General Category > Functional Surgery Questions
Occlusal plane tipped down
secondtimearound:
It's just basic mechanics.
1) If you rotate the upper jaw 10 degrees clockwise, you're going to have an abnormally clockwise tilted maxillary plane after that.
2) If you don't do a BSSO as well, your back teeth won't meet.
Here's a 10 degree clockwise posterior impaction of the maxilla without BBSO:
Back teeth don't remotely meet and the maxillary plane is absurdly rotated.
Here's 4 degrees clockwise of both jaws which gives a more reasonable compromise among the planes:
One other interesting thing to observe is how dramatically your mandibular plane (line along the bottom of your jaw) changed and went clockwise from preop. Again for reference, your preop angle was almost flat:
An incredible and enviably square jaw!
I don't know how it went so CW inclined just from a BSSO advancement. That BSSO destroyed your square mandibular angles and looks like they're not coming back. If you want that back, you'd need mandibular angle implants. But that's a more minor issue potentially.
secondtimearound:
I just found something incredible. I was trying to figure out how your mandibular plane seemed to have been turned so clockwise in the post op relative to your occlusal angle (I edited my post while you were replying - might want to re-read it), so I did an overlay of your before and after cephs.
It looks like a mess, but the before is the red and the after is black/blue/green. I lined them up based on the S and N points, as those were not changed by surgery (unless you had brain surgery as well):
What we see is there is an INCREDIBLE amount of distortion from one ceph to the next.
How is this possible? Aren't cephs supposed to be standardized?
If this is the case, maybe we shouldn't trust our cephs very much at all.
This is absurd.
ditterbo:
As Kavan said - if his entire maxilla was dropped down - not just rotated, then the jaw naturally has less upward rotation to do before it meets the upper teeth. So his mandibular plane angle is bigger, as a result. You haven't shown how bad your gum show is when smiling, but pretty surprised it's not sort of on the severe end of tooth show after so much maxilla advancement and downward maxilla grafting.
kavan:
--- Quote from: secondtimearound on January 01, 2018, 06:49:30 PM ---I just found something incredible. I was trying to figure out how your mandibular plane got obliterated and turned so clockwise in the post op (I edited my post while you were replying - might want to re-read it), so I did an overlay of your before and after cephs.
It looks like a mess, but the before is the red and the after is black. I lined them up based on the S and N points, as those were not changed by surgery (unless you had brain surgery as well):
What we see is there is an INCREDIBLE amount of distortion from one ceph to the next.
How is this possible? Aren't cephs supposed to be standardized?
If this is the case, maybe we shouldn't trust our cephs very much at all.
This is absurd.
--- End quote ---
I've seen distortion on after cephs even when I calibrated a linear measure.
secondtimearound:
--- Quote from: kavan on January 01, 2018, 06:53:04 PM ---I've seen distortion on after cephs even when I calibrated a linear measure.
--- End quote ---
These things are f**king useless then if this degree of distortion is possible from one ceph to another.
OP, did you get your before and after cephs at the same location? Can you recall any differences in how they were taken?
You can't compare these with this degree of distortion. It makes no sense.
Even a CT is just a few hundred xrays. I HOPE they're not subject to the same distortion effects... (?)
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