Beneficial role of periosteum in distraction osteogenesis of mandible: its preservation prevents the external bone resorption.

Distraction osteogenesis (DO) is a surgical process of new bone generation through the gradual extension of two segments of existing bone. DO is applied for maxillofacial surgeries to manage defects in mandibular continuity. Vertical DO with an oral device is often employed to augment the alveolar bone height for better implant anchorage for esthetic purposes or functional prosthetic requirements. To determine how the periosteum affects the vertical DO in mandibular reconstruction, we extracted the teeth and resected the alveolar parts of the mandible on both sides of dogs, along with removal of the surrounding periosteum in the right, but not left side. Three months later, box-shaped bone segments (vectors) were prepared from the resected alveolar part, and the segments were vertically elongated using a distraction device on both sides at 0.9 mm/day for one week. The extent of bone formation after distraction was determined with micro-focused computed tomography and by measuring incorporation of tetracycline and calcein with confocal laser scanning microscopy. During the initial two months after distraction, new bone formation was observed more prominently in the left side than in the right side of mandible with the periosteum. However, this difference was less clear during the bone-remodeling period. One notable change was the reduced height of the alveolar part of the right-side mandible, a sign of external bone resorption, observed in two out of three dogs at 6-month post-consolidation. These findings suggest that preservation of periosteum prevents the external bone resorption during the vertical DO of mandible.