Bio-Oss is natural bovine bone mineral, which has the property of bone conduction. It is recommended to be used in two- or three-walled bony defects with an ample supply of pleuripotential cells. Two cases are reported. The first was an intentional replantation, because of previous trauma, of a hopeless tooth affected with severe periodontitis. The tooth was replanted after complete elimination of granulation tissue. Bio-Oss, together with a guided tissue regeneration (GTR) membrane, was used to enhance periodontal regeneration. After 2 years of follow- up, the replanted tooth was quite stable. In the second case, Bio-Oss, together with bone taken from the retromolar area, was used in a sinus lift grafting procedure after the removal of two supernumerary teeth from the floor of the maxillary sinus. Four months after grafting, an orthodontic treatment was applied to move the two adjacent teeth through the grafted site and align them in the proper position. The clinical results of the two cases were satisfactory.