Alveolar ridge maintenance with solid nonporous hydroxylapatite root implants.

Animal studies were carried out to determine a simple technique of implantation of nonresorbable polycrystalline hydroxylapatite solid root forms and the biocompatibility of the material placed in fresh extraction sockets. An appropriately shaped root form was evaluated, and alveolar bone preservation was investigated in dogs and primates. It was found that bone and soft tissue would migrate across the HA root implant when placed 2 to 3 mm below the alveolar bone crest without soft-tissue closure. It was not necessary to use roots that fit the socket from the apex to the alveolar crest. An average of 2 mm more alveolar bone was preserved in fresh extraction sites as compared to control sites. The results of the animal studies indicated the appropriateness of a clinical trial in human beings.