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A deviation in my views  

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TGW
 TGW
TGW Admin Admin

Changing the relative position/rotation of the maxilla isn't the goal, the goal is to grow it to its full potential size.

In my opinion, the idea of up/down swing isn't correct - what an underdeveloped maxilla really means is a lack of anterior-posterior depth in the maxilla and nasal passages, and underdevelopment of the sinuses.

This is an illustration of the upper palate/bottom of the maxilla. It can be extrapolated to the entire nasomaxillary complex. The upper palate does naturally slope downward from the throat to the front teeth.

You can see that the amount of growth/size in the inferior/downward direction is virtually the same. The difference is just the amount of depth, how much the nasomaxillary complex has grown forward.

An underdeveloped nasomaxillary complex looks downward grown because it's got more of it's downward development completed, and the forward development that needs to accompany it hasn't happened. 

The maxilla doesn't need to move forward or swing up, the nasomaxillary complex needs to GROW forward. Its position doesn't need to change, its size needs to increase. And as the size of the nasal breathing passages increases, the size of the sinuses which shape the face also increase. 

But that's just my new opinion, it's up for debate

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Posted : 08/11/2019 11:48 am
oatmeal
Eminent Member

So basically we can visualize an underdeveloped maxilla by the steepness of it, and to fix it and needs to grow forward, gradually making it less steep?

 

 

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Posted : 08/11/2019 11:52 am
TGW
 TGW
TGW Admin Admin

This doesn't preclude the possibility that the nasomaxillary complex also rotates upwards as it grows. Both happen, but the rotation goes with the anterior-posterior growth 

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Posted : 08/11/2019 11:54 am
TGW
 TGW
TGW Admin Admin
Posted by: @oatmeal

So basically we can visualize an underdeveloped maxilla by the steepness of it, and to fix it and needs to grow forward, gradually making it less steep?

I think so. And, like my post script comment says, the upward rotation is a part of the forward growth. 

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Posted : 08/11/2019 11:56 am
Bunnygal liked
EddieMoney
Reputable Member

As simplified as this sounds, it depends. Yes to the entire complex has to grow. In some cases it May rotate clockwise or clockwise depending on where the deficiency was.

I always had the view that forward movement made no sense. In many cases, I have seen maxillary progress result in a higher Mew line or the maxilla even moving DOWN slightly (especially in the cases of severe overbites) lengthening the face but creating a better aesthetic nonetheless 

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Posted : 08/11/2019 1:21 pm
PolHolmes
Active Member

The best way to increase this is to increase IMW?

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Posted : 08/11/2019 5:44 pm
sinned
Estimable Member

@admin

I've had some posts about how AGGA treatment seems to reduce vaulted palates. It seems as though AGGA in it's forward expansion, changes the teeth's position and the front of the maxilla to a more forward and upward position.

This is personally what I think happens in expansion, whether laterally or forward. This is why ( https://www.youtube.com/watch?v=nHn6vWY25F0 ) the bigger the palate/maxilla, the flatter it will be. It's basically the same as your illustration except the right end of each line travels upward and forward. If we imagine that the left is an illustration of vaulted palate and the right is a flat one, basically when you expand where the teeth end up isn't level horizontally with it's starting position, whether you expand laterally or longitudinally. Image result for forwardontics results

This boy was treated with the bow appliance, you can see how the forward expansion achieved by the appliance pulling his arch forward has also made him look less "downswung", which supports what you're saying. However, he still lacks undereye support, so I still think there's an element of the maxilla dropping down and back a bit, or back and up however you view it, if you see the movement of the front of the maxilla it drops down but the back of the maxilla seemingly stays level or goes up.

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Posted : 08/11/2019 6:35 pm
dopafacker
Eminent Member

How about people with good lower maxilla but have bad upper maxilla? Should you push your posterior 3rd more? 

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Posted : 09/11/2019 10:49 am
EddieMoney
Reputable Member
Posted by: @dopafacker

How about people with good lower maxilla but have bad upper maxilla? Should you push your posterior 3rd more? 

Examples? What is a bad upper maxilla? 

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Posted : 09/11/2019 3:30 pm
EddieMoney
Reputable Member

Mew lines honestly mean nothing. People with deep bites often have short Mew lines already. Any expansion they get will be 1-2mm. And longer faced people can simply expand to appear shorter faved via widening the midface and allowing the mandible to swing up. But notice the mandible would also adjust. Short faced people have their mandible tucked in and pronounced mentolabial angles. The face sometimes has to grow longer or shorter. It really isn't all about facial shortening or much forward movement of the maxilla at all.

