My Bottom Teeth Are Overlapping? (photo)

I agree that you should first consult with your dentist on what he/she says about how they plan to prevent relapse in your case. But it is also important to wear your retainers as much as possible after your treatment. I say this to all of my ortho patients. It might seem silly at first, but...

The purpose of a retainer is simply to hold things in place, not move them.  While your retainer (more likely a functional appliance) may seem to have this effect, its effects are likely minor and not permanent. The only real way to treat you would be braces again combined with surgery...

The correct sequence of treatment is to have  your orthodontic treatment completed prior to placing the dental implant.  This will allow for proper spacing for the implant and a superior aesthetic result.  Good luck.