How long does it take for the root of a tooth to die from abscess?

Varies: Usually if a tooth has become infected in the nerve canal, then it is hard to place a time frame on when the tooth will "die." some teeth actually die and never abscess, the roots being naturally filled in or calcified. If there is a question of symptoms, then you may want to have it checked out before you start developing more severe symptoms- pain, swelling, etc.

See a dentists: The sooner you treat the infection the better the prognosis and the healing of the tooth. A tooth that is infected is either slowly dying or already dead. Go see a dentist asap.