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How does expansion pressure applied to the maxilla, end up creating expansion of the mandible?
Considering the DNA appliance, specifically. As everyone here knows, it applies outward force behind the teeth and the alveolar ridge of the maxilla to create expansion. From what I've seen in the forum here, it seems like the maximum expansion you can really hope to pull off is maybe about 5mm?
Ok so ... how does it work out that the mandible also grows in conjunction? I mean, I assume it does, right? It would have to, or else patients would probably end up with horribly misaligned bites if only the upper structures increase by 5mm but nothing at all happens with the size/shape of the mandible?
With the DNA appliance there is only the upper device, there is nothing directly applying force on the lower jaw ... so what causes any expansion of the mandible? I can think of three potential causes - wondering if any(/all?) of these are perhaps the case, or are there other potential active pathways I'm not thinking about?
- Genetic activation - after all, it is called "epigenetic orthodontics" ... so there's just some sort of signal/protocol that your body automagically knows to follow. Maxilla growing? Initiate equivalent growth in mandible.
- Transference of forces via TMJ - given that this is the only connection point, are there any forces effectively transferred from the maxilla growth via the joint ... to apply outward pressure to the mandible, and that creates a similar level of expansion?
- Transference of forces via eating - chewing represents a direct physical contact between the upper and lower structures, albeit intermittent/temporary. So maybe as you're eating every day as the maxilla expands, that ends up putting pressures on the mandible that helps foster expansion.
Thoughts? I'm fascinated by how any osteogenesis in the mandible happens as a result of maxillary expansion pressures ...
The mandible follows through occlusal forces (ie chewing)
Here's a basic explanation of the mechanics, as shown through the images, the top tooth has shifted to the left, when the teeth come together and experience occlusal forces through chewing, it shifts the bottom tooth slightly to the left as well. The mandibular buccal cusp will naturally fall into the maxillary fossa, just like gravity will roll a ball down a hill, the occlusal forces from chewing put the teeth in a cusp-fossa relationship. This is a very basic explanation and it doesn't always turn out like this, otherwise malocclusions wouldn't exist, there are other factors affecting occlusion, however, all other factors aside, this is how the teeth will meet. This is just my own theory but I believe there's changes in the soft tissue as well, ie the cheeks and lips. When the upper arch expands the cheeks/lips expand as well so there's less forces being placed on the bottom arch by the cheeks and lips.
The mandible can simply protract forward to maintain occlusion. To imagine this, jut your mandible to where your lower teeth are in front of the upper teeth. The upper arch expanding in all directions would cause the teeth to come forward to meet the jutted lower position.
Fascinating - so it was #3, eating/chewing. Makes sense!
Another question - if you don't mind my asking? So if the lower jaw is growing in overall circumference due to those outward forces from eating, technically you are achieving osteogenesis in the mandible - correct? I'm actually wondering if the DNA appliance might have a positive secondary side-effect of helping me with a little bit of gum recession due to some bone loss in my jaw due to some poor oral hygiene in the past (I'm much much better about it now though). I'm not necessarily assuming I'll get that extra benefit ... but if osteogenesis is being triggered in order to grow the mandible overall, it has to make me wonder if that might happen naturally (even if perhaps only minimally) as a result?
Unfortunately I don't think gum recession/alveolar bone loss can be reversed, but honestly I'm not too sure. It isn't necessarily growth, but more accurately described as remodeling, which can include growth if that makes sense. The bone will resorb and deposit on already existing bone, so while a wider arch means in the end there's more bone, the alveolar bone you lost that supports the tooth most likely will not grow back. You could maybe look into SFOT, I don't know too much about it myself but apparently it helps with lack of alveolar bone, if I remember correctly they add freeze-dried bone and move the the teeth through that newly added bone. Another thing to be aware of with bone loss is it can get worse as you age, so best keep up oral hygiene and diet so you don't end up losing more bone in the future.
Thanks, I'll look into SFOT.
Yeah, I figured that getting some bone loss side-benefit from the DNA was probably a long-shot.
I'm also going to look into a local periodontist that knows how to use enamel matrix derivatives like emdogain to see if that might help. And while I am curious to talk to an oral surgeon about distraction osteogenesis ... it feels like something like that is too extreme to attempt for what I'm trying to fix. The only other possible approach I've come across is from this company, but I can't seem to track down a local provider that lists that as a service. They had an older webpage which made it sound like it might be an approach that could work, but that page was in their "R&D" section, and is now offline: