As far as the US, Miss Manners sums it up perfectly
"Dear Miss Manners,
When and where is it acceptable to use a toothpick?
When: When there is something stuck in your teeth. Where: In spaces between your teeth. Oh, and in the bathroom."
But in certain parts of the world such as Asia and Brazil, using the tootpick at the table is considered ok. An old Chowhound topic
What brought this up is that I was dining at one of the pricer restaurants in Antigua, GT, an old-school Continental type of joint with waiters in tuxes. The meals starts with a warm napkin to clean you hands that is presented in a basket next to a red rose.
Anyway, after the entree, along with a dish of cardomon to cleanse the palate, there's a toothpick container. This isn't at the end of the meal, where you can slip the toothpick in your pocket and retreat to the rest room.
So it got me thinking. In those societies where this is acceptable ... this site came up with a few questions I'd like to know
"Should the left hand be used when handling the TP?
Should one cover one's mouth, whilst TPing?
What should be done with the detritus?
A) Placed on napkin
B) Spat into the fan too share around
C) Saved for when hungrey later
D) If saved, what is the time limit"
There is a book on the history of the toothpick where the author says in an NPR interview
"Petroski also finds that the toothpick has adapted across cultures. In Japan, traditional toothpicks are pointed at one end only. Decorative grooves at one end enable the end of the toothpick to be broken off to indicate that it has been used. The stub also provides a rest to keep the soiled part from touching the table. In Portugal and other countries, toothpicks are often hand-carved and receive elaborate ornamentation."
Another link on toothpick history says that "The prophet Muhammad assigned the care of this important tool to a servant called the "master of the toothpick."
So, in those societies that toothpick, what are the rules for using it? How does one become the master of the toothpick?