Correcting a gummy smile - how much can they correct?

[Guest guest]

Hey just a brief question that occured to me:

When I went for my OS consult he said that I should have upper surgery

to correct my gummy smile, but the other OS who was present said

something along the lines of it being able to be improved, but not

eliminated.

Why is this? What factors affect how far they can move the upper jaw?

I ask because I'm sure Ive seen patients with a huge amount of

correction - going from something extreme like 2-3cm of gum showing to

near 0.

Thanks!