I had orthodontic treatment; do I need to keep wearing the fixed braces?

I had orthodontic treatment, and I am still wearing the fixed braces.

Actually, my orthodontic treatment was completed a long time ago, but some of the fixed wire on the upper teeth has come loose, and the lower wire is completely gone. Recently, when I look in the mirror, I feel that my lower teeth are shifting a bit, so I'm worried. I'm not sure if I need to go back to the hospital.