If a tooth is broken and the dental pulp exposed (the nerve visible through the broken part) then the nerves is at risk of becoming more infected and eventually die. Partial removal of the pulp and protection of this surface can be done.
The surface of the nerve is carefully prepared and then a non-toxic sealing material is placed. This is done under a microscope and then a protective restoration is placed. Usually the dental pulp survives following this and remains healthy, allowing the tooth to continue to develop.