Abstract
We studied histopathologically five cases of prolonged retained primary teeth which were collected at the Department of Pedodontics, School of Dentistry, Hiroshima University. The teeth of the five cases were decalcified and made into specimens which were stained with hematoxylin-eosin, azan and thionin-picric acid.
The results obtained were as follows:
1) All of the cases had one prolonged retained primary tooth, but only one case had a missing successive permanent tooth and in the other cases for successive permanent teeth malposition was observed.
2) Considerable secondary dentin was formed in the wall of the pulp but the odontoblastic layer was not found in most cases.
3) For the pulp in all cases we did not observe the normal state and in most cases we observed periodontal membrane which had entered into the area of the root resorption. In the only case which had a missing successive permanent tooth, we found the component cells fo the pulp but that pulp showed regressive change, for example vacuolar degeneration, atrophy and fiberalized.
4) In one case the root was a little resorbed at the apex and in one case the root was almost totally resorbed, but we did observe root resorption in all cases.
5) We observed proliferation of cementum or cementoid for the resorbed lacunae in almost cases but only one case had the typical resorbed lacunae like Howship's lacunae. In particular we observed proliferate cementum in the wall of the coronal pulp.
