Purpose: To evaluate whether adding bone substitute materials to autogenous particulated bone (PAB) might have an effect on the density of the grafted bone after maxillary sinus augmentation. Materials and Methods: Thirty healthy patients undergoing lateral antrostomy were included. Sinuses were augmented at random with PAB (n = 10) (control group); a mixture of PAB and beta-tricalcium phosphate (ß-TCP) (n = 10) (experimental group); or a mixture of PAB, ß-TCP, and hydroxyapatite (HA) (n = 10) (experimental group). A sample of each graft material was obtained at time of maxillary sinus augmentation, and microcomputed tomography (µ-CT) analyses were performed. Five months later, samples of the augmented areas (n = 23) were harvested by means of a trephine bur, and µ-CT analyses of these samples were performed. Density values for the bone were compared to the data obtained 5 months before from the original material. Results: All groups showed increasing density values after a healing time of 5 months. Because of a high dropout rate, the sample size was too small to compare the groups statistically. Conclusions: Bone density increased after maxillary sinus augmentation for both PAB alone or in combination with substitute materials based on HA and/or ß-TCP particles. A larger sample size and a split-mouth design would help to reliably reveal significant differences between the single materials. Keywords: bone mineral density, bone replacement materials, maxillary sinus floor augmentation, microcomputed tomography