Outcomes of alveolar segmental 'sandwich' osteotomy with interpositional particulate allograft for severe vertical defects in the anterior maxilla and mandible.

The purpose of this study was to report the outcomes of interpositional osteotomy with mineralized allograft in the treatment of alveolar vertical defects in preparation for implant placement. Thirteen defects (11 maxillary and two mandibular) were treated with osteotomy segments ranging in length from two to five missing teeth. The segments were positioned 5-7 mm coronally, with the gap space filled with allograft and then fixated with titanium hardware. Vertical bone augmentation was analyzed by superimposing pre- and post-surgical cone beam computed tomography images and stratified based on the length and number of missing teeth in each edentulous segment. The mean vertical bone gain was 3.7 ± 1.6 mm in the area of greatest vertical defect and the mean length of the transport segment was 20.5 ± 8.1 mm. These segments represented two-, three-, four-, or five-tooth edentulous sites; the mean vertical bone gain for these segments was 1.7 ± 0.5 mm, 3.8 ± 1.0 mm, 4.6 ± 0.9 mm, and 6.7 ± 0.0 mm, respectively. Stability of vertical height gain was found to be directly proportional to the span length of the osteotomy segment, with the largest five-tooth segment achieving the greatest gain. Vertical bone gain in two-tooth segments was minimal, indicating a moderate amount of resorption.