Full block or split block?—Comparison of two different autogenous block grafting techniques for alveolar ridge reconstruction

To evaluate radiographic bone gain after alveolar ridge augmentation with two different designs of autogenous block graft harvested from the mandible. Alveolar ridge defects were evaluated by preoperative cone beam computed tomography (CBCT) and grafted in a staged approach using intraoral block grafts. The ridge augmentation was either performed using the full-block technique (group 1) or the split-block technique (cortical plate with autogenous bone chips) (group 2). After 4 months of bone healing, a further CBCT scan was performed before implant placement. Horizontal and vertical bone gain were measured. In this retrospective study, 91 patients were grafted with block grafts (36 patients with full-block grafts; 55 patients with split-block grafts) resulting in 171 block grafts in total. The mean horizontal bone gain was 3.37 ± 0.71 mm in group 1 and 5.79 ± 2.20 mm in group 2. A linear mixed-effect model also showed a statistically significant group difference (p < 0.001, estimate: 3.455, 95% CI: [2.082-4.829]). The mean vertical bone gain was 2.85 ± 0.73 mm in group 1 and 7.60 ± 1.87 mm in group 2. A linear mixed-effect model also showed a statistically significant group difference (p: 0.029, estimate: 3.126, 95% CI: [0.718-5.557]). Mean marginal bone level was 0.33 ± 0.37 mm (group 1) and 0.17 ± 0.29 mm (group 2). The split-block technique resulted in a greater bone gain than the full-block technique. This effect was observed in both the vertical and the horizontal dimensions.