Prof. Dr. Wachtel, Munich/Germany, demonstrates the regenerative periodontal therapy of an extended periodontal defect of a lower front tooth. He shows the necessary steps in this surgery and explains the key factors of success in this case. As part of regenerative periodontal therapy, a double-split flap is used to treat an extensive defect of a lower anterior tooth (41). First, in the vestibular area a mucoperiosteal flap is elevated treating the tissue very gently to avoid perforations. Fibers that are attached to the defect need to be cut. The papillae are carefully pushed towards the lingual area and detached, so that also a lingual full flap is lifted. The deep periodontal defect is fully exposed and thoroughly cleaned. Next, in the vestibular area an internal flap is prepared within the mucoperiosteal flap. In order to provoke bleeding, little perforations are drilled into the compact bone. Before a mixture of Emdogain and autologous bone is applied into the defect and condensed, the root surfaces next to the defect area are cleaned again and conditioned with EDTA. The bone material was harvested from the vestibular alveolar bone with a piezo-technique. In order to obtain a close tension-free wound closure and primary wound healing, the internal flap is placed on top of the filled defect and sutured to the lingual full flap. This second, internal flap facilitates the complete coverage of the defect in a layer-wise fashion and promotes primary healing which is of utter importance for the success of this regenerative treatment. Finally, the external flap is replaced and the wound edges of the vertical releasing incision are accurately adapted and fixed with microsurgical sutures. In the areas of the papillae the flaps are secured with modified mattress sutures.