If a dental nerve dies (e.g. due to a deep hole in a tooth or molar), the dentist will remove the nerve from the tooth. The dead tooth nerve is removed through a small hole in the tooth and the space inside the tooth is filled with a rubber-like material. This treatment is usually adequate. Sometimes, however, an infection or a cyst occurs at the tip of the tooth root.
The doctor will discuss the treatment options with you in detail.