How well aligners work depends on the type of movement, not the severity of the case
The question "is my case too severe for Invisalign" is usually the wrong question. Clear aligners are not weaker on severe cases — they are weaker on certain TYPES of movement, whether the case is mild or severe.
Aligners handle tipping crowns, closing spaces, mild arch expansion and rotating teeth with a flat cross-section very well. They are markedly harder work for intruding teeth, moving roots bodily along their axis, rotating round canines and premolars, or closing large extraction spaces — because a tray grips only the crown and has no mechanical purchase to transmit force down the root.
That is why the composite attachments bonded to the teeth are not an accessory but the main force-transmitting component, and it is why an honest plan sometimes concludes that your case should use braces, or braces for the difficult phase and aligners to finish.




