A long-term evaluation of osteoinductive HA/beta-TCP ceramics in vivo: 4.5 years study in pigs.

It has been proved that some material-dependent calcium phosphate ceramics have intrinsic potentials to induce osteogenesis. But there is little literature concerning about the tissue response in long-term. The aim of this study is to evaluate the safety of the osteoinductive biocreamics and the stability of the newly formed bone after long-term tissue response. Porous calcium phosphate ceramics rods which contain hydroxyapatite (HA) and beta-tricalcium phosphate (beta-TCP) were implanted in the dorsal muscles of Banna Minipig Inbreding Line. After 4.5 years, all the implanted rods with surrounding tissues were harvested and stained with hematoxylin and eosin for histological observation. The 7 months' rods were also harvested as short-term comparison. The histological results showed that compared with the short-term rods, amount of bone tissue formed after 4.5 years. And the newly formed bone in this bioceramics neither disappeared nor gave rise to uncontrolled growth. The bone growth in this bioceramics seemed to be self-confined. The surrounding soft tissues were normal and no tumor cell was found. We conclude that instead of disappearing or giving rise to out of control, the induced bone tissue trends to be further matured. And this bioceramics thus might have potentials in future clinical use.