I had my first adjustment a few days ago. Already before the adjustment, one of my canines moved back quite a lot, pretty much already eliminating the space between it and the premolars (which is the main issue I wanted to get fixed with the braces, or rather, which is the main thing I used as reason of why I wanted braces to the ortho

).
During the appointment, the ortho tightened the holding clasps of both appliances quite a lot, to provide better anchorage for the active elements to do their work. She adjusted the springs of my lower incisors and activated my upper lateral incisors to start pushing them out. The springs moving in my wisdom teeth were activated a lot (which really hurt!). When inserting the plate, those springs now get caught on the surfaces of my wisdom teeth, so I need to push them out with my fingers. She also activated the move-canines-back springs, but I think one of them is blocked by another wire and doesn't actually touch my canine.
I asked her about the expansion screws and when / how / if they'll be activated. She said she doesn't need to gain much space. If and when needed she'll just turn them during my normal adjustment appointments.
Given this, I don't think I can answer your question regarding the effectiveness of expanders in young adults as I won't really need much expansion / it'll only be so slight that it doesn't matter.
I mentioned the sores in my lips and cheeks I talked about in my previous post to the ortho and she adjusted a few things here and there to hopefully reduce them. Three days later I can say that it didn't really help and with the new activations other parts of my tongue now also get pinched and start to hurt. I also mentioned the impressions of the upper plate in my hard palate tissue due to my subconscious sucking in the night (which don't
really bother me). She smoothed the edges a little bit (although I know that won't help as my dentist also tried everything over the five years of me wearing the bruxism guard without any success). I used that as argument for why I wanted my top brace to cover my full palate which unfortunately they didn't do. I'll continue mentioning it, in the hopes that I'll get that wish fulfilled at least for my retainer

(which user retained made me even more envious about)
With the tightened clasps, my upper plate hangs now even lower in my palate, reducing the space for my tongue even more. The plastic now goes below my lateral incisors and is even visible from the outside (which I guess doesn't really make much difference as the plastic from the lower bite plane is already very visible). It also strongly affects my speech again. I was finally at a point where I could talk pretty well, and now, again, I sound like I have just gotten the braces…
The pain was about as I expected. When I got the upper plate six weeks ago and my lower plate was adjusted slightly, I already realized that the strongest pain occurs roughly in the timespan 4-12 hours after putting in the braces after the adjustment. An advantage of removable appliances is that this time I was able to time wearing them in such a way that the strong-pain-time was while I slept. With fixed braces I imagine you can't time your adjustments that well and might have meals with that strong ache, which explains quite a lot of tips surrounding soft food after adjustments. In my case, I was able to continue eating normally, though some things like crunchy fries weren't too much of a joy to eat

I guess another difference is that only some of teeth were activated, while after a wire change with brackets all teeth are activated in some way or another.
Three days later, I still feel constant pressure and some slight ache, both of which I really enjoy though!
Regarding the missing labial bow and the two missing clasps from the invoice, I asked the ortho. Those elements are really missing. The bottom appliance was supposed to have a labial bow and it's also missing two clasps. She said that she'll definitely need the labial bow to properly align the incisors, which we all were already wondering about and expecting. The technician forgot to / didn't work them into the appliance. I need to bring the bottom brace to the ortho next Tuesday evening. On Wednesday the technician will be there and add the missing elements. Thursday morning I have another appointment where I'll be fitted the lower plate again, and possibly have a few more adjustments.
Additionally, on the bottom brace one spring broke. I think that happened during the adjustment when the ortho was bending it with the pliers, as it was already broken when I was back home and looking at the braces the first time since the adjustment. Either way I'll mention it when handing over the bottom plate next week to make sure that it can be repaired if needed.
retained said:
Interesting to hear that speech is slightly difficult for a time when you take them out. I certainly found that after wearing my simple retainer / bite plate absolutely full time for a few year.
Your anecdotes about that were exactly what I was immediately thinking about when I realized that phenomenon. It's crazy how quickly the body can get used to or even dependent on something like that.