The Tooth Fairy was a mythical fairy creature from Earth mythology. The Tooth Fairy had the power to grant little children money in exchange for lost teeth which the children would naturally lose as they grew into maturity.
In 2376, B'Elanna Torres exclaimed that she didn't care who she had to ask, including the Tooth Fairy, if it would save her mother from damnation in Gre'thor. B'Elanna at the time was experiencing a near death vision of the Barge of the Dead and had come to believe that her own mother Miral was damned as well for B'Elanna's sins. (VOY: "Barge of the Dead")