Yes, teeth can relapse after Invisalign!

But the beauty of Invisalign is that you get clear retainers afterwards that look and feel just the Invisalign trays, so patients are more likely to wear them as opposed to the old plastic and wire ugly retainers of yesteryear.

All teeth will shift after teeth straightening if not held in place or a couple years. I always tell my patients that retainers need to be worn forever at nite if they want to keep their straight teeth. I still wear my retainer and I had braces 20 years ago.