The bonding of glass ceramics to bone.

In this study the bonding behaviour of glass ceramics, containing apatite and wollastonite, to bone tissue is shown to vary depending on the amount of alumina they contain. We have experimented with three types of material: A.W-GC, AW-6 and AW-AL. Rectangular plates were implanted into the tibiae of rabbits. Ten weeks later a segment of bone around the plate was removed for examination, and the load of breaking by traction (failure load) was measured by an autograph. This was lowest for AW-AL and highest for A.W-GC (with AW-6 in between), and the figures differed significantly from each other (P less than 0.01). The interface was examined by a scanning electron micro-analyser and an energy dispersive X-ray micro-analyser (SEM-EPMA) and the reactive zone, the calcium-phosphorus rich layer, was assessed. Silicon and magnesium decreased, the calcium did not change, and the phosphorus increased. The reactive zone of A.W-GC was wider than that of AW-6. A Ca-P rich layer was not present between AW-AL and the bone. It is suggested that the strong bonding between glass-ceramics and bone was made through the formation of the Ca-P rich layer.