Author Topic: Advice needed on ceph / impaction / surgery plan  (Read 13253 times)

TWGOAT

  • Newbie
  • *
  • Posts: 49
  • Karma: 3
Re: Advice needed on ceph / impaction / surgery plan
« Reply #15 on: December 09, 2021, 02:10:09 PM »
Gotcha. You should work on fixing that tongue thrust before any surgery to avoid relapse, opening of the bite, etc. There are even videos on YouTube showing how to do this.

Yes its fixed now for the most part, which is why my bite is stable, but it wont be completely fixed until i get more tongue space, since swallowing is hindered by my recessed jaws.

Thanks !

kavan

  • Global Moderator
  • Hero Member
  • *****
  • Posts: 4029
  • Karma: 426
Re: Advice needed on ceph / impaction / surgery plan
« Reply #16 on: December 09, 2021, 04:57:19 PM »
Yes i understand what you mean.

I asked this surgeon and he says he doesnt do posterior downgrafting.

From what kavan said i thought it wasnt needed since i have an open bite.

Ill ask the next surgeon if he can rotate the complex enough without downgraft

Posterior downgraft is not 'needed' for someone with anterior open bite AND excess gum show to the posterior smile. When AOB results from the back teeth closing FIRST, the front teeth (top and bottom) don't meet. The lower jaw can't swing up to close the front of the bite. When EXCESS to the posterior maxilla contributes to EXCESS of GUM SHOW to the back of the smile, a posterior downgraft would INCREASE the unwanted excess. Posterior downgrafting is based on the rotation of a triangle around a FIXED point. I included such an illustration to the post I made to GJ. A lot of things done in maxfax have basis in elementary geometrical principles which are needed to be underbelt (already learned) to relate them back to concepts in maxfax surgery proposals.

Also, look at a clock. Divide it in half vertically. Both a swing between 6 to 12 in either a clockwise direction or a counter clockwise direction are UPWARD swings. So, if the back part of the maxilla needs an upward swing to decrease both excess gum show and AOB, that's what posterior impaction relates to; clockwise rotation between 6 o'clock and 12 o'clock (left side of the clock). If the front of the maxilla also needs an upward swing between 6 o'clock and 12 o'clock, that's what anterior impaction relates to; counter clockwise rotation (right side of the clock).
Please. No PMs for private advice. Board issues only.

TWGOAT

  • Newbie
  • *
  • Posts: 49
  • Karma: 3
Re: Advice needed on ceph / impaction / surgery plan
« Reply #17 on: December 09, 2021, 05:58:58 PM »
i understand the geometry principles that you explain kavan, it's just that i'm trying to imagine how much rotation is achievable with a 2mm differential, like GJ mentions seems it maybe wouldn't be enough ?

I know the goal is basically to get the maxilla / teeth almost parallel to the ground, then the mandible will follow, it's just i'm wondering if the wedge removed will be big enough to do that.


GJ, not sure what you mean when you say the entire complex, i thought that was implied that we are talking about the whole complex rotating. For example in my case if the front and back is impacted, then why would i need a downgraft after an impaction ?

would be easier to visualize on the 3D planning, i'll make sure to ask the next surgeon since he does that lol

like in this portion of the vid when Alfaro rotates the whole complex, you can see the gap created at the back of the maxilla (in this case when he does it there's no impaction). Since i need more rotation than that, i think that's where GJ is thinking about the posterior downgraft

 https://youtu.be/TJUK6WZ07fM?t=1796


GJ

  • Administrator
  • Hero Member
  • *****
  • Posts: 1493
  • Karma: 215
Re: Advice needed on ceph / impaction / surgery plan
« Reply #18 on: December 09, 2021, 06:02:47 PM »
why would i need a downgraft after an impaction ?

Because you're going to be recessed unless you get large CCW.

Kavan and your surgeon are banking on 2mm net to close that much recession? It's impossible.
We don't know what he means by "CCW rotation" in the plan. Could mean the small anterior impaction, or it could be he wants to rotate the complex.
Millimeters are miles on the face.

