Interproximal Reduction (IPR): Burs, Strips and Chairside Instruments for Aligner Cases

Interproximal reduction, or IPR, is one of the most common chairside steps in clear aligner treatment, and one of the least forgiving: the enamel you remove does not come back. Done well, it creates the small amount of space a treatment plan calls for. Done carelessly, it leaves rough, over-reduced contacts. This guide explains what IPR is, when it is done, how burs and strips divide the work, a general technique outline, and the DeutscheDT.com instruments that fit the job, starting with the Busch No. 8392 fine grit diamond needle bur.

What is interproximal reduction (IPR) and why is it done?

Interproximal reduction (IPR), also called enamel stripping or slenderizing, is the removal of a thin, planned layer of enamel from the contact surfaces between neighboring teeth. The space it creates lets teeth move into alignment without being pushed forward or outward, and it can also reshape a contact so two teeth sit more naturally against each other. The amount, the tooth surfaces and the order all come from the treatment plan set by the orthodontist or the aligner company, usually shown in a stage-by-stage IPR chart. The clinician's job is to deliver that plan precisely and leave smooth, polished enamel behind.

When is IPR used?

IPR is most often used to relieve mild to moderate crowding without extractions or expansion, to correct a tooth-size discrepancy between the upper and lower arches, and to reshape triangular or overly broad contacts so teeth fit together more closely. It is a standard part of many aligner cases, where it is timed to specific stages of treatment so that each new set of trays has the room it was designed for. Whether a case needs IPR at all is a diagnostic decision, not an instrument decision.

IPR burs vs strips: which instrument does what?

Three families of instruments reduce interproximal enamel, and most practices combine them:

• Diamond burs work on a high-speed handpiece with water spray. A slim needle-shaped diamond fits into a tight contact where little space exists, so a bur is a common way to open a contact that is still closed.
• Abrasive strips are hand-held, flat and controllable. Strips refine and contour the surface once a contact is open, remove the last tenths of reduction, and polish.
• Motorized discs and oscillating systems are a third route, common in orthodontic practices. DeutscheDT.com does not stock them; we carry the bur and the strip-holding side.

A common sequence is a bur to open a tight contact, then strips to refine, contour and polish. A bur removes enamel quickly, which is why a fine grit and a light touch matter.

The Busch No. 8392 needle bur

The Busch No. 8392 016 is a slender, fine-grit diamond needle bur on an FG (friction grip) shank, sold as a pack of two. Clinicians commonly use needle burs of this figure for IPR. The red ring marks a fine grit, so the bur takes enamel away gently and leaves a smoother surface than a coarse diamond, which means less polishing afterward. Busch's product data for this bur does not set IPR parameters.

The cross-reference to other manufacturers' numbers is on the product page and in the Bur Comparison Chart. For what the ring colors mean, see the Bur Color Coding and ISO Guide. The wider fine-grit range is in the Fine Diamonds | Red Ring collection.

A medium-grit option: the Busch No. 850 012

Our range also includes the Busch No. 850 012 FG, a 1.2 mm medium-grit diamond taper (cone) round bur with ISO classification 806 314 199 524 012, sold as a pack of six. It is not sold as a dedicated IPR bur: its listed use is crown preparation. Some clinicians use a slim, medium-grit diamond of this kind to open a tight contact in IPR, before refining with a fine-grit bur and strips. The same rules apply: the treatment plan sets the amount, and technique is the clinician's decision.

IPR technique: a general outline

This outline is general clinical practice, not a Busch instruction for these burs. Follow the treatment plan and your own protocol.

1. Read the plan. Confirm which contacts are to be reduced, by how much and at which stage. The plan sets the amount; the bur does not.

2. Prepare and protect. Polish and dry the area, check the contact with floss, and place a protective strip or wedge to shield the adjacent tooth and the gingiva. Where the contact is closed, a separating step may be needed first.

3. Open the contact. With water spray, work in light, intermittent strokes from the contact outward, keeping the head moving so it does not dwell on one point. Clinicians choose the bur and grit to suit the contact; a fine-grit needle bur removes less, a medium-grit slim diamond removes more. Stop well short of the planned amount.

4. Refine with strips. Move to abrasive strips to take the surface to its final dimension and recontour it. Strips held under tension at both ends stay flat against the proximal surface: the Strip Grip® strip holding tweezers clamp each end of a 2.5 to 3.0 mm strip, as described in our guide to interproximal finishing.

5. Measure. Check the space with a feeler gauge or the aligner company's gauge, and compare it to the plan before moving to the next contact.

6. Polish and protect the enamel. Finish with fine strips to remove bur marks, then apply topical fluoride. A smooth surface collects less plaque, which matters because the contact area is hard for the patient to clean.

7. Record it. Note the amount reduced at each contact in the chart so later stages and refinements stay consistent.

Other chairside instruments in an aligner workflow

IPR is one step in a longer chairside sequence. Helmut Zepf makes the vertical (No. 33.720.43) and horizontal (No. 33.720.44) aligner pliers for adjusting and seating trays, and the OrthoMASTER A-Punch aligner pliers (No. 33.720.42) with a Ø 6 mm punch for the aligner technique. All three are in the aligner pliers collection. For clean-up around bonded attachments and brackets, see our guide to orthodontic debonding burs and polishers, and for the pliers family the 2026 orthodontic pliers guide.

Good practice and limits

Enamel is a limited layer, and IPR should stay within the amounts the treatment plan prescribes for each surface. Avoid dwelling with the bur on one spot, always use water spray, and replace a bur that has lost cutting efficiency rather than pressing harder. Check the contact afterward, because a rough or open contact traps plaque. Reprocess burs according to the manufacturer's instructions; our Dental Bur Reprocessing and Sterilization Guide covers the Busch cycle. Terms used in this article are defined in the Orthodontic Instrument Glossary.

Frequently asked questions

What does IPR stand for in dentistry? Interproximal reduction: the planned removal of a thin layer of enamel from the contact surfaces between teeth, also called enamel stripping or slenderizing.

What is the best bur for IPR? There is no single answer; it depends on the contact and the clinician. A slim diamond bur is a common choice because it fits into tight contacts. Clinicians commonly use fine-grit needle burs such as the Busch No. 8392 016, and some use a slim medium-grit diamond such as the No. 850 012 to open a tight contact first.

How much enamel can be removed with IPR? The amount is set per surface by the treatment plan from the orthodontist or aligner company. Follow that protocol; this article does not set limits.

Are IPR burs or strips better? They do different jobs. A bur opens a tight contact quickly; strips refine, contour and polish. Most clinicians use both.

Does IPR hurt? Many patients feel little because only a small amount of enamel is removed, though some feel pressure or sensitivity. Water spray and light strokes help, and the clinician decides whether anesthesia is needed.

Is IPR the same as enamel stripping? Yes. IPR, enamel stripping, slenderizing and approximal reduction all describe removing enamel from the proximal surfaces.

Choosing IPR instruments from DeutscheDT.com

Start with the Busch No. 8392 016 bur, add Strip Grip strip holders for refining and polishing, and keep the aligner pliers on the tray for delivery visits. The Busch No. 850 012 bur is an option some clinicians use for opening a tight contact. The burs are made in Germany by Busch & Co. GmbH, and the hand instruments by Helmut Zepf. Browse the Fine Diamonds | Red Ring collection for the wider range.

This article is intended as an educational reference for dental professionals and does not replace clinical judgment, the treatment plan, or manufacturer instructions for use.