Background: The aim of this study was the evaluation of the clinical success and complication rates associated with autologous bone grafts harvested from the mandibular ramus for alveolar ridge augmentation and the identification of possible risk factors for graft failure.

Methods: In a consecutive retrospective study 86 patients could be included. In these patients a total of 104 bone grafts from the mandibular ramus were harvested for alveolar ridge augmentation. Medical history, age of patient, smoking status, periodontal status and complications were recorded. The need for bone grafting was defined by the impossibility of installing dental implants of adequate length or diameter to fulfill prosthetic requirements, or for aesthetic reasons. The surgical outcome was evaluated concerning complications at the donor or at the recipient site, risk factors associated with the complications and graft survival. All patients were treated using a two-stage technique. In the first operation bone blocks harvested from the retromolar region were placed as lateral or vertical onlay grafts using augmentation templates and were fixed with titanium osteosynthesis screws after exposure of the deficient alveolar ridge. After a healing period of 3–5 months computed tomography scans were performed followed by virtual implant planning and the implants were inserted using guided dental implantation.

Results: 97 of the 104 onlay bone grafts were successful. In only 7 patients a graft failure occurred after a postsurgical complication. No long-term nerve damage occurred. Postoperative nerve disturbances were reported by 11 patients and had temporary character only. After the healing period between 4 to 5 months, 155 implants were placed (39 in the maxilla, 116 in the mandible). A final rehabilitation with dental implants was possible in 82 of the 86 patients. Except the 7 graft failures, all recorded complications were minor complications which could be easily treated successfully without any long-term problems. Complications at the donor site were recorded in 3 patients and 17 patients experienced complications at the recipient site. Three of 7 patients with graft failure, were secondarily augmented with a new retromolar graft, harvested from the contra-lateral site and dental implants could be successfully inserted later. No association between complications and smoking habit, age of patient, jaw area, and dental situation (tooth gap or free dental arch) could be detected.

Conclusions: Retromolar bone grafts are an effective and safe method for the reconstruction of small- to medium-sized alveolar defects of the maxilla and mandible prior to dental implantation and show a low graft failure rate.