The Secret Behind Vietnam’s 2,000-Year-Old Black Teeth Fashion Is Now Out

Researchers recreated a 2,000 year old recipe to see how ancient people dyed their teeth black.

By Rupendra Brahambhatt

Two thousand years ago, in what is now northern Vietnam, beauty did not mean bright white teeth. It meant glossy black smiles, a cultural practice that may look peculiar to Western eyes but which remains widespread to this day across some parts of Asia.

Archaeologists have found ancient skulls with darkened teeth across the continent, but they could never be sure—was the staining intentional, caused by burial soil, or simply the result of chewing betel nut? 

“Tooth blackening, the deliberate modification of teeth to achieve a lustrous black appearance, is well documented in modern Vietnam, but its ancient practice remains elusive,” the study authors note.

Now, a new study offers the earliest direct scientific evidence that people deliberately blackened their teeth as far back as the Iron Age. The discovery reveals new insights about ancient beauty standards and, at the same time, also shows how chemistry can unlock hidden cultural stories preserved in human remains.

Cracking the mystery of ancient teeth stains

The research focused on human remains excavated from the Dong Xa site in northern Vietnam. The burials dated back between about 1,800 and 2,200 years ago, with one individual from roughly 400 years ago. 

According to the researchers, dark teeth alone are not enough to prove intentional cosmetic treatment. Teeth can turn brown or black from iron-rich soil after burial. Chewing betel nut—a long-standing tradition in the Asia-Pacific—also stains teeth a reddish-brown color. So how could researchers tell the difference?

To solve this potential confusion, the team turned to non-destructive scientific tools. They selected teeth from three individuals and analyzed them using scanning electron microscopy and portable X-ray fluorescence. These methods allowed them to examine the surface of the enamel and identify its composition without damaging the remains.

The results were surprising. The ancient teeth showed unusually high levels of iron and sulfur. These two elements are key ingredients in iron–tannin reactions, which produce a deep black pigment known as iron–tannate. 

“We identify a diagnostic signature of tooth blackening in ancient samples, pointing to iron salts, likely combined with tannin-rich substances, as the primary active components responsible for the coloring process,” the study authors note.

Iron-tannates are natural compounds found in certain plants such as gallnuts or pomegranate rind. One Iron Age tooth also contained high levels of iron oxide, suggesting repeated application of an iron-rich paste. This pattern did not match staining from soil or betel nut chewing. 

“If you’re chewing betel nut, your teeth are going to look brownish black—not the deep black that we’re seeing here,” Yue Zhang, first author of the study and a researcher at Australian National University, said

Recreating a 2,000-year-old beauty recipe

To move beyond observation and strengthen their case, the researchers recreated the ancient method. They stained a modern animal tooth with an iron-gall mixture similar to traditional Vietnamese recipes. 

When they analyzed this modern sample, its chemical signature closely matched that of the 2,000-year-old teeth—high iron and sulfur in similar proportions. This experimental match provided strong evidence that ancient communities were using a deliberate, chemically sophisticated technique.

In Vietnam, tooth blackening was once widespread across major ethnic groups and minority communities, regardless of gender or social class. According to early 20th-century accounts, the process could take up to 20 days. 

People would apply iron–tannin pastes repeatedly, then polish the teeth with ash or coconut tar to create a mirrorlike black finish. The chemical evidence from Dong Xa aligns closely with these documented methods.

“The unique double-dyeing method, with few ethnographic parallels, required approximately 20 days to complete, with the entire process sometimes extending even longer. The resulting blackened teeth remained stable throughout an individual’s lifetime, needing only minimal touch-ups every two to three years to preserve their luster,” the study authors explained.

The timing also makes sense. Around 2,000 years ago, during the Dong Son cultural period and the broader Iron Age, iron tools and materials became more accessible. With iron utensils and sulfur-rich minerals readily available, communities had the raw ingredients needed to produce stable black pigments.

What’s attractive depends on culture

Instead of assuming discoloration was accidental or unhealthy, scientists can now look for specific chemical fingerprints to determine whether a cosmetic tradition was involved.

“The study offers the first archaeological insight into blackened dental traits in relation to the modern Vietnamese practice, thereby extending the ethnohistorical record by approximately 2000 years,” the researchers note.

Moreover, it highlights how beauty standards differ across cultures and time. In Vietnam, black teeth were once associated with adulthood, identity, and attractiveness. Ancient poems and folk songs even praised the deep black smile. What modern Western culture often sees as unusual was, for centuries, a celebrated ideal.

There are still some questions that remain unanswered. For instance, the study authors examined only three individuals from one site. Researchers cannot yet say how widespread the practice was during the Iron Age or how exactly it spread across Southeast Asia. 

Future work could analyze more burials across the region to trace how and exactly when tooth blackening emerged and evolved.

The study is published in the journal Archaeological and Anthropological Sciences.

(Source : zmescience.com)