Harold pinged me offline and pointed out that if you torch a gold
crown with the tooth still in it, it may offgas mercury vapor. Some
teeth were filled with amalgam before crowning, as he pointed out.
Heads up, guys. We don't want to lose any of you.
Instant Gratification Takes Too Long!
Amalgam fillings are always removed before a tooth is crowned.
The reason that an amalgam filled tooth gets a crown in the first place,
is mostly, that there is new decay around or even under the filling, so
the tooth has to be cleaned and the amalgam is removed to make place for
either an inlay, overlay or a full crown. You cannot prep a tooth
properly for a crown, with the amalgam still in place.
It not necessary to put a torch to a tooth with a crown still on it.
Since the tooth has already been extracted, it will have become brittle
rather rapidly, because it is no longer fed by blood vessels and nerves.
Just take a pair of pliers to it, and it'll break in pieces quite easily.
BTW, before I became a goldsmith, I spent three years in dental school
at the university of Amsterdam trying to become a dentist.