There seems to be some confusion about retainers and I wanted to help shed some light on the subject.
Let's start with the basics. Teeth are anchored in bone. Teeth move in response to a force which can come in the form of braces, fingers, tongue, lips and cheeks, and even something like a popcorn kernel can apply force to move teeth.
After orthodontic treatment, be it via traditionial braces, lingual braces, or Invisalign, a retainer will be needed to keep teeth in the newly moved position.
The question always arises how long is retainer use needed? Let me ask you this: if you go to the gym to get in shape, do you stop going once you have achieved your ideal body? Of course not, you need to continue to go to the gym to maintain the body you worked hard for. The same concept applies to your teeth after orthodntic treatment.
As I said before, teeth are in bone and move in respose to force. As you age, your tongue, lips and cheeks will apply different forces to your mouth and teeth. In addition, although you may be done growing your bone is constantly undergoing remodeling. As this bone change occurs in your jaw bones your teeth can be subject to change also.
So to answer your question: How long do I need to wear my retainers? How long do you want your teeth to be straight? Please remember that at some point you can wear retainers at night only and you may even be able to wear them every couple of nights once your teeth reach a state of equilibrium. But complete discontinuation of retainers will result in loss of that perfecct smile your worked hard to get. So keep those teeth in tip-top shape and wear your retainers.
If you have any further questions please contact your orthodontist or dental care provider.