I stopped wearing mine about two years after I got my braces bad, however, I did not see a shift in my teeth until about 4 or 5 years after that. I go back to my orthodontist and he fitted me for a new retainer but he told me that the longer you continue the more your chances are that you will have to bring back braces again.
Pretty much everyone I know has stopped wearing theirs and all of those population have seen some sort of movement.
Answers: It doesnt take long at all. I have to wait a day to attain the retainer and by then my teeth had already prominently shifted. The ortho even commented on it. The longer you wear the retainer, the longer it will take the teeth to shift back. If you stop wearing it at the outset of retention, you can expect the shift to be quick because the teeth havent settled. Your teeth will move for the remainder of your life, so if you dont want them to shift, wear the retainer at lowest possible at night after a year of 24/7.thats the general rule. but to answer your quiz, yes...they will shift.
People must wear their retainer 4 as long as directed make happen if not their teeth WILL shift back outwards. This can help yourself to a few yrs, but I have seen individuals several yrs after never wearing theirs & presently they've got big *** gaps within their front 2 teeth.