Reconstruction of mandibular vertical defects for dental implants with autogenous bone block grafts using a tunnel approach: clinical study of 50 cases

The objective of this study was to evaluate the outcomes of mandibular vertical defect reconstruction with autologous bone and the use of a sub-periosteal tunnel approach in preparation for dental implant insertion. Forty-three consecutive patients with an atrophic posterior mandible were reconstructed using this method. Two thin laminae of cortical bone, obtained by splitting blocks harvested from the retromolar area, were fixed in a box-like framework containing cancellous and particulate bone. The goal was to achieve an alveolar ridge width of >= 5.5 mm and an effective bone height (EBH) of >= 10.5 mm for dental implant insertion (>= 3.4 mm diameter, >= 9.5 mm length). Fifty reconstruction procedures were performed. The mean EBH was 7.1 +/- 1.3 mm pre-treatment and 12.3 +/- 1.1 mm post-treatment (mean increase 5.2 +/- 1.4 mm). Complete graft loss was recorded in two cases; the remaining complications were minor. After a mean consolidation period of 3.5 months, 96 dental implants were placed. No failure of osseointegration was observed at follow-up (mean 32.9 months). The average bone height reduction was 0.9 mm (graft vertical resorption 17.4%). Reconstruction of posterior mandibular vertical defects using two autogenous cortical bone blocks with particulate bone between them, combined with a tunnelling technique, provided good healing with no wound dehiscence and minimum resorption of the grafted bone, favouring a substantial vertical bone gain.