When teeth become infected or when the dental nerve within the tooth dies the tooth will require a endodontic therapy commonly known as a root canal, this procedure is required to preserve the tooth.
A Root canal is preformed there the nerve cavity is entered, nerve tissue and any infection is removed. The nerve chamber are shaped so the canal or canals can be filled with a natural occurring plant product called gutta percha a rubber like product. In most cases Endodontic Procedures (root canals) allow the dentist to save teeth.
Root Canal teeth over time will dehydrate or dry out resulting in the tooth becoming brittle, this is why crowning (capping) the tooth is recommended.