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The downward and forward growth of the adult jaw  

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EddieMoney
Reputable Member

I was noticing something about the way jaws grow in primates. 

Notice the downward and forward growth simultaneously of the jaw in this monkey. Now, humans do not experience such pronounced levels of growth as we are more neotenous. But look below.

The first guy was a kid (Mac Miller) in his 20s I believe. Notice how his maxilla looks like it is behind his nasion despite the fact it has forward projection and counterclockwise rotation. Meanwhile Michael Fassbender's maxilla looks like it is ahead of his nasion.

So similar to chimps and other primates, our jaws grow both forward AND downward. But this isn't indicative of recession, but rather complete bone development. As the maxilla grows in all directions, the facial height may increase, too 

I am sure Mac Miller had a Mew line much shorter than Fassbender, but it only serves as an indicator that facial height is yet again not a very useful tool in showing whether someone ideally developed or not.

I post this to again show that the whole concept of "upswing" seems to be irrelevant for adults when we consider how the maxilla grows. However widening can yield results as if upswing happened. Look at Fassbender's wide face. It doesn't matter if it is longer in vertical height. 

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Posted : 26/11/2019 11:34 am
Pame
 Pame
Trusted Member

So basically wide arch = good face?

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Posted : 26/11/2019 12:55 pm
EddieMoney
Reputable Member
Posted by: @pame

So basically wide arch = good face?

I have yet to see am arch that is wide on a face that grew just downward without also growing forward. If such a thing exists in nature I have yet to see it.

Considering the midface ratio can be affected through added width I think there is something to this. I also think that for those thinking that their occlusal plane needs to drastically change (aka significant rotation) seem misguided. Your face can develop a decent jawline with a good midface ratio even if your facial vertical length increases. 

I think I am just seeing facial development in a different way than I previously did. I was all about the vertical shortening but now I realize that may not matter much at all. 

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Posted : 26/11/2019 2:36 pm
TGW liked
PaperBag
Trusted Member

Good post. I was thinking about this last night while looking at the Crane and remembering that them promoting a forward and downward pulling angle was criticized. Expansion and pulling down (in whichever order is preferable, if it matters) sounds like it would resolve a stuck mandible for those with class 2 bites. My face seems compact enough, (but not pug-faced) though the ratios are bad. I probably do need some lengthening, as imagining a total upswing might make my head look like it was crushed with a hydraulic press.

@EddieMoney With all of your posts emphasizing the need for widening, wouldn't a Schwarz appliance be a key component for getting results? @Progress expanded by several mms with a similar expander but it seemed to not make a huge difference for future change.

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Posted : 26/11/2019 7:13 pm

Looks like the worse looking guy has molars that are vertically too high in relation to his front teeth.

this is exactly the problem i need to fix. i need to bring those upper back teeth down so I can look like the better looking dude (who's back teeth slope downwards)

you can see that their upper front 6 teeth are quite similar in positon and angle, but past the canines, the younger dude curves up and the older dude curves down

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Posted : 26/11/2019 8:11 pm
printfactory
Eminent Member

I don´t think a wide palate means you automatically have good forward growth. My palate isn´t that bad (~37mm IMW) but I have seen faces that have mine or even lower IMW and much better forward growth.

 
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Posted : 27/11/2019 7:50 am
EddieMoney
Reputable Member
Posted by: @printfactory

I don´t think a wide palate means you automatically have good forward growth. My palate isn´t that bad (~37mm IMW) but I have seen faces that have mine or even lower IMW and much better forward growth.

 

What are you measuring your palate with? Are these from an impression?

Also, do you have any examples of narrow palates with good development? I haven't seen this. Narrow palates accompany narrow skulls, usually. Maybe some palates look narrow compared to their total fwhr?

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Posted : 27/11/2019 8:41 am
printfactory
Eminent Member

@eddiemoney

Yes, impressions + caliper. I don´t have any specific examples right now, but sometimes people would post their face and IMW, which lead me to that assumption. Also afaik the average IMW nowadays is around 37-38mm and when I compare myself to people on the street I´d say 80-90% have better forward growth than me. 

