IPR and Attachments in Clear Aligner Treatment, Explained

By Bridge Dental Laboratory · 12 October 2026

Two things appear in most clear aligner treatment plans and generate most of the questions we get back: interproximal reduction (IPR) and composite attachments. Both look like extra complications on a plan. Both are there because the alternative is a case that does not track.

IPR: making space

Interproximal reduction means removing a very small amount of enamel between adjacent teeth to create space.

Teeth need somewhere to go. Where there is crowding, a plan has broadly three options: expand the arch, extract, or create space between the teeth. IPR is the third — and for mild to moderate crowding it is often the least invasive way to get the result.

The important detail is when. A plan does not just say “IPR” — it specifies which contacts and at which stage. That is because the space has to exist at the point the planned movement needs it. Create it all at the start and teeth drift into it unhelpfully; create it late and the aligner has been fighting a tooth with nowhere to move.

Attachments: giving the aligner something to hold

A clear aligner is a smooth shell over smooth teeth. It is very good at tipping teeth, and much less good at anything that needs grip — rotating a round-ish tooth like a premolar, or extruding a tooth, where there is nothing for the tray to pull against.

Attachments solve that. They are small composite shapes bonded to specific teeth, shaped and positioned so the aligner has a surface to push or pull against. The aligner is made with matching recesses, so the tray seats over them and the force goes where the plan intends.

That is why attachments turn up on particular teeth rather than all of them — they are placed where a specific movement needs them.

Placing them accurately

Attachments only work in the position the setup was designed around. A few millimetres out and the aligner does not seat as planned.

Which is why, where a case includes bonded attachments, we supply an attachment template with the batch. It locates each one against the teeth in the planned position, so chairside placement is quick and matches the digital setup rather than approximating it.

Both are proposals, not instructions

Worth saying plainly: the IPR and attachments in your plan are our proposal based on the movements you have asked for. They are not fixed, and they are not a clinical decision we are making on your behalf.

Everything in the plan is adjustable before you approve it — and at that stage, changes cost nothing. If you would rather avoid IPR on particular contacts, prefer fewer attachments, or want the sequence handled differently, say so at review and we will re-plan around it. The thing to avoid is discovering a preference after trays have been printed to a setup.

How it fits the workflow

You will see the proposed IPR and attachment placements in your treatment plan, alongside images of each arch and a time-lapse of the planned movement, so you can review the whole approach before anything is manufactured.

See clear aligners for the full service, or clear aligners with a 3-day treatment plan for how the workflow runs from scan to fitted trays.

FAQ

Common questions

What is IPR in clear aligner treatment?

Interproximal reduction — removing a very small amount of enamel between adjacent teeth to create space. It is one of the ways a plan makes room for alignment without extractions, and where it is needed the treatment plan specifies which contacts and at which stage.

What are aligner attachments for?

Attachments are small composite shapes bonded to specific teeth. They give the aligner something to grip and push against, so it can deliver movements it could not achieve on a smooth tooth surface alone — rotations and extrusions in particular.

How do I place the attachments accurately?

Where a plan calls for bonded attachments, we supply an attachment template with the case. It locates each attachment in the position the plan was designed around, so placement is quick and matches the digital setup.

Why does my treatment plan specify IPR at a particular stage?

Because space has to exist at the point the planned movement needs it — not before and not after. The plan sets out which contacts and when, so the sequence of movements works as designed. Doing it all at the start, or late, changes how the case tracks.

Can I change the IPR or attachments in a plan?

Yes — tell us before you approve. The plan is yours to adjust at the planning stage, and changes there cost nothing. Once trays are printed to a setup, altering the approach means re-planning, so it is worth raising anything you are unsure about during review.

Does every aligner case need attachments and IPR?

No. Simpler cases often need neither. They appear in a plan when the movements being asked for require grip, space, or both — which is why the plan tells you what it is proposing and why, for you to approve or change.

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