抄録
It is important, in the prosthetic therapy, to prevent the alveolar ridge from the bone resorption after tooth extraction and denture insertion.
For the purpose of preservation, the authors have studied the procedure of root-submergence in which only the root of a tooth is retained intentionally in the alveolar socket below the mucoperiosteum.
However it should not be applied to the fractured roots, the decayed roots, and the roots with an extended periapical infection. These cases should be regarded as a contraindication of the root-submergence procedure, to which the authors apply a hydroxyapatite ceramics implant(HAC)inserted into the fresh alveolar socket just after tooth extraction.
There are two types of cone and particle in the HAC. It has been reported in a study comparing the effect of the two forms, that the cone type is more effective than the particle type to prevent bone resorption. The authors utilize the cone type HAC under the criteria determined preliminarily, that is, in addition to the above mentioned contraindication of the root-submergence procedure, the presence of abutment in the region adjacent to the HAC to be submerged.
The following results were obtained.
1. The presence of HAC is useful to prevent the bone resorption around the abutment adjacent to the submerged HAC and, on the other hand, the abutment works to support the occlusal force and serves to reduce the imposition of the ridge retaining the HAC.
2. It is possible to apply the HAC to the cases as well in which there is no abutment around the region to submerge the HAC and the HAC stands isolated.
3.We can expect a successful result if the HAC is fixed steadily in the socket and immobile during initial stage inserted into the socket.
4.We should be afraid of having an unsuccessful prognosis in those who have some general diseases and/or the following alveolar conditions:
1) having a curved tooth root
2) having a shallowed socket
3) having little expansion of the wall
