When a deep cavity or impact injury damages the live inner tissue of a primary (baby) tooth, we try to preserve as much of the pulp (nerve) as possible. Whenever possible, we do a pulp treatment on that tooth that removes only the part of the live pulp in the crown. The pulp that extends to the root of the tooth is left intact. 

This treatment can also be done on a permanent tooth that has not yet fully developed. By leaving the root as intact as possible, the tooth has its best chance to continue to develop normally.