Histologic study of the cellular events during rat mandibular distraction osteogenesis

ObjectiveThe cellular events, underlying bone regeneration through rat mandibular distraction osteogenesis (DO) was examined using micro computerized tomography (μCT), histology, and histochemistry.Study designAfter 5-day latency, mandibles were distracted at 0.2 mm/12 h for 10 days, and fixed at latency 5 days (L5D), distraction 3, 6, 10 days (D3D, D6D, D10D), and consolidation 1, 3, 6, 10 weeks (C1W, C3W, C6W, C10W).ResultsThe μCT demonstrated radiopacity at the distraction gap (DG) during C1W, which was filled with new bone at C6W and C10W. At D3D, collagen fibers were aligned along the axis of the distraction vector. At D6D, alkaline phosphatase–positive osteoblasts and intramembranous ossification was observed. Collagen bundles became thicker with new bony trabeculae at D10D. Type II collagen–immunopositive areas first appeared at C1W. At C3W, cartilage tissue and endochondral ossification were found. By C6W, the entire DG had been bridged by new bone. The C10W specimens showed mature lamellar bone.ConclusionMandibular DO produces bone through both intramembranous and endochondral ossification.