Partial dental orthodontics

Has anyone ever tried partial orthodontic treatment only on the front teeth?

I only want to straighten my two upper front teeth, but if I get a partial correction, do I have to wear braces on all my upper teeth?

There are cases where braces are placed behind the teeth so they are not visible. Is it possible to do that from the beginning?

I'm curious about how long it takes to stabilize after correction and how much time is needed.