 

Maybe another factor playing into this is how big the skull was supposed to grow. People who have genetically  overall smaller bones would look more developed with 37mm IMW than someone who was supposed to have bigger bones. 

 

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Posted : 27/11/2019 11:46 am
EddieMoney
Reputable Member
Posted by: @printfactory

@eddiemoney

Yes, impressions + caliper. I don´t have any specific examples right now, but sometimes people would post their face and IMW, which lead me to that assumption. Also afaik the average IMW nowadays is around 37-38mm and when I compare myself to people on the street I´d say 80-90% have better forward growth than me. 

 

Maybe another factor playing into this is how big the skull was supposed to grow. People who have genetically  overall smaller bones would look more developed with 37mm IMW than someone who was supposed to have bigger bones. 

 

Maybe actual millimeters don't matter but just the jaw growing to its optimal development.

But I would still be curious what these supposed narrow palate people with great jaw development look like. Like I said I haven't seen it. 

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Posted : 27/11/2019 11:57 am
printfactory
Eminent Member

@eddiemoney

I didn´t mean great development, just better than mine. Saying average IMW equals average forward growth and average jaw development is too simple. There must be other factors playing a role too to explain cases like mine.

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Posted : 27/11/2019 1:45 pm
TGW
 TGW
TGW Admin Admin
Posted by: @eddiemoney
Posted by: @pame

So basically wide arch = good face?

I have yet to see am arch that is wide on a face that grew just downward without also growing forward. If such a thing exists in nature I have yet to see it.

Excellent observation, it's hard to even imagine what a face growing like that would look like. 

 

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Posted : 27/11/2019 2:53 pm
printfactory
Eminent Member

Hmm, maybe we could say naturally wide arch = good face. 

To get a wide arch naturally, the tongue needs to exert force on the palate. That force is partly transferred on other bones like the sphenoid who impact the whole face. 

I had an acrylic expander as a teenager and invisalign+retainer after that. So I got a somewhat average palate through that procedure, but all the cranial growth that would´ve happend if my tongue had been on the roof of my mouth didn´t take place.

So previous orthodontic work could explain why some people have an okay palate, but still not really a well developed face.

 
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Posted : 27/11/2019 3:12 pm
PaperBag
Trusted Member

@printfactory That could be the explanation for some people, yes. Expanders aren't uncommon during orthodontic treatment, though I didn't get one and still have an IMW over 40mm. (and could probably use another few mms) I have a vaulted palate, so my room for progress seems pretty much capped unless I use an expander that drops the palate down. The DNA and apparently Schwarz supposedly accomplish this, according to some.

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Posted : 27/11/2019 5:28 pm
EddieMoney
Reputable Member
Posted by: @paperbag

Good post. I was thinking about this last night while looking at the Crane and remembering that them promoting a forward and downward pulling angle was criticized. Expansion and pulling down (in whichever order is preferable, if it matters) sounds like it would resolve a stuck mandible for those with class 2 bites. My face seems compact enough, (but not pug-faced) though the ratios are bad. I probably do need some lengthening, as imagining a total upswing might make my head look like it was crushed with a hydraulic press.

@EddieMoney With all of your posts emphasizing the need for widening, wouldn't a Schwarz appliance be a key component for getting results? @Progress expanded by several mms with a similar expander but it seemed to not make a huge difference for future change.

I don't know specifically why a Schwartz appliance. Why not Homeoblock or DNA?

ReplyQuote
Posted : 28/11/2019 10:59 pm
EddieMoney
Reputable Member
Posted by: @printfactory

@eddiemoney

I didn´t mean great development, just better than mine. Saying average IMW equals average forward growth and average jaw development is too simple. There must be other factors playing a role too to explain cases like mine.

I think those measurements may not take things into account like tooth size. What if people with bigger teeth need greater expansion?

Also, it is still possible that people with good development can appear to have narrow palates. Henry Cavill appears this way because his intercanine distance isn't very great. His intermolar distance however is wide. He has a parabolic palate which gets wider toward the molars and narrower toward the canines, making his front palate narrower.

