POLYACTIVE(R) AS A BONE-FILLER IN A BEAGLE DOG-MODEL

Calcification is a crucial step in the bone-bonding mechanism of PEO/P BT hydrogel copolymers (Polyactive(R)), a new generation of bone-fille rs. A beagle dog study was conducted to determine whether the preopera tive presence of a calcium phosphate layer (precalcification) on a PEO /PBT 80/20 copolymer would further increase the bone-bonding rate. Sta ndard bone cavities were filled with either precalcified or nonprecalc ified porous cylindric PEO/PBT 80/20 implants, or hydroxyapatite granu les held together with PEO/PBT 70/30, or were left unfilled. A signifi cantly higher percentage of mineralized component was present in the c avities filled with the precalcified PEO/PBT 80/20 copolymer than in t he control defects. As a result of swelling by fluid-uptake, the press -fit inserted copolymer implants showed a significant reduction in por e size, thus preventing optimal bone ingrowth. Both precalcification o f the copolymer and underfilling of the defect, to create space for th e copolymer to increase in diameter, stimulate postoperative calcifica tion and bone ingrowth in PEO/PBT 80/20 copolymers. (C) Munksgaard, 19 96.