Soft or hard tissue problem?

[kavan]

I'm getting a bit confused regarding what the horizon actually is here. It seems like the meassurements you made, assume the absolute horizon in the ceph, but isn't that a bit ambigious reference to meassure with? As I remember the situation when taking the ceph, it was more like "put your head here", and maybe not my natural head posture. Wouldn't it make more sense to meassure the ANS-PNS rotation against horizon with the FH-Horizon, which is not ambigious, compared to the relative horizon which may change depending on how the head is positioned when taking the ceph. I'm thinking, if the green line would be FH-Horizon, then the angle would be lower than 11.

It's not ambiguous when I make clear I measured relative to an absolute horizon of the photo which is perpendicular to the vertical of the cephalostat. However, if you can find the  Frankfurt Horizont in the ceph, you can measure relative to that.
'Po' point (needed for FH) is sometimes difficult to see on a ceph. For that reason the Steiner analysis uses the 'S' point.

Not all people have a FH that is 'horizontal' and based on my eyeballing your ceph, but just approximating where the 'Po' point would be (but not being able to exactly find it), it looks like your FH is not 'horizontal'.

[Dogmatix]

It's not ambiguous when I make clear I measured relative to an absolute horizon of the photo which is perpendicular to the vertical of the cephalostat. However, if you can find the  Frankfurt Horizont in the ceph, you can measure relative to that.
'Po' point (needed for FH) is sometimes difficult to see on a ceph. For that reason the Steiner analysis uses the 'S' point.

Not all people have a FH that is 'horizontal' and based on my eyeballing your ceph, but just approximating where the 'Po' point would be (but not being able to exactly find it), it looks like your FH is not 'horizontal'.

I'm not sure if what I'm pointing at got through completely. There's no ambiguity in what is meassured, it's completely clear.
What I'm confused about is how to interpret the 11 deg angle. If we agree that this angle is based on how I hold my head when taking the ceph, in a way where if I tilt my head either up or down, it will change. If so, this also implies that it's hard to evaluate if there's an abnormal rotation of ANS-PNS, as I could go back, take another ceph and get a different result.

If the angle would be meassured with FH-plane, I couldn't go back and take another ceph to get another result, it would be a fixed relation.  I'm not in any way qualified to make an absolute mark where the FH-plane is, but I think it's safe to say that the ceph would be rotated CW, and when I do some guessing it seems atleast 5 degrees. If the ceph is rotated 5 degrees, the 11 degree angle would be decresed to 6, which would put the analysis in a different context, saying that ANS-PNS is rotated CW compared to norm.

When saying that the norm is 7 deg, what is the definition of this norm. Is it defined as a meassurement of ANS-PNS to the absolute horizon? It seems like there must be a strict definition of how this angle is meassured when there's a norm attached to it. "if you can find the  Frankfurt Horizont in the ceph, you can measure relative to that." This sounds like I can meassure relative to anything I like, and maybe even find a horizon that will make it follow the norm.

I'm not sure how you mean when you say that everyone doesn't have a FH-plane, and that mine is not horizontal. It's surely not horizontal with the ceph, which is basically what this question is all about, where I mean that I don't remember anyone pointing out for me to hold my head in a "natural" position when doing the x-ray.

In some sense, the goal of such surgery is to get a balanced facial profile, and it seems like meassurement with FH-plane would be a more strict definition and put the jaws in a relation with the skull, while meassurement with the ceph horizon or posture horizon is more fuzzy, and I'm trying to understand how this is normally handled.

[kavan]

I'm not sure if what I'm pointing at got through completely. There's no ambiguity in what is meassured, it's completely clear.
What I'm confused about is how to interpret the 11 deg angle. If we agree that this angle is based on how I hold my head when taking the ceph, in a way where if I tilt my head either up or down, it will change. If so, this also implies that it's hard to evaluate if there's an abnormal rotation of ANS-PNS, as I could go back, take another ceph and get a different result.

If the angle would be meassured with FH-plane, I couldn't go back and take another ceph to get another result, it would be a fixed relation.  I'm not in any way qualified to make an absolute mark where the FH-plane is, but I think it's safe to say that the ceph would be rotated CW, and when I do some guessing it seems atleast 5 degrees. If the ceph is rotated 5 degrees, the 11 degree angle would be decresed to 6, which would put the analysis in a different context, saying that ANS-PNS is rotated CW compared to norm.

When saying that the norm is 7 deg, what is the definition of this norm. Is it defined as a meassurement of ANS-PNS to the absolute horizon? It seems like there must be a strict definition of how this angle is meassured when there's a norm attached to it. "if you can find the  Frankfurt Horizont in the ceph, you can measure relative to that." This sounds like I can meassure relative to anything I like, and maybe even find a horizon that will make it follow the norm.

