Dens invaginatus occurs as a result of the invagination of the enamel organ. These cases may present difficulties with respect to its diagnosis and treatment because of canal morphology. It frequently leads to caries, pulpal, and periodontal involvement with necrosis and loss of attachment. The knowledge of classification and anatomical variations of teeth with dens invaginatus are of great importance for correct treatment. This article presents two case reports of two different types of dens invaginatus along with profound review of the literature regarding etiology, epidemiology, and histology. It discusses clinical appearance and diagnosis, and it provides guidelines for decision-making and treatment of invaginated teeth.