Attachment Selection and Design
Attachments serve several purposes in aligner therapy. The most basic function is retention. In order to fully express prescribed movements, the aligners have to be fully seated. Aligners have a flexibility that needs to be compensated when seated onto arches that require movement. The second function of attachments is to facilitate movement by changing the shape of the tooth to provide an active surface for pushing.
The active surface of the optimized attachment is oriented to deliver the desired forces while simultaneously extruding, rotating or providing root control. Each attachment has a specific surface where the aligner provides that pressure, while the non-active surface is relieved to avoid any interference.
When it comes to Invisalign treatment, the use of attachments is an important step to achieving the best results. But what attachment is the most effective for the desired movement? That answer depends on the desired function of the attachment, and the type of movement planned.
For retention, conventional attachments are very effective. Greater retention can be achieved by increasing the size of the attachment from 3 mm to 4 mm or 5 mm width. Retention provides anchorage and also locks the aligner better when using inter-arch elastics.
For active movements, optimized attachments have been designed by data-driven analysis. These attachments are customized by Align Technology’s software to deliver specific force systems. They are added when the intended movement meets a certain threshold. When these attachments match the desired force system, they are the recommended selection when you are considering traditional attachments vs. aligner optimization. Some movements do not meet the criteria to generate an optimized design. This is where modifications to conventional attachments can be made to approximate the designs of optimized attachments normally selected for the desired movements. Using 3D controls, the position and amount of bevel can be adjusted to match a similar, optimized design.