Thank you for your detailed reply and your time. I've looked into the topic again and think I understand it better now.
I know that the Roof of the hard palate is also the floor of the nose. The floor therefore remains connected to the maxilla even after the Lefort 1 cut, which completely separates the upper jaw from the skull in DJS.
The maxilla is then moved forward (like the mandible), because of the DJS. If only that were to happen, it is maybe possible (the odds are higher) that the expansion of the whole nasal cavity after the surgery could be achieved by turning on the turn key of the expansion device (the exact name of the expander my surgeon uses is "GNE").
Because in this case, the maxilla is (simply put) only moved horizontally. It was not moved down in a downgrafting procedure, which would have created a gap that would have had to be filled with material (such as natural bone). The vertical distance between the skull, maxilla, hard palate and everything that goes with it remains the same.
But in my case, the posterior maxilla would be downgrafted by 3-4mm, to achieve a CCW-Rotation. This gap is then filled with material, probably natural bone. This means, that the maxilla and the skull would be "connected" again.
Back to the topic of the hard palate. The hard palate is both, the floor of the nose and the roof of the mouth. For this reason, the floor of the nose would also be expanded with the expander device in the weeks after the surgery, because this area is not affected by the Lefort 1 Cut. The hard palate isn't cut horizontally in the middle or anything weird like that, which would separate the floor of the nose and the roof of the mouth.
In my eyes, the problem is, that the floor of the nose with the area of the nasal passage, which lies under the Lefort Cut, is only a very small part of the nasal passage. I have attached 3 pictures where you can see a skull example showing how my surgeon does the DJS with CCW and downgrafting. In the picture of the front view, I marked in red the area of the nasal passage that I think would be expanded.
In order for the expansion to affect the whole nasal cavity, the expansion would have to involve the bones to the left and right of the large main part of the nose cavity, which lie above the Lefort cut.
I drew the areas in green. I know that good expansion (like EASE+MSE) also has an effect up to the cheekbones (which is why many people have a optically wider face after) and that the lower nasal cavity expands more than the area at the top between the eyes. It's just a rough sketch.
To have an impact on these essential areas in green, the pressure of the expansion would also have to affect the areas where the Lefort cut with the downgrafting took place.
The problem I see is stability. Because the expansion by turning on the turn key (sorry for my bad english, i dont know how to articulate it different) of the expander device happens in the weeks after the surgery. After what I read in the testimonials (but I'll ask him myself also) of the people, who did the expansion with my surgeon the same way i described it (putting in the device shortly before the surgery, then DJS, then expansion in the weeks after), the expander device only remains on the palate for a total of 4 weeks after placing it there on the surgery day.
I know that's a very short timespan for a expansion device to stay in the mouth and I'm not 100 percent sure if my surgeon would actually do it that way. I will clarify it later, but what is clear is that the actual expansion takes place shortly after the surgery.
During this period, the entire jaw is still very unstable due to the DJS. The whole thing is held together with plates, which are removed after 6 months when the bones have grown well together again. This includes the area where the Lefort 1 cut and the downgrafting took place.
In my opinion, it is therefore unlikely that the expansion would affect the areas above the Lefort cut, which would result in the majority of the nose cavity not being expanded (since it lies above the Lefort cut).
Ron from Jawhacks talks in his Youtube-Video "How MSE Works" about the DOME-Procedure (min 5:40). He explains that the sutures that connects the maxilla with the zygoma (cheek bone) are cut on both sides. This is done so that the pressure, which is created by the expansion, isnt transferred to the cheekbones. So the resistance of the cheekbones decreases, which simplifies the expansion.
However, this has the consequence that the optical changes that you get through an expansion like EASE+MSE (in which the suture between the maxilla and zygoma is not cut) cannot be achieved, because these are accomplished by pushing the zygoma/cheek bones outwards (which does not happen in the DOME, because of the cuts).
I have to admit that it is based on Rons Video not entirely clear to me whether the zygomas will be cut completely (which would be quite invasive, which I cannot really imagine) or whether incisions will only be made to weaken the areas, not to cut them completely.
In Rons Interview "Pt 3 - Dr. Vaughan Compares SARPE, DOME and MSE", Dr. Vaughan says (min 5:53), that the cuts, which are made in a normal SARPE (without DJS or something like that of course) are similar to the cuts made in a DOME. The difference is the places where the cuts are made, with SARPE the cuts are made in the area like those of the Lefort 1 cut, while the DOME cuts are like i said in the sutures between the maxilla and the cheekbones. There are also cuts made in the suture of the palate, but thats not the point here.
At min 5:35, Dr Vaughan says that the SARPE cuts are less invasive (and therefore also the DOME ones, because he says they are basically the same), which also overlaps with what I heard about the SARPE cuts in the Lefort 1 area, that they are just incisions and not a complete cut of the bone like the Lefort 1 Cut in a DJS. This complete cut must be made in a DJS in order to be able to advance the Maxilla.
With this background, in my opinion it now appears that even incisions (not complete cuts) as with DOME reduce the chance that the areas after the incisions (with DOME the cheek bones, with SARPE the bones above the Lefort 1 cutting area) get changed/influenced by the palate expansion.
By this logic, SARPE procedures would admittedly reduce the chances of significantly improving nasal breathing. I know that there are still people who have improved nasal breathing after the SARPE procedure and also Dr. Vaughan says in the interview that he and Dr ting use SARPE and DOME to primarily improve nasal breathing, which doesn't make complete sense to me. But I think that it is simply the case with incisions that they reduce the chances of improved nasal breathing through a SARPE, but that its still possible, that the nasal cavity above the Lefort incision areas can be expanded. Correct me if you think different or i get something wrong.
Referring to my case, where not only incisions, but a complete cut is made with Lefort 1 (+ the downgrafting and the added bone material, which makes it even more less likely) I think it is very unlikely that the expansion shortly after the DJS would improve my nasal breathing (in a significant amount).
Sorry for the long article. This is just my perspective and how I see everything, you're welcome to share your perspective.