I'm not sure how you mean when you say that everyone doesn't have a FH-plane, and that mine is not horizontal. It's surely not horizontal with the ceph, which is basically what this question is all about, where I mean that I don't remember anyone pointing out for me to hold my head in a "natural" position when doing the x-ray.

In some sense, the goal of such surgery is to get a balanced facial profile, and it seems like meassurement with FH-plane would be a more strict definition and put the jaws in a relation with the skull, while meassurement with the ceph horizon or posture horizon is more fuzzy, and I'm trying to understand how this is normally handled.

You're a bit too confused for me to unconfuse. If you want to use the Frankfurt H then you need to find exactly where point 'Po' is and also point 'Or' where Po is not that easy to find on a ceph. I've approximated both on your ceph to demonstrate that your FH is not a 'pure' horizont and is approx. 11 degrees from a pure horizont.

A 'pure' horizont would be one that is perpendicular to the vertical of the cepholastat. Not everyone's FH is a pure horizont. I can't fathom what is so hard to understand about that.

If you are concerned about your head position, which looks right to me, then have your doc mark out the POINTS, especially the FH and measure the angles yourself OR find some ceph analysis place on the net that will mark out the points on your ceph.

The easiest ones to find are 'S' and 'N' which the line connecting those points are rarely pure horizonts either but as used as 'horizontal' planes in Steiner analysis.

[Dogmatix]

You're a bit too confused for me to unconfuse.

Lol. Never had someone sum up my life in one sentence with such accuracy

I've approximated both on your ceph to demonstrate that your FH is not a 'pure' horizont and is approx. 11 degrees from a pure horizont.

A 'pure' horizont would be one that is perpendicular to the vertical of the cepholastat. Not everyone's FH is a pure horizont. I can't fathom what is so hard to understand about that.

If the definition of a pure horizon is that it's "perpendicular to the vertical of the cepholastat", then there's nothing hard to understand about the terminology. What I'm trying to figure out is if such meassurement can be used with confidence when taking a decission, or comparing to a norm, since it can be altered by the patient and the instructions of the nurse when taking the x-ray.

I may walk around with my head horizontal to the FH-plane, or maybe not, who knows. Putting my head in a machine to take an x-ray while sitting down doesn't seem to be an accurate way to evaluate if my FH is a pure horizon in my normal life. If I would put my head in the x-ray and orient the FH-plane with the horizon of the cepholastat, we would have a result telling me that my ANS-PNS is significantly rotated CW.

The easiest ones to find are 'S' and 'N' which the line connecting those points are rarely pure horizonts either but as used as 'horizontal' planes in Steiner analysis.

This seems as good as the FH-plane to me. Wouldn't using this horizon tell me that ANS-PNS is significantly rotated CW, if the norm is 7 degrees with steiner analysis as well?

[kavan]

Your question/confusion is predicated on the assumption that you are NOT aligned properly with what is meant to be measured. So all your confusing pondering is a moot point unless you can demonstrate that you are NOT aligned properly.

Let me put it this way, if your ANS-PNS were not overly rotated CCW in orientation (disregard the # of degrees with the pure horizont I made!), do you think you would have the DEEP BITE your you have or the low angle mandibular plane?

[Dogmatix]

.

Let me put it this way, if your ANS-PNS were not overly rotated CCW in orientation (disregard the # of degrees with the pure horizont I made!), do you think you would have the DEEP BITE your you have or the low angle mandibular plane?

The first thing I think of as a cause of the deep bite and low angle mandibular plane is the class 2 relation and overjet, allowing it to grow that way. Trying to figure out how a different rotation of the ANS-PNS would've change the development of the bite, but it only seems like it would put the jaws in a strange relation.

It's actually same confusion from my end here as well. Evaluating if the maxilla is overly rotated by using the mandible as reference, assume that the mandible is correct, when it actually could be the mandible that has "wrong" position.

I think this discussion concludes what we're already discussed. When fixing issues like this there's no clear answear what is the "correct" movement. Surgeon offers further ccw rotation even though it may be argumentet that it's already overly rotated, since it's the best he can do with the situation.

What I was pursuing was a way to measure that doesn't have a reference that is mobile and can be changed, as I'm a bit insecure about my head posture and want to exclude myself from the equation if possible, and it would also motivate further ccw rotation. FH-plane and steiner hz plane are both such planes that are attached to the skull, and you would have to be a real dare devil trying to have surgery to change those. When looking at displacement diagrams and cephalometric analyzis,  it seems like surgeons often look at the cephs rotated to one of these planes and that surgeons maybe evaluate the situation with one of these rotations?

[kavan]

You have not demonstrated WHY you think your head is not oriented correctly. Do you realize that IF you tried to tip your head CW 11 degrees, the cephalostat (angled part) would preclude that? So, what is it about the ceph that makes you think that if you held your head differently, you would have the 'correct' alignment for the ceph and your FH would be parallel with the horizont?

