Endodontics is the treatment that consists in the removal of the dental pulp to avoid tooth extraction in order to preserve it. This intervention is performed when the injury has progressed a lot and reached the pulp.
Both cavity and dental fracture can cause pain, but depending on the extent of the injury it can be more or less intense. That intensity can give us a hint about the severity of the injury, although some tests must be carried out to determine the magnitude of the problem like testing the sensitivity to cold or heat, a teeth inspection by a practitioner, an x-ray of the internal part, etc… Generally if the pain is mild it can be solved protecting the dental pulp with protective solutions.
The problem is when the dental pulp is damaged. In these cases it needs to be removed. The practitioner will first remove the pulp using a local anesthetic thereafter the duct must be completely sterile, otherwise this situation would continue getting worse inside the tooth, and finally he will proceed with the dental filling and sealant.
In some occasions a crown must be placed in order to protect the remaining tooth.