A method to produce platelet-rich plasma and platelet concentrate using a double centrifuge technique in combination with the fibrin adhesive Tisseel is described. This technique constitutes the basic mixture for augmenting and improving an inadequate bone site. Also described is a procedure by which autologous bone or bone substitute is added to this mixture to increase the volume of grafting material. Platelet concentrates cause growth factors to be delivered to graft sites in an intense form, while Tisseel serves as a standardized, pharmaceutically manufactured fibrin adhesive. Schlagwörter: alveolar ridge augmentation, factor XIII, fibrin tissue adhesive, plasmapheresis, platelets