Vietnamese lady with blackened teeth
The oldest direct evidence of black-painted teeth in Iron Age Vietnam has been identified. It is a combination of iron, walnut, sulfur, ash and coconut.
Around two thousand years ago, in communities north of present-day Vietnamthe ideal of beauty did not involve white, straight smiles, but rather shiny, uniform black teeth.
The practice, known as “tooth darkening” or “tooth painting,” is well documented in several regions of Asia and in particular Vietnam, but its antiquity has always been difficult to prove reliably in the archaeological record—until now.
In a study in Archaeological and Anthropological Sciences on January 22, researchers say they have found the earliest direct scientific evidence that darkening was deliberate as early as the Iron Age.
The investigation focused on human remains excavated from the site of Dong Xain northern Vietnam. The graves analyzed date, above all, from a period between approximately 1,800 and 2,200 years ago, with the inclusion of a much more recent individual, approximately 400 years old.
The problem, the authors point out, is that dark teeth on ancient skeletons do not, in and of themselves, constitute proof of an intentional cosmetic change. Color may result from post-depositional natural processes: soils rich in iron can stain the enamel, and the consumption of areca nut, Traditional in many regions of Southeast Asia and the Pacific, it tends to dye teeth reddish-brown.
To distinguish between these hypotheses, the team turned to non-destructive techniques. Teeth from three individuals were selected and examinations were carried out using scanning electron microscopy and portable X-ray fluorescence, which allow the enamel surface to be observed and its chemical composition to be identified.
Unusually high levels of iron and sulfur were detected in old teeth. The combination is characteristic of reactions between iron and tanninscompounds present in several plants that produce a deep black pigment known as iron-thanate (in free translation, he calls it iron–tannate). According to the researchers, this chemical “signal” is compatible with an intentional application of substances rich in iron salts combined with tannic materials.
One of the Iron Age teeth also had high concentrations of iron oxidewhich suggests repeated applications of an iron-rich paste. This pattern does not coincide with the typical color caused by the soil nor with the browner stain associated with the consumption of nuts typical of the region.
It was then up to scientists to reproduce the method. They used a modern animal tooth and applied an iron-gall mixture to it, similar to traditional recipes known in Vietnam. When they compared the chemical “signature” of the experimental tooth with that of teeth two thousand years old, they found a close match: iron and sulfur in similar proportions.
According to ethnographic descriptions and reports from the beginning of the 20th century, tooth darkening in Vietnam could involve a prolonged process, with repeated applications of iron-tannin pastes over several days, followed by polishing to obtain a shiny and uniform finish. According to the ZME, there are records that the final stage could include substances such as ash or coconut derivativescreating an almost mirrored effect. The study suggests that the pattern found in Dong Xa is close to this type of “layered” method, designed to produce long-lasting color, requiring only occasional touch-ups throughout life.
It is also important to remember that around two thousand years ago, during the Dong Son cultural period and in the broader context of the Iron Age, ferrous tools and materials became more accessible.
