[Experimental study of bone resorption after tooth extraction with implanted hydroxyapatite tooth root substitute]

Hydroxyapatite (HAP) tooth root substitute implantation have been applied to extraction sockets in many studies for purpose of preservating alveolar bone. Dimensional changes were measured with sectioned study cast of cephalometric X-ray photo. In this study, dimensional changes were determined by newly developed evaluation system which utilizing image analyzer (Immunomedica Co., Ltd.), in a view of conserving alveolar ridges beneath the denture base. Cone shaped HAP tooth roots (5 or 6 mm in length) were implanted to one subject and disk-like shaped HAP tooth roots (2 mm in length) were also implanted to the other subject. Preservation of alveolar bone was observed in both shaped HAP tooth roots implanted site compared to control site. Bony ankylosis between HAP tooth root and alveolar bone, observed on 1 month after histological specimens, may contribute to this result. Smaller changes of blood flow compared to controls were obtained on implanted site, which were measured with Laser Doppler blood flow meter (Perimed KB; Sweden) on buccal mucosa. We consider that HAP shows good biocompatibility and HAP tooth roots implantation decrease the wound volume consequently.