Traditionally, people in the Philippines, Palau, Yap, the Marianas (Lessa, 1975,  
54- 84), and Japan (Kurashina, PC) blackened their teeth for cosmetic purposes.  Although many westerners find this practice revolting, the people who practiced teeth-blacking did it for aesthetic reasons (Lessa, 1975, 95).  In Japan the  
process was limited to the geisha girls.  This goes beyond just the inadvertent staining of the teeth caused by chewing betel nut.  Habitual betel nut chewing,  
with pepper leaf and lime causes a dark-brown color.  Although many of these  
people chewed betel nut, this staining was a black as pitch  (Lessa, 1975, 94). 

A good description of betel nut chewing comes from the Drake expedition.  
"Three ingredients go into making of an envelope of the concoction.  First is 
the betel nut itself, its appearance being like that of a large acorn. It is the 
reddish seed of the areca palm (Areca catechu), and must be broken down into fragments or slices.  The plant whose leaves supply the wrapper for the nut is  
the betel pepper (Piper betel) and is allied to the kava used by Fijians and Polynesians.  The leaves impart an agreeable zest to the nut.  The nut kernel is mixed with air-slaked lime, carried characteristically in a bamboo container.  
When these three ingredients are chewed they redden the saliva, which is  
produced in superabundance and often oozes untidily from the mouth.  The 
veteran chewer shamelessly sprays his surroundings with his crimson expectorations. The effect of  habitual chewing is to discolor the teeth a dark  
brown.  Betel contains a harmless narcotic stimulant" (Drake 1628: 82-84  
cited in Lessa, 1975, 84). 

The stains that I was looking for came from more than just the betel nut  
chewing described above. 

Mariana Islands: 

The ancient Chamorus stained their teeth black.  In the Marianas Pigafetta 
observed in 1521 "........Their teeth are red and black, for they think that is  
most beautiful" (Blair and Robertson 1903-1909:XXXIII, 97 cited in Lessa,  
1975, 117-118).  "Formerly the women used to dye their teeth black with  
certain kinds of herbs, but this practice has fallen into disuse"  
(Freycinet, 311 in French &  49 in unedited micronfilm translation).  It seems 
likely that they used the same process as Yap. The Yapese used the cooked and pounded leaf of the kell tree mixed with mud from a particular swamp 
(Russell, PC).  Chamorus call the kell tree, puteng.  The scientific name is Barringtonia asiatica.  The box like fruit float and look like little pyramids.  Fisherman in the past used the puteng seeds for fish poisoning. 

The Spanish Mission Letters from the 1670s  describe the staining process  
as witnessed by a priest.  Chamorus fed young women through a funnel for two weeks while the stain took hold. 

Below you will find Dutch Jesuit priest Father Pierre Coomans' (Father Francis Hezel spells it Coomans and Coemans in his book) 1673 comments on Chamoru physique, costumes, hair, teeth blackening, and dances.  The information is from Document 1673 L2 - History of the Mariana Island Mission for the 1667-1673 period.  The historical narrative of the events in the Mariana Islands from 1667  
to 1673.  It is a translation by Rodrique Lvesque of the Latin report.  My  
comments are in brackets preceded by my initials (ljc).  This is reprinted with  
the permission of Rodrique Lvesque. 

