How the Invisalign® system works - Aligners, attachments, buttons and elastics.

- How removable plastic aligners, tooth attachments (bumps), and buttons with rubber bands are able to straighten your teeth. | Diagrams and pictures.

The aligners you wear with the Invisalign® system are entirely different from conventional braces. And you may wonder, how are these flimsy-looking appliances actually able to move your teeth?

The Invisalign® system.

This page and its diagrams explain how they work. It also details how Invisalign® attachments and buttons with bands assist the process, as well as how they're placed and what they look like.

1) How plastic removable tooth aligners are able to move teeth.

With any removable braces system (Invisalign®, ClearCorrect®, eCligner®, ClearPath® Simpli 5®, etc...), it's the fit of the aligner over your teeth that generates the forces that straighten them.

a) Each aligner starts out "ill-fitting" on purpose.

When you initially start wearing an Invisalign® aligner, you'll probably notice that it doesn't seem to fit quite right. It may feel snug, or even a bit too tight. It might be hard to get in and out.

That's because it hasn't been shaped to fit your teeth. It's been shaped to fit the alignment that your teeth need to have at the end of the two weeks after you've finished wearing it.

b) Each aligner is responsible for just one step of your treatment.

When your Invisalign® aligners are made, each one is fabricated on an individual dental cast.

 Picture of a patient's entire series of Invisalign® aligners.

A series of tooth aligners (4 sets of upper and lower appliances).

The alignment of the teeth on that cast represents one individual stage of the series of stages that will, collectively, be used to straighten your teeth. (As shown in your Invisalign® treatment animation.)

c) Each aligner just repositions specific teeth.

Since each aligner's shape represents a future arrangement of your teeth (not their current one), when it's worn it won't exactly fit right in some regions. And it's the teeth in these areas that the aligner has been designed to move.

It may just be a few teeth, or possibly many. It just depends on what tooth movements are called for at that particular stage in your treatment plan.


How orthodontic aligners (i.e. Invisalign®) works

Animation showing how Invisalign® tooth aligners work.

a) Aligner #1 creates some tooth realignment.
b) Aligner #2 finishes the job.

d) It's the "misfit" of the aligner that causes you teeth to move.

When an aligner is worn, its "misfitting" region will apply a constant, gentle pressure to the teeth it encases.

And, gradually, this pressure will guide your teeth into an alignment that perfectly matches the aligner's shape.

The aligner's fit will change.

As evidence of the movement it generates, you should notice that during the two weeks that you wear an aligner its fit will gradually become more relaxed. This isn't because the aligner has changed, it's the alignment of your teeth that's different.

Potential discomfort.

Overall, the tooth movement process may cause some pain, especially during the first few days of wearing each successive aligner. (Use this link for details and remedies.)

As a solution for this annoyance, the eCligner® system makes use of three individual aligners, each have a different thickness, for each stage of the tooth moving process.

The thinnest appliance, which applies the lightest force, is used initially. The needed tooth movements for the stage are then completed using the latter two aligners, each of which is thicker and thus delivers a greater force.

The idea is that the use of a gradually increasing force helps to minimize the patient's discomfort levels.

e) Each aligner only straightens your teeth a little bit.

The amount of tooth movement that each individual aligner produces is quite small. Usually, each one's designed to move its selected group of teeth only about .25 millimeters. That's on the order of about one one-hundredth of an inch.

That may seem tiny. But after a whole series of aligners has been worn (10, 20, possibly even 30 or more), the total amount of tooth movement that can be accomplished can be quite substantial.

Enough so to transform your crooked old smile into a new perfect one.

Removable aligner systems use standard orthodontic techniques.

The appliances used with removable systems (Invisalign®, ClearCorrect®, Simpli 5®) are quite different than conventional braces. But beyond that, it's business as usual.

Plastic tooth aligners accomplish their goals using the same basic orthodontic approaches that dentists have always used. For more information and example animations, use this link: How standard orthodontic techniques are used with Invisalign®.

2) What are Invisalign® "attachments"?

Treating some patient's cases requires the use of "attachments" (bumps). (With the ClearCorrect® system this type of add-on is referred to as an "engager.")

They are:

Invisalign® attachments.

Illustration of Invisalign® tooth attachments.

