To specify, I’m talking about violently ripping a healthy fingernail off, a la torture. Will a new nail grow to replace the lost one? I assume there must be some sort of a nail root inside the fingertip without one no new growth is possible. Any ideas?
My dad got his finger caught in a button and the fingernail ripped out once while working at his factory job a lng time ago, it never grew back.
My middle finger nail was almost completely detached playing (field) hockey; it just hung on by a little bit of skin. I cut through it a few hours later. The nail completely regrew and although a little flattened, is fairly normal.
Fingernails grow from a germinal matrix at the base of the nail.
If this is left undisturbed, a new nail will grow. The new nail will be normal if the bed of the original nail was not torn or otherwise disrupted.
Ordinarily a nail that is mechanically ripped off will separate at the germinal matrix and leave it behind. Since there are so many ways to injure a finger a more specific answer is not possible.