We describe a case with severely compromised edentulous ridge in the mandible, which previously received marginal resection and radiotherapy due to oral cancer at the mouth floor. Through careful evaluation, the patient had 30 dives of hyperbaric oxygen therapy (HBO) before implant surgery. The edentulous ridge was rehabilitated with 4 endosteal implant fixtures, and palatal mucosa grafting vestibulosulcoplasty. The case had been followed for 4 years with stability of bone and a satisfactory result of rehabilitation.