Purpose: To evaluate long-term survival rates and radiographic stability of sinus floor elevations carried out using a two-layer grafting technique. Materials and Methods: Records were analyzed for patients treated with sinus floor elevations using a modified technique. Phycogenic hydroxyapatite (Algipore, Dentsply Sirona Implants) and autogenous bone particles harvested from intraoral sites were grafted in two distinct layers after elevation of the sinus mucosae. In this approach, the basal part of the sinus floor is grafted with autogenous bone, while the cranial part is grafted with the phycogenic hydroxyapatite. In some cases, implants were placed simultaneously, such that the entire surface of each implant was covered by autogenous bone particles. A titanium membrane was used to close the sinus window, and the implants were loaded 3 months later. In two-stage approaches, the implants were inserted 3 to 4 months after the grafting and loaded after 3 additional months. Panoramic radiographs were taken after the grafting procedure, after implant insertion, after the prosthetic restoration, and then annually for 10 years. These radiographs were used to measure the height between the implant shoulders and the top of the graft. Results: Of the 214 sinus floor elevations performed on 129 patients using the bilayering technique, 198 procedures in 118 patients were included in the study (136 one-stage and 62 two-stage). Membrane perforations during surgery occurred in 17.9% of the procedures and were sutured and sealed with fibrin glue. A total of 487 implants were placed in the grafted areas. No severe postoperative complications occurred, but three implants were lost throughout the 10-year follow-up period. A small decrease of vertical height was observed between the grafting surgery and the stage-two surgery (mean: 1.8 mm). After that, no bone height was lost over the 10 years. Conclusion: The layer grafting technique in combination with sinus floor elevation resulted in radiographically stable vertical bone height for 10 years. This technique enabled early placement and loading of implants in the grafted areas. The survival rate obtained with this procedure is similar to that expected for implants placed in nongrafted areas. Schlagwörter: Algipore, autogenous bone, bilayer technique, biomaterial, bone augmentation, graft stability, sinus floor elevation