The effect of osteopenia on the osteointegration of different biomaterials: histomorphometric study in rats

The osteointegration of Hydroxyapatite (HA), Titanium (Ti-6Al-4V: Ti), Zirc onia (ZrO2), Alumina (Al2O3) and 2 biological glasses (AP40 and RKKP) was c omparatively investigated in normal and osteopenic rats by means of histomo rphometry. Thirty-six Sprague Dawley female rats were left intact (Group C) while 36 were ovariectomized (Group OVX). Group C and OVX were further div ided into 6 subgroups. After 16 weeks all animals were submitted to the fem oral implant of nails made of the above-mentioned materials. Eight weeks af ter implantation the animals were euthanized, the femurs were harvested for histomorphometric analysis. The data showed that: (1) all the tested mater ials were biocompatible in vitro; (2) no significant differences existed in Affinity Index (AI) of Group C; and (3) results from paired comparison app lied to the AI showed significant differences among the Groups C and OVX. T he AI did not significantly change among intact groups, while it significan tly decreased when some materials were implanted in OVX subgroups (AP40, Zr O2 and Ti-6Al-4V: p < 0.0005, p < 0.05 and p < 0.01). It is confirmed that bone mineral density is a strong predictor of the osteointegration of an or thopedic implant and that the use of pathological animal models is necessar y to completely characterize biomaterials. (C) 2000 Kluwer Academic Publish ers.