If you’re looking into Invisalign, you may have seen “IPR” on your treatment plan and wondered what it means. It sounds technical, but it’s a routine part of a lot of orthodontic treatment. Here’s what it involves.
What IPR actually is
IPR stands for interproximal reduction. We take off a very small amount of enamel from between certain teeth so there’s room for them to move.
You’ll also hear it called slenderising, enamel reduction or stripping, and it’s been part of orthodontics for decades. The amount is much smaller than most people imagine: usually somewhere between about 0.1mm and 0.5mm at a single contact point, where the side enamel is typically around 1mm thick or more. It’s planned in advance on your digital treatment plan, measured, and checked as we go.
Why IPR is sometimes needed
Crowded teeth need somewhere to go. IPR makes that room without taking a whole tooth out.
When teeth are crowded, the arch isn’t wide enough for them to line up. There are only three ways round that: widen the arch, take a tooth out, or make the teeth very slightly narrower. IPR is the third, and for mild to moderate crowding it’s often the least invasive.
It has other uses too. It can improve how the top and bottom teeth meet. It can close the small dark triangles that sometimes show between the gums and the teeth once they’re straight. And it can help the result stay put after treatment. Not everyone needs it. Whether it’s in your plan depends on your teeth and what the plan is trying to do.
Does IPR hurt?
Most people feel a bit of pressure or a faint vibration and nothing more. You don’t usually need an injection.
That’s because only the outer enamel is involved, and enamel has no nerves. We use fine abrasive strips or a small rotating instrument, a fraction of a millimetre at a time, and it usually takes a few minutes at most. If you’re anxious about it, tell us. We can go more slowly, stop whenever you like and show you what we’re doing.
Is IPR safe, and will it damage my teeth?
Planned properly and done by a GDC-registered dentist, IPR is a well-established procedure with a long track record.
The amount of enamel removed stays well inside recognised limits, and we smooth and polish the surfaces afterwards. Research hasn’t shown more decay on reduced surfaces where people keep their teeth clean. What matters is that it’s planned on a proper digital set-up, measured rather than guessed, and checked against the plan. That’s one reason it matters who does your Invisalign, and why remote or mail-order aligner companies that never examine you in person are a different thing altogether.
Does the enamel grow back?
No. Enamel doesn’t regenerate, so IPR is permanent. That’s exactly why we keep the amount small and plan it in advance.
It’s less dramatic than it sounds. The teeth end up a fraction of a millimetre narrower, you can’t see the difference, and the contact points are reshaped, not left open. But you can’t undo it, so it’s fair to ask about it before you start.
Will my teeth be sensitive afterwards?
Some people notice mild sensitivity to cold for a few days. Most notice nothing.
If it happens, it normally settles on its own. A sensitive-teeth toothpaste for a week or two is usually enough. If it goes on longer than that, tell us. It’s worth us having a look, not something to put up with.
When IPR is not the right answer
Severe crowding, some bite problems and some rotations need more space than a fraction of a millimetre can give. In those cases fixed braces, extractions or a referral to an orthodontist is the better route.
If that’s you, we’ll say so at the consultation and won’t start a treatment that isn’t right for your case. Better to hear it at the start than halfway through.
How we approach IPR at Toothi
At Toothi in Edgware, Invisalign treatment is planned digitally and carried out personally by Dr Ali El-Kabengi (GDC 270807), a general dentist with a special interest in Invisalign.
If IPR is in your plan, we’ll explain why, show you on your 3D scan exactly where and how much, and answer your questions before anything starts. We won’t do anything you haven’t understood, and you can take the plan away to think about.
You can see the whole picture, including a simulation of your finished smile, at your free Invisalign consultation and iTero scan in Edgware. If you’re weighing up what treatment involves, our Invisalign guide covers how it works and who it suits, our Invisalign price guide for London sets out what patients actually pay, and our full published fee list shows every price we charge. Individual results vary from person to person.
If you’re local to North London, our Invisalign in Edgware page explains the consultation, the iTero 3D scan and your package options.
Invisalign results from our patients
A few of the smiles we’ve straightened at Toothi in Edgware.
Photos of our own patients, shared with their consent. Individual results vary.
Frequently asked questions
How much enamel is removed during IPR?
Usually between about 0.1mm and 0.5mm at each contact point, depending on how much space your plan needs. Side enamel is typically around 1mm thick or more, so it’s a fraction of what’s there. The exact amount is planned in advance and measured as we go.
Is IPR done all at once or throughout treatment?
Usually in stages. We may make a little space early on and add more later as the teeth move and the contacts change. Your plan sets out roughly when, and we confirm it at each review rather than doing it all at the first visit.
Can I have Invisalign without IPR?
Often, yes. Plenty of cases need none at all, especially where the problem is gaps rather than crowding. The digital plan shows whether you need it, and we’ll tell you before treatment starts, not partway through.
Does IPR make teeth look different?
Not so anyone would notice. The teeth become very slightly narrower and the contact points are reshaped and polished. Where dark triangles have opened up between straightened teeth, it can actually make them look better.
Who should carry out IPR?
A dentist registered with the General Dental Council, working from a planned digital set-up and seeing you in person. Remote aligner companies that never see you in the chair can’t do IPR or check the result, which matters if your plan needs it.
What if I have a question once treatment has started?
Ask whenever you like. Call the practice on 020 3148 2444 or get in touch. We’re open seven days a week, and reviews during treatment are part of the plan, not an extra.
Have a question about your own treatment plan? Book a free, no-obligation Invisalign consultation with an iTero 3D scan at Toothi in Edgware, two minutes from Edgware Station and open seven days a week. Call 020 3148 2444 or book online.
Page reviewed by the Toothi London team · Updated 16 September 2026