TWGOAT

  • Newbie
  • *
  • Posts: 49
  • Karma: 3
Re: Advice needed on ceph / impaction / surgery plan
« Reply #19 on: December 09, 2021, 06:05:53 PM »
Actually, NM. I don't have the time or desire to argue, and that's where Kavan decided to take this with the condescending tone.

But what you need OP, is to figure out when he writes "CCW rotation" in the plan, is that from rotating the entire complex along a point, or is it from the anterior impaction. Because if it's the latter, you will be very recessed after. Might be a good idea to close the posterior bite surgically, too, because when they cut that wedge out you basically solve the posterior gummy smile issue. You can then rotate the entire complex, which is what you need.

I'm not going to argue because I don't have the time, energy, or desire, and I'm not going to stand a moderator being condescending.

Well that is what i am trying to understand, from what i read on here, you achieve rotation through impaction or posterior downgraft.

Not sure what you mean when you say cut a wedge and then rotate, i thought cutting a wedge is also resulting in the rotation at the same time.

From what we discussed yes he will rotate everything to bring it where we need but i'm trying to understand if the differential impaction is enough, i just don't see how a couple mm could bring a 20 degree rotation.

TWGOAT

  • Newbie
  • *
  • Posts: 49
  • Karma: 3
Re: Advice needed on ceph / impaction / surgery plan
« Reply #20 on: December 09, 2021, 06:10:22 PM »
Because you're going to be recessed unless you get large CCW.

Kavan and your surgeon are banking on 2mm net to close that much recession? It's impossible.
We don't know what he means by "CCW rotation" in the plan. Could mean the small anterior impaction, or it could be he wants to rotate the complex.

it means the whole complex, but i thought it was with the 2mm only. As you say i don't see how 2mm could bring that much rotation lol.

I thought impacting 5 in front and 0 in the back would bring more rotation and be a better result but what do i know about the numbers ahah

Look at this case, she has a before really similar to mine, i'm awaiting an answer whether she had impaction / downgraft or both, but that is approx how much rotation i need, maybe more.

If she says she had just a couple mm impaction and no downgraft we'll have our answer lol

https://imgur.com/a/AggY9UN

GJ

  • Administrator
  • Hero Member
  • *****
  • Posts: 1493
  • Karma: 215
Re: Advice needed on ceph / impaction / surgery plan
« Reply #21 on: December 09, 2021, 06:43:05 PM »
Not sure what you mean when you say cut a wedge and then rotate

https://www.youtube.com/watch?v=VzUmMOCyBTA

The open bite is so small I was thinking ortho to fix it, but fixing it surgically might kill two birds with one stone (you fix the posterior gummy smile and close the anterior open bite). Maybe when he says he is going to impact the back 3mm he's talking about something like this. Something would have to be done to the anterior as well. A few mm of impaction.

The bottom line is: if you want a more correct profile, you're going to have to have a large CCW rotation of both jaws. Impaction (which you do need) is not going to cut it, and trying to make that up with an absurdly large genio isn't a good solution. The main reason I don't like his plan is it doesn't seem to include large CCW. It implies as written linear movement after impaction, and any CCW you get is going to be small from the impaction only. That's why I said clarify with him on what that "ccw rotation" line means. Is it just impaction, or is he rotating the complex after impaction to get the 10mm of lower jaw advancement? The former will rotate your jaw a very small amount and leave you unimpressed with your profile.
Millimeters are miles on the face.

kavan

  • Global Moderator
  • Hero Member
  • *****
  • Posts: 4029
  • Karma: 426
Re: Advice needed on ceph / impaction / surgery plan
« Reply #22 on: December 10, 2021, 10:49:25 PM »
I'm including the geometric gist of the tutorial I entered last night which was removed.
I shall assume you have some basic geometric familiarity underbelt as to relate to my explanations. That's because CCW-r, how it works, is based on a very fundamental geometric principle which is the ROTATION OF A TRIANGLE.

