Long-term behaviour of active glasses in sheep mandibular bone.

Granules of a glass (A) prepared according to Hench's formula and a new vitreous material for biological applications (AKRA 15) were used for repair of bone defects in the dental field. The behaviour of these materials implanted in holes drilled in sheep's mandibular bone was examined 4, 8, 12 month after implantation. Microradiographic analyses, optical and scanning electron microscopic observations, and X-ray microprobe evaluations were carried out using undecalcified, methacrylate-embedded sections of the jaw containing the granules. After one year the granules of A disappeared, but not important bone growth was observed also in the holes containing AKRA 15. SEM and microprobe showed: disappearance of Na and Si ions at different stages; increase of P and Ca up to 4 month and then decrease, but in different ways in the two glasses; unexpected appearance of K ions after 4 month only in AKRA 15.