* Is the mercury leaking out because of the fracture? Not likely.
* Should I just have the tooth pulled? No.
* Do crowns typically cause problems? No.
* How important is the "dam" and alternative air source? Nobody has any accurate info on that, just opinions. For one tooth it may not be worth the bother of trying to find a dentist who does it right. Fill the tooth with diamond crown composite. No nickel in the crown,it is toxic.