Impaction + forward upper jaw movement = cancel each other out?

[sanddunes]

I saw this touched on briefly in some other threads but I wanted to discuss it some more. 

If a jaw is impacted 1mm and moved forward 5mm, what is the net change on tooth/gum show? 

In my case, I do not have a gummy smile at all.  My jaw is supposed to be impacted 1mm and moved forward 5mm.  The impaction worries me, because the last thing I need is my gums going up when I do not have a gummy smile right now as it is.  I don't want my upper lip hanging down over my front teeth when I smile.  And impaction can age people and make the face shorter if done too much. 

Right now I have no tooth show when speaking, and the Dr. has said that for guys, 1-2 mm tooth show is ideal when speaking.   He claims I will end up with MORE tooth show in spite of the impaction due to the forward jaw movement, and that the gum show won't change much with a 1mm impaction.  But if my gums are fine as is now, isn't even 1mm too much?  Or does it get cancelled out by the forward jaw movement?

[pekay]

Are there any before/after of modified LeForts on "normal" male patients?

I've only seen one before by that South African surgeon and not only was the picture extremely small but the kid (looked to be 15) had a cleft lip

[x]

In addition to OP's concern, I've been wondering about how rotation effects tooth show

for example in clockwise rotation:



I see two counteracting forces here that would simultaneously increase and reduce tooth show. On one hand the anterior part of the maxilla moves downward which in theory would of course increase tooth show. On the other hand, the horizontal projection of the maxilla is lessened which would decrease tooth. So to what extent does the vertical cancel out the horizontal?

And vice versa with CCW rotation, where horizontal projection is gained but vertical length is lost.

[Braced4life]

Question? I was told by an oral surgeon that if just your upper jaw is advanced to correct an underbite, the lower jaw moves along with it forward...is this true? How could this be if they are just cutting the upper, I am confused, but this came straight from a consult I had with an oral surgeon..

[Braced4life]

I don't know, he was first surgeon to tell me this? Don't see how possible, my surgeon said he moved upper 6 mm to jump the underbite, which makes sense.. Don't understand what this guy is talking about. Nothing was rotated, had a very basic movement of upper advanced. He said upper is fixed lower is the only jaw that is mobile that's why it is moved along with upper..don't get it.