Alveolar bone should be augmented to an adequate height and width for an implant to have satisfactory functional, biological, and aesthetic properties. Large osseous defects often require block grafts harvested from the symphysis or ramus. However, surgical complications and the necessity of donor sites have led to using allogeneic grafting materials. Two patients with severe bone defects on their mandibular posterior and maxillary posterior teeth were selected to be the subjects of this study. These 2 patients needed their implant fixtures removed due to implant failure. They received alveolar ridge augmentation using commercial block allografts, and after an integration period of several months, an implant was placed. The short-term results suggest that block allografts may be suitable bone-replacement materials for augmenting alveolar defects, especially for bone grafts in bone defect areas caused by removing failed implants.