If you’ve started looking into Invisalign, you may have come across the term “IPR” in your treatment plan and wondered what it means. It sounds technical, but it is a routine, well-established part of many orthodontic treatments. Here is a plain-English explanation.
What IPR actually is
IPR stands for interproximal reduction: the careful removal of a very small amount of enamel from between certain teeth to create space for them to move.
It is sometimes called slenderising, enamel reduction or stripping, and it has been part of orthodontics for decades. The amount involved is far smaller than most people picture — usually somewhere between about 0.1mm and 0.5mm at a single contact point, against side enamel that is typically around 1mm thick or more. It is measured, planned in advance on your digital treatment plan, and checked as it is carried out.
Why IPR is sometimes needed
Crowded teeth need somewhere to go, and IPR creates that room without removing a whole tooth.
When teeth are crowded there is simply not enough width in the arch for them to line up. There are only three ways to solve that: make the arch wider, take a tooth out, or make the teeth themselves very slightly narrower. IPR is the third option, and for mild to moderate crowding it is often the least invasive of the three.
It has other uses too. It can improve how the upper and lower teeth meet, it can close the small dark triangles that sometimes appear between the gums and the teeth once they straighten, and it can help a result settle more stably once treatment finishes. Not everyone needs it — whether it forms part of your plan depends entirely on your own teeth and what the plan is trying to achieve.
Does IPR hurt?
Most people feel little more than light pressure or a faint vibration, and anaesthetic is not usually needed.
The reason is that only the outer enamel is involved, and enamel contains no nerves. The work is done with fine abrasive strips or a precise rotating instrument, a fraction of a millimetre at a time, and it usually takes a few minutes at most. If you are anxious about it, say so — we can go more slowly, stop whenever you want, and show you what is happening as we go.
Is IPR safe, and will it damage my teeth?
When it is planned properly and carried out by a GDC-registered dentist, IPR is a well-established procedure with a long clinical track record.
The amount of enamel removed stays well inside recognised limits, and the surfaces are smoothed and polished afterwards. Research into IPR has not shown an increased rate of decay in reduced surfaces where oral hygiene is good. What matters is that it is planned on a proper digital set-up rather than improvised, that the amount is measured rather than guessed, and that someone is checking the result against the plan. That is one of the reasons it matters who carries out your Invisalign treatment, and why remote or mail-order aligner services that never examine you in person are a different proposition altogether.
Does the enamel grow back?
No. Enamel does not regenerate, so IPR is permanent — which is exactly why the amount is kept small and planned in advance.
In practice this is less dramatic than it sounds: the teeth are narrower by a fraction of a millimetre, the change is not visible, and the contact points are reshaped rather than left open. But it is a one-way step, and it is a fair thing to ask about before you start.
Will my teeth be sensitive afterwards?
Some people notice mild, short-lived sensitivity to cold in the days afterwards; most notice nothing at all.
If it does happen it normally settles on its own. A sensitive-teeth toothpaste used for a week or two is usually enough. Tell us if it lingers beyond that, because it is worth a look rather than something to put up with.
When IPR is not the right answer
Severe crowding, certain bite problems and some rotations need more than a fraction of a millimetre of space, and in those cases fixed braces, extractions or a referral for specialist orthodontic care is the better route.
We will tell you plainly at the consultation if that is true for you, rather than start a treatment that is not right for your case. Being told honestly at the start that aligners are not the right option for your case beats finding out 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 part of your plan, we will explain why it is there, show you on your 3D scan exactly where and how much, and answer your questions before anything begins. Nothing happens without you understanding it first, and the plan is yours to take away and 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 are weighing up what treatment involves overall, 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.
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 the reduction is a fraction of what is there. The exact amount is planned in advance and measured as it is carried out.
Is IPR done all at once or throughout treatment?
Usually in stages. A little space may be created early on, with more added later as the teeth move and the contacts change. Your plan sets out roughly when, and we confirm it at each review appointment rather than doing everything at the first visit.
Can I have Invisalign without IPR?
Often, yes. Plenty of cases need no enamel reduction at all, particularly where spacing rather than crowding is the issue. Whether you need it comes out of the digital plan, and we will tell you before treatment starts, not partway through.
Does IPR make teeth look different?
Not in a way anyone notices. The teeth become very slightly narrower and the contact points are reshaped and polished, which can actually improve the look where dark triangles have opened up between straightened teeth.
Who should carry out IPR?
A dentist registered with the General Dental Council, working from a planned digital set-up and examining you in person. Remote aligner services that never see you in the chair cannot carry out IPR or check the result, which is a meaningful difference when your plan calls for it.
What if I have a question once treatment has started?
Ask at any point. Call the practice on 020 3148 2444 or get in touch — we are 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 Dr Ali El-Kabengi (GDC 270807) · Updated 16 September 2026
