I wasn't very clear.
Regarding the removal of teeth:
When the teeth are removed you're left with a gap, say 7mm or so (the width of the tooth). Then you get the braces, and the teeth move within the gum to close that gap. So what happens to the actual size of the gum, does it shrink as it now has to hold less teeth, or are the spaces which were left effectively just moved to the back of the gums so they are not visible. If it is the latter, then I still have space in my gums to play around with, so I could in theory move all my lower teeth backwards to create an overjet?
Regarding the surgery:
My bit is now correct, class I. I'm asking if it is possible to just have BSSO (no upper jaw work), by somehow moving my lower teeth backwards in the gum to create an overjet, then I could bring the jaw forward and still have a correct bite. Clearly, if I move my lower jaw forward without moving the teeth back, I would get an underbite. The reason I ask is that I'm wondering if I can get away with just lower jaw surgery, not double. Perhaps this is a stupid idea, but I'm just trying to understand how it works and what my options are. I hope my question makes sense