At the start of this year, a back tooth crumbled as I ate a French fry, earning me my 1st crown.
The dentist told me old amalgam expanded, caused my tooth to crack and crumble.
Mine was a 2 appointment process. Day 1 clean up the site, measure for a permanent crown, place the temporary. Go back for a 30 minute appointment to fit and seat the new crown.
For a few months, it was uncomfortable when I bit back there, but I don't even notice it now.