OBJECTIVE To esthetically and functionally restore a 40-mm canine mandibular discontinuity defect using a custom-made titanium bone-grafting tray packed with autologous iliac bone. METHODS Individualized titanium bone-grafting trays were made using a reverse engineering, computer-aided design, and rapid prototyping technique. A 40-mm discontinuity defect in the right mandibular body was created in 10 hybrid dogs. The defect was restored immediately using the tray that was densely packed with autologous cancellous iliac particles and covered with trimmed iliac chips. Sequential radionuclide bone imaging was performed postoperatively at 2, 4, 8, 12, and 24 weeks. The ratio of activity between the grafted mandible and the contralateral native mandible on each transaxial slice was calculated. The mean activity ratio was analyzed at each time point to evaluate the bone metabolism and reconstitution of the grafts. The subjects were sacrificed at 4, 12, and 24 weeks after grafting. The specimens were evaluated by postmortem gross dissection, biomechanical testing, 3-dimensional microcomputed tomographic scanning, and histologic examination. RESULTS All the subjects tolerated the grafting operation well. Over an observation period of 24 weeks, tray extrusion occurred in 3 of the 10 subjects. Bony continuities were reconstructed in 9 of the 10 subjects. Radionuclide bone imaging revealed that the tracer uptake increased in the grafted mandible, and the radionuclide ratio between the graft and the native mandible decreased with time. Gross evaluation, microcomputed tomographic examination, biomechanical testing, and histologic examination demonstrated corticalization of the grafts. CONCLUSIONS The use of a customized technique using reverse engineering, computer-aided design, and rapid prototyping tray containing autologous cancellous bone is a potentially powerful grafting technique for the reconstruction of mandibular discontinuity defects.