Severe hypodontia or even adontia
in children are very rare conditions, most often associated with congenital syndromes such as Down syndrome (trisomy 21)  or ectodermal dysplasia .
has so far been confined or noted only in some members of the subfamily Mylodontinae; specifically in the Plio-Pleistocene genera of Mylodon from South America and Paramylodon from North America (McAfee, 2007, 2009).
There was partial adontia
with only one conical incisor tooth.
Chemotherapy administered to any child before development of secondary dentition may result in a variety of dental abnormalities, including adontia
, hypodontia, microdontia, root stunting, and enamel hypoplasia.