Author Topic: Occlusal plane tipped down  (Read 664 times)

mazilla

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Occlusal plane tipped down
« on: January 01, 2018, 04:10:52 PM »
I had bimax surgery for sleep apnea 2 years ago. Ever since I felt something was off. I felt I was advanced too much, and that I was left with bimax protrusion. I have now studied my pre and post op cephs on cephx.com and discovered that my occlusal plane was flat preop, but I had 10 degrees of CCW rotation anyways. Now I feel that is what makes me feel I look off, the unnecessary rotation. I was left class III and with a very small nasolabial angle due to the rotation.

I feel like my case was a simple case of straight advancement, but my surgeon gave me both anterior and posterior downgrafts although I did not want more tooth show and my occlusal plane was already flat.

Please help and advise.

 Pre: https://imgur.com/a/S8vzX
 Post: https://imgur.com/a/HVb0w

secondtimearound

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Re: Occlusal plane tipped down
« Reply #1 on: January 01, 2018, 04:16:43 PM »
I told you in the other thread, your jaws were rotated too much CCW and your occlusal plane is unjustifiably tilted CCW now relative to all the rest of your facial planes which are in really good alignment.

You do not need the jaws moved forward or backwards at this point, as they are in great alignment from that perspective.

You need to decide if you need anterior impaction at this point. This is determined primarily by how much of your upper front teeth are visible when you part your lips at rest. For a man, you want at most 1-2 mm ideally. Women is more like 4 mm (rough estimate here). If you have more than 1-2 mm of teeth showing with your lips apart at rest or your smile has become gummy, you might benefit from some anterior maxillary impaction. But I don't think you need anterior maxillary impaction despite that you mentioned you believe you do. At most you could impact the anterior aspect 1-2 mm if needed.

Otherwise what you need is posterior impaction of the maxilla by at least 3-4 degrees to get your occlusal plane back closer to the normal range. This requires revision BSSO and LF1, as you can't reorient the maxilla without reorienting the mandible as well.

The rotation will help to retrude your lower jaw a bit which has become a bit overprominent from the prior surgery as well.

Sucks doesn't it? Hard enough going through these surgeries once. Let alone twice. I feel your pain. At least yours is a relatively simple case at this stage.

ditterbo

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Re: Occlusal plane tipped down
« Reply #2 on: January 01, 2018, 04:41:59 PM »
I told you in the other thread, your jaws were rotated too much CCW and your occlusal plane is unjustifiably tilted CCW now relative to all the rest of your facial planes which are in really good alignment.

You do not need the jaws moved forward or backwards at this point, as they are in great alignment from that perspective.

You need to decide if you need anterior impaction at this point. This is determined primarily by how much of your upper front teeth are visible when you part your lips at rest. For a man, you want at most 1-2 mm ideally. Women is more like 4 mm (rough estimate here). If you have more than 1-2 mm of teeth showing with your lips apart at rest or your smile has become gummy, you might benefit from some anterior maxillary impaction. But I don't think you need anterior maxillary impaction despite that you mentioned you believe you do. At most you could impact the anterior aspect 1-2 mm if needed.

Otherwise what you need is posterior impaction of the maxilla by at least 3-4 degrees to get your occlusal plane back closer to the normal range. This requires revision BSSO and LF1, as you can't reorient the maxilla without reorienting the mandible as well.

The rotation will help to retrude your lower jaw a bit which has become a bit overprominent from the prior surgery as well.

Sucks doesn't it? Hard enough going through these surgeries once. Let alone twice. I feel your pain. At least yours is a relatively simple case at this stage.

I'm more eyeballing the hypothetical changes then doing the definitive geometry on a ceph, but pretty sure any anterior impaction creates additional CCW, which you'd have to counterbalance with even more posterior impaction. Also keep in mind that some people have complications with anterior impaction, reducing support of their malar/submalar soft tissue and causing them to droop post op, making them appear older. Also, upper tooth show naturally reduces with age. I just don't see much upside with anterior impaction unless you really value poor upper tooth show over all this. IMO that's a compromise you should just accept as an objective improvement if you were to partially reverse the bimax.  Research whether bringing back the maxilla a tad would be less risky than an anterior impaction. I don't know myself but removing bone, from the front, sounds more risky than removing some of whatever they use to push the maxilla forward.

