I do have experience with having one Schwartz expander after another.  They are just the simple active plate expanders.

I'm not sure I can answer all of your questions, but I can tell you from my experience two things. 

1)  I got the same indentations.  After simply not wearing thr expander for maybe a week, the indentations went away by itself.

2)  I would advise having at least a month between when you stop wearing your old expander and when you make impressions for the new one.  This allows for better stability when you begin using the new one.

@mr_man

Thank you for your reply.

Ah, I thought they would. In terms of stability, what would your opinion be on: reaching the expander's extreme, and then continue wearing the expander as a retainer? I can imagine this may prevent the indentations disappearing - but won't taking it out entirely result in unnecessary retraction? Is it simply the necessary evil to make sure the new expander fits appropriately?

I would say, if you're not worried about stability and want to keep all of your gains, to simply keep wearing the expander that you already have as a retainer, then get the impressions done for your new expander, then keep wearing your old expander until your new one arrives.

In my own experience, I find that after using the expander for a long time and then taking it out, after a while my teeth settle to a stable position, and even though my total expansion has relapsed somewhat, the expansion in the palate itself still mostly remains.  When I begin with the next expander, I'm more confident that the teeth aren't tipped any more than they should be because they've already "settled", and the next round of expansion will still bring new expansion in the palate itself.  Just my own observations.

Posted by: @mr_man

I would say, if you're not worried about stability and want to keep all of your gains, to simply keep wearing the expander that you already have as a retainer, then get the impressions done for your new expander, then keep wearing your old expander until your new one arrives.

In my own experience, I find that after using the expander for a long time and then taking it out, after a while my teeth settle to a stable position, and even though my total expansion has relapsed somewhat, the expansion in the palate itself still mostly remains.  When I begin with the next expander, I'm more confident that the teeth aren't tipped any more than they should be because they've already "settled", and the next round of expansion will still bring new expansion in the palate itself.  Just my own observations.

As an update to this, I ended up largely following your advice and it was mostly correct. However, after I made the new impressions, I did periodically reintroduce the old expander while I waited for my new one, as there seemed to be "too much" retraction at times. As time went on, the retraction became less and less, suggesting that while removing the used-up expander to achieve stabilisation is necessary, removing it entirely can also be counterproductive. I would say that, after I decided to remove it, I went from wearing it 50% as much as I used to, to one day a week, by the time the new expander arrived.

Hi I'm new here and I recently ordered a y plate expander. If you don't mind me asking, have you been turning both screws for forward and sideways expansion or just the sideways one? And how often do you turn the screws? 

FYI, I've never used more than an active plate (sideways only), but I DO know that with the Y-plate, you'll want to be extremely slow and careful with the forward screw compared to the sideways screw

Posted by: @glitterpumas

Hi I'm new here and I recently ordered a y plate expander. If you don't mind me asking, have you been turning both screws for forward and sideways expansion or just the sideways one? And how often do you turn the screws? 

1 turn on both left & right every 1-4 days, when it gets loose. After the first few turns, you will need to file down the expander, especially the top and back ridges (and wherever else it persistently hurts), to maintain adequate fit.

Do you have a crossbite? If so, you will have to expand (very) disproportionately on one side. But slow movement on the less impacted side will inevitably result in alveolar drift. Not sure what the solution to this is.

Regarding the front screw, screw turns there should be only to keep up with natural expansion (i.e. mewing).