Endodontics is the part of dentistry that deals with the diagnosis and treatment of the infection of the dental pulp (nerve). When tooth decay attacks the tooth, the first thing that is damaged is the enamel. If it keeps progressing, it affects the dentin and, if it advances further, reaches the pulp where there is the nerve.
The cavities progress slowly so they are easy to detect before they are too large. They are often discovered through an X-ray. They don't always hurt. Sometimes you don't feel pain until the nerve has been reached. When the decay reaches the nerve it is infected and therefore it is inflamed and it feels pain. If inflammation persists, the nerve may lose its vitality. At that time no longer disturbs, but produces pus, which comes to the tip of the root, and results in an abcess. By the time the decay reaches the nerve is when you need to perform the root canal treatment, which consists of opening a cavity in the tooth and removing the nerve that has been affected by tooth decay.
After their disinfection, which is fundamental, the root canals are filled with a material similar to plastic. This whole process is very delicate and can sometimes be very complex depending on the nature of each tooth.
This process prevents tooth removal, but leaves it more weakened than when it had his healthy nerve (without being affected by the decay), so sometimes it is necessary to place a tooth crown on top.