Sassouni analysis and what it means

[ODog]

My preop maxilla position according to Sassouni was retruded 11 mm. My mandible was retruded 5.75 mm. FWIW, my SNA was 78.37 (mean 82) and SNB was 77.74 (mean 79).

I was advanced on both jaws 6 mm.

My post op Sassouni report shows the maxilla is still retruded 6 mm and mandible is protruded 1.5 mm. My SNA is 81.84 and SNB 81

So it looks like my SNA and SNB angles have normalized, however the Sassouni analysis still shows upper jaw retrusion.

I’m trying to understand what these numbers mean exactly. Does this mean it’s 6 mm retruded relative to my lower jaw? So I’m an underbite still? Since I’m getting a revision anyway, I’m wondering what else I can do to get the best results. Should I get further advancement?

Is it even possible to get a chimp lip when the maxilla is retruded according to the Sassouni analysis? Or is that only in cases where the maxilla becomes prognathic? Although there ARE cases of people getting the full upper lip even though their Sassouni is normalized (close to 0). For my case, I was warned about getting into chimp territory with my proposed plan - i am grateful to those generous posters here who made me very aware of this potential  - but I didn’t get that result. I’m not sure why. Does it have anything to do with my maxilla being hypoplastic preop?

When I smile, I’m now noticing my upper teeth lack a combination of TRANSVERSE, VERTICAL, and HORIZONTAL overlap of the bottom teeth. It looks like my smile doesn’t POP; it looks lacklustre and kind of fades into my face. I don’t know how else to describe it or what’s causing it.

I’m primarily concerned with my BITE now. I assumed that this was a virtual guarantee with my first jaw surgery so I was more focused on craniofacial changes, etc.. I really don’t know about all the bite variations tbh and I can’t tell what I need from looking at my own. So hoping some people can help out.

Again here’s my smile https://imgur.com/a/i6Gk6h5

For comparison my preop bite vs. Present: https://imgur.com/a/YiQNG9P

It looks like my surgeon DID impact me posteriorly, my Ortho thinks so as well, as I’m no longer showing gum on the sides but he says he DID NOT impact me which doesn’t make sense to me lol.

[Lazlo]

your bite looked way better before.

jesus christ all this surgery, ortho and you have less gum show afterwards? Doesn't make sense.

By the way, what's a Sassouni analysis and how do you get one?

[ODog]

your bite looked way better before.

jesus christ all this surgery, ortho and you have less gum show afterwards? Doesn't make sense.

By the way, what's a Sassouni analysis and how do you get one?

PM me your before and after cephs and I’ll get you the report. Make sure the cephs have the soft tissue outline.

My upper lip isn’t working properly yet, there’s no way I could have LESS gum show than before when I was advanced 6 mm and dropped down 3 mm. I think it’s just the lip isn’t lifting all the way yet. I have less gum show on the sides but isn’t that a good thing ?

[Dogmatix]

There are a lot of different analysis, as you already know from the documents you have. The Sassouni analysis seems to be a mathematical representation of the face where they prolong the Mandibular plane, occlusal plane, palatal plane and the anterior cranial base plane until they meet posteriorly. The idea is that these planes shall intersect in one single point, the point 'O'.
From this, it's also defined that some landmarks shall be placed at an equidistance from the point 'O', which means that these landmarks are placed on a circle with a radius equal to the equidistance.

Deviations in this analysis is based on how close the planes are from intersecting at the point 'O' and how big deviation each point have from being placed on the same distance from the point 'O', which is why you see that the mean values of each meassurement is 0. The "perfect" face have 0 deviation from having the landmarks placed on these imaginary circles. Other analysis as e.g Steiner, I believe have mean values based on actual population(?)

I found this slide show about it.
https://www.slideshare.net/tanviandrade9/sassounis-analysis

[ODog]

There are a lot of different analysis, as you already know from the documents you have. The Sassouni analysis seems to be a mathematical representation of the face where they prolong the Mandibular plane, occlusal plane, palatal plane and the anterior cranial base plane until they meet posteriorly. The idea is that these planes shall intersect in one single point, the point 'O'.
From this, it's also defined that some landmarks shall be placed at an equidistance from the point 'O', which means that these landmarks are placed on a circle with a radius equal to the equidistance.

