Why Pure Plastic Isn't Always Enough
A plain aligner tray can grip the visible crown of a tooth well enough to tip or slide it in a simple direction, but some movements need more than that. Rotating a rounded tooth such as a premolar, or moving a tooth vertically into or out of the bite, needs a firmer contact point than smooth plastic alone can provide, since the tray has nothing to grip against on a curved surface. SmartForce attachments solve that: small, tooth-coloured composite shapes bonded onto specific teeth that give the aligner tray something to push and pull against for that particular movement.
Attachments are tooth-coloured but sit slightly raised on the tooth surface, so they can catch the light and are visible on close inspection, though they are considerably less noticeable than the metal brackets and wires of fixed braces. Not every tooth in a treatment plan gets one; the digital treatment plan decides which teeth need an attachment based on the specific movement required for that tooth, not as a routine addition to every case.
The composite material used for an attachment is the same type of tooth-coloured filling material dentists use for other restorative work, chosen and shaped to sit at a specific point on the tooth where the aligner needs extra grip. It is bonded directly to the enamel using standard dental bonding technique, the same underlying process used to place a tooth-coloured filling, which is why it can be removed cleanly at the end of treatment without damaging the tooth surface underneath.
How Attachments Facilitate Complex Tooth Rotations
An attachment works by giving the aligner a mechanical anchor point on the tooth. Instead of relying on the flat surface of the crown alone, the aligner tray clips over the raised attachment shape, which lets it direct a more specific force, extrusion (pulling a tooth further out of the bone), rotation, or a more controlled tipping movement, onto that individual tooth as the digital plan requires.
The number and position of attachments in a case are set out in the treatment plan according to which teeth need to move and how, so a case involving several rotations or vertical movements will typically have more attachments than a case that is mostly closing small gaps. There is no fixed or typical number of attachments per case this page can state, since it depends entirely on the individual plan.
Attachment shapes also vary by the movement they are designed to support: some are simple rectangular shapes that add general grip, while others are designed with a specific angled surface intended to catch the aligner plastic at a precise point during a particular stage of treatment. The digital plan places each one at the point in the tooth movement sequence where it is needed, and some attachments are added or removed partway through treatment as the plan progresses from one type of movement to the next.
Maintenance, Cleaning, and Dealing with Dislodged Buttons
An attachment can debond (come loose) occasionally, most often while removing a tray, and there is no reliable figure for how often this happens across patients generally, since it depends on individual factors including how the tray is removed each time. If an attachment comes off, the response is straightforward: keep wearing the aligners as instructed and contact the clinic to have it re-bonded. Trying to fix or replace an attachment at home is not something to attempt, since it needs to be placed and bonded correctly for the tray to fit as planned.
One thing worth checking is whether a tray still seats fully once an attachment has come off, since the shape it was gripping is now missing from the tooth. If the tray still seats normally and there is no visible gap, continuing to wear it as planned while waiting for the clinic appointment is usually reasonable; if it will not seat properly, contact the clinic promptly rather than waiting for the next scheduled review. The clinic will judge whether the tray can be re-worn as is, or whether the attachment needs re-bonding before the tray fits correctly again.
Attachments sit close to the gumline, which is exactly where plaque tends to collect, so brushing carefully around each one is part of daily cleaning during treatment. The aligner tray itself should be removed before eating or drinking anything other than plain water, and teeth are brushed normally with the tray out rather than brushed while it is in.
The trays themselves also need regular cleaning, separately from brushing teeth. Rinsing a tray under cool water when it comes out, and cleaning it as the clinic recommends, helps prevent a build-up of plaque or staining on the plastic and around the attachment recesses moulded into it. Hot water is best avoided for cleaning trays, since heat can distort the SmartTrack plastic and affect how well the tray fits.
Attachments themselves are not painful to have on the teeth day to day. The pressure that comes with a newly fitted tray is a normal part of each stage of treatment and generally settles within a few days as the tray beds in. If an attachment edge feels sharp or rubs against the cheek or lip, tell the clinic rather than filing or adjusting it, since it is a bonded dental material, not something to manage at home.
Attachment Removal Process at Treatment Completion
Attachments are removed by the treating clinician at the appropriate point in treatment, using a rotary instrument to remove the bonded composite material, followed by polishing the tooth surface. This is a routine, in-clinic step, not something that happens automatically when treatment finishes, and it does not leave a permanent mark on the tooth once the surface has been polished. Most attachments come off at the same appointment, once the clinician has confirmed the final trays have done their job and the result matches the treatment plan; a small number of cases may keep an attachment slightly longer if it is still needed for a retainer fit check.
For the full picture of how Invisalign treatment works from start to finish, including when attachments are typically placed, see Invisalign in Tasmania. For what to do day to day while wearing aligners with attachments in place, see the daily wear protocol, and for how aligners compare with fixed braces overall, see Invisalign vs metal braces.