I finally got the energy and redid my impression yesterday, and thought I’d share the side by side comparison (I edited out a rogue cat hair, but other than that, there have been no touchups). They've been rotated and resized to match as closely as possible.

Though for some reason the after photo looks narrower than the before, there has been no expansion or regression.

That said, in person, I do see lots of minuscule changes, and almost a smoothing out of the arch so to speak. I re-measured, and the distance between my 2nd molars is 36 mm. 1st molars is still 31. Again, keep in mind my bicuspids were extracted when I was a teenager. 

I can see why intermolar widths are oftentimes taken at the central groove. Using a caliper, the points lock into place, and it’s also easier to gauge tipping. Measuring at the gum line makes it a bit more difficult to remeasure placement — but I do think the gumline is still the place to look at when it comes to mewing.

Things to take into consideration:

•  There is a margin of error both in taking the impression and then in casting it. I could have shifted my bite, altering the impression during the process. And the bubbles and poor execution of the casting add a variable to the error.
• I could not make an exact replica of angle and location for each cast when taking photos. They’re propped up with folded up tissue paper, as the back is very round.
• It’s most likely much more accurate to go to a dentist for this.

I’m going to keep doing the casts once a month just to make sure there isn’t something significant going wrong, and am also going to start adding the base molds. But I don’t think I’ll be getting really nitpicky in comparing until every 3 or maybe even 6 months. There needs to be a clear and large leap in measurements before I can trust the impressions.

I’m also going to be starting intra-oral photo documentation via Mike Mew’s youtube video.

But I thought it was interesting, and wanted to follow through on sharing!