Braces are used to move teeth by putting the right amount of force on the teeth over the right amount of time.
Invisalign is an orthodontic treatment that moves teeth through the use of a series of clear plastic trays called aligners.
Retainers are used after orthodontic treatment to stabilize the teeth in their new locations.
A palatal expander is an orthodontic device used to widen the upper jaw. It is usually used to help put the upper teeth in a better biting alignment with the lower teeth.