I have thought that parabolic palates can give that illusion. But if they seem more narrow toward the front it may also he possible that they developed decently since the maxilla also got long as well as wide.

These parabolic maxillae are probably at their best development where the front would appear narrow simply due to the tongue pushing them forward as well as sideways. This could be due to the downward growth that happens along with forward growth. Sure, the canines aren't super far apart but as long as the IMW is high the mandible has enough room to protract forward.

@printfactory is your face short naturally? Also, are your canines far apart or closer together? Is your palate U shaped (canines and molars are about at the same width give or take), parabolic (\_/), or elliptical (rounded)?

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Posted : 28/11/2019 11:12 pm
EddieMoney
Reputable Member
Posted by: @printfactory

Hmm, maybe we could say naturally wide arch = good face. 

To get a wide arch naturally, the tongue needs to exert force on the palate. That force is partly transferred on other bones like the sphenoid who impact the whole face. 

I had an acrylic expander as a teenager and invisalign+retainer after that. So I got a somewhat average palate through that procedure, but all the cranial growth that would´ve happend if my tongue had been on the roof of my mouth didn´t take place.

So previous orthodontic work could explain why some people have an okay palate, but still not really a well developed face.

 

Yes, previous orthodontic work may have also pushed your jaw back as opposed to it growing naturally. I think this is very feasible. 

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Posted : 28/11/2019 11:15 pm
PaperBag
Trusted Member
Posted by: @eddiemoney

I don't know specifically why a Schwartz appliance. Why not Homeoblock or DNA?

Not specifically. I mentioned the DNA appliance in my other post right above your reply; it and the Homeoblock could also be used if they're all going to do the same thing. It's just that the Schwarz is a standard palate expander and will be infinitely easier for most people to find someone to treat them with it versus the other appliances.

ReplyQuote
Posted : 29/11/2019 1:50 am
Progress
Member Moderator

Allow me to share something that could be relevant to your thread. A while ago I had a hunch that ante-gonial notch could, at least in some cases, point to lack of maxillary molar height, which would then lead to upward compression of the the mid-jawline in order to achieve molar contact. By googling around for suitable pics to test this idea with, I found a pic @newuser posted a year ago that offered an illuminating comparison:

While these are two different skulls, it's interesting how there is not that much difference between their maxillae, which is contrary to what one would expect based on the jawlines. The overwhelmingly largest differences are found in mandibular shape, zygomatic height and the posterior cranial base. What seems surprising is that such a small change in maxillary molar height results in so different mandibular shape - and that all of this difference is achievable with seemingly identical maxillary positioning and shape. Another surprising thing is how the mandibular arch does not move in position, but rather only changes in pitch. The condyles and nasal openings are identically positioned, which implies that practically all action is happening in the alveolar bone or near it.

The question is: what exactly leads to this favorable downward development of the maxillary alveolar process? I have a couple of possible ideas:

1) intra-oral vacuum. When the teeth are apart and cheeks sucked in, the resulting vacuum will generate a pull that develops the alveolar ridge downward.

2) Expanding the maxilla causes molars to swing down and the zygos to rise up, essentially increasing the amount of bone between the two.

 

In addition, the mechanisms that the animation above suggests are quite different and subtler than what Mew has illustrated:

 

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Posted : 29/11/2019 7:02 am
EddieMoney
Reputable Member
Posted by: @progress

Allow me to share something that could be relevant to your thread. A while ago I had a hunch that ante-gonial notch could, at least in some cases, point to lack of maxillary molar height, which would then lead to upward compression of the the mid-jawline in order to achieve molar contact. By googling around for suitable pics to test this idea with, I found a pic @newuser posted a year ago that offered an illuminating comparison:

While these are two different skulls, it's interesting how there is not that much difference between their maxillae, which is contrary to what one would expect based on the jawlines. The overwhelmingly largest differences are found in mandibular shape, zygomatic height and the posterior cranial base. What seems surprising is that such a small change in maxillary molar height results in so different mandibular shape - and that all of this difference is achievable with seemingly identical maxillary positioning and shape. Another surprising thing is how the mandibular arch does not move in position, but rather only changes in pitch. The condyles and nasal openings are identically positioned, which implies that practically all action is happening in the alveolar bone or near it.

