A tooth that fails to erupt into a normal functional position by the time i
t normally should is considered impacted. Impactions of primary teeth are e
xtremely rare, but when it does occur it usually involves the first and sec
ond molars. The purpose of this article is to present a case of a four-year
-old patient with an impaction of an inverted primary mandibular incisor. O
n the basis of the patient's family history, the case might be considered a
s microform of ectodermal dysplasia.