Refinement aligners

A refinement is a further set of aligners, made because the teeth have not followed the planned movement closely enough. You are still in active treatment. A retainer comes later and holds the teeth once that movement has stopped. Refinements are common: teeth do not always move exactly as the computer plan predicts. Whether the extra aligners cost you anything depends on your treatment agreement, and the terms vary widely between providers.

Why extra trays are needed

Teeth may not move as far as planned, even when the trays are worn properly. In a 2020 study of 38 adults who wore Invisalign as instructed, teeth on average reached about half of the movement planned for them, and rotations were the least accurate. Align, which makes Invisalign, told orthodontists in 2023 that most of its comprehensive cases finish with one additional set of aligners or fewer.

Illustrative reasons a clinician may order more trays:

• A tooth did not keep up. Rotations were the least accurate movement in that study, so one tooth may lag while the rest move on.
• The trays were not worn enough. Fewer hours than prescribed means the teeth do not keep up with the trays, and later trays then stop fitting.
• An attachment came off. Invisalign's instructions say a missing attachment that is not replaced can affect treatment time or the result.
• The starting record did not match the teeth. Trays made from an inaccurate impression or scan may not fit; ask whether new records are needed.
• Dental work changed a tooth. A new crown or filling after your impressions or scan can change how the trays fit.
• You want a further change. At the end, you and the clinician may agree on extra movement to improve the finish.

The person who prescribed the aligners has to decide which of these applies. A photograph shows what is visible; the clinician's examination decides the next step.

Mid-course correction or finishing touches

A refinement can happen at two points. A mid-course correction is made when the trays stop fitting or the teeth stop keeping up partway through, so the rest of the original series is replaced with a new plan. A finishing refinement happens after the last planned tray, to close small gaps or correct teeth that did not quite get there. Both mean new trays from new records, but a mid-course correction usually means stopping the old series early.

Some problems need more than aligners. Aligners are sometimes combined with other appliances, such as fixed braces, when they will not reach the result alone; your orthodontist can tell you whether that applies to you.

What happens, step by step

1. The problem is spotted. Usually at a check-in, from photos or a visit, or because a tray does not fit fully. If an aligner stops fitting, contact the clinician before changing trays or forcing it.
2. You are reassessed. The clinician reviews your teeth, in person or from photos, and decides whether more aligners are the right answer.
3. New records are taken. A new scan at an office, or a new impression kit for a remote service. Attachments may be removed or replaced.
4. A new plan is made. Ask to see the revised plan, and what it is expected to achieve, before new trays are made.
5. The trays are made and delivered. Ask how long this will take; it varies by provider.
6. You wear the new series. Usually on the same schedule as before, with check-ins.
7. The result is checked again. Then retainers, or occasionally another round.

While you wait

Ask the clinician, before the old series ends:

• Should I keep wearing my current or last tray full time while I wait, and for how many hours?
• What should I do if that tray stops fitting?
• How long will the new trays take to arrive?
• Will my attachments change, and when?
• How many more trays, and how much longer, do you now expect?
• Is this included in my fee, and if not, what will it cost?

What providers say about extra aligners

These are published terms from four companies, checked on October 22, 2026. They are examples, not a ranking. Read the terms in your own agreement.

"Free refinements" usually depends on proving you followed the instructions, so keep your progress photos. And a company that defines success as a percentage of the preview may treat your case as finished once that figure is reached, even if you are not fully satisfied.

Time and money

Extra trays add time. Invisalign's own page says mild to moderate cases often finish in 12 to 18 months, and that more involved cases can take longer, including where extra aligners are part of the plan. Ask the clinician for a revised estimate once the new plan is made.

There is no single US price for refinements. At an orthodontist's office, ask whether further aligners and the visits they need are included in your fee, and for how long. With a remote company, check its terms before you buy. How to read a quote, including refinements and retainers, is in what clear aligners cost in the United States.

Retainers come later

A retainer holds the result after active tooth movement has stopped. If the clinician says more movement is still needed, that is a refinement, or another form of active treatment. The American Association of Orthodontists says you will likely need retention for life. Care once treatment has actually finished is in care after aligner treatment.

Which problems are a poor fit for aligners alone, before anyone starts, is in what clear aligners can and cannot fix. How a remote plan handles extra trays is covered in how at-home aligner treatment works.