Eleven sinuses were grafted with a magnesium-enriched bioceramic bone substitute in granules (SINTlife) mixed with 10% autogenous bone retrieved from intraoral donor sites. Bone biopsies retrieved after 8 months were visually and quantitatively analyzed with microcomputed tomography (microCT). MicroCT evaluation of the grafted material was feasible, since the radiodensity of the bone substitute was different from the density of mineralized bone. MicroCT showed good integration of the graft in all treated cases. The tested bioceramic bone substitute, mixed with autogenous bone, seemed to have a positive effect in sinus grafting, with values of total mineralized tissue volume around 66%. Residual graft particles occupied 31% of the total volume of the specimen. Particles of the ceramic bone substitute seemed mainly unresorbed. MicroCT analysis evaluated several morphometric parameters, demonstrating that the newly formed bone could be used for placement and loading of implants.