Although the Triangle is 'ABC', when we let A=ANS, B=PNS and C=pog point (outer most point on chin), it becomes the facial triangle that maxfax surgeons use to look at how applicable CCW-r posterior downgrafting is going to be depending on the patient because each person has pretty much a unique triangle constructed from points ANS, PNS and pog point.

Included is a diagram of a triangle; ABC rotated x degrees around fixed point A. The green triangle is a tracing of the blue triangle subsequent to a CCW rotation of x degrees.

The illustrations shows how the points B and C displace subsequent to the rotation. B drops down to B' and C goes outward to C'. So, how much C goes outward to C' is going to be directly proportional to how much B drops to B' via a CCW-r of X degrees. The obvious thing to note here is that the triangle does NOT change. It's the SAME triangle with the vertexes (and all the points on its lines (or 'legs') displaced by the rotation alone. The green triangle is the SAME triangle as the blue one. The blue one just shows where the green triangle would be after a CCW r of x degrees.

When we relate the displacements of the points (vertexes) of the triangle to a posterior downgraft, we can conceptualize something 'wedging down' to rotate the triangle by x degrees. So, the downgraft could be conceptualized as wedge ABB' where vertical linear distance between B and B'is the longest distance measure of the downgraft. (Surgeons give that mm meaure but usually don't relay the degree measure of the rotation). B going to B' via the rotation the downgraft affects causes C to go outward to C' (pog point to be advanced). So, how much C goes outward to C' is a function of the linear distance of BB'which in turn, is a function of the rotation the downgraft gives. Again, the obvious thing to observe is the triangle does NOT change in SHAPE. It only changes in POSITION when rotated. Hence, it is the rotation ALONE that shifts C outward to position C'. Since C=pog point, C'= pog point going outward via rotation of the trangle when we rename it; Triangle ANS PNS pog. (Keeping in mind that everyone has a DIFFERENT triangle.

OK. So, I thing you probably get the concept that the LARGER the posterior downgraft, the MORE outward distance the pog point will shift out via the rotation alone and how the basic concept of that is related to the fundamental geometric principle that describes the rotation of a triangle; ABC around a fixed point. (in this example I chose A). So, the principle is pretty straight forward (assuming again you have some geometry underbelt to ID with the principle). But surgeons look at the unique geometry of someone's FACE; in particular the CONSTRUCT of each person's unique triangle formed by ANS, PNS and pog.

How much the pog point can be brought outward is a direct function of how much they can shift the posterior maxilla DOWNWARD with the rotation. The larger the degree measure of the rotation, the more posterior maxilla shifts downward and the more the pog point goes outward.
So a limitation of how much to get the pog point to shift outward will be how much they can shift the posterior maxilla downward for that not to negatively affect the aesthetics of the smile or the function of the bite. In your case, excess posterior gummy smile and AOB are also part of your problem set in addition to the recessive mandible (and chin). Hence a large CCW-r via posterior downgraft with aim to maximize outward advancement at the pog point via the rotation of your triangle would tend towards shifting your excess posterior gum show MORE downward and contributing MORE to AOB. Whether or not the surgeon you consulted with does posterior downgraft, the limitations I mentioned are ones that surgeons who DO do the pdg (and significant ones at that) LIMIT the extent of them. So, 2 other things in your problem set LIMIT the 'solution' being that of a significant posterior downgraft solving the extend of all the recession to the mandible. That's why the BSSO and chin augment together are relied on to IMPROVE much of the recession.

As to combined impaction with a net CCW, THAT is a rotation but differs from that of rotating a triangle on which CCW posterior downgraft is based because unlike a triangle not being changed or altered, your triangle would be altered. For example AC (ans to pog) and BC (pns to pog) are  made shorter by the impaction. I mention that just to point out that although you are getting a net rotation, the model on which posterior downgrafting is based on is that of a triangle that changes ONLY in position via the rotation but not it's shape.

