ABSTRACT
Before the 19th century, decayed teeth were usually repaired, if at all, by packing pellets of gold foil into the cavities. This technique can be quite effective, for gold is easily welded under pressure, even at low temperatures, but the process is slow and painful. The royal dentist and his alchemist did not make the necessary leap of imagination. Modern amalgam is a remarkable material. Its thermal and mechanical properties are close to those of the tooth substance that it replaces; a filling withstands exposure to hot liquids or iced drinks without causing discomfort, and wears down at the same rate as the surrounding tooth. The history of mercury goes back to the beginning of chemistry—indeed, to the beginning of alchemy. The earliest records describe the use of mercury in the second century BC by Chinese alchemists in their search for the elixir of life, which would confer immortality on its possessors.
