I got braces at age 28, and had them removed when I was 31. I wore my retainer for the length of time I was suppose. At age 42, I started getting "teeth pain", and had an evaluation done by a new orthodontist - my teeth had moved. My options were to wear braces again, and I figured, 6 months tops! After a work up - he said 28 months! So I elected to have a new retainer made that I wear 2x/wk to keep my teeth in place. The doc said it is much harder to move "older" teeth, and they have a tendency to try and move back to their original place.