to the teeth

1. Completely, fully, as in Obviously new to skiing, they were equipped to the teeth with the latest gear . This idiom dates from the late 1300s. Also see armed to the teeth ; fed to the gills .

2. Also, up to the or one's teeth . Fully committed, as in We're in this collaboration up to our teeth . [First half of 1900s] Both of these hyperbolic usages allude to being fully covered or immersed in something up to one's teeth.