I have a Porcelain bonded to precious metal (gold) crown fitted recently on the 6 upper left tooth.
Once it was fitted the dentist asked me to check the result and I noticed that on the inner side the crown has a visible black margin 1-2 mm. It looks like exposed metal. I asked the dentist about this and he reassured me that this is done deliberately to "balance the temperature" that should prolong the live of the crown. The crown feels too high as well.

Is this correct? I am not really confident about it as I do not have such a margin on another crown that has been done sometime ago.

many thanks