A Class 2 Div 2 can benefit from the maxilla LOWERING itself from a jammed up position due to overactive masseters. These people would either need to STOP chewing or chew differently. But the maxilla can swing DOWN and make their face more aesthetic by exposing soft tissue. This downswing of the soft palate would cause a minor upswing of the alveolar ridge which would effectively move the incisors forward and the bite more open. In turn the face would lengthen, pushing out the soft tissue around it. The more open bite would push lips out making a short face into a forward face. But the maxilla would still come DOWN in the posterior so as to shift forces of the mandible into the alveolar ridge, which would open the bite via mandible clockwise rotation. 

Now in terms of incompetent lip/bimax cases, the Mew line would LENGTHEN, moving the maxilla away from the nose. The lips would hold the teeth back and the mandible would slide forward to pull the tongue back against the soft palate, pulling it down the same way as in the Class 2 Div 2. Except in a Class 2 Div 1 the downward palate allows the mandible to swing forward to maintain occlusion. In both cases of Class 2 the mandible is back. The difference is the Class 2 Div 1 Lip incompetence means the alveolar ridge must come back while the mandible slides forward, changing the alignment of the maxillary teeth to a slight retrocline while the mandibular teeth do the exact same thing (because the lips push them back). So this open bite clockwise closes on the alveolar ridge and counterclockwise rotates on the soft palate to allow the mandible to slide forward in its condyle. All the while a lip seal closes the bite. 

In both Class 2 Cases, the maxilla must come down. But one results in forward movement of the alveolar ridge while the other results in backward movement. But in both cases the soft palate is pushed down. 

Class 2 Div 2 and Class 2 Div 1 can both benefit from expansion. In either case they carry with them a more protracted mandible position. But in both cases downward movement helped to free mandible motion. One just involves a greater lip seal (Div 1) while the other a decreased usage of the masseters and less usage of the molars. Both cases can benefit from BETTER chewing habits, not necessarily more. 

The common denominator is that forward movement may not happen. But it doesn't matter in the long run if the relationship of the mandible has changed relative to the maxilla. All of this allows for more muscle activation and better soft tissue support. I doubt my Mew line has moved much. But the facial gains have outweighed the expectation of making my face shorter. 

My maxilla may have never moved significantly. But the expansion has allowed for greater mandibular range of motion. My underbite is almost gone. All but 3 of my incisors are over my mandible now. I have a functional frostbite but it is soon to be a regular human overbite just by a few millimeters. In all of this I doubt my Mew line decreased much. But my mandible can position itself much more comfortably. My soft tissue is so well supported. My face has maybe lengthened a bit but it looks all the more healthy and balanced. My eyes seem more lifted. My cheeks more robust. My lip seal has gotten near excellent. My resting face now looks more "alive" than ever before. But I doubt my maxilla ever moved at all. 

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Posted : 09/11/2019 9:03 pm
qwerty135
Active Member

@admin What you're saying about the downward component of growth being there, but the anteroposterior(front-back) component not being there, makes sense, especially when we consider palatal vault and how it's helped with palate expansion...Like, the steepness of the palate will decrease with lateral expansion, although the overall downward component stays the same, just because the slope is decreasing as the transverse dimension increases in length. Seems like there could be a very similar mechanism.

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Posted : 11/11/2019 6:02 pm
qwerty135
Active Member

@admin What do you think about Harvold's experiments where the maxilla changed shape/position unfavorably in growing and nongrowing monkeys(at the same rate) after correct tongue posture was blocked? How would that be explained by your theory of the fascia?

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Posted : 14/11/2019 12:25 am
Progress
Member Moderator

There is probably truth to this. As it was said earlier, AGGA operates on the same premise too. Moreover, this idea forces us to ask how important the posterior tongue even is in the first place, besides mere lateral expansion? It would seem that the anterior tongue has prime importance in allowing the jaws to advance by developing the alveolar ridge forward.

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Posted : 14/11/2019 9:17 am
EddieMoney
Reputable Member
Posted by: @progress

There is probably truth to this. As it was said earlier, AGGA operates on the same premise too. Moreover, this idea forces us to ask how important the posterior tongue even is in the first place, besides mere lateral expansion? It would seem that the anterior tongue has prime importance in allowing the jaws to advance by developing the alveolar ridge forward.

In the case of someone with bimax, the tongue has pushed the alveolar ridge further than it needs to go. But expanding it laterally via posterior engagement is definitely still needed since the stretched out maxilla becomes more wide, giving the teeth room to occlude ideally without excessive overjet.

The maxilla didn't go anywhere, but the alveolar bones did move further back. Yet the lateral expansion allowed the mandible to come forward.

So in this particular case, lateral expansion + lip seal brought more balance to the face. 

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Posted : 14/11/2019 4:36 pm
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As you undergo correction in the near future, please consider keeping records for your own sake and for others. Pictures of dental impressions, scans, medical reports reports can be very helpful even with all personally identifying information blocked out.

Your input could help many, many people

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