Root
The hard part of the tooth is actually not a living structure. The living structures are the nerves and blood vessels that are inside the tooth.
Enamel is called the dentine part of the tooth
Pulp
The part of a tooth that is exposed and above the gum is called "crown", not to confuse with a crown that is prothesis to restore a heavily damaged tooth. The part of a tooth that is hidden inside the bone is called "root".
The part of the tooth that fits into the socket of the jaw(mandible) or maxilla(for upper teeth) is the "root" of the tooth.
Crown
The visible portion of the tooth is called the crown. The submerged portion is called the root.
The living part is biotic and the non-living part is called abiotic.
crown
The part of a tooth where the nerve and blood vessels are found is called the pulp chamber.
The part of the tooth that is covered with enamel is the crown.