In the north Europe generally speaking using a tooth-pick at the table was considered rude, and even in the France, Italy or Spain, many people held their napkin in front of their mouth while useing a tooth-pick in public.
I agree it was fashionable in the late 60s and 70s for restaurants to put tooth-picks out and it does seem to have gone out of fashion again, as has the other 70s fashion of kissing French fashion on one or either cheek of the person you are greeting.
Personally, I excuse myself and go to the toilet if I want to comb my hair, pick my teeth or renew my make-up. As a child I was also taught that while you might get away with blowing your nose at the table in Britain, I must never, ever do so when visiting relations in Denmark. There you had to restrain yourself, as leaving the table for any reason at all, during a meal was considered bad manners.