Posterior impaction sounds correct to me, but to clarify 2xaround,  pretty sure that does require redoing the BSSO such that the lower jaw/teeth are moved backward.  If he doesn't do a multi-peice lefort, then the upper incisors will flare out less, due to the posterior impaction, essentially reversing some of prominence in the upper lip and philthrum/that whole region (w/e it's called). 

Frankly though I don't get the issue with a divergent occlusal plane alone as the impetus for a revision, unless your open mouth smile looks off and is bothering you in the way it looks past your front incisors. Michael Phelps has a similar occlusal plane, I think.

kavan

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Re: Occlusal plane tipped down
« Reply #3 on: January 01, 2018, 05:17:47 PM »
What bothers me is not the occlusal plane itself, which I had not noticed until now, what bothers me is protruding mouth, protruding teeth (with I already had preop, but the CCW made much worse), mandible too far forward, and too small nasolabial angle.

I was downgrafted anteriorly and posteriorly in my 1st surgery, so if they remove the whole HA whatever they put in both my anterior and posterior maxilla, that would derotate my jaws by 10 degrees, and leave my occlusal plane as it was pre-op, and solve the things I dont like about my result. So the impaction would not be removing my own bone, but whatever they put in there to downgraft my maxilla.

I still dont get why I would need BSSO, my lower teeth would not need to move backwards, just my mandible being rotated with the maxillary rotation, but I might be missing something here.

Should be obvious that since your mandible was advanced about 2cm and a BSSO cut was part of that and since you don't like your 'over advanced' lower jaw, a BSSO cut would be needed to push it backwards.
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ditterbo

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Re: Occlusal plane tipped down
« Reply #4 on: January 01, 2018, 05:23:40 PM »
What bothers me is not the occlusal plane itself, which I had not noticed until now, what bothers me is protruding mouth, protruding teeth (with I already had preop, but the CCW made much worse), mandible too far forward, and too small nasolabial angle.

I was downgrafted anteriorly and posteriorly in my 1st surgery, so if they remove the whole HA whatever they put in both my anterior and posterior maxilla, that would derotate my jaws by 10 degrees, and leave my occlusal plane as it was pre-op, and solve the things I dont like about my result. So the impaction would not be removing my own bone, but whatever they put in there to downgraft my maxilla.

I still dont get why I would need BSSO, my lower teeth would not need to move backwards, just my mandible being rotated with the maxillary rotation, but I might be missing something here.

Soft tissue is unpredictable is the point, particularly when you remove support of any kind, new or old. Just identifying risks.

secondtimearound

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Re: Occlusal plane tipped down
« Reply #5 on: January 01, 2018, 06:22:23 PM »
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.
« Last Edit: January 01, 2018, 06:36:13 PM by secondtimearound »

secondtimearound

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Re: Occlusal plane tipped down
« Reply #6 on: January 01, 2018, 06:49:30 PM »
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

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Re: Occlusal plane tipped down
« Reply #7 on: January 01, 2018, 06:52:26 PM »
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

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Re: Occlusal plane tipped down
« Reply #8 on: January 01, 2018, 06:53:04 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.

I've seen distortion on after cephs even when I calibrated a linear measure.
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secondtimearound

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Re: Occlusal plane tipped down
« Reply #9 on: January 01, 2018, 07:00:15 PM »
I've seen distortion on after cephs even when I calibrated a linear measure.

These things are fucking 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... (?)

kavan

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Re: Occlusal plane tipped down
« Reply #10 on: January 01, 2018, 08:36:07 PM »
These things are fucking 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... (?)

Well, they are not to useful for overlaying the before with the after. They are used to make a displacement diagram on the same one for charting out a surgery.

ETA: You would have to try to scale them down to be same 'size' and then orient so the the Sella turica of both fit into each other. Tedious task. But that would have to be done to even see extent of distortion.
« Last Edit: January 01, 2018, 08:44:43 PM by kavan »
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secondtimearound

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Re: Occlusal plane tipped down
« Reply #11 on: January 01, 2018, 08:43:28 PM »
Well, they are not to useful for overlaying the before with the after. They are used to make a displacement diagram on the same one for charting out a surgery.

