Process development of a virally-safe dental xenograft material from porcine bones

A process for manufacturing virally-safe porcine bone hydroxyapatite (HA) has been developed to serve as advanced xenograft material for dental applications. Porcine bone pieces were defatted with successive treatments of 30% hydrogen peroxide and 80% ethyl alcohol. The defatted porcine bone pieces were heat-treated in an oxygen atmosphere box furnace at 1,300°C to remove collagen and organic compounds. The bone pieces were ground with a grinder and then the bone powder was sterilized by gamma irradiation. Morphological characteristics such as SEM (Scanning Electron Microscopy) and TEM (Transmission Electron Microscopy) images of the resulting porcine bone HA (THE Graft®) were similar to those of a commercial bovine bone HA (Bio-Oss®). In order to evaluate the efficacy of 1,300°C heat treatment and gamma irradiation at a dose of 25 kGy for the inactivation of porcine viruses during the manufacture of porcine bone HA, a variety of experimental porcine viruses including transmissible gastroenteritis virus (TGEV), pseudorabies virus (PRV), porcine rotavirus (PRoV), and porcine parvovirus (PPV) were chosen. TGEV, PRV, PRoV, and PPV were completely inactivated to undetectable levels during the 1,300ºC heat treatment. The mean log reduction factors achieved were ≥4.65 for TGEV, ≥5.81 for PRV, ≥6.28 for PRoV, and ≥5.21 for PPV. Gamma irradiation was also very effective at inactivating the viruses. TGEV, PRV, PRoV, and PPV were completely inactivated to undetectable levels during the gamma irradiation. The mean log reduction factors achieved were ≥4.65 for TGEV, ≥5.87 for PRV, ≥6.05 for PRoV, and ≥4.89 for PPV. The cumulative log reduction factors achieved using the two different virus inactivation processes were ≥9.30 for TGEV, ≥11.68 for PRV, ≥12.33 for PRoV, and ≥10.10 for PPV. These results indicate that the manufacturing process for porcine bone HA from porcine-bone material has sufficient virus-reducing capacity to achieve a high margin of virus safety.