reasons for retained primary teeth

what are the three reasons for retained primary teeth?

o   1- there may be no permanent successor

§  Therefore, the tooth remains

o   2-there may be ankylosis of the primary tooth

§  A condition in which the alveolar crest of bone fuses in the cervical area with the cementum of a resorbing root

§  All the root may have been resorbed, the tooth remains firmly in place, preventing the permanent tooth belwo form erupting

§  May be for years, and yet when the ankylosed tooth is removed, the permanent tooth with begin to erupt

o   3-the permanent tooth does nto erupt in its normal position and therefore does not cause resoprtion of the primary tooth root/s and the tooth remains

§  Frequently seen in the anterior mandibular area

·         Permanent teeth erupt apically, rather than apically and labially

·         Both sets of anterior teeth will be seen

EMBRYO TEST TOMORROW!