[Experimental study of hydroxyapatite (HA) granules filled around the titanium implant]

To compare the diference of the bone formation between immediate and delayed implantation, and evaluate the role of the hydroxyapatite (HA) in immediate implantation.

HA coated titanium implants were implanted into the femurs of adult dogs, the diameter of the socket was 6.5 mm and 3.5 mm respectively, HA coated titanium implants (all with the diameter of 3.5 mm) were placed into the latter sockets, and was considered to be the model of delayed implantation. The implantation in the 6.5 mm socket were considered to be the model of immediate implantation. The immediate implantation was divided into two groups, HA granules were filled in between the bone and implant in one group, and no HA particles was filled in another group. Animals were killed at 1,2,3 and 4 months post operation.

Immature new bone formation was found on all specimens one month after implantation, and the amount of new bone formation in HA particles filled group was much more than that group without HA particles. In the HA granules group, there was no marked difference from the group of implantation in 3.5 mm socket. Mature new bone was observed four months later after operation, and no marked difference was found in the amount of new bone between HA granules filled implantation in 6.5 mm socked and implantation in 3.5 mm socket.

Implantation of HA granules is helpful to the stability of the implant and plays a role in the healing of implant with surrounding bones.