Here is your ceph rotated (CW) 11 degrees. So that now your FH is on the horizont as pretty much your ANS-PNS. Does that make it any easier for you?

[april]

Just to clairfy, is NHP the correct posture/alignment for taking a ceph? Or are techs adjusting patients to a specific plane, prior to the ceph being taken?

[kavan]

Just to clairfy, is NHP the correct posture/alignment for taking a ceph? Or are techs adjusting patients to a specific plane, prior to the ceph being taken?

Great question and very succinctly expressed so it's clear (to me) what you are asking.

Assuming that NHP stands for Natural Head Position, here is a link to an article (although there are many articles on this) on the subject matter.

https://www.sciencedirect.com/science/article/pii/S2395921516301179#fig0005

When reading the article, it's important to differentiate 'Natural Head Position' from 'Natural (head) POSTURE' because both sound so similar.

Here is an excerpt from the article regarding the Frankfurt Horizont:

[The Frankfort Horizontal Plane (FHP) is one of the most used planes in cephalometry. It was adopted with the purpose of orienting the skull in a similar way to the natural head position. In cephalometric practice this plane presents two difficulties: a) Problems in locating accurately its two reference points, especially Porion, b) The operator assumes that the Frankfurt plane is parallel to the true horizontal plane which does not occur in many individuals, there have been observed differences of up to 10 degrees and even more.17 Arnett mentions:18 no one walks with the Frankfort plane parallel to the ground and we can have a patient in natural head position but with the Frankfurt Plane inclined upwards or downwards.]

And another concept from the study:

[ Concepts used in the study.

Natural head position (assisted)   It is defined as an innate, physiological and reproducible position of the head. It is obtained when the patient is in a relaxed position, sitting or standing, looking into the horizon or into an external reference point (mirror, mark on the wall, etc.) at eye level2., 3., 4., 5., 6., 7., 8., 9., 10., 11., 12., 13. or at the same level as the olives

Natural head posture (orthoposition)   It is the physiological position that a person shows when giving a step forward. This posture is different among individuals and may vary if the person has nasal obstruction or other physiological anomalies2,3,29]

[april]

Oh boy, I had no idea natural head posture and natural head position were two different things. Thanks for the reference, Kavan. I'm going through some of the other references linked too.

I think my head position looks different in about half of my cephs. This may be because I've been to 2-3 dental radiology places over the years (different machines and different operators). I can't remember if I was told to look to the horizon or not, but definetly never had an external reference point such as a mirror.

The next question I've been wondering about is if there's a significant change to the way one naturally holds their head after surgery -- in class II's correctly corrected I would assume so given increased airways and less need for self-posturing.

[kavan]

Oh boy, I had no idea natural head posture and natural head position were two different things. Thanks for the reference, Kavan. I'm going through some of the other references linked too.

I think my head position looks different in about half of my cephs. This may be because I've been to 2-3 dental radiology places over the years (different machines and different operators). I can't remember if I was told to look to the horizon or not, but definetly never had an external reference point such as a mirror.

The next question I've been wondering about is if there's a significant change to the way one naturally holds their head after surgery -- in class II's correctly corrected I would assume so given increased airways and less need for self-posturing.

Natural head posture and natural head position are so confusing. I know.  Class 2's often tilt their head up so jaw does not blend into neck too much. I guess if the lower jaw is brought forward, they would have to compensate less that way.

[Dogmatix]

Oh boy, I had no idea natural head posture and natural head position were two different things. Thanks for the reference, Kavan. I'm going through some of the other references linked too.

I think my head position looks different in about half of my cephs. This may be because I've been to 2-3 dental radiology places over the years (different machines and different operators). I can't remember if I was told to look to the horizon or not, but definetly never had an external reference point such as a mirror.

The next question I've been wondering about is if there's a significant change to the way one naturally holds their head after surgery -- in class II's correctly corrected I would assume so given increased airways and less need for self-posturing.

What is clear is that there is a relation between forward head posture and OSA

https://www.ncbi.nlm.nih.gov/pubmed/27894543
https://www.ncbi.nlm.nih.gov/pubmed/9633167
https://www.intechopen.com/books/sleep-apnea-recent-updates/head-posture-and-upper-cervical-spine-morphology-in-patients-with-obstructive-sleep-apnea

What would seem logical to me is that the forward head posture is a way for people with OSA to open their airways mechanically, by moving their head forward and tilting it up. Same movement as a maxillomandibular advancement does. To me it seems like there could be a relation that if the airways are opened with a MMA surgery, the need for a forward head posture could be relieved.
Everything below the publications are my own thoughts and not anything I've been able to get confirmed by anyone.