Dr. Greg Jorgensen
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Rio Rancho, NM 87124

The Jorgensen Orthodontics Blog

What Is Interproximal Reduction In Orthodontics?

Posted by Dr. Jorgensen on May 24th, 2011

Smiling girlThe size and shape of the teeth can have as much to do with the appearance of your smile as anything that the orthodontist does with braces during treatment. Sometimes the teeth themselves must be altered to give the best orthodontic result. Interproximal reduction is one procedure that your orthodontist may use to make the teeth fit and look their best.

Interproximal reduction (IPR) is a simple procedure during which your orthodontist uses very precise tools to change the shape and size of your teeth, primarily on the sides where they touch each other. This is done for three reasons. First, the upper or lower sets of teeth may be naturally the wrong size and don’t fit together well. Second, the shape of individual teeth may not allow them to lay next to each other ideally. This can adversely affect the appearance of a smile even though the teeth may fit perfectly. And third, IPR is used in cases of mild crowding so that the removal of teeth can be avoided.

When the teeth are the right sizes, the upper and lower sets fit together like gears. The upper teeth are naturally wider because they fit on the outside of the bottom teeth. This is most obvious when comparing the size of the upper and lower front teeth. If the upper teeth are too wide or the lower teeth are too narrow, an overbite, crowding of the upper teeth, or spaces present in the lower arch may result. If the upper teeth are too narrow or the lower teeth are too wide, there will be spaces in the upper, crowding in the lower, or an underbite relationship. Dr. Wayne Bolton was the first dentist to scientifically explain this back in 1958. If the upper and lower arches do not match because of their size, orthodontists say that the patient has a “Bolton discrepancy.”

There are two options for correcting a Bolton discrepancy – making the teeth in the smaller arch bigger (composites, veneers, or crowns) or making the size of the teeth in the bigger arch smaller (interproximal reduction). In most patients there is plenty of extra enamel between the teeth. Using very thin diamond embedded tools, your orthodontist can polish away small amounts of enamel to allow your teeth to fit better. This is a quick, painless procedure than can be done without anesthesia. Not only does it solve the size problem, it is a far more permanent solution than adding artificial materials to the natural teeth in the smaller arch.

The second time your orthodontist may use interproximal reduction during your treatment is when you have teeth shaped such that they don’t fit next to each other very well. This is most obvious in the front part of the mouth where two triangular shaped teeth are touching near the biting edges but there are triangular-shaped spaces closer to the gum line. These are sometimes called “dark triangles.” The presence of dark triangles is determined by the shape of the teeth and the height of the gums between them. Your dentist can tell you how much each of these two variables contributes to your situation and if using IPR will improve the appearance of your smile.

The last reason for using IPR is when there is too much crowding to align the teeth as they are, but not enough to justify removing any. Interproximal reduction not only reduces crowding, it also creates smooth, flat surfaces that keep the teeth straight better after the braces have come off. Substantial amounts of space can be created by removing only tiny amounts of tooth structure from multiple teeth. If only ¼ mm of enamel is polished from each side of the six lower front teeth, the total amount of space created is 3mm!

Research supports the use of interproximal reduction by showing no increased decay on the altered surfaces, greater stability after treatment, and no increase in sensitivity when the amount of enamel removed is kept within reasonable limits. Ask your orthodontist if interproximal reduction is right for your particular situation.

NOTE: The author, Dr. Greg Jorgensen, is a board-certified orthodontist who is in the private practice of orthodontics in Rio Rancho, New Mexico (a suburb on the Westside of Albuquerque). He was trained at BYU, Washington University in St. Louis, and the University of Iowa in the United States. Dr. Jorgensen’s 25 years of specialty practice and nearly 10,000 finished cases qualify him an expert in two-phase treatment, extraction and non-extraction therapy, functional orthodontics, clear aligners (Invisalign), and multiple bracket systems (including conventional braces, Damon and other self-ligating brackets, Suresmile, and lingual braces). This blog is for informational purposes only and is designed to help consumers understand currently accepted orthodontic concepts. It is not a venue for debating alternative treatment theories. Dr. Jorgensen is licensed to diagnose and treat patients only in the state of New Mexico. He cannot diagnose cases described in comments nor can he select treatment plans for readers. Please understand that because he has tens of thousands of readers each month, IT IS IMPOSSIBLE FOR HIM TO RESPOND TO EVERY QUESTION. Please read all of the comments associated with each article as most of the questions he receives each week have been asked and answered previously. The opinions expressed here are protected by copyright laws and can only be used with written permission from the author.

