It is difficult for both prosthodontists and their patients with large marginal defects to achieve a satisfactory prosthodontic result, because retention, support, and stability of the prosthesis are limited and recovery of esthetics is unsatisfactory owing to large mandibular defects. Alveolar ridge augmentation therapy is performed to compensate for such problems. We have experienced a good prognosis of prosthodontic treatment for over 10 years in two patients with large marginal defects of the partially edentulous mandible, who had undergone grafting of porous hydroxyapatite blocks to their bone defects. It has been reported that porous hydroxyapatite blocks are unsuitable for edentulous patients, because the mucosa covering the hydroxyapatite block is too thin and delicate to support dentures. We, therefore, designed the denture to prevent concentration of occlusal stress on the mucosa. In both of these two cases, we achieved recovery of occlusal function and esthetics by affixing denture to the large marginally resected defect augmented with a graft of porous hydroxyapatite block.