Attachments are small composite shapes bonded to tooth surfaces that give aligners something to push against. Without them, many movements would depend only on the natural contours of the crown, which offer little grip for extrusion, rotation or root control.
What attachments do
- Increase retention so trays stay fully seated
- Provide active surfaces for extrusion and intrusion
- Create force couples for rotation and root movement
- Anchor teeth that shouldn't move while others do
Common attachment types
| Type | Typical use |
|---|---|
| Vertical rectangular | Root control and rotation, especially on canines and premolars |
| Horizontal rectangular | Retention and extrusion or intrusion support |
| Beveled | Directional force, such as extrusion, with an active surface angled to the movement |
| Ellipsoid or rounded | Retention with a lower profile and easier cleaning |
| Optimized or custom shapes | Designed by the planning software for a specific movement on a specific tooth |
Placement principles
- Place the active surface facing the direction the tooth needs to be pushed.
- Keep attachments on sound enamel where possible; restorations need a material-specific bonding protocol.
- Avoid placing attachments too close to the gingival margin, where they trap plaque and are hard to bond in a dry field.
- Consider esthetics on upper anterior teeth and use the smallest attachment that achieves the movement.
Why attachments fail
- Contamination during bonding, most often from saliva or moisture
- Voids or bubbles in the composite
- Excess composite flash that interferes with tray seating
- Wear from repeated tray insertion and removal, or from grinding
- Placement on restorations without surface preparation
Maintaining attachments during treatment
Check attachments at every visit. A missing or worn attachment reduces control of the movement it supported, so replace it promptly using the template tray. Remind patients to seat trays with finger pressure or seating aids rather than biting them into place, which can chip attachments.
Removing attachments
At the end of treatment, remove attachments with a finishing bur and polish the enamel carefully. Scan for final retainers after removal so the retainer fits the final tooth surfaces.
Infinity Aligner plans show every attachment in the 3D review, and certified providers can adjust shape or position before approving the case.
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