It is released into the atmosphere, and is a very significant source of environmental mercury pollution. More recent crematoria have scrubbers to specifically remove it from the flue stream.

I couldn't imagine what else would happen, nor that it's being removed beforehand. At least they're starting to scrub it.

I also wonder about it with respect to burial. There are arguments about just how inert/stable it is, in one's mouth.

Fill a field with small deposits that will reside for decades if not centuries...

Long term problem. But, like other metal toxins, one that doesn't simply decay and go away.

Well, it’s bound to silver in the amalgam so I’d assume it’d stay together…

At those temperatures?

Maybe they pull the teeth beforehand? I don't really know.