used Invisalign throughout, and I’m now also introducing Angel aligners as an option, as more patients become interested in the choice. The underlying principle is the same — small, planned, gentle movements over time.

Whatever system we use, every one of my patients finishes with retainers — both bonded (fixed) retainers and removable ones — because a straight result is only worth having if it stays straight.

In the next piece, a question I get from people who assume the moment has passed: is orthodontics still worth it as an adult?

Dr Farnaz Motamedi is a specialist orthodontist at BDS Dental and an NHS consultant who plans every aligner case personally. To find out whether Invisalign suits you, contact the practice here. You can also book online here.