Histomorphometric analyses of hydroxyapatite-coated and uncoated titanium implants. The importance of the implant design.

Hydroxyapatite-coated and uncoated titanium screws were inserted in the rabbit tibial metaphysis and evaluated by histomorphometry after 6 months of follow-up. There was no difference in direct bone contact between the HA-coated implants and the uncoated controls. The effect of HA-coating on screw-shaped implants seems to be uncertain, in contrast to unthreaded cylindrical designs, where there is more abundant documentation in favour of HA-coated implants.