As to rotation of the 'whole maxilla mandible complex', well, that's what basically happens with any rotation of the maxilla even when done with no posterior downgraft. A rotation of the mandible is effected via what ever rotation is done to the maxilla. In your case, both a posterior impaction and an anterior impaction will allow the mandible to rotate upwards and decrease it's angle of inclination. That, in turn, allows the BSSO to move 'forward' along less of a steep mandibular plane angle. Even posterior impactions alone gets the mandible to swing upwards when you consider it's the excess to the posterior maxilla thrusting the mandible downwards because it can't rotate up to close the bite.

As to pursuing posterior downgrafting, I don't mean to discourage about doing so given it's a good idea to get differing opinions. So, you would need to consult with doctors who do it. They will look at the entirety of your problem set in relation to what ever limitations it would have to maximizing the downgraft to maximize outshifting of the pog point.
Please. No PMs for private advice. Board issues only.

GJ

  • Administrator
  • Hero Member
  • *****
  • Posts: 1493
  • Karma: 215
Re: Advice needed on ceph / impaction / surgery plan
« Reply #23 on: December 11, 2021, 06:13:20 AM »
What needs to be answered is whether after impaction, if the entire complex can be rotated. Nobody has been able to answer that, but if I were you I'd focus my research on that question. Find some academic papers on the topic or ask your surgeons.

It's not the same as rotating the jaws before impaction (i.e. it wouldn't "undo" the impaction) where you'd necessarily be left with a posterior gummy smile, and this is because the starting point for the posterior (and the entire maxilla) would be higher after impaction. So, hopefully this is possible.

If it's not, you're stuck with a severely recessed profile after the 2mm net CCW via impaction.
Millimeters are miles on the face.

kavan

  • Global Moderator
  • Hero Member
  • *****
  • Posts: 4029
  • Karma: 426
Re: Advice needed on ceph / impaction / surgery plan
« Reply #24 on: December 11, 2021, 08:36:23 AM »
What needs to be answered is whether after impaction, if the entire complex can be rotated. Nobody has been able to answer that, but if I were you I'd focus my research on that question. Find some academic papers on the topic or ask your surgeons.

It's not the same as rotating the jaws before impaction (i.e. it wouldn't "undo" the impaction) where you'd necessarily be left with a posterior gummy smile, and this is because the starting point for the posterior (and the entire maxilla) would be higher after impaction. So, hopefully this is possible.

If it's not, you're stuck with a severely recessed profile after the 2mm net CCW via impaction.


Well, haven't you asserted that's what he should have; combined impaction followed by a massive posterior downgraft?
Are you saying that it would be unfair to assume you had the answer/explanation as to how that's done?


Please. No PMs for private advice. Board issues only.

TWGOAT

  • Newbie
  • *
  • Posts: 49
  • Karma: 3
Re: Advice needed on ceph / impaction / surgery plan
« Reply #25 on: December 11, 2021, 08:45:35 AM »
i'll ask again GJ (my last 2 posts were deleted, can you not do that please?), i thought like kavan says that you mean impacting to reduce maxilla length then downgrafting, what are the other ways to rotate if not these 2 ?

To me if the posterior maxilla is impacted it doesn't make any sense to downgraft it after since you're basically adding bone where you just removed it, so not sure what you mean when you say rotate the entire complex after the impaction, when the impaction is what makes the rotation from what i gather
« Last Edit: December 11, 2021, 09:19:39 AM by TWGOAT »

TWGOAT

  • Newbie
  • *
  • Posts: 49
  • Karma: 3
Re: Advice needed on ceph / impaction / surgery plan
« Reply #26 on: December 11, 2021, 09:10:24 AM »
I'm including the geometric gist of the tutorial I entered last night which was removed.
I shall assume you have some basic geometric familiarity underbelt as to relate to my explanations. That's because CCW-r, how it works, is based on a very fundamental geometric principle which is the ROTATION OF A TRIANGLE.

Although the Triangle is 'ABC', when we let A=ANS, B=PNS and C=pog point (outer most point on chin), it becomes the facial triangle that maxfax surgeons use to look at how applicable CCW-r posterior downgrafting is going to be depending on the patient because each person has pretty much a unique triangle constructed from points ANS, PNS and pog point.