An attachment allows the aligner a more positive grasp on the tooth.

  • Small tooth-colored dots of dental bonding (white filling material) that are placed at specific locations on specific teeth. (They're usually placed at about the middle of the tooth, meaning at a level that's halfway between its biting edge and gum line.)
  • They may be rectangular, square, circular, ellipsoidal or triangular in shape. The shape and orientation of a button is dictated by the purpose it serves (such as tooth rotation, translation, intrusion or extrusion).

An example of size:

  • An ellipsoidal (oval) attachment might measure about 1/16th of an inch wide, a little more than that in height, and roughly 1/32nd inches thick (about the same thickness as a credit card).

a) Why are attachments needed?

Some types of alignment changes are difficult to accomplish with removable braces.

  • It might be that the needed movement itself creates the challenge, such as rotating a tooth or extruding it (bringing more of it above the gum line).
  • In other cases, some characteristic of a tooth (size, shape, angulation) may make it difficult for the aligner to apply pressure to it.

In situations like these, placing an attachment may be the solution that's needed.

The idea is that this added bump provides an anchor point (a handle of sorts). One that helps to direct the forces of the aligner more effectively to the tooth.

  • 1/16th of an inch thick vertically aligned rectangular attachments are often placed on teeth to assist with translation (moving into an adjacent space), tipping, torquing or rotational movements.
  • 1/16th of an inch thick horizontal beveled rectangular attachments are frequently used to aid with intrusive (pushing in) or extrusive (pulling out) tooth movements.
Will your case require attachments?

Even before it's begun, your dentist will be able to tell you if any phase of your treatment will require the placement of attachments. Your digital treatment simulation (like Invisalign's ClinCheck® animation) will show you on which teeth and when during your treatment process they'll need to be placed.

Some systems place less dependence on the use of attachments than Invisalign®. This is possible in part due to the outline shape they give their aligners.

  • Invisalign® appliances have scalloped edges (the aligner follows the actual shape of the patient's gum line).
  • In comparison, eCligner® and ClearCorrect® aligners have a design where they have a straight-across edge that extends over the patient's gums just slightly. This extra length tends to make them more retentive and thus better able to direct their forces to the wearer's teeth without the use of attachments.

Examples of Invisalign® attachments.

Pictures showing how much Invisalign® tooth attachments show.

While attachments may not be easy to see, they're never totally invisible.

b) How visible are Invisalign® attachments?

How much your attachments will show will depend on:

  • Where they're placed. (Of course, needing them on your front teeth is the most obvious situation.)
  • How well the color of the bonding used matches the shade of your teeth.

    (In some cases, the patient's tooth shade isn't an exact match with any of the colors the dentist has to offer.)

However, no matter how much they do show, just keep in mind that they're less visible than conventional braces would be.

(We discuss the issue of attachments and buttons and how they affect the visibility of your Invisalign® treatment on this page.)

c) How are Invisalign® attachments placed?

Placing attachments is simple. It makes use of the same basic bonding technique that's used with many other dental procedures. And don't worry; no anesthetic (shot) is required.

Attachments are placed using a template.
  • Your dentist will receive a clear plastic template from the Invisalign® people. It will look a lot like a regular aligner, with the exception that it has small bulges in it that correspond to specific locations, on specific teeth, where your attachments need to be placed.
  • Your dentist will clean and prepare the surface of your teeth for the bonding process. (A few very simple steps.)
  • They'll then fill the bulges in the template with tooth-colored dental bonding (dental composite). The shape of the bulge creates the shape of the attachment being placed (rectangular, square triangle, round, ellipsoid).

    (Your dentist will try to pick a color of composite that matches your teeth as closely as possible. They may even ask for your opinion about the match.)

  • The filled template is then seated over your teeth and your dentist will cure the bonding by shining a blue-colored light on it.
  • Once it's hardened, your dentist will remove the template and trim away any excess. The small bump of bonding that then remains on your tooth is your new attachment, all set to go.

d) Attachments can be a minor nuisance.

