An endodontist is a certified specialist in the dental pulp (nerve).
Teeth have several parts. On the outside above the gum line in a normal healthy younger person the teeth are covered with enamel. Enamel is the hardest substance in the body. It is a protective coating for the teeth. When our teeth erupt, all of the tooth that protrudes from the gums is covered with enamel. There are no nerve endings in enamel and it is not connected to any nerve endings. You can scratch it, chip it, or sand it and you will not feel any irritation. Underneath the enamel is the dentin. The dentin is softer than the enamel. Although there are no nerve endings in dentin, there are thousands of tubules in dentin that lead to the pulp (nerve) that lies inside of the dentin. For this reason, dentin that is not covered with enamel is usually sensitive to cold, hot, or palpation (touching it with something). The dentin and the enamel are hooked together with a very strong bond. Below the gum line of a young healthy person the roots are made entirely of dentin except for a thin coating of material called cementum that aids in attachment between the dentin of the root and the surrounding bone holding the teeth in place. On the inside of the dentin is the dental pulp (nerve). The pulp is made up of some nerve tissue, but what makes up the bulk of the dental pulp are blood vessels. There are other soft tissue elements inside the dental pulp. The nerve structure of the dental pulp is a little different from nerves in other places in the body. Nerves in teeth have fairly undifferentiated nerve cells. This is why scratching on a dentin surface of a tooth (like an exposed root or somewhere where enamel has been chipped or worn off the tooth) feels the same as putting cold or hot on the tooth. Everything that irritates the tooth feels “cold”.
Sometimes the pulp of a tooth becomes sick. This can happen when dental caries (a cavity) reaches so deeply into the tooth that it enters the space where the pulp is located. It can also become sick when a tooth is cracked into the pulp, or has been hit and the pulp coming out the end of the root is severed or stretched. Sometimes long term inflammation (like when a filling has to be placed very close to the pulp because that is where the decay went) can cause the pulp to become sick. When the pulp of a tooth becomes irritated, it cannot swell like other soft tissues in the body because it is enclosed with a hard substance (the tooth). Without this ability to swell, sometimes a tooth becomes abscessed when it has been irritated. This is another way to say the tooth has died or become pus filled. This is an infection. Since the blood supply of a tooth is minimal, once a dental pulp turns to abscessed material (pus), it cannot rebuild itself. When a tooth reaches this point, as long as there is sufficient bony support around the tooth and there is enough total structure remaining to reconstruct the tooth, the remnants of the pulp can be removed and the tooth kept in place and used like a living tooth. Other material is placed as sort of a cork inside the empty pulp space after the pulp is removed and the pulp space is made large enough for a sealing agent to be placed all the way to the end of the root. Usually the material of choice is called gutta percha, and is made from the sap of a certain kind of tree from the Malay islands. There is also a sealer (like glue) that is placed with the gutta percha. Yes, what I am describing is a root canal.
An endodontist is a root canal specialist. Most root canals in North America are completed by general dentists—over 90%. The more complicated root canals are usually referred to an endodontist. The conditions requiring an endodontist include anatomy that is unusual like very curved roots or canals that are very small. As well, if access is difficult (the patient can’t open very wide or for very long) an endodontist is often used instead of the general dentist completing the root canal treatment himself. An endodontist is also used when a root canal has been done and fails for an unknown cause, or the treatment becomes too complicated for the general dentist to complete after the work has been started but has not been finished. If failure occurs after a root canal is completed (sometimes years later), often there is an undetected and thus unfilled portion of the root canal system. This can happen when the anatomy of the root canal system is not what is expected and the unexpected part of the system is quite small or in an unusual location inside the tooth. If part of the root canal system is not treated, the tooth often does not fully recover after root canal treatment is done. Usually an endodontist can still save the tooth. When a root canal is needed, the only other treatment that can be done to relieve the pain of an abscessed tooth is extraction. Antibiotics are often used before a root canal is done, and sometimes after.