"Most of them [ljc - Chamorus] are tall, and strong in body, in such a way that  
they are very experienced among [other] Indians; it is generally agreed that 
none others can be found to be equal to them in strength.  And they do not  
ignore the qualities of their own body, for, the main reason why we wear clothes, 
and our people keep saying that, is that they are not so skilled at making elegant clothes; what if they are not, that cannot be the extreme reason for their lacking clothes.  They do not use any clothes, other than what our poor father Adam used  
to wear.  But that does not mean that modesty is completely gone; women hide 
their shame either with the leaf from a tree, or some plate from a tortoise shell. Nevertheless, the married women want to dye their hair, and all [women? 
] want [ljc - end of page 74] to dye their teeth, and patiently spend a lot of time 
doing so for the women seek to have them [their hair] look white, not being  
satisfied with what nature provided them, with.  Therefore, what nature  
denied, they seek with some effort.  They anoint the whole head and their 
hair with a mixture of lime [ljc - calcium hydroxide or afok in Chamoru]  
and oil, then expose themselves to the burning rays of the sun at noon, for 
hours, rather, for days on end.  Whenever the head is burning hot, they sprinkle 
it with sea water, if you look at it, you show your appreciation.  They spend no 
fewer efforts in bothering to dye their teeth black, and I do not know why  
they think it makes them beautiful, or majestic.  In order to do this, they 
spend some sweat; they mix black coloring [ljc- crushed Puteng (Chamoru), 
fish poison tree (English) - Barringtonia asiatica (scientific name) leaves were  
used in Yap] with some gum [ljc - In Yap mud from one particular swamp  
was used.] to make it long-lasting.  They often reserve an entire day to anoint 
that one tooth; nevertheless, this care, and above all this time, taken for this 
unction [process] will take up as many as 14 days, during which time the teeth 
must not touch anything.  That is why they suffer a continuous torment, with  
only a funnel, to give sustenance to their body, so as not to die.  When the  
effect has been obtained, the neighbors and friends organize a formal feast,  
as if as many Ethiopians as teeth had come into the world. And in no other  
way do they show that a progressive step has been made, as when they  
organized these frequent feast among themselves.  For instance, they cover themselves from the naval down to the knee with a skirt, and they usually 
decorate themselves with some rather long nerves from leaves, then prepare wreaths with small flowers that look like hyacinths to place on their forehead, 
and they also add a precious-looking collar made of discolored glass beads 
[ljc - keep in mind that Chamorus had contact with Europeans for over 150  
years in 1673], or if none are at hand, some local stones in any case yellow, 
but this they very rarely wear.3 [ljc-Lvesque's footnote states:  This color 
could perhaps be translated as 'yellowish,' or 'golden.'  The wife of a Carolinian 
chief, who had drifted to the Philippines about a decade earlier, carried such 
a collar of beads, described as made up of material unknown to Europeans, but resembling amber.  They are no doubt related to similar beads still preserved in Palau, but by no means unique to those islands then.  (ljc-Palauan women, 
of high status, still wear these.  The large beads looks like yellow plastic but  
it is a natural substance not found in Palau.  Today they wear a single piece of  
this carefully shaped yellow stone slightly smaller than a betel nut on a black  
string.)  No one knows were this material came from.  (ljc- Dr. Kurashina  
thinks that this material comes from China)] On their chest, as well as on  
the back, they hang some tortoise shell, with some small pieces of coconut shells artistically crafted.4  [ljc - Lvesque's footnote states:  The expression 
'as well as' could also be translated 'rather and.'  I think that Fr. Coomans is describing two pairs of half-coconut, or pieces of tortoise shells tied both on the chest and on the back of a dancers.  A similar coconut-shell dance is still  
performed in the Philippines today.  In any case, the shells on one's back are  
used by one's partner in a dance, to make rhythmic noise.]  Through the left arm they slip in a piece of wood in the shape of a half-moon, and from the fingers 
of the right arm hang [ljc- end of page 75] some castanets,1 [[ljc - Lvesque's 
footnote states:  I imagine that some small stick was tied to each right-hand  
finger, and the fingers tapped upon the wooden half-moon on the left arm.   
(ljc - other accounts say the castanets were lots of shells tied to a stick 
that was rhythmically shaken.)] and they begin to dance and sing, accompanying 
the numerous voices with gestures in unison.  And the men do not abstain  
from the feasts either. They especially delight in their games and sport  
matches; they come from all districts with as many javelins as possible to  
participate in the latter, and they lay them out to sell among themselves.  Then 
they begin the games, throwing the javelins at one another [ljc - in other  
accounts it is said that there was competition in throwing accuracy, 
in agility in dodging spears, and that men actually caught the spears thrown at  
them], from a distance, and from close by; they are very skilled at avoiding  
them with elegance.  Nevertheless, the game is often not bloodless.2 [[ljc- 
Lvesque's footnote states:  What I have translated as "javelins" is  "hastas"  
[i.e. shafts] in Latin.  It is clear that such spears had no tips, but they could  
] still produce nasty puncture wounds, when they found their mark.]  They 
oil their bodies before the game" (Lvesque,  Vol. 6:1995, 74-76). 

 Father Coomans died in the Mariana Islands after 1685 (Hezel, 1989, 89). 

Teeth blackening for cosmetic purposes is well documented in the Mariana  
Islands, Yap, Palau and the Philippines.  Humans will go to great lengths make themselves more attractive.  For some it is teeth whitening and for others it  
is teeth blackening. Having personally suffered betel nut stained teeth, perhaps teeth blackening would be an improvement.  Nevertheless, I cannot imagine being fed with a funnel for two weeks while the stain set.