Abstract
1) We encountered a case of impacted E and consequent malpositioning of the succeeding permanent tooth germ and congenitally missing tooth germs for 3|3 in a girl, six years old at first examination.
2) The patient's medical history and family record were uneventful and the cause of development could not be clarified clinically.
3) Histopathological investigation of the extracted E showed formation and close cementing of osteoid tissue in the resorption lacunae of the dentin at the root region. Ankylosis was confirmed.
4) Marked degenerative changes such as hyaline degeneration and the calcareous degeneration were observed in the pulp tissue near the floor of pulp chamber where ankylosis was observed.
5) Judging from the findings of the histopathological investigation, the probability of infraclusion of the deciduous tooth could not be excluded; that is, E had erupted and remained submerged for some reason and was enclosed by the surrounding tissue.
6) An observation on a scanning electron microscope of the cementum and dentin of E showed resorption lacunae of various sizes.
