skin of teeth

e·nam·el cu·ti·cle

the primary enamel cuticle, consisting of two extremely thin layers (the inner one clear and structureless, the outer cellular), covering the entire crown of newly erupted teeth and subsequently abraded by mastication; it is evident microscopically as an amorphous material between the attachment epithelium and the tooth. Synonym(s): adamantine membrane, cuticula dentis, dental cuticle, membrana adamantina, Nasmyth cuticle, Nasmyth membrane, skin of teeth

skin of teeth

Anatomy
Primary enamel cuticle (see there); cuticula dentis (enameli) [NH3].
Vox populi 
A colloquial phrase for having “barely” done something; as in, to have made the flight by the skin of one’s teeth.

e·nam·el cu·ti·cle

(ĕ-namĕl kyūti-kĕl) Primary enamel cuticle, consisting of two extremely thin layers (the inner clear and structureless, the outer cellular), covering entire crown of newly erupted teeth and subsequently abraded by mastication; evident microscopically as an amorphous material between the attachment epithelium and the tooth.
Synonym(s): adamantine membrane, cuticula dentis, dental cuticle, membrana adamantina, primary cuticle, skin of teeth.