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At Dong Xa in northern Vietnam, three burials preserved teeth coated in a dark layer too deliberate to dismiss as ordinary staining.<\/p>\n
Working from those remains, archaeologist Yue Zhang at the Australian National University<\/a> matched the ancient coating to intentional tooth blackening.<\/p>\n Two of the teeth came from the Iron Age and a third from about 400 years ago, extending the practice across a long stretch of Vietnamese history.<\/p>\n That continuity made the dark enamel harder to treat as an isolated curiosity and set up the need to test what had actually colored it.<\/p>\n Not caused by betel chewing<\/p>\n Betel chewing was the obvious alternative, because earlier work had already linked dark teeth<\/a> in ancient Vietnam to betel residues.<\/p>\n Yet earlier Vietnamese betel stains were reddish-brown, not the dense black seen at Dong Xa and in later blackened smiles.<\/p>\n Burial chemistry also fell short, since random soil exposure would not lay down the same iron-sulfur signal on separate teeth.<\/p>\n By ruling out those two paths, the study narrowed the answer to a cosmetic treatment mixed and applied by people.<\/p>\n Iron and plants used for tooth blackening<\/p>\n What made the color last was likely tannins<\/a>, natural plant chemicals that readily bind metal, mixed into the paste.<\/p>\n When heated extracts met iron salts<\/a>, iron compounds that dissolve and react easily, the mixture could turn intensely dark.<\/p>\n Air exposure then finished the job, because oxygen helped lock the pigment into a black, more durable coating.<\/p>\n That chemistry also explains why the same ingredients colored medieval inks and textiles, giving the custom a chemical backbone.<\/p>\n Long and careful tooth process<\/p>\n Vietnam\u2019s most elaborate recipes did not stop at a single smear of dye, and the process could stretch for 20 days.<\/p>\n Workers first roughened the tooth surface, then laid down plant extracts, acids, and sticky binders over several nights.<\/p>\n Polishing with ash or coconut tar likely supplied the mirrorlike finish that made blackened teeth look deliberate and refined.<\/p>\n Because the treatment demanded time, discomfort, and upkeep, the result probably signaled commitment as much as appearance.<\/p>\n Across Asia and beyond, tooth blackening marked beauty, adulthood, and the boundary between people and something less human in one broad review<\/a>.<\/p>\n Outside experts<\/a> saw the Dong Xa teeth as proof that a living custom reached deeper into history.<\/p>\n At Chiang Mai University<\/a>, environmental archaeologist Piyawit Moonkham read the find as evidence that the custom once stood in public view.<\/p>\n \u201cIt suggests that this practice might have been more common and celebrated among prehistoric and early historic communities,\u201d Moonkham said.<\/p>\n Iron use made this possible<\/p>\n The custom appeared when iron tools, weapons, and probably mines were becoming easier to reach in northern Vietnam.<\/p>\n That mattered because utensils could leach iron into heated plant mixtures, feeding the dark reaction behind the dye.<\/p>\n \u201cAnd sulfur is everywhere in nature,\u201d Zhang said, underscoring how ordinary ingredients could support a specialized cosmetic tradition.<\/p>\n Placed beside early Chinese descriptions of blackened teeth to the southwest, the chemistry made the old references harder to dismiss.<\/p>\n Practice continued for centuries<\/p>\n This was not a one-skull oddity, because blackened teeth appeared on many Iron Age individuals linked to the Dong Son world.<\/p>\n The paper noted that at least one-fifth of observed people showed dental color changes, and some reports pushed near 40%.<\/p>\n A later burial from about 400 years ago carried the same black coating, suggesting long continuity rather than a brief fad.<\/p>\n That rise also fits another study<\/a> suggesting older tooth removal gave way to less damaging marks of adulthood.<\/p>\n Limits of the evidence<\/p>\n Only three archaeological teeth went through the new analysis, and preservation problems forced the team to work carefully.<\/p>\n Two Iron Age teeth kept patches of sediment, while the younger sample had begun to crumble before testing.<\/p>\n Because the method left the remains largely intact, future researchers can examine more collections without cutting apart rare specimens.<\/p>\n That balance between care and proof may matter as much as the black teeth themselves, especially for museum-held remains.<\/p>\n Tooth blackening in modern times<\/p>\n The Dong Xa teeth also connect a deep past to memories still within reach in parts of Vietnam.<\/p>\n Historical accounts describe blackening as a multistep craft that lasted into modern times before Western standards drove decline.<\/p>\n Some communities kept the practice much longer, preserving recipes that link plant extracts, iron utensils, patience, and polish.<\/p>\n Seen beside the ancient burials, that survival makes the custom less like an isolated curiosity and more like cultural continuity.<\/p>\n Blackened teeth now stand beside bronze drums, graves, and old texts as direct evidence that bodily style carried real social weight.<\/p>\n More samples from Vietnam and neighboring regions could show whether the chemistry stayed local, traveled with people, or spread with ideas.<\/p>\n The study is published in Archaeological and Anthropological Sciences<\/a>.<\/p>\n \u2014\u2013<\/p>\n Like what you read? Subscribe to our newsletter<\/a> for engaging articles, exclusive content, and the latest updates.<\/p>\n Check us out on EarthSnap<\/a>, a free app brought to you by Eric Ralls<\/a> and Earth.com.<\/p>\n \u2014\u2013<\/p>\n","protected":false},"excerpt":{"rendered":"A new study has found that people in ancient Vietnam were blackening their teeth with an iron-rich paste…\n","protected":false},"author":2,"featured_media":493448,"comment_status":"","ping_status":"","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[10],"tags":[59,102,56,54,55],"class_list":{"0":"post-493447","1":"post","2":"type-post","3":"status-publish","4":"format-standard","5":"has-post-thumbnail","7":"category-health","8":"tag-gb","9":"tag-health","10":"tag-uk","11":"tag-united-kingdom","12":"tag-unitedkingdom"},"_links":{"self":[{"href":"https:\/\/www.newsbeep.com\/uk\/wp-json\/wp\/v2\/posts\/493447","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/www.newsbeep.com\/uk\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/www.newsbeep.com\/uk\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/www.newsbeep.com\/uk\/wp-json\/wp\/v2\/users\/2"}],"replies":[{"embeddable":true,"href":"https:\/\/www.newsbeep.com\/uk\/wp-json\/wp\/v2\/comments?post=493447"}],"version-history":[{"count":0,"href":"https:\/\/www.newsbeep.com\/uk\/wp-json\/wp\/v2\/posts\/493447\/revisions"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/www.newsbeep.com\/uk\/wp-json\/wp\/v2\/media\/493448"}],"wp:attachment":[{"href":"https:\/\/www.newsbeep.com\/uk\/wp-json\/wp\/v2\/media?parent=493447"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.newsbeep.com\/uk\/wp-json\/wp\/v2\/categories?post=493447"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.newsbeep.com\/uk\/wp-json\/wp\/v2\/tags?post=493447"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}![\"Comparison](\"https:\/\/www.newsbeep.com\/uk\/wp-content\/uploads\/2026\/03\/tooth-blackening_vietnam_skeleton-comparison_AAS_1s.webp.webp\")
<\/a>Comparison of dental residue possibly resulting from different practices: (a) reddish-brown staining on teeth from Gua Harimau, Sumatra (courtesy Prof. Truman Simanjuntak; photograph by Hsiao-chun Hung); (b) a black pigment layer on teeth from Dong Xa, Vietnam. Credit: Archaeological and Anthropological Sciences. Click image to enlarge.Black teeth showed identity<\/p>\n