Influence of pre-implant bone augmentation on diving fitness: An in vitro study

Abstract

Purpose: Autogenous bone grafts are commonly used for pre-implant bone augmentation or defect coverage in the maxillofacial region. Particulate bone or bone blocks without a vascular pedicle are normally used for this purpose. The objective of this study was to investigate the effects of hyperbaric conditions on the cell activity of augmented bone under pressure changes such as those to which combat divers and mine clearance divers are exposed. Materials and Methods: Systematic studies were performed using an animal model (isogeneic Lewis rats). We collected bone chips (n = 4) from rat femurs with a Safescraper; and obtained isogeneic bone blocks (n = 4) with a bone rongeur. Bone samples were exposed to three simulated 45-min dives to 5.0 bar using oxygen or compressed air. Bone chips and blocks that were not exposed to pressure served as controls. After 9 and 15 days of in vitro cultivation, osteoblast proliferation rates were assessed in a Neubauer counting chamber and the results were statistically analyzed. Results: Irrespective of the atmospheric conditions, bone blocks showed significantly higher proliferation rates (P = 0.05) than bone chips. When exposed to compressed air during simulated dives, both groups showed considerably lower proliferation rates than the control groups. When exposed to oxygen, both groups showed significantly higher proliferation rates than the control groups. Conclusion: Depending on the breathing gas used, changes in atmospheric conditions during simulated dives can lead to a decrease in osteoblast activity. Patients who underwent bone augmentation should therefore be advised not to dive using compressed air until osseointegration is complete.