Anna K. Jacobs and Michael R. Jackson’s new musical Teeth, now at Playwrights Horizons, is an adaptation of the 2007 cult classic film of the same name (written, produced, and directed by Mitchell Lichtenstein). Both tell the story of Dawn O’Keefe (Alyse Alan Louis at Playwrights), who has taken a purity vow along with her fellow youth group members, cheekily named Promise Keeper Girls (PKGs) in the adaptation.