A healthy tooth consists of two main parts the crown and the root and is comprised of enamel, dentine and pulp (nerve) tissue.
The part of the tooth that you can see in the mouth is called the crown and it is covered by an external layer of Enamel. Enamel is the hardest tissue in the body and consists of dead cells. It cannot be regenerated and plays no part in tooth sensitivity.
If, however, enamel is removed by wear such as acid erosion or dental decay exposure of the underlying dentine can initiate extreme sensitivity. The dentine is a living layer of cells that extends through out the tooth.
Dentine tubules convey impulses to the central pulp chamber where the nerve resides.Damage to the nerve of a tooth results in the death of the living tissue and abscess formation. The most likely occurrence for this event to take place is through dental decay or fracture of the tooth as a result of an accident. Once bacteria invade the pulp chamber the process is irreversible and leads to death of the nerve and formation of a dental abscess so often characterised by pain and swelling.