Speciﬁc terms are used to describe the nature of tooth agenesis. Hypodontia is most frequently used when describing the phenomenon of congenitally missing teeth. Many other terms to describe a reduction in the 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. The term hypodontia is used when one to six teeth, excluding third molars, are missing, and oligodontia when more than six teeth are absent (excluding the third molars). The long-term management of hypodontia in the esthetic zone is a particularly challenging situation. Although there are essentially two distinct approaches to managing this problem; that is space closure or opening for prosthetic replacements, implant or autotransplantation. These patients often manifest with many underlying skeletal and dental problems and a multidisciplinary approach for management of this condition is recommended. Two treatment approach including space closure and space reopening are described in details in this chapter.
Missing is one of the most dental anomalies in practice of dentistry and they may affect the self-esteem and social wellbeing of the patients. This condition is often complicated by dental anomalies associated with hypodontia such as impacted teeth, microdontia, delayed eruption and taurodontism. Hypodontia reportedly affects between 3% and 8% of the population. Hypodontia is a common problem seen by the general dentist and is usually referred to the orthodontist. [1, 2] Agenesis means that a dental bud fails to develop or is not present at birth. This problem leaves an empty space in the arch which causes plentiful problems. Speciﬁc terms have been used to describe the nature of tooth agenesis.
Anodontia is named complete absence of teeth.
Hypodontia means missing teeth, but usually less than six teeth.
Oligodontia or partial anodontia is defined absence of six or more teeth.
Anodontia and oligodontia are rare, however, hypodontia is relatively a common problem. Many other terms are also used to describe a reduction in the number of teeth in the literature such as aplasia of teeth, agenesis of teeth, absence of teeth, lack of teeth, and congenitally missing teeth