Endodontics is a branch of conservative dentistry dealing with treatment of teeth with inflammatory conditions of the pulp and periapical tissues. Root canal treatment is often the only way to save a caries-affected tooth from extraction.
Deep, untreated carious cavity leads to bacterial infection of the tooth pulp and development of irreversible inflammation, which may be accompanied by severe pain ailments. Withholding root canal treatment at this stage leads to development of pulp necrosis and chronic inflammation of the tissues surrounding the root (periapical lesion). Exacerbation of the chronic inflammation in the vicinity of the root constitutes the cause of abscesses and severe pain.