SANDWICH OSTEOTOMY FOR VERTICAL AND TRANSVERSAL AUGMENTATION OF THE POSTERIOR EDENTULOUS MANDIBULAR SITES FOR DENTAL IMPLANT

The atrophy of the edentulous mandible can compromise the insertion of dental implant. In this context, ideal implant positioning is limited by inadequate height and width. Sandwich osteotomy osteogenesis has the advantage of restoring vertical bone deficit and also restoring transverse dimension without undesired bone segment displacement, is less time-consuming and is less uncomfortable for the patient. Bormann et. al. assessed that vascularized bone can be reached by autograft interpositioning sandwich osteotomy with osteosynthesis, vertical-gain ranged from 2.0 to 7.8 mm (mean 4.6 mm) after 12 months follow up. The retrospective study by Jensen measured the median vertical gain in posterior mandible was 6.0 to 7.0 mm. For the severe atrophy case, alveolar distraction osteogenesis has the greatest potential for vascularized vertical-gain with report of bone gain range from 4.0 to 15.0 mm (mean 9.9 mm). However the failure of augmentation due to infection was a major disadvantage, also the need for absolute compliance of the patient and his family is of utmost importance (for daily rotation of the distraction screw). Even though there was an advanced technique, Byung H. C. said that onlay collagen augmentation with sandwich osteotomy, range from 8.4 to 1.0 mm (mean 9.8 mm) can be vascularized, the bone isgoing to resorpt range from 1.5 to 3.0 mm (mean 2.1 mm) after 3 month. Bovine collagen matrix has excellent mechanical properties for stabilizingthe fragment. However the disadvantage of this method is that there is a possibilityof shallow vestibule, so the reducing lower sulcus depth is requiring a later vestibuloplasty. Conclusion, segmental mandibular sandwich osteotomy is recommended to meet the dimensional requirementsof pre-implantboneaugmentationinatrophicposteriormandible.