Bone healing in porous implants: a histological and histometrical comparative study on sheep

Tissue integration in four types of porous implant materials (Interpore 200 (R) or Corallin hydroxyapatite, hydroxyapatite blocks, hydroxyapatite granu les and polymethylmethacrylate) was evaluated in vivo. Porous blocks measur ing 20mm x 10mm x 8mm were implanted in mandibles and iliac crests of sheep . Bone healing in porous blocks was studied at 2 and 6 months after implant ation. The behavior of the material itself was also analyzed. Histological and histomorphometrical analysis revealed bone healing depending upon heali ng time and material. On the basis of analysis of variance, differences in amounts of bone ingrowth at 2 and 6 months were statistically significant ( p = 0.0039 in mandible; p = 0.0351 in iliac crest). The longer the time spa n, the more mineralized tissues were observed in the specimen. Our data con firmed that hydroxyapatite has osteoconductive capacities. Porous PMMA was found to be biocompatible, but it showed less bonegrowth within the pores. Interpore 200(R), which had the highest surface to volume ratio was found t o display the highest level of osseointegration and biodegradation. (C) 200 0 Kluwer Academic Publishers.