PRELIMINARY EVALUATION OF HYDROXYAPATITE CEMENT AS AN AUGMENTATION DEVICE IN THE EDENTULOUS ATROPHIC CANINE MANDIBLE

Objective. The purpose of this study was to answer the following two q uestions: (1) Can hydroxyapatite cement in combination with deminerali zed freeze dried bone feasibly augment the dimension of an atrophic ed entulous canine mandible? (2) What is the histologic fate of an augmen tation graft composed of hydroxyapatite cement and demineralized freez e dried bone placed on the surface of an atrophic edentulous canine ma ndible? Study Design. Each of four mixed-breed canines (weighing 50 to 60 pounds) underwent bilateral mandibular dental extraction (canine t o second molar) and radical alveolectomy. After 4 months of healing, a bilateral subperiosteal mandibular augmentation graft was put into pl ace, with hydroxyapatite cement/demineralized freeze dried bone on the surface of one hemimandible and porous granular hydroxyapatite and de mineralized freeze dried bone on the surface of the other hemimandible . The animals were killed after functioning on a soft diet for 9 month s, and the grafted hemimandibles were harvested. Results. Both hydroxy apatite cement and granular hydroxyapatite grafts appeared to augment the edentulous atrophic canine mandible. On histologic exam, the hydro xyapatite cement grafts showed osteoconduction and subperiosteal and e ndosteal osteonal bone formation, whereas the granular hydroxyapatite grafts showed only osteoconduction. Neither graft material showed chro nic or acute inflammation. Conclusion. Hydroxyapatite cement can funct ion feasibly as a mandibular augmentation device. The histologic fate of hydroxyapatite cement is different from that of granular hydroxyapa tite. It has a fate comparable to autogratt or allograft cortical bone grafts.