The term is not defined here since the finding requires a radiograph, as is true for anodontia and for the other designation of tooth agenesis, hypodontia. The terms hypodontia and oligodontia are sometimes used interchangeably in the literature while on other occasions hypodontia is used for selective agenesis of six or less missing teeth while oligodontia is applied when there are more than six missing teeth. Tooth agenesis or oligodontia/hypodontia can be mistaken for delayed eruption and again a radiograph is needed for diagnosis. Absence of teeth may be congenital (tooth agenesis) or acquired. The incidence of congenital absence of teeth is different depending on the type and position of the tooth [Gorlin et al., ].