Central incisor syndrome

Solitary median maxillary central incisor (SMMCI) is a rare dental anomaly. It is usually considered as a minor manifestation (variant) of holoprosencephaly (HPE).


It is estimated to occur in 1:50,000 live births.


It is a complex disorder consisting of multiple, mainly midline defects of development resulting from unknown factor(s) operating in utero about the 35-38 day from conception. The etiology is uncertain.


A missense mutation in the SHH gene (I111F) at 7q36 may be associated with SMMCI .


Up to 90% have choanal atresia, midnasal stenosis or pyriform aperture stenosis.

Radiographic features

  • single, midline central maxillary incisor
  • midpalatal vomerine ridge
  • v-shaped palate