The aim of this case report was to evaluate the histologic and radiographic new bone formation following maxillary sinus reentry surgery without a bone graft. A 61-year-old woman was referred with a failure of a sinus augmentation procedure. A reentry procedure was performed to retreat the sinus complication. The procedure involved removal of the bone graft plus debridement of the sinus. No additional bone graft material was used. A cone beam computed tomography scan was taken 6 months following the reentry procedure. During implant placement surgery, a core biopsy specimen was retrieved, stored, and prepared to obtain thin ground undecalcified sections. The histologic and radiographic analysis showed formation of new bone at the time of implant placement. At 18 months following implant placement, successful evidence of integration was determined by implant stability and radiographs. Space maintained by the previously elevated sinus membrane at the time of sinus reentry was sufficient to induce formation of bone without regrafting. However, more cases involving survival of implants placed in augmented sinuses without the use of bone grafts at the time of reentry are needed to confirm the results of this case report study.