Included is a diagram of a triangle; ABC rotated x degrees around fixed point A. The green triangle is a tracing of the blue triangle subsequent to a CCW rotation of x degrees.

The illustrations shows how the points B and C displace subsequent to the rotation. B drops down to B' and C goes outward to C'. So, how much C goes outward to C' is going to be directly proportional to how much B drops to B' via a CCW-r of X degrees. The obvious thing to note here is that the triangle does NOT change. It's the SAME triangle with the vertexes (and all the points on its lines (or 'legs') displaced by the rotation alone. The green triangle is the SAME triangle as the blue one. The blue one just shows where the green triangle would be after a CCW r of x degrees.

When we relate the displacements of the points (vertexes) of the triangle to a posterior downgraft, we can conceptualize something 'wedging down' to rotate the triangle by x degrees. So, the downgraft could be conceptualized as wedge ABB' where vertical linear distance between B and B'is the longest distance measure of the downgraft. (Surgeons give that mm meaure but usually don't relay the degree measure of the rotation). B going to B' via the rotation the downgraft affects causes C to go outward to C' (pog point to be advanced). So, how much C goes outward to C' is a function of the linear distance of BB'which in turn, is a function of the rotation the downgraft gives. Again, the obvious thing to observe is the triangle does NOT change in SHAPE. It only changes in POSITION when rotated. Hence, it is the rotation ALONE that shifts C outward to position C'. Since C=pog point, C'= pog point going outward via rotation of the trangle when we rename it; Triangle ANS PNS pog. (Keeping in mind that everyone has a DIFFERENT triangle.

OK. So, I thing you probably get the concept that the LARGER the posterior downgraft, the MORE outward distance the pog point will shift out via the rotation alone and how the basic concept of that is related to the fundamental geometric principle that describes the rotation of a triangle; ABC around a fixed point. (in this example I chose A). So, the principle is pretty straight forward (assuming again you have some geometry underbelt to ID with the principle). But surgeons look at the unique geometry of someone's FACE; in particular the CONSTRUCT of each person's unique triangle formed by ANS, PNS and pog.

How much the pog point can be brought outward is a direct function of how much they can shift the posterior maxilla DOWNWARD with the rotation. The larger the degree measure of the rotation, the more posterior maxilla shifts downward and the more the pog point goes outward.
So a limitation of how much to get the pog point to shift outward will be how much they can shift the posterior maxilla downward for that not to negatively affect the aesthetics of the smile or the function of the bite. In your case, excess posterior gummy smile and AOB are also part of your problem set in addition to the recessive mandible (and chin). Hence a large CCW-r via posterior downgraft with aim to maximize outward advancement at the pog point via the rotation of your triangle would tend towards shifting your excess posterior gum show MORE downward and contributing MORE to AOB. Whether or not the surgeon you consulted with does posterior downgraft, the limitations I mentioned are ones that surgeons who DO do the pdg (and significant ones at that) LIMIT the extent of them. So, 2 other things in your problem set LIMIT the 'solution' being that of a significant posterior downgraft solving the extend of all the recession to the mandible. That's why the BSSO and chin augment together are relied on to IMPROVE much of the recession.

As to combined impaction with a net CCW, THAT is a rotation but differs from that of rotating a triangle on which CCW posterior downgraft is based because unlike a triangle not being changed or altered, your triangle would be altered. For example AC (ans to pog) and BC (pns to pog) are  made shorter by the impaction. I mention that just to point out that although you are getting a net rotation, the model on which posterior downgrafting is based on is that of a triangle that changes ONLY in position via the rotation but not it's shape.

