Primary and secondary reconstruction of mandibular continuity defects with vascularized bone is currently the standard of care at many institutions. The most commonly utilized donor sites for such bone flaps include the scapula, iliac crest, fibula, and radius. Recently, interest has grown in the placement of osseointegrated implants into these flaps to facilitate functional dental rehabilitation. There are no studies comparing the bone available from each of these flaps into which osseointegrated implants can be placed. In this cadaver study, the dimensions of bone available for implant placement from the iliac crest, scapula, fibula, and radius osseous flaps were measured. The iliac crest and fibula flaps had bone dimensions consistently adequate for implant placement. Bone available for the safe placement of implants into the scapula flap was found in the majority of specimens. The radius flap group had the highest number of specimens that were inadequate for implant placement. The majority of the specimens with bone inadequate for implantation were from females. Clinical implications of this study regarding flap selection are discussed.