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Vertical bone augmentation is aimed at regenerating bone extraskeletally (outside the skeletal envelope) in order to increase bone height. It is generally required in the case of moderate to severe atrophy of bone in the oral cavity due to tooth loss, trauma, or surgical resection. Currently utilized surgical techniques, such as autologous bone blocks, distraction osteogenesis, and Guided Bone Regeneration (GBR), have various limitations, including morbidity, compromised dimensional stability due to suboptimal resorption rates, poor structural integrity, challenging handling properties, and/or high failure rates. Additive manufacturing (3D printing) facilitates the creation of highly porous, interconnected 3-dimensional scaffolds that promote vascularization and subsequent osteogenesis, while providing excellent handling and space maintaining properties. This review describes and critically assesses the recent progress in additive manufacturing technologies for scaffold, membrane or mesh fabrication directed at vertical bone augmentation and Guided Bone Regeneration and their in vivo application.

This study reports on the development of an additively manufactured polycaprolactone (PCL) biphasic scaffold for achieving vertical bone augmentation. The biphasic scaffold consisted of a space maintaining 3D-printed outer shell into which a highly porous melt electrospinning writing membrane was inserted. This emulated the architectural arrangement of the native jawbone composed by the cortical plate and alveolar bone. The biphasic scaffold was further functionalised with a heparinised hyaluronic acid/gelatine hydrogel containing Bone Morphogenetic Protein-2. Its performance with respect to vertical bone augmentation was assessed in an extraskeletal ovine model. For the purposes of comparison, 7 different groups were implanted for 8 weeks under a polymeric protective dome: Empty, Biphasic scaffold with the hydrogel (PCL-Gel), PCL-Gel with 75 or 150 µg of BMP-2 (PCL-BMP-75 and PCL-BMP-150), hydrogel (Gel), Gel containing 75 or 150 µg of BMP-2 (Gel-BMP-75 and Gel-BMP-150). This resulted in more bone formation in the elevated space in the BMP-2 containing groups, particularly the PCL-BMP specimens, whereby full height was achieved as measured by microcomputed tomography and histology. Interestingly, there was no significant bone volume increase with the higher dose of BMP-2. In a separate cohort of animals previously implanted with 2 samples of the Gel-BMP-150 and PCL-BMP-150 groups, a surgical re-entry at 8 weeks of healing was performed. The protective domes were removed, and one implant was placed on one specimen per group. Bone stability of the augmented bone structure was assessed at 8 weeks and demonstrated that the biphasic scaffold prevented bone resorption, whereas the hydrogel underwent extensive vertical bone loss. This was attributed to the space maintenance properties of the biphasic scaffold.