I haven't worn braces in over 15 years... I was *also* supposed to have a permanent retainer.. but guess what, only one of my lower teeth have barely shifted, and I have an extremely small mouth. I do not mind having a tooth, or even few that has barely shifted. I will NEVER go back in to get the permanent retainer.
The many different types of retainers I wore (for several years) were torture. One even exploded in my mouth and cut up and scarred the roof of my mouth. If I absolutely had to do something to straighten my one tooth.. I would do invisaline.