Options for steep MP angle

[ODog]

Hi guys again,

My surgery is in a few weeks. I have a class 3 bite, small upper jaw in all 3 dimensions, VMD posteriorly causing a slight anterior open bite; nothing major. My lower jaw is not retrognathic but it’s rather small and not forward enough, and the MP angle is steep. Since I have no upper tooth show at rest, CCW is only possible via posterior downgrafting, which is what I want to ask today about. But first...

I will be getting both jaws advanced about 6 mm and a 5 mm genio, along with maxilla widening and posterior impaction. This should shorten my LAFH a bit, but won’t change my MP.

I think my surgery will give good results. I have a very flat/ recessed face. My upper lip-nose angle is 90 degrees. So moderate Bi-max advancement will bring good aesthetic improvement. Yes the chimp look is possible but I believe my advancement is not huge and bringing the lower jaw forward will offset the upper jaw advancement.

My question is regarding my options for addressing the steep MP angle, which is a big aesthetic problem for me. What are the criteria for posterior downgrafting? I believe Kavan in another thread said the OP needs to be steep and can’t be flat to do CCW via posterior downgrafts. Can someone elaborate on this?.

Here is my x-ray, https://imgur.com/a/CM9vXbk.... is my OP flat or steep?  Would I be able to get just CCW in a second surgery at a later date?  If not, I guess my only options are Chin Wing (likely can’t get this after BSSO) or jaw angle implants to addresss the vertical deficiency?

[kavan]

Hi guys again,

My surgery is in a few weeks. I have a class 3 bite, small upper jaw in all 3 dimensions, VMD posteriorly causing a slight anterior open bite; nothing major. My lower jaw is not retrognathic but it’s rather small and not forward enough, and the MP angle is steep. Since I have no upper tooth show at rest, CCW is only possible via posterior downgrafting, which is what I want to ask today about. But first...

I will be getting both jaws advanced about 6 mm and a 5 mm genio, along with maxilla widening and posterior impaction. This should shorten my LAFH a bit, but won’t change my MP.

I think my surgery will give good results. I have a very flat/ recessed face. My upper lip-nose angle is 90 degrees. So moderate Bi-max advancement will bring good aesthetic improvement. Yes the chimp look is possible but I believe my advancement is not huge and bringing the lower jaw forward will offset the upper jaw advancement.

My question is regarding my options for addressing the steep MP angle, which is a big aesthetic problem for me. What are the criteria for posterior downgrafting? I believe Kavan in another thread said the OP needs to be steep and can’t be flat to do CCW via posterior downgrafts. Can someone elaborate on this?.

Here is my x-ray, https://imgur.com/a/CM9vXbk.... is my OP flat or steep?  Would I be able to get just CCW in a second surgery at a later date?  If not, I guess my only options are Chin Wing (likely can’t get this after BSSO) or jaw angle implants to addresss the vertical deficiency?

What Kavan said was that since you had a close to flat OP, lack of front tooth show and vertical maxillary excess to the posterior jaw with anterior open bite, surgery for that would most likely be POSTERIOR IMPACTION and bringing down the front teeth which is CLOCKWISE rotation and not CCW.

[ODog]

What Kavan said was that since you had a close to flat OP, lack of front tooth show and vertical maxillary excess to the posterior jaw with anterior open bite, surgery for that would most likely be POSTERIOR IMPACTION and bringing down the front teeth which is CLOCKWISE rotation and not CCW.

But the posterior impaction wont affect the MP angle. So I guess there’s nothing I can do about that ?

[Post bimax]

But the posterior impaction wont affect the MP angle. So I guess there’s nothing I can do about that ?

Your MP would be technically "less steep" when your jaw is closed if you correct your AOB via posterior impaction.  Right now, your back teeth are colliding before the front reaches proper occlusion so your bite is 'open' in the front. If you impact the posterior maxilla, your bite will close further with your mandible swinging further toward 'flat'.

It's hard to say how much of a difference this would make aesthetically though.

[Post bimax]

But the posterior impaction wont affect the MP angle. So I guess there’s nothing I can do about that ?

If you want to change your MP without changing your OP, you would have to drop the back of the mandible somehow without affecting your bite. Like in some kind of modified chin-wing.

[ODog]

Your MP would be technically "less steep" when your jaw is closed if you correct your AOB via posterior impaction.  Right now, your back teeth are colliding before the front reaches proper occlusion so your bite is 'open' in the front. If you impact the posterior maxilla, your bite will close further with your mandible swinging further toward 'flat'.

It's hard to say how much of a difference this would make aesthetically though.

Yeah the mandible moves up and forward but it’s rather a minor change. I suppose I’ll have to address the vertical deficiency in the back separately.

[ditterbo]

Even Gunson levels of CCW will barely lower a given MP angle. I think the only big improvement to be made there is with filler or jaw angle implants, as things currently stand.

[PloskoPlus]

Even Gunson levels of CCW will barely lower a given MP angle. I think the only big improvement to be made there is with filler or jaw angle implants, as things currently stand.

I agree

[ODog]

Just want to update this topic...

My surgery is Monday. My surgeon has planned to NOT impact the posterior maxilla because he would have to “bring down the front part a lot more” to give adequate tooth show. So he’s going to bring down the front to match the back instead of shortening the back. I think he agrees that impaction would lessen the steepness of my MP (probably minor change though), but that more aesthetic improvement will be with more tooth show. Somehow he sees the impaction as problematic or counter to his objectives, which I don’t fully understand tbh.

Personally, I don’t see how impaction would affect anything. If anything, it would also reduce my lower facial height which would be a good thing because it’s the long part of my face. Or maybe it wouldn’t be a good thing because I have a deep labiomebtal fold (I think due to strong soft tissue chin pad) which would worsen with reduced lower facial height, especially with the genioplasty. A deeper fold is generally seen in people with short face, and so the increased vertical height of my lower face probably softens this fold which would be even worse were the height to be reduced?

Here’s my labiomental fold: https://imgur.com/a/fAcvvhM

Maybe he’s right or wrong to forgo impaction. I don’t know. I guess I’ll have to look into another surgery to lengthen the posterior jaw at a later date to bring things into final balance.

[ODog]

Even Gunson levels of CCW will barely lower a given MP angle. I think the only big improvement to be made there is with filler or jaw angle implants, as things currently stand.

Interesting you say that.

Also, wouldn’t a better aesthetic outcome be achieved by lowering the MP angle via Ramus drop down as opposed to keeping the short Ramus and fixing the steepness via rotation? It seems the former would give a more masculine appearance. Males are supposed to have sharp MP and goinal angles DUE to the Ramus being vertically longer, or at least ideally,  so that would be a crucial part in aesthetics. 

Obviously, if there were no option to lengthen the Ramus, then leveling the jawline via rotation would be the best solution. But then you won’t be able to lengthen the Ramus afterward to any significant degree, which let’s be honest, is crucial for male aesthetics.