Wearing attachments isn't usually too much of an issue. But there are some aspects of having them that can be annoying. For example:

  • When you're not wearing your aligners, they may feel sharp or irritating to your lips, tongue or cheeks. With time however, you should get used to them, at least to some degree.
  • When you eat, you may find that food accumulates around them. So, be careful if you're eating in public.
  • The fit of an aligner over its attachments can be quite snug, especially if you have several of them. And this can make putting your appliance in or taking it out difficult, or even painful.

Attachments are easily removed.

Animation showing the removal of an Invisalign® tooth attachment.

One method is to buff them off using a dental drill.

e) How are attachments removed?

Taking an Invisalign® attachment off is easy.

Your dentist will simply use their drill and gently buff its surface with a dental bur, sandpaper disk or polishing stone until it's been completely removed.

This is a painless procedure. No anesthetic is needed.


f) What should you do if you have an attachment come off?

It's doubtful that having an attachment come off will create an emergency situation.

  • You may feel some roughness or sharpness on the surface of your tooth when your aligner is out.
  • Your aligner may not fit as snugly until the attachment is replaced.
Let your dentist know.

All attachments are placed for a reason. And if you have one come off, you should let your dentist know immediately so they can make plans with you to replace it.

Remember, an attachment provides an anchor point that allows your Invisalign® braces to more effectively control that tooth's movement. If one is lost, your aligner may not be able to accomplish the task it was designed to do.

3) What are Invisalign® "buttons"?

An Invisalign® button.

Picture of an Invisalign® button with elastic band.

One end of the elastic band is anchored on the button.

"Buttons" are the term Invisalign® uses for small plastic or metal brackets that serve as anchor points for elastic bands ("rubber" bands). As examples:

  • One button may be placed on an upper eyetooth and the other on a lower molar, with an elastic band running between them (see picture).
  • In some cases, the second anchor point for the elastic may be the Invisalign® aligner itself.

a) When are buttons and elastic bands needed?

Just as with attachments, buttons and elastics are used to assist the dentist in creating tooth movements that the aligners, on their own, would otherwise have difficulty making.

Your dentist will be able to tell you, before your treatment is begun, if buttons and elastics will be required.

b) How are buttons placed?

Buttons come pre-made from Invisalign®. They are bonded onto your teeth using a simple process that requires no anesthetic.

c) How much do buttons show?

  • A dentist will usually position a button close to the tooth's gum line (this creates clearance between it and the aligner). This positioning helps to keep its visibility to a minimum.
  • Of course, no matter where your buttons are placed, the elastic running to them will be obvious. Choosing clear or ivory colored rubber bands helps to blend them in.

(We discuss the issue of attachments and buttons and how they affect the visibility of your Invisalign® treatment on this page.)



Topic Menu ▶  Dental Braces



Reusing Invisalign Trays

Hello: I had a 6 month Invisalign Treatment Plan. A total of 14 Trays back in 2011 and it was a great success!
I had a Metal Retainer placed on my Bottom Teeth after my Treatment Plan was complete. The Metal Retainer kept breaking & I eventually gave up & stopped going to my Dentist. It is now 2017, 6 years later & my Teeth have been shifting back. I decided to try the Treatment Plan again but on "My Own" because I kept "All" of my Invisalign Trays but I no longer have the "Buttons/Attachments" on my Teeth which did fix my one "Crooked" Tooth. I have also seen another Orthodontist who advised another Treatment Plan, which I declined but was told I could "reuse" my "Old Trays if I still have all of them, which I do. Would you advise "Reusing" the Invisalighn Trays without the Buttons?



Your orginal set of Invisalign trays provided a path from your original (crooked) alignment to the (perfect) end result.

It is true that when the alignment of teeth relapses the teeth tend to shift back to their original position. But it's unlikely that your teeth are at that exact same point where they were at the beginning of the first time around. And then as you discuss, you won't have the buttons which help the trays grasp the teeth and manipulate them.

It is common that when an Invisalign patient gets off track that they are asked by their dentist to back up and rewear the previous set or two, and possibly that is what that dentist was referring to. Possibly they are under the impression that the relapse has been so slight that that will work.

But expecting to repeat your entire course of treatment, not knowing that you have the exact same starting point, and then without the buttons ... that seems unrealistic and something we couldn't encourage.

Add new comment

Plain text

  • No HTML tags allowed.
  • Lines and paragraphs break automatically.
Please answer the question so we know you're a human.