Deviations in this analysis is based on how close the planes are from intersecting at the point 'O' and how big deviation each point have from being placed on the same distance from the point 'O', which is why you see that the mean values of each meassurement is 0. The "perfect" face have 0 deviation from having the landmarks placed on these imaginary circles. Other analysis as e.g Steiner, I believe have mean values based on actual population(?)

I found this slide show about it.
https://www.slideshare.net/tanviandrade9/sassounis-analysis

Ah I see, so Sassouni is more so about facial balance (each plane not diverging too far from the point of how the planes of a theoretical perfect face would converge), than it is about absolute projection with population averages like in Steiner’s analysis?

So my Sassouni’s analysis doesn’t necessarily mean my maxilla is retrognathic relative to the population avg. projection of point A, just that my maxilla PLANE is 6 mm off from ideal? In other words, a person could have a well-projected maxilla but if the occlusal plane is tipped down for example, it will deviate from 0?

[Dogmatix]

Ah I see, so Sassouni is more so about facial balance (each plane not diverging too far from the point of how the planes of a theoretical perfect face would converge), than it is about absolute projection with population averages like in Steiner’s analysis?

So my Sassouni’s analysis doesn’t necessarily mean my maxilla is retrognathic relative to the population avg. projection of point A, just that my maxilla PLANE is 6 mm off from ideal? Am I getting it ? Lol.

I can only say that if your goal is to have a face where the planes converge at one point, and that these landmarks are placed on the same distance from this point, then the values from this analysis can be used. If such face is considered balanced, perfect or ideal is at least not clear to me, it's more a mathematical convention. Often mathemathical symmetry can be interesting though, there are cases where e.g the golden ratio and other symmetry is sometimes linked to aesthetics.

I actually don't know if steiner reference values are based on population, but values like ANB are at least much less complex to understand the meaning of, it's just one angle and it's clear it's linked to the overjet and mandibular projection with reference to the maxilla and skull.

I would say that Sassouni analysis is of course interesting to look at, but it seems like there are far more modern ways to evaluate aesthetic proportions, if that is what your question is about.

[ODog]

I can only say that if your goal is to have a face where the planes converge at one point, and that these landmarks are placed on the same distance from this point, then the values from this analysis can be used. If such face is considered balanced, perfect or ideal is at least not clear to me, it's more a mathematical convention. Often mathemathical symmetry can be interesting though, there are cases where e.g the golden ratio and other symmetry is sometimes linked to aesthetics.

I actually don't know if steiner reference values are based on population, but values like ANB are at least much less complex to understand the meaning of, it's just one angle and it's clear it's linked to the overjet and mandibular projection with reference to the maxilla and skull.

I would say that Sassouni analysis is of course interesting to look at, but it seems like there are far more modern ways to evaluate aesthetic proportions, if that is what your question is about.

I see what you’re saying. In the slide it does say these landmarks are the same distance in actual well-proportioned faces as analyzed in a study of 100 people, so it is at least based on actual human faces and not entirely theoretical. But you’re right it’s not obvious how relevant these numbers are to aesthetics.

Which analyses do you think are most relevant to evaluate aesthetics? I can then share those reports here.

[Dogmatix]

I see what you’re saying. In the slide it does say these landmarks are the same distance in actual well-proportioned faces as analyzed in a study of 100 people, so it is at least based on actual human faces and not entirely theoretical. But you’re right it’s not obvious how relevant these numbers are to aesthetics.

Which analyses do you think are most relevant to evaluate aesthetics? I can then share those reports here.

It also says that in the population of 100, only 16 were found to fall within a "well proportioned" face, and as established, no link to aesthetics at all presented.

There are some studies on aesthetics. E.g from ArnettGunson.
http://www.orthodonticproductsonline.com/2009/09/can-beauty-be-quantified-2009-09-07/

[ODog]

It also says that in the population of 100, only 16 were found to fall within a "well proportioned" face, and as established, no link to aesthetics at all presented.

There are some studies on aesthetics. E.g from ArnettGunson.
http://www.orthodonticproductsonline.com/2009/09/can-beauty-be-quantified-2009-09-07/

Very interesting article, thanks!

So does anyone think I need anything other than maxillary widening?