High temperatures can destroy biofilms, as can some chemicals, but neither approach is safe to use inside the delicate interior of a human tooth.

ECONOMIST: Using a plasma torch to clean your teeth

Tooth enamel begins to form in the human embryo when a specialised layer of cells, called ameloblasts, in the embryonic tooth bud secretes amelogenin proteins.

BBC: By BBC News Online Science Editor Dr David Whitehouse

They include human teeth, the skull of a woolly rhinoceros, mammoth tusks and a tooth, flint tools and the antler of a giant deer.

BBC: Jersey Post mammoth stamps mark archaeological history