Dens invaginatus (DI) is a rare congenital dental malformation characterized by enamel or cementum folded into dentine. Such teeth are susceptible to caries, pulp infection or necrosis and periradicular lesion. The complex anatomy of this disease results in difficult treatment and a high rate of therapeutic failure. Therapeutic options, such as debriding and filling invagination, root canal treatment (RCT) and intentional replantation, vary according to the morphology and infection of the involved tooth. The present study reports five cases of DI with chronic apical periodontitis. The treatment strategies and procedures, including RCT, removing the invagination, intentional replantation and surgical treatment, are discussed according to the classification and the condition of pulp and periapical tissue. The study also reports the prognosis: All patients were followed up for ≥12 months and all teeth demonstrated periapical healing and clinical asymptomatic. In summary, appropriate treatment is based on accurate analysis of the anatomical variation in different types of DI and intentional replantation is a reliable and viable treatment to preserve the tooth.