Protein-chemical analysis of Bio-Oss bone substitute and evidence on its carbonate content.

Abstract The natural bone substitute Bio-Oss is used in periodontal and maxillofacial surgery to fill bone defects and permit reossification. Recent reports have suggested the presence of TGF β and of substantial amounts of protein in Bio-Oss and have questioned its position as a biologically inert material and its safety in clinical applications (Honig et al., Plast Reconstr Surg 1999;103:1324; Schwartz et al., J Periodontol 2000;71:1258). Bio-Oss was therefore subjected to a detailed biochemical, histochemical and biophysical analysis. In three different types of extracts of Bio-Oss no evidence for the presence of protein based on SDS-PAGE and silver staining was detected. In addition, as shown by Western blotting, there was no immunochemical evidence for the presence of the potential growth-inducing factor TGF β . Furthermore, micropolished sections of Bio-Oss failed to be stained with McNeal's Tetrachrome as did microtome sections treated with Goldner's Trichrome. However, Bio-Oss was strongly stained with the protein dye Coomassie blue. This staining was virtually irreversible and is attributed to the carbonate content of Bio-Oss which was detected by thermogravimetry–mass spectrometry. Thus, within the limits of the assay conditions, Bio-Oss does not contain protein material to a measurable extent.