[Dens invaginatus--its etiology, incidence and clinical characteristics (I). A review]

Dens invaginatus is a rare malformation of teeth, showing a broad spectrum of morphological variations. A genetical determination cannot be excluded. The incidence of dental invaginations cannot be determined exactly, the data from different investigations range from 0.25% to 10%. The majority of epidemiological studies present an incidence of more than 2%. Most affected are maxillary lateral incisors, bilateral occurrence is not uncommon (43%). The aetiology of dens invaginatus is still not entirely known. Most probably the invagination has its origin in a deep folding of the foramen caecum during tooth development which in some cases may even result in a second apical foramen. The invagination presents a predisposition for carious lesions, often resulting in early pulp necrosis and apical periodontitis. Endodontic therapy may present several complications due to complex morphology of the root canal system of teeth with invaginations. The paper reviews the different theories on the aetiology of dens invaginatus, classifications, incidence and clinical aspects of this malformation.