I am also wanting to know.

I bought a Swartz Appliance for upper/lower jaw but as a 27/28 year old, it was too late to get any meaningful expansion.

They are all tooth borne devices that have little to no benefit if you are old enough that your sutures have sealed.

If you are <25 if might be worth a shot otherwise you are just wasting time and money.

@Agendum What was the rate of expansion you were trying with it? And why under 25? Most orthodontists would argue the suture fuses by age 16 or 18, yet people who expand as adults don't say age 25 is a limit.

@paperbag

The "25" number was popularized by Dr. Mew (not sure if the son or the father), as an approximate cut-off. The reasoning is that, for our ancestors the average lifespan was 50 years, and half of that, 25, would be their midlife; at that point, it should be considered unlikely that the body would change hugely.

Personally, I don't consider that "rule of thumb" seriously. It seems arbitrary to me, and he could have chosen to take 3/4 of 50 instead of 1/2 just as easily. Besides, we  have plenty of evidence that the human body can substantially change past puberty in a multitude of ways, if environmental stressors change (though the speed of this and degree to which it happens may be lesser). A person at 50 can still lose weight and strengthen their bones through exercise and a better diet. Our bodies don't become static blocks after we finish puberty. This idea applies to mewing as well.

@Elwynn Indeed, that theory is pretty weak. Hopefully it wasn't Mike who said that, since he presents a case of a 30-something year old woman here and says he expands 40 year olds. 

@paperbag

There's a functional orthodontist in my area whom I had a consultation with. I decided against doing treatment there only because of the hefty price tag, which I couldn't afford at the time; otherwise, I would have gone through with it. In any case, his oldest patient was almost 80 years old, and he informed me that he still succeeded in widening his palate with a palatal appliance. I didn't see records of this (I didn't ask), but I have no reason to distrust him, and his reviews are very positive.

@elwynn

Wow, that's very promising. I imagine it would have been a fixed appliance, but still. On a side note, I wonder if slight dental movement that removable expanders tend to cause would be a good thing for those who don't have proclined teeth, which would probably be most people.