grind one’s teeth—have feelings of great anger or annoyance though not fully manifesting what one feels:
- If there is one thing calculated to make British artists grind their teeth, it is to be faced with generalizations about national characteristics.
grit one’s teeth—endure pain, discomfort, etc. without complaint; accept a difficult situation and deal with it in a determined way:
- He gritted his teeth and held on tightly to his assailant even as the rest of the gang rained blows on him.