The world's oldest-known formula for toothpaste, used more than 1,500 years before Colgate began marketing the first commercial brand in 1873, has been discovered on a piece of dusty papyrus in the basem*nt of a Viennese museum.
In faded black ink made of soot and gum arabic mixed with water, an ancient Egyptian scribe has carefully described what he calls a "powder for white and perfect teeth".
When mixed with saliva in the mouth, it forms a "clean tooth paste".
According to the document, written in the fourth century AD, the ingredients needed for the perfect smile are one drachma of rock salt - a measure equal to one hundredth of an ounce - two drachmas of mint, one drachma of dried iris flower and 20 grains of pepper, all of them crushed and mixed together.
The result is a pungent paste which one Austrian dentist who tried it said made his gums bleed but was a "big improvement" on some toothpaste formulae used as recently as a century ago.
The discovery of the formula caused a sensation among Austria's normally sedate dentists when it was disclosed at a dental congress in Vienna.
Dr Heinz Neuman, who attended the meeting where the recipe was unveiled, said: "Nobody in the dental profession had any idea that such an advanced toothpaste formula of this antiquity existed."
On trying it himself, he said: "I found that it was not unpleasant. It was painful on my gums and made them bleed as well, but that's not a bad thing, and afterwards my mouth felt fresh and clean. I believe that this recipe would have been a big improvement on some of the soap toothpastes used much later."
Modern toothpaste is produced by mixing sodium fluoride, a cleansing product that gives the paste its bulk, with triclosan, a whitener, and E number flavourings.
The recipe was written in Greek, the official language of Egypt for about 1,000 years until the last temples closed in the sixth century AD.
It was discovered among part of the largest collection of ancient Egyptian documents in the world - 180,000 items up to 3,500 years old, including stone and clay tablets - gathered by the Habsburgs, the rulers of the Austro-Hungarian empire.
The foundation of the collection was a mass of papyri, purchased in 1878 after being found on a rubbish dump outside the ancient Egyptian city of Crocodilopolis.
Dr Hermann Harrauer, who heads the papyrus collection at Austria's National Library in Vienna and who found the recipe, said: "It's a fascinating document. It was written by someone who obviously had some medical knowledge, as he used abbreviations for medical terms.
"As papyrus was hard to come by, it was often reused, and this document had on the back details of correspondence between monasteries, implying that perhaps the person who wrote it was connected with them in some way.
Maybe he was a monk. By the fourth century AD, Egypt had been Christianised and Christian monks were also physicians, and this would fit in with what we know."
Dr Harrauer's team is painstakingly translating and filing the documents, of which only a fraction have so far been deciphered. He said: "We still don't have an idea about half of what is here. It's a treasure trove waiting to be opened."
Dentists have recently discovered the beneficial properties of the iris, which has been found effective against gum disease and is now in commercial use again.
