In this clinical study, a 1:1 mix of particulate cancellous bone and marrow (PCBM) and bovine deproteinized bone (Bio-Oss) was used to fill cavities after elevating the sinus mucosa for major sinus dehiscences. Ten patients with edentulous posterior maxillae were treated with 12 sinus augmentation procedures according to a 2-stage technique, and 30 Frialit-2 endosseous implants were used to complete the implant-prosthetic rehabilitation. Bone cylinders were removed at second-stage surgery immediately prior to implant placement (5 to 7 months after grafting), and histologic evaluation was performed. The results showed that Bio-Oss is a reliable osteoconductive material and its association with PCBM leads to the formation of new bone with an increased overall density Keywords: bone substitutes, bone transplantation, dental implants, maxillary sinus, preprosthetic oral surgical procedures