The delay method: a new surgical technique for enhancing the bone-binding capability of HAP implants to bone...

To confirm the efficacy of a new apatite-implantation technique, in vivo research was undertaken on 12 dogs. The project was designed to determine the time-dependent effects on alveolar tissues surrounding implant cavity preparations without implantation in bone. In addition, a group of hydroxyapatite (HAP) implants was placed immediately after cavity preparation (conventional method). A second group was placed after a delay of 2 weeks (delay method). Hemorrhagic infiltration occurred within the cavity and into the surrounding fatty marrow, a phenomenon attributed to cavity preparation. Subsequent to absorption of infiltrated blood cells into the surrounding marrow, fibrous tissue was formed, followed by osseous formation initiated by the original bone. Formation of newly formed, thin trabeculae reached a peak at 14 days. Most of the original marrow near the cavity, where few trabeculae were originally present, was transformed into thin trabecular-forming areas. In addition, sinusoidal capillaries and hematopoiesis were formed at the site. At 30 days, the number of new trabeculae and sinusoidal capillaries formed decreased, and adipose cells began to appear. These results indicate that tissue surrounding the prepared cavity was centrally activated at 14 days, and that this activation may be beneficial in the biologic ability of an apatite implant to advantageously affect bone binding and chemical bonding activity. It is concluded that bone formation was faster and wider around implants placed by the delay method than that surrounding conventionally placed implants. These results indicate that more efficient bone formation around implants was encouraged by bone activation stimulated during the 14 day delay period.