An experimental study of healing around hydroxylapatite implants installed with autogenous iliac bone grafts for jaw reconstruction.

The purpose of this study was to evaluate the use of hydroxylapatite implants (HA) with autogenous bone grafts for jaw reconstruction. After autogenous iliac bone grafts were transplanted to 36 rabbit mandibles, an HA implant was installed into the graft immediately (IM group), or 90 days (90D group), or 180 days (180D group) later. The animals were killed 7, 14, 30, 60, 90, and 180 days after the HA implant placement. The healing process was examined histologically, and histomorphometric measurements were made with a computer-based image analyzer to quantify the percentage of HA-bone bonding and trabecular bone in the medullary cavity. In the IM group, the HA-bone bonding tended to be deterred by fibrous tissue, and the rate of HA-bone bonding (BBSR) was less than that of the other groups. The trabecular bone around the implants tended to decrease after 30 days in all groups. However, the average of the trabecular bone specific volume (tVsp) in the 90D group was about 10% higher than that in the other groups. From these results, it is concluded that in clinical use of HA-coated dental implants with autogenous bone grafts, the time of installation should not be immediately after the bone graft, but when there is sufficient newly formed trabecular bone to enhance HA-bone bonding.