those permanent retainers always have skeeved me out. the boy has one and it's so... weird. i had two of the removable retainers but i lost them years ago. so far so good with the teeth though, and truthfully i don't think they could ever return to the way they were in the beginning.
i do have this weird thing though. i don't naturally produce enough enamel for my teeth, so i have to periodically get them sealed. otherwise, despite my best efforts with brushing and flossing, i get bad cavities.