MORPHOLOGY OF OSTEOGENESIS IN BIOACTIVE GLASS INTERFACE

Bone formation around bioactive glass implants (S56.5P4) in the trabec ulous subchondral bone in the distal femur of rabbits was studied by h istology and scanning electron microscopy. Three types of tissue: bone , connective and hematopoetic tissue developed around the implants res ulting in lamellar new bone covering 76 % of the surface of the implan ts at twelve weeks. Bone formation around implants began as woven bone changing mainly to lamellar, osteon like new bone in contact with the S56.5P4 surface. Endochondral ossification was absent. In the area of bone containing hematopoetic tissue, new bone grew often as a thin la yer along the implant surface. However, bone seemed to form adjacent t o the implant surface through osteoconduction. Only 21 % of the implan t surface was covered by loose connective tissue. Some proteoglycan co ntaining thin fluid filled spaces were seen ten days after implantatio n. In few areas with apparent breakdown of the implant surface decreas ed amount or no bone formation was observed. Von Kossa method stained the reaction layer as two parallel dark brown lines, toluidine blue as two blue stripes, whereas van Gieson did not stain the rection layer at all. In conclusion, the present histological results indicate bone bonding, which is a physico-chemical process observed between S56.5P4 implant and host bone.