Congenital absence of permanent teeth among Irish school-children.

The Orthodontic records of 3,056 patients attending a Regional Orthodontic Unit were examined, to assess the prevalence of hypodontia. Orthopantomogram radiographs were available for all patients. The congenital absence of third molars was not considered. The prevalence of hypodontia was 11.3% which was high in comparison with previous studies. However it was in keeping with more recent studies from the U.K. and Ireland.