Got hit by a car and has some head and neck issues that a specialist treated using modified invisilgn trays

At first they were very tight. You have to use your finger to find the spot to pop them loose. Mine is in the back left of my upper tray. Most find the spot in the back part of the tray by their molars. Once it pops loose it comes out easily. A new tray will be tight for a day or two and may cause headaches but they go away quickly.

I’ve got to the point where I’m actually changing trays every 3 days with no problem.

I wear them all day and night except to eat and I often take the top tray out to talk to people since it’s a bit awkward with both in and the people I’m talking to get distracted by it.