Tooth agenesis review

Abstract

Background: Tooth agenesis means absence or incomplete development of tooth. It is a common human anomaly, which according to Online Mendelian Inheritance in Man database affects approximately 20% of the population. Third molars are most commonly affected teeth, followed by upper lateral incisors or lower second premolars. Agenesis differs by continent and gender. Prevalence of dental agenesis in females is higher than in males. The prevalence for both sexes is higher in Europe and Australia than in North American Caucasians. In literature, several terms are used to describe the anomalies in number of teeth. Oligodontia is term, which is used to describe situations where more than six teeth are missing, apart from the third molars. Anodontia, extremely expressed oligodontia, is used to describe complete absence of teeth. Hypodontia describes more complex cases including defects in number of teeth and also abnormalities in size, shape, development and eruption of remaining dentition. Hypodontia is one of the manifestations of congenital defect of dental lamina development. Although dental agenesis is occasionally caused by environmental factors, such as infection (e.g. rubella), different kinds of trauma in the apical area of the dentoalveolar processes (fractures, extraction of temporary tooth), chemical substances or drugs (e.g. thalidomide, chemotherapy), or radiation therapy, in a majority of cases, hypodontia has genetic causes. Hypodontia can occur as an isolated condition (non-syndromic hypodontia) or can be associated with a systemic condition or syndrome (syndromic hypodontia). It is frequently associated with other anomalies such as microdontia, peg-shaped lateral incisor, palatally displaced canines, taurodontism and delayed formation and eruption of other teeth.

Keywords

• tooth agenesis
• hypodontia
• oligodontia
• anodontia