The aim of this retrospective study was to compare clinical and radiographic outcomes of the interpositional (inlay) augmentation technique in atrophic posterior partially edentulous mandibles using three different types of block bone grafts: autogenous bone block harvested from the iliac crest, deproteinized bovine bone mineral block, and collagenated equine bone block. A total of 115 patients were included with a 4.2-year mean after-loading follow-up. Data seem to suggest that heterologous bone blocks are similar in results to autogenous bone blocks, so they might be considered preferable as they avoid invasive harvesting surgeries.