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Purpose The objective of this investigation was to assess vertical bone augmentation using deproteinized bovine bone mineral (DBBM) infused or not with recombinant human bone morphogenetic protein (rhBMP-2) in rabbit tibiae. Materials and methods A total of 18 female rabbits (New Zealand) received two blocks of DBBM in each tibia. The DBBM blocks were randomly assigned into four experimental groups: DBBM (only the bone graft); DBBM associated with absorbable collagen sponge (ACS); DBBM plus rhBMP-2 (1.5 mg/mL); and DBBM infused with rhBMP-2 (1.5 mg/mL) in an ACS carrier. Animals were sacrificed after 12 weeks, and the tibiae containing the DBBM blocks were dissected and analyzed radiographically (microcomputed tomography [micro-CT]), histologically, and immunohistochemically. Results Micro-CT analysis showed a considerable increase in bone volume (BV) and BV/tissue volume in the rhBMP-2/ACS group compared with all the others. Trabeculae thickness also increased in the rhBMP-2/ACS group compared with the DBBM/ACS group. Trabecular number, separation, and bone mineral density were not different among groups. Histomorphometric evaluation showed increased newly formed bone in the rhBMP-2/ACS group compared with the DBBM and DBBM/ACS groups. The amount of residual bone graft was statistically higher in the rhBMP-2 groups compared with the DBBM/ACS group. Immunohistochemical analysis showed that the vascular endothelial growth factor (VEGF) expression was more intense in the rhBMP-2/ACS group compared with the DBBM/ACS group. The immunopositivity for type 1 collagen tended to be higher in the two groups with rhBMP-2. Conclusion Collectively, the results of this study suggest that the addition of rhBMP-2 in an ACS carrier placed on top of the DBBM graft enhanced bone formation in this animal model.

Among the factors that should be considered for the rehabilitation of atrophic jaws is mainly the anatomy of edentulous jaw, which offers trouble installing fixtures in view of the proximity to the maxillary sinus and nasal cavity. There are several possibilities to rehabilitate atrophic arcs, autogenous grafts, distraction osteogenesis, angled and short implants have been widely used in clinical practice. Thus, advanced surgical techniques are disclosed in the literature, such as the all-on-four standard technique. This technique consists of inserting four implants for a complete rehabilitation, and inclining a previously straight distal implant 45°, allowing anchorage in better bone (jaw previous zones), use of longer implants and decreasing the size of the prosthetic cantilever. The purpose of this literature review was to evaluate the scientific articles who observed the behavior of dental implants installed by the all-on- four technique in the maxilla. Initially, using the key words, 62 articles were obtained. After applying the inclusion criteria, 19 articles were selected. In each study the following were evaluated parameters: success rate of angled and axial implants, bone loss, and prosthetic complications. Finally, seven studies contemplated the requirements to be in this review. The literature of the art "all-on- four" standard in edentulous jaws showed that both angulated and axial implants have high success rate (92.8% to 99.3%) and similar bone loss. Therefore, the all-on-four standard technique is a viable option in the medium- and long-term for immediate fixed prosthetic rehabilitation in atrophic jaws.