The pulp or soft inner tissue is vital during the tooth's development. Once a tooth fully matures, it can survive without the pulp because the tooth is nourished by the tissues surrounding it. The pulp is usually 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 crack or cavity destroys these protective layers, the pulp is exposed to irritants and bacteria in your mouth. This can result in inflammation, infection, and, eventually, an abscess. Periodontal (gum) disease or a severe blow to the tooth can also damage the pulp. Endodontic therapy removes the damaged pulp, and usually, the tooth returns to a healthy condition.

If an abscess was present before treatment, the healing process might take up to 2 years.