It may be tempting to expect this section to cover in detail loss of teeth, from trauma, periodontal disease or tooth decay, to talk about consequences of loss of teeth, prevention by a good regime of oral hygiene and possibly to discuss restoration options. However, such aspects of loss of teeth will not be covered here (or elsewhere on our website) – these are themes that firmly belong, and are dealt with, in the field of dentistry rather than oral & maxillofacial surgery.
Here we refer to developmental abnormalities when we talk about missing teeth. In order for healthy teeth to develop (from week 6 to 8 of pregnancy for primary (baby) teeth; from week 20 of pregnancy for permanent teeth), their development has to happen at the right time and in synchrony with other growth and development of the foetus. If teeth fail to develop at the right time of pregnancy, no teeth will develop. The resulting conditions are anodontia (absence of teeth) or hypodontia (fewer teeth than normal) after birth.
The complete absence of teeth, anodontia, is very rare and usually occurs in conjunction with some rare genetic disorder (hypohidrotic ectodermal dysplasia) that causes defects to a number of tissues that all derive from early embryonic ectoderm (the outer embryonal layer).
Hypodontia, the absence of one or more teeth, in contrast is one of the most common developmental abnormalities. Permanent teeth are more often affected than baby teeth, and hypodontia is often combined with smaller than average size of the remaining teeth. The most commonly affected teeth are a missing third molar (wisdom tooth, 25 to 35 % of the population), followed by a missing second premolar or lateral incisor (2 to 3 % each). Hypodontia is also associated with some genetic disorders such as Down syndrome or Crouzon syndrome (a craniofacial syndrome).
Further reading: Diagnosis