Pre-implantological bone formation in the floor of the maxillary sinus in a self-supporting space

Introduction: In edentulous patients the form and size of the maxillary sinus vary greatly. Therefore sinus floor augmentation is a standard procedure for implantological purposes. As the sinus membrane cannot be characterized as periosteum, various augmentation materials are used. Hypothesis: an artificially generated space underneath the sinus membrane in the floor of the sinus will lead to spontaneous callus forming and a stable bony consolidation without augmentation material. Methods: Ten edentulous patients with highly atrophic maxillae were selected. Augmentation of the sinus floor was carried out in a split-mouth study design: On one side a combination of autogenous and xenogenous bone was used, and on the contralateral side a sinus membrane elevation was performed without using any substitutes. After a 6-month interval bone specimens from the test regions were harvested during implant placement. Results: Clear histological evidence of new bone formation was found in all human bone specimens. An active de-novo bone formation process could be proven by the presence of Haversian systems (osteons) displaying osteoblastic and osteoclastic activity. Conclusion: In the maxillary sinus of edentulous patients a spontaneous callus-derived de-novo bone formation is possible by elevating the sinus membrane without using augmentation materials.