Pulp, Root Canal, and Periradicular Conditions

The main cause of pathological pulp, root canal, and periapical conditions is the presence of bacteria in the tooth. Bacteria can enter the dentine-pulp complex via various pathways such as through caries, cracks, fractures, and broken-down restoration margins. The pulp initially attempts to wall off the invading bacteria and their endotoxins with reparative or reactionary dentine. However, if the invasion continues (i.e. no treatment is provided), the pulp becomes inflamed (pulpitis). Reversible pulpitis is the first stage and if not treated, it progresses to irreversible pulpitis, followed by a brief ‘necrobiosis’ stage while the pulp is progressively necrosing, so there is both irreversible pulpitis and necrotic, infected pulp tissue present. The pulp necrosis and infection progresses to involve the entire pulp, and within a few months, the root canal system becomes pulpless and infected. In conjunction with this progression of disease in the root canal system, the periapical tissues become inflamed (apical periodontitis). This inflammatory process is dynamic with various phases of acute or chronic inflammation. It can also progress to develop acute or chronic abscesses and sometimes facial cellulitis. In some cases, if epithelium is present in the periapical tissues, a pocket cyst may develop and this may progress to become a true cyst. Following appropriate endodontic treatment, the periapical tissues usually heal and return to a clinically normal state although in some cases there may be some scar tissue present.