78 comments so far in response to “What Is Interproximal Reduction In Orthodontics?”

  1. haley says:

    how much space can be created to push back protruded teeth with IPR? i have straight teeth little to no crowding my teeth go out a little bit and he wants to extract 4 teeth i’m sure there’s a more conservative way he wants to push it back 2-3 mm

  2. zehra says:

    hi,I am 31 years old and I was having the two upper baby canines non falling.I went to an orthodontist, he made some examinations, he started treatment with first gaining place for the permanent upper canines,then the baby canines have been extracted.İt’s been 6 months from the beginnig of the treatment.My problem is that now the upper front tooth have gone protruded,overjet.Befor my treatment I did not have any overjet.I ask my doctor about this situation, he tells me that my lower jaw is retracted and because there is not enough space for the canines it must be done like this.But now I cannot close my mouth like before and my cheeks are like weakened, people says I do not look like before in a bad way. My doctor proposed to extract two upper first molars to reduce the overjet with a risk of collapsing the upper lip.But I don’t even want any collapse in my upper lip. I was wondering if it could be possible to correct that overjet with IPR instead of extraction ?

    • Your front teeth moved forward because your canines needed more space. If you needed 4mm of space (2 on each side), you’d need 4mm of IPR and that would be way too much. Sometimes extractions are the only way to prevent what you are experiencing.

      • zehra says:

        Thanks for your quick answering, you said if I need 4 mm of space it would be too much of IPR. But in your review above if I had understood correctly it is possible to gain 3 mm of space with IPR of only ¼ mm of enamel polished from each side of the six front teeth. I was wondering if 3 mm of space is not enough to retract the upper front teeth at a level satisfying ? I am an opthalmologist so I can understand if you could explain me in details. Thank you sir.

        • In my experience, the maximum amount of IPR that I feel comfortable with would be between 3mm and 4mm in an entire arch. That equates to 1.5mm to 2.0mm of retraction. That is about the thickness of a dime and really not noticeable to the naked eye. I don’t think that IPR is a good approach to overjet reduction. It just doesn’t accomplish enough for the amount of tooth alteration required

  3. Lisa says:

    Hi Dr. Jorgensen, My new Ortho wants to perform IPR for a very small black hole inbetween my front two teeth and on all my teeth so they can go back smoothly. Along with my bottom jaw because I have one tother poking out (stopped wearing my retainer long time ago for the bottom) I’m worried that IPR may not bring them back to being straight and tightly together when I wear my clear retainer braces to push them back then long term plastic retainers? I’m worried it’s not safe and will make my teeth spaced out with gaps and not go back and look pretty. Meanwhile I met with another Ortho who quickly just suggested I either purchase a new retainer or go through an entire Invisalign procedure for 2 years. Isn’t that crazy how I received 2 different opinions from to Professional DDS? Pleas help, Please advise, Thank you in advance!! Lisa

    • Performing IPR on crooked teeth alone will not get them straight again. The teeth will need to be guided to their new (or former positions) by either braces or aligners. I use IPR all the time, but it is always done as part of treatment so that I can make sure the teeth are straight and the gaps closed.

  4. molly says:

    Does getting IPR hurt? How much can get shaved off (in cm) before hitting there nerves? How long would it take if someone were to get 7 teeth on the bottom slenderized?

    • Interproximal reduction is a fast and simple procedure that does not require anesthesia. I perform it every day and patients are very comfortable. The amount of enamel that is polished away on each surface ranges between 0.2mm and 0.5mm. The procedure itself takes less than a minute for half a dozen teeth.

  5. Yajayra says:

    Hello Dr. Jorgensen,

    I’m currently in braces. In the beginning of my treatment, my orthodontist recommended for me to extract two teeth from the left side of my mouth (one top one bottom) due to severe overcrowding. Now I’m about 2 years into my treatment and have noticed a deviation in my midline. It is slightly off by what I believe to be 2mm (could be up to 3mm), and is off centered from my facial midline (nose). It is really starting to make me feel self-conscious…I will be going to my next appointment soon and will bring up my concern to her, but wanted to know if IRP could be an option in fixing my midline? Is it possible to create the space needed and to move my teeth in the other direction? Do you have any other recommendations for treatment? Thank you in advance!

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