I get this question sometimes when a patient has a toothache and my diagnosis for their ache is a dead nerve. We refer to a dead nerve as a “necrotic pulp” or a “pulpless tooth.” It’s a logical question, as the assumption is that tooth pain must come from the nerve within the tooth. It’s possible to get a toothache from the pulp of the tooth when the tooth nerve is damaged or irritated; this however is a different diagnosis, referred to as “pulpitis.” So, how can a dead nerve cause the tooth to ache? The reason is the pain isn’t coming from inside the tooth; rather it’s coming from the ultra-sensitive nerve endings around the outside of the tooth called the “periodontal membrane.” The dead pulp tissue, composed of blood vessels and nerve tissue, creates a steady diet of food for bacteria to live within the hollow area inside the tooth called the “pulp cavity” or “chamber.” This growth of bacteria and the accumulation of their dead remnants (“puss”) in a confined space causes pressure to build. The pressure on the nerve tissue within the periodontal membrane creates intense pain, usually perceived by the patient as emanating from within the tooth.
This puss formation within the bone at the root tip(s) causes destruction of the bone, often visible on an X-ray as a dark area. This is one way the dentist diagnoses the source of the toothache and decides how to treat it. This invites a new question: how do we treat a tooth with a dead nerve so that the pain goes away? Extraction of the tooth is certainly an option, but let’s assume we want to save the tooth. In this case, we must perform “root canal therapy.” In a nutshell, a root canal is a way to clean and fill the inside of the root canal spaces within the root structure. A soft rubber filling material called “gutta-percha” is used to fill the void inside the root canal spaces or tunnels. Once the dead pulp is cleaned from within the tooth, and the space is filled with gutta-percha, there is no longer a food source for bacteria, thus the body can begin the healing process on the outside of the tooth where the abscess spread into the bone and created the pain to begin with.