There is no dental condition known as ”black teeth”. You can have stained teeth from bad diet and bad habits such as smoking, or your bone may be naturally darker but there is no medical condition or illness that will make teeth black. However there is a cultural tradition of tooth blackening which is deliberate and still popular in some regions in Asia.
Many tourists have encountered older Vietnamese women whit black teeth. As it turns out the color is obtained from chewing betel. A betel chew is made out of beat leaf, slivers of areca palm nut and some lime paste. This mix is wrapped in a leaf of the betel pepper vine. A woman will then insert this little pouch inside her cheek and chew on it. The betel chew is a mild stimulant and it relieves toothaches as well as suppresses the appetite. The chewing of betel is quite wide-spread in Southeast Asia – it actually turns teeth brown but some Vietnamese women have their teeth lacquered for beauty reasons.
The chemistry of tooth blackening is complicated and the betel chewing is only a part of the process of deliberate tooth staining. In Vietnam a red resin obtained from secretions of an insect that sucks the sap of a host tree, is used as a dye to further the appearance. This dye is next diluted with lemon juice of alcohol and after being stored for a couple of days the dye is applied with pressure to the teeth. Next an application of iron or copper covers it in blue-black enamel-like surface.
The tradition of tooth blackening originates from marriage rites. A woman is deemed to be ready to be married after she undergoes her first tooth blackening ceremony. During this process usually three applications are made since saliva washes out the medicals. During this time a woman is unable to eat solid food and has to drink through a straw. Other than discomfort due to some hunger there are little side effects of this procedure. Some women say that their mouths swell up or that their gums burned and stung.
The cultural reasons for tooth blackening is due to a belief that only wild animals, demons and savages had long white teeth. Originally, some Vietnamese would blacken their teeth in order to not be mistaken for an evil spirit. There are ancient statues in Vietnam that depict people holding objects in front of their teeth when speaking to royalty – this was done out of respect from having the royalty exposed to the servants’ white teeth. Some people in Vietnam still hold a hand in front of their mouth when they speak, out of the respect.
Another reason besides tradition is that tooth blackening prevents tooth decay in people who can’t afford dental care and those who have had their teeth blackened keep a full set of teeth longer than people who have not undergone this procedure. Additionally, because of teeth blackening people are eating healthier and live longer.