Periosteal expansion osteogenesis using highly purified beta-tricalcium phosphate blocks: A pilot study in dogs

Background: In highly atrophic edentulous jaws, the augmentation of the alveolar process is standard treatment for dental implantation because of the lack of alveolar bone height and width. Our aim was to examine periosteal expansion osteogenesis in a dog model, based on the concept of distraction osteogenesis, using a highly purified beta-tricalcium phosphate (beta-TCP) block instead of an original bone segment. Methods: Three beagle dogs weighing 10 to 12 kg were used. The beta-TCP block was placed at the lateral surface of the mandibular bone. Two titanium screws were inserted from the lingual aspect to push the block to the buccal side. After a latency period of 8 days, during which primary wound healing occurred, the lingual screws were advanced by similar to 0.5 mm/day for 8 days. Specimens were taken 8 weeks after lingual screw adjustments ceased and were analyzed by hematoxylin and eosin, tartrate-resistant acid phosphatase (TRAP), and Villanueva bone staining. Results: The alveolar form at the experimental region was changed dramatically following lateral expansion with the beta-TCP block. Newly formed bone was observed in the gap between the bone and the beta-TCP block, as well as on the lateral surface of the block. Moreover, the replacement of large parts of beta-TCP with newly formed bone was observed in the beta-TCP block area. However, newly formed bone was not observed over the upper parts of the block, and multinucleated TRAP-positive cells were attached to the beta-TCP in the periphery of this area. Conclusion: The highly purified beta-TCP block worked as an activator for the soft tissue, including the periosteum, as well as a space maker to induce an osteoblastic response in the periosteum.