ECTOPIC BONE INDUCTION IN POROUS APATITE-WOLLASTONITE-CONTAINING GLASS-CERAMIC COMBINED WITH BONE MORPHOGENETIC PROTEIN

To accelerate the integration of ceramic implants with the surrounding bone and to search for a suitable carrier for bone morphogenetic prot ein (BMP), we studied ectopic bone induction in porous apatite-wollast onite-containing glass ceramic (A-W GC) combined with partially purifi ed bovine BMP (bBMP) and recombinant Xenopus BMP-4/7 (rxBMP-4/7). Poro us A-W GC rods [4 mm in diameter, 5 mm in height, 70% porosity, 200 mu m mean pore size, 17.54 +/- 3.82 MPa (mean +/- SD) compressive streng th] were used. An apatite coating formed on the surface of porous A-W GC that had been immersed in simulated body fluid at 36.5 degrees C fo r 7 days. in experiment 1, porous A-W GC rods were combined with eithe r bBMP, collagen, or with both bBMP and collagen. The rods were implan ted into subcutaneous pouches in rats and were harvested 4 weeks after implantation. Low-energy radiographic, scanning electron microscopic (SEM), and histological examinations showed ectopic bone formation and within the rods only in the porous A-W GC combined with the bBMP and collagen group. Quantitative analysis also revealed that this group al one showed a significant increase in bone formation. In experiment 2, porous A-W GC rods were combined with rxBMP and collagen, implanted in to rats, and harvested as described above. SEM and histological examin ation showed ectopic bone formation around and within the rods. Becaus e of its relatively high mechanical strength, ease of handling, and go od osteoinductivity, porous A-W GC combined with BMP and collagen may be clinically useful in patients with large cancellous bane defects or craniomaxillofacial lesions. (C) 1997 John Wiley & Sons, Inc.