As to rotation of the 'whole maxilla mandible complex', well, that's what basically happens with any rotation of the maxilla even when done with no posterior downgraft. A rotation of the mandible is effected via what ever rotation is done to the maxilla. In your case, both a posterior impaction and an anterior impaction will allow the mandible to rotate upwards and decrease it's angle of inclination. That, in turn, allows the BSSO to move 'forward' along less of a steep mandibular plane angle. Even posterior impactions alone gets the mandible to swing upwards when you consider it's the excess to the posterior maxilla thrusting the mandible downwards because it can't rotate up to close the bite.

As to pursuing posterior downgrafting, I don't mean to discourage about doing so given it's a good idea to get differing opinions. So, you would need to consult with doctors who do it. They will look at the entirety of your problem set in relation to what ever limitations it would have to maximizing the downgraft to maximize outshifting of the pog point.

so do you think i can gain enough rotation in degrees with the differential impaction ?

i found this case online just for numbers comparison, 6mm anterior impaction / 5mm posterior impaction, 2 deg CCW rotation occlusal plane:

https://imgur.com/a/rbw56b3

She was way less recessed than me

kavan

  • Global Moderator
  • Hero Member
  • *****
  • Posts: 4029
  • Karma: 426
Re: Advice needed on ceph / impaction / surgery plan
« Reply #27 on: December 11, 2021, 09:59:13 AM »
so do you think i can gain enough rotation in degrees with the differential impaction ?

i found this case online just for numbers comparison, 6mm anterior impaction / 5mm posterior impaction, 2 deg CCW rotation occlusal plane:

https://imgur.com/a/rbw56b3

She was way less recessed than me

Well, TBH, my explanation as to the basic concept posterior downgrafting is based on (rotation of a triange) wasn't really an invitation to analyze someone elses unique situation and apply to yours.

The objective of it was to explain in terms of the rotation of a triange that your case has limitations with reference to the concept of posterior downgrafting as it relates to the rotation of a triangle where the shape of it is not at all changed.

So, in effect, I'm concluding your advancement would be less than it would be compared to someone who didn't start with the same things that would limit getting an extensive posterior downgraft to maximize the outward projection of the pog point. So, I think you can expect IMPROVEMENT but not total correction.

As to net CCW-r, well, yes, that's an angle measure based on subtraction of angles where as the mm differential is a linear measure. But the calculation is going to differ depending on the shape of the entire 'cut out' from the maxilla and the linear measure of line ANS-PNS.

On a side note, the more PRAGMATICAL thing to do would be to ask, on your consults, for a contour displacement diagram which basically is a tracing of your present profile with ceph landmarks on it with an overlay of a tracing of the proposed changes to it.
Please. No PMs for private advice. Board issues only.

TWGOAT

  • Newbie
  • *
  • Posts: 49
  • Karma: 3
Re: Advice needed on ceph / impaction / surgery plan
« Reply #28 on: December 11, 2021, 10:05:48 AM »
Thank you, yes i understand the geometric principles discussed.

I will ask the next surgeon since he offers 3D planning so will be easier to visualize.

GJ

  • Administrator
  • Hero Member
  • *****
  • Posts: 1493
  • Karma: 215
Re: Advice needed on ceph / impaction / surgery plan
« Reply #29 on: December 11, 2021, 11:28:47 AM »
Are you saying that it would be unfair to assume you had the answer/explanation as to how that's done?

I don't know how it's done, but since the jaw can move in any dimension, I'd imagine it's possible.

Maybe baking it into the posterior wedge cut/impaction so when it's reattached there's margin to swing it down. It's not up to me to answer that, though. He needs to ask the surgeon. I'm just saying what he needs. And if he doesn't get that, he'll be disappointed.

Quote
To me if the posterior maxilla is impacted it doesn't make any sense to downgraft it after since you're basically adding bone where you just removed

Take it to the extreme with a thought experiment and say they impact your maxilla so its height is only 1mm total. Then they CCW rotate it. You really think that would result in a posterior gummy smile? The starting point when it begins rotation matters. The impaction moves it up, and then it can be rotated it from a higher starting point.

Maybe I'm wrong or missing something that can't be done, but that's how I imagine it working out and getting the best of both worlds.
Millimeters are miles on the face.