Once you've had your teeth straightened, whether with braces or Invisalign, they will always want to move back into their original position. This is known as relapse, and it's a huge problem in orthodontics. Once your orthodontic treatment is complete, your dentist will fit retainers for you. They may be glued in, removable, or a combination of the two. These retainers must be worn for life. This sounds like a big commitment, but once you get used to it it's easy.
Watch this video to see what happened to Dr Georgia when she go slack with her retainers. Why do dentists always make the worst patients?