Cronaca quotes a story from Discovery News about a recently-found 4th-century Egyptian papyrus containing what is alleged (by DN, not Cronaca) to be "the world's oldest-known recipe for toothpaste".

The claim is demonstrably false. The Roman physician Scribonius Largus, who lived in the first half of the first century A.D., gives three recipes in chapters 59-60 of his Compositiones ('Prescriptions'). Here is the first:

A toothpaste which makes teeth shiny and strengthens them: sprinkle a pint of barley flour with vinegar that has been mixed with honey, knead it for a while, and divide it into six lumps. When these have been separated, mix in half an ounce of rock salt, then cook in the oven until they turn to charcoal. Then you should grind up these lumps and mix in enough spikenard to give them an odor. Augustus' sister Octavia used this recipe.

No, I don't know what spikenard smells like: there is useful information and a picture here. Nor can I say whether the recipe calls for half an ounce of salt for each lump or for all six combined: the Latin is ambiguous. I suppose only a taste-test would tell. Just to complicate things, a Roman pound contained only 12 ounces: whether it was larger or smaller than a modern pound I do not know.

The second recipe is too complex to translate tonight: ingredients include sun-dried radish rind and finely ground glass, so I won't be trying it out. Here's the third:

Messalina, wife of our deity Caesar, uses this recipe: one pint of deer antlers burned in a new pot and reduced to ashes, an ounce by weight of Chian mastic, an ounce and a half of sal ammoniac.

Chian mastic is an aromatic gum from (obviously) Chios. Sal ammoniac is a particular kind of rock salt from Ammon in North Africa. Messalina is the notorious wife of Claudius, who married another man in a well-attended public ceremony thinking he wouldn't notice. He was generally quite oblivious: on the evening of the day he had ordered her execution, he asked his slaves why she wasn't at dinner. The mention of Messalina as empress dates this recipe to between 41 (accidental accession of Claudius) and 48 (death of Messalina). She was a great-granddaughter of Octavia, so it looks as if an interest in toothpaste ran in the family. We know that Scribonius accompanied Claudius on his conquest of Britain in 43, which again dates him firmly in the early-to-middle first century.