The question is: what exactly leads to this favorable downward development of the maxillary alveolar process? I have a couple of possible ideas:

1) intra-oral vacuum. When the teeth are apart and cheeks sucked in, the resulting vacuum will generate a pull that develops the alveolar ridge downward.

2) Expanding the maxilla causes molars to swing down and the zygos to rise up, essentially increasing the amount of bone between the two.

 

In addition, the mechanisms that the animation above suggests are quite different and subtler than what Mew has illustrated:

 

Is it just me or is the skull with the smaller mandible a female skull? It lacks a brow ridge and has a completely vertical forehead. The mandible is also smaller. 

Also, which skull would experience the intra oral vacuum? The robust skull? 

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Posted : 29/11/2019 8:13 am
Progress
Member Moderator

Good point, it absolutely is a female skull. Yes I assume that the arches in the male skull could be result of intra-oral vacuum. My reasoning is that in a closed vacuum, everything gets pulled towards the center of the vacuum. So the upper and lower molars along with cheeks and sides of tongue all get pulled towards the center that resides somewhere in the space between the dental arches.

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Posted : 29/11/2019 8:30 am
Progress
Member Moderator

@varbrah also posted this great illustration highlighting the direction of maxillary sutures a while ago:

With this in mind, I wonder how useful pushing upward with the tongue could even be in the first place. You almost end up pushing against the sutures instead of disarticulating them. Intra-oral vacuum on the other hand could be more able to create the kind of force vector that sutural growth demands.

 

 

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Posted : 29/11/2019 11:21 am
EddieMoney
Reputable Member
Posted by: @progress

@varbrah also posted this great illustration highlighting the direction of maxillary sutures a while ago:

With this in mind, I wonder how useful pushing upward with the tongue could even be in the first place. You almost end up pushing against the sutures instead of disarticulating them. Intra-oral vacuum on the other hand could be more able to create the kind of force vector that sutural growth demands.

 

 

To me this all helps to facilitate understanding of why a suction hold would be beneficial as opposed to trying to jam your tongue up and trying to lift the maxilla with it. Seems to me the suction hold on the posterior third will pull down the molars, causing lengthening of the ramus and decreasing the gonial angle. 

And in none of this does the vertical facial height decrease. But the added cheekbone prominence and palate width will all widen the face, making it appear shorter.

Maybe this is why suction is part of the system as opposed to tiring out one's tongue trying to shorten their midface. 

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Posted : 29/11/2019 5:58 pm

@progress

@eddiemoney

looking at @progress' skull gif-the maxillairy tooth 2nd furtherest to the left, is pointing more forwards in the better skull. It’s like a 90 degrees difference. so relative to the molars, could a more forward tongue positon allow the suction to pull these teeth down, AND pointing more forwards....   could this contribute to a desirable forward upper incisor angle?. It would also push the mandible teeth forwards (to meet the more forward upper teeth), but would be angled backward...which presumably helps the lower incisors to be angled back, pushing the chin and mandible forward and creating a more open bite

also, I understand that incisive papilla contact is benifical for body posture, but for maxilla rotation would it be better to curve the front tongue downwards....allowing the posterior tongue to sit further forward? I know someone had a theory that pushing the tongue too far forward will jam the bones of the hard palate, but i doubt many of us will be able to do that unless we stick our tongue past our teeth.

also, does anyone believe that the upwards force of the tongue during swallow and rest, actually contributes to development? or is it simply a by-product of good resting tongue posture and oral vacume. Just because upwards force is generated, doesnt mean it serves any purpose...if there were zero negative consequences then we wouldn't evolve out of it. Unless the upwards force also helps keep the entire skull together?

thoughts appreciated

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Posted : 30/11/2019 5:34 am
Fiver
Active Member

Does anybody know of a picture of a skull with a downward grown face without an open bite?
If the maxilla really is back and downward the distribution of the force from the tongue could be quite different than in a normal developed skull.

