In dentistry, hypodontia is the condition at which the patient has missing teeth as a result of their failure to develop. Hypodontia describes a situation where the patient is missing up to 6 teeth, excluding the 3rd molars. Missing third molars occur in 9-30% of population. In primary dentition the maxilla is more affected, with the condition usually involving the maxillary lateral incisor.
The condition of missing over 6 teeth, excluding 3rd molars or wisdom teeth, is called oligodontia. The condition for missing all teeth, either primary and/or permanent), is called anodontia. A similar condition is hyperdontia, in which there are more than the usual number of teeth.
Many other terms to describe a reduction in number of teeth appear in the literature: oligodontia, anodontia, aplasia of teeth, congenitally missing teeth, absence of teeth, agenesis of teeth and lack of teeth.