Root canals are required due to trauma, a severe fracture, or bacterial invasion of the nerve and blood supply. Once any of these factors reach or get close enough to the nerve of the tooth, it causes severe pain. Root canals can also be required after a deep filling due to a deep cavity. The nerve can be irritated enough even without nerve exposure, which can result in severe pain. This is the traditional “toothache” people feel when they go to the dentist urgently. In order to stop the pain, the nerve is removed and the canals are thoroughly disinfected. After disinfection, it is filled with a biocompatible material. After the root canal is complete, a lab fabricated post or prefabricated post may be required depending on the extent of tooth destruction due to disease, trauma, or fracture. The post will provide extra support for the subsequent crown that is needed.