Edit:
Not sure how I can include pictures, but I found something interesting regarding the "pulling-down" theory: 

https://en.wikipedia.org/wiki/Medial_pterygoid_muscle

One head of the pterygoideus internus (a muscle of mastication) is attached to the maxilla.
So maybe biting on something with the front part of your jaws could pull the back of the maxilla down, 
while simultaneously pushing the front part up, thus providing the forces necessary for a rotation of the maxilla.

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Posted : 30/11/2019 9:04 am
printfactory
Eminent Member
Posted by: @eddiemoney
Posted by: @printfactory

@eddiemoney

I didn´t mean great development, just better than mine. Saying average IMW equals average forward growth and average jaw development is too simple. There must be other factors playing a role too to explain cases like mine.

@printfactory is your face short naturally? Also, are your canines far apart or closer together? Is your palate U shaped (canines and molars are about at the same width give or take), parabolic (\_/), or elliptical (rounded)?

I have the classically downward grown face with a long mid-face, dorsal hump, antegonial notches and weak lower third and a slight deep bite, palate is elliptical. 

 

facegettingworseandworse Swallowing seems important. I have found this study where they treat a class 3 patient non-surgically with a tongue appliance: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3700158/

In the discussion section it says:

The pressure of the tongue during swallowing might reach 5 pounds in each swallowing. The frequency of swallowing is about 500–1200 times in 24 h. This intermittent force is transferred through the tongue appliance to the deficient nasomaxillary complex.

I guess even without such an appliance swallowing can at least transfer some kind of force to the maxilla.

 

ReplyQuote
Posted : 30/11/2019 5:52 pm
Posted by: @facegettingworseandworse

@progress

@eddiemoney

looking at @progress' skull gif-the maxillairy tooth 2nd furtherest to the left, is pointing more forwards in the better skull. It’s like a 90 degrees difference. so relative to the molars, could a more forward tongue positon allow the suction to pull these teeth down, AND pointing more forwards....   could this contribute to a desirable forward upper incisor angle?. It would also push the mandible teeth forwards (to meet the more forward upper teeth), but would be angled backward...which presumably helps the lower incisors to be angled back, pushing the chin and mandible forward and creating a more open bite

also, I understand that incisive papilla contact is benifical for body posture, but for maxilla rotation would it be better to curve the front tongue downwards....allowing the posterior tongue to sit further forward? I know someone had a theory that pushing the tongue too far forward will jam the bones of the hard palate, but i doubt many of us will be able to do that unless we stick our tongue past our teeth.

also, does anyone believe that the upwards force of the tongue during swallow and rest, actually contributes to development? or is it simply a by-product of good resting tongue posture and oral vacume. Just because upwards force is generated, doesnt mean it serves any purpose...if there were zero negative consequences then we wouldn't evolve out of it. Unless the upwards force also helps keep the entire skull together?

thoughts appreciated

any ideas guys? 

I'm not disagreeing with this thread, but if definitely looks Mac miller has a more clockwise rotated maxilla. 

what is going on with the bruce lee actor here?  Very rare to see faces like that? with the long 90 degree ramus with clockwise maxilla.....

Does michele rodrigez have a manly look because her maxilla is slightly too far forward or incisors which are proclined?