Yeah but that is nonsense when there is this level of distortion. How can you judge that the planes are accurate or that the angles are accurate when one part (the SN line) is so contracted compared to another part (the jawline) in one ceph but not the other?

We are debating millimeters and just a few degrees of angling of components, and the whole picture we're basing this on is cartoonishly distorted.

kavan

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Re: Occlusal plane tipped down
« Reply #12 on: January 01, 2018, 09:18:34 PM »
Yeah but that is nonsense when there is this level of distortion. How can you judge that the planes are accurate or that the angles are accurate when one part (the SN line) is so contracted compared to another part (the jawline) in one ceph but not the other?

We are debating millimeters and just a few degrees of angling of components, and the whole picture we're basing this on is cartoonishly distorted.

I see what you mean. His S-N line differs in both.  You should double check with mazilla that these cephs, both of them, are DIRECT ceph files from his doctor. When he prior posted his cephs, they were actually PHOTOS he took from the doctor's computer screen and not to scale and showed they were photoed at different angles.  I distinctly remember making fun of that. Like I asked him 'what was that piece of hardware the doctor put in your nose?' (I knew it was a photo shot) and his answer was it was the CURSER on the computer screen he photoed. The problem was that he requested removal of his cephs after I pointed out the crappy presentation and later insisted I remove from my files. So, now I have no way to cross reference if the cephs he sent to ceph X were his photo shots of them on the screen.

IF in fact these cephs were made from his crappy photo shots of his cephs on his doctor's computer screen, DISREGARD them.

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secondtimearound

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Re: Occlusal plane tipped down
« Reply #13 on: January 01, 2018, 10:25:19 PM »
I see what you mean. His S-N line differs in both.  You should double check with mazilla that these cephs, both of them, are DIRECT ceph files from his doctor. When he prior posted his cephs, they were actually PHOTOS he took from the doctor's computer screen and not to scale and showed they were photoed at different angles.  I distinctly remember making fun of that. Like I asked him 'what was that piece of hardware the doctor put in your nose?' (I knew it was a photo shot) and his answer was it was the CURSER on the computer screen he photoed. The problem was that he requested removal of his cephs after I pointed out the crappy presentation and later insisted I remove from my files. So, now I have no way to cross reference if the cephs he sent to ceph X were his photo shots of them on the screen.

IF in fact these cephs were made from his crappy photo shots of his cephs on his doctor's computer screen, DISREGARD them.

That makes sense and is actually reassuring because I would hate to think my cephs or anyone's cephs could be that ridiculously distorted. What would we be accomplishing by analyzing them if they are?

OP you need to request a digital copy of your original cephs if you want to compare properly.

Either way the same advice applies though. If you want your jaws to be more like they were, get ~4 degrees of CW rotation with revision LF1/BSSO. There's not much else to be said than that. As we've all stated, you don't need retrusion of your jaws which will just give you back your sleep apnea and put you into a retruded profile.

If the rotation is done with referencing your upper front incisor as if it is in a "fixed" position, the lower jaw will come back a bit on its own from the rotation reducing its prominence a bit.

kavan

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Re: Occlusal plane tipped down
« Reply #14 on: January 02, 2018, 08:46:55 AM »
These diagrams were made with the actual cephs sent from my doctor, not with the pictures I took with my phone.

I dont understand the distortion.

OK. I needed clarification of that due to the past cephs you put up. There is distortion.
As I said in a prior post to secondtimearound, I've seen distortion in other people's b/a cephs too when trying to scale them so each fits onto the unchanged landmarks of the other. 

As I said, I've seen that type of distortion in other b/a cephs. The only explanation I can think of is a change in head posture (even if it's a small angle change). I've noticed it because there is a distinctive landmark (S ; Sella turcica) that looks like a cross between Ancient Persian script (xa) and the saddle of an invading Ottoman. The orientation/shape of that landmark changes and as if it is photoed at an angle.  Steiner used that landmark because it was easy to see on an X ray and because the CENTER of it (where the dot is placed to make the S point) does not change where as the landmark for the Frankfort horizont was harder to spot. But when there is a shape change to that very distinctive landmark where it looks like it was shot at a different angle and when scaling down both cephs does not make an exact overlay to this landmark, it would reveal the head orientation for the ceph has changed.
















« Last Edit: January 02, 2018, 09:01:31 AM by kavan »
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