The procedure involves removing inflamed or damaged tissue from inside a tooth and cleaning, filling and sealing the remaining space. The pulp, or soft inner tissue of your tooth, is normally surrounded and protected by a layer of dentin. Above the gumline, the dentin is protected by a layer of enamel; below the gumline, the dentin is covered by cementum. When a deep cavity, decay or crack destroys these protective layers, the pulp is exposed to the bacteria in your mouth. This can result in inflammation, infection and, eventually, necrosis (pulp death). A severe blow to the tooth can also damage the pulp. Irritants may then escape from the end of the root and cause a diseased area (apical lesion) in the bone.
Root canal treatment removes the damaged pulp and irritants. This allows the bone surrounding the root end to repair and heal. Steps of the operation is depicted below, click on each image for better viewing.