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Posted : 01/12/2019 8:22 pm
EddieMoney
Reputable Member
Posted by: @facegettingworseandworse
Posted by: @facegettingworseandworse

@progress

@eddiemoney

looking at @progress' skull gif-the maxillairy tooth 2nd furtherest to the left, is pointing more forwards in the better skull. It’s like a 90 degrees difference. so relative to the molars, could a more forward tongue positon allow the suction to pull these teeth down, AND pointing more forwards....   could this contribute to a desirable forward upper incisor angle?. It would also push the mandible teeth forwards (to meet the more forward upper teeth), but would be angled backward...which presumably helps the lower incisors to be angled back, pushing the chin and mandible forward and creating a more open bite

also, I understand that incisive papilla contact is benifical for body posture, but for maxilla rotation would it be better to curve the front tongue downwards....allowing the posterior tongue to sit further forward? I know someone had a theory that pushing the tongue too far forward will jam the bones of the hard palate, but i doubt many of us will be able to do that unless we stick our tongue past our teeth.

also, does anyone believe that the upwards force of the tongue during swallow and rest, actually contributes to development? or is it simply a by-product of good resting tongue posture and oral vacume. Just because upwards force is generated, doesnt mean it serves any purpose...if there were zero negative consequences then we wouldn't evolve out of it. Unless the upwards force also helps keep the entire skull together?

thoughts appreciated

any ideas guys? 

I'm not disagreeing with this thread, but if definitely looks Mac miller has a more clockwise rotated maxilla. 

what is going on with the bruce lee actor here?  Very rare to see faces like that? with the long 90 degree ramus with clockwise maxilla.....

Does michele rodrigez have a manly look because her maxilla is slightly too far forward or incisors which are proclined?

Michelle Rodriguez has a strong lower third. That makes her look more masculine. 

ReplyQuote
Posted : 01/12/2019 11:19 pm

@fiver

I agree that front teeth chewing/biting is important to an extent, but I have a strong feeling it’s largely the tongue and or other muscles that make the biggest difference. 

If it was simple enough to just chew with the front teeth to send the front maxilla up and molars down, I don’t think we’d be here discussing this.......just my personal feeling

it may help keep the incisors up, but they won’t go any further with chewing alone, if this picture is accurate

ReplyQuote
Posted : 02/12/2019 5:02 am

appreciate all your responses Eddie, and everyone else too

 

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Posted : 04/12/2019 4:13 am

maybe CCW rotation will not result in ramus lengthening IF the maxilla is already clockwise rotated, especially if your bite currently favours the front teeth.....meaning the molars will come down to meet the bottom teeth....

I wounder if people with more of a closed bite have an advantage in this respect......but then again I suppose anyone who keeps teeth apart will have an equal playingfield for rotation. Although progress said his mandible progression has suffered due to lack of teeth contact over his journey......

also I posted that photo of Michele flying a chopper in Avatar, anyone else love that movie? Definetly not the most original but as if I care, thought it was beautifully executed. And the extended editions are actually better than theatrical

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Posted : 04/12/2019 4:21 am
Progress
Member Moderator
Posted by: @facegettingworseandworse

maybe CCW rotation will not result in ramus lengthening IF the maxilla is already clockwise rotated

If you look at the pic you posted where the circummaxillary sutures are highlighted, it becomes quite apparent that ramus would lengthen as maxilla grows down and forward. The purpose of the rami is to ensure that the mandibular molars meet the maxillary molars at correct height, so naturally the latter coming down would cause the rami to adapt.

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Posted : 04/12/2019 9:44 am

Thanks for responding progress

 

Looking at that skull again, the bottom teeth are further ahead of the upper teeth which they connect with. Mine are the opposite because my clockwise maxilla is trapping the mandible too far back, which is reinforcing this AND also reinforcing maxillary molars which are pointing diagonally backwards instead of diagonally forwards. If one can increase inter cainine width, you apparently have more room to artificially bring the mandible further forward and bite with the upper and lower incisors closer together. Wheather this will impact rotation I don’t know. But it could create better tooth angle.

Our tongues are also further back than ideal, and I cant help but think that even with mewing, we are not activating the area which will actually rotate the maxilla, because it is trapped back with everything else. Again I come back to the method where the jaw is brought forward slighly and the tongue tip is curved downwards in order to aviod pushing incisors as the posterior tongue comes further forward. This could also relate to the angle of the maxillairy teeth......

It does also seem that downward growth could be belped by tipping the head up slighly, because it gives the posterior tongue more room to pull down. However I struggle with this because I have a tongue tie....

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Posted : 05/12/2019 2:25 am