{Tooth powder}, a powder for cleaning the teeth; a dentifrice. {Tooth rash}. (Med.) See {Red-gum}, 1. {To show the teeth}, to threaten. ``When the Law shows her teeth, but dares not bite.'' --Young. {To the teeth}, in open opposition; directly to one's face. ``That I shall live, and tell him to his teeth .'' --Shak.