**2. Biosafety of bone grafting material**

Contagious substances should be absent in an ideal biocompatible bone grafting material. Carbonate, Calcium phosphate and Sulfate bone graft materials are typically biocompatible with no risk of being rejected by the host. Virus, Prion and bacterial contamination of bone grafting materials are not of our concern in autogenous or alloplastic bone grafts. The preva‐ lence of HIV infection in freeze-dried bone and demineralized freeze-dried bone allografts has been reported to be 1 in 8,000,000 and 1 in 2.800.000 respectively. The prevalence of bovine

spongiform encephalopathy transmission with bovine xenograft reckoned to be less than that of being hit by lightning.

Thus, the risk of disease transmission from an allograft or xenograft is almost zero as long as the disinfection/sterilization protocols are followed by manufacturers. The world health organization affirmed that bone is classified as type IV (no transmission) for prion diseases. Therefore all currently available bone graft materials are secure and reliable concerning disease transmission potential.
