Purpose: Dental implant installation in the posterior maxilla depends fundamentally on the presence of an adequate bone quantity. Tooth loss in the posterior maxilla is followed by extensive loss of the alveolar ridge and increased maxillary sinus pneumatization that often makes implant installation difficult to achieve. Maxillary sinus floor augmentation is traditionally the common surgical technique to overcome this situation. When the deficiency in the vertical dimension relates more to severe ridge resorption, crestal ridge augmentation should also be considered. Posterior maxillary sandwich osteotomy combined with sinus augmentation, using inter–positional bone graft might be a viable option to address this problem. This study describes a successful implementation of this technique to solve a severe vertical osseous ridge defect under the sinus floor. Material and Methods: A two–stage lateral wall sinus floor augmentation combined with inter–positional sandwich osteotomy followed by the insertion of dental implants with adequate length and diameter was performed. Deproteinized natural bovine bone mineral (DBBM) covered by a resorbable collagen membrane were used. Rehabilitation of this area was completed by a standard prosthetic protocol. Results: As a result of completing the above procedure favourable bone mass and form was created to enable implant placement in positions that are optimal from a prosthetic and esthetic point of view in terms of reshaping the alveolar crest and normali- zing the interocclusal distance improving the crown–implant ratio. Conclusion: This case demonstrates a step–by–step illustration of an innovative technique for overcoming a vertical ridge defect combined with increased maxillary sinus pneumatization. It can be concluded that this novel technique is recommended to meet the dimensional requirements of bone augmentation both crestal and intrasinusal in severe atrophic posterior maxilla to achieve an improved alveolar plane, equalized crown–to–implant ratios, and a more favourable gingival shape.