The present study reports on a 3-year clinical and radiologic follow-up investigation of dental implants placed 3 and 6 months after sinus augmentation in 14 patients. Augmentation was performed with a synthetic bone substitute material composed of nanocrystalline hydroxyapatite. The aim of the study was to determine how the integration period of the bone substitute material, that is, 3 months or 6 months, influences implant integration within the patient's upper jaw. Therefore, the following clinical and radiologic parameters were investigated: implant being in situ; Periotest value; and presence of peri-implant osteolysis, bleeding on probing, plaque, and soft tissue recession around the implants. At the follow-up investigation 3 years after placement, 23 of 24 implants were in situ and suitable for prosthetic rehabilitation. No implants in either study group were mobile or showed peri-implant osteolysis. Only a few implants showed plaque or soft tissue variations. Within its limits, the present study showed comparable clinical performance of dental implants placed 3 months after sinus floor augmentation to implants placed 6 months after augmentation. The results of all investigated parameters were in accordance with results found in the literature. It can be concluded that augmentation with the applied synthetic bone substitute material already forms a sufficient implantation bed 3 months after augmentation, which enables long-term, stable, implant-retained restoration. These findings might contribute to a reduced healing time after augmentation, which would be favorable for patients and clinicians.