[Bone augmentation of the extremely atrophic anterior mandible, using allogeneic block grafts, via submental approach].

Edentulous patients with advanced resorption of the mandible (atrophic mandible) suffer major discomfort when using dentures. Furthermore, placing dental implants is impossible due to lack of sufficient bone volume. In the past, several methods of bone grafting to the anterior mandible have been proposed. Most of them were unpredictable in either the short or long-term. In 2002 a technique for bone grafting of the anterior mandible via a submental approach was published. A wide reflection of the soft tissue was followed by implant placement. Autogenous particulate posterior iliac crest bone graft was used. The presence of the implants did not allow for contraction of the soft tissue and bone resorption. The addition of bone volume to the chin improved the facial aesthetics of the patients due to a fuller appearance of the chin and tightening of the skin of the neck. The submental approach changes the spatial orientation of the surgeon and placement of implants in the correct location and angle become challenging. Placement of the implants too far buccally was a prosthetic problem. A major disadvantage of autogenous bone grafting is the necessity to operate a donor site. The increasing experience in use of allogenic bone grafts with resorbable collagen membranes, allowed us to modify the submental approach for bone grafting of the anterior atrophic mandible, avoiding a donor site surgery. We chose to perform the bone graft as a first stage surgery, in which, via a submental approach allogenic bone blocks were adapted and fixated to the anterior mandible with titanium screws, xenograft and resorbable collagen membranes were used. A few months (>4) were allowed for graft consolidation and then a second stage surgery was performed, via an intraoral approach dental implants were placed. In this way we avoided loss of orientation and had a familiar setting for implant location and angulation. Five patients with atrophic mandibles were treated using this surgical protocol. Based on cone beam CT imaging, average bone height in the anterior mandible prior to treatment was 5.52 mm. After bone graft, the average gain in bone height was 12.74 mm. No major post-operative complications were noted. After bone graft consolidation, 4 or 5 dental implants were placed, most of the implants used were longer than 11.5 mm. 22 implants were placed, out of which 21 integrated (95.5%). Some of the patients were rehabilitated with overdentures and locators and some with PFM bridges. All patients were followed up for more than a year and no implant failure was recorded. Bone grafting to the anterior mandible using allogenic blocks with collagen membranes via a submental approach with second stage implant placement seems to be a viable solution for rehabilitation of the atrophic mandible.