odontogenesis imperfecta

[ĭm′pər-fĕktə]
n.
  1. An odontogenic developmental anomaly characterized by deficient formation of enamel and dentin causing the affected teeth to exhibit a marked reduction in radiopacity so that unusually large pulp chambers with thin enamel and dentin are seen.
The American Heritage® Stedman's Medical Dictionary Copyright © 2002, 2001, 1995 by Houghton Mifflin Company. Published by Houghton Mifflin Company.