Defect Repair in the Rat Mandible With Bone Morphogenic Proteins and Marrow Cells

Objective  To investigate the ability of a bone growth factor mixture and bone marrow cells to repair a critical size defect of the rat mandibular body. Design  Prospective, randomized controlled trial. Subjects  Thirty-seven male Fischer rats. Interventions  Critical size defects 4 mm in diameter were created in the left mandibular bodies of the rats. The defects were filled with a bone marrow cell suspension (group 1), a synthetic bone matrix consisting of bovine collagen and calcium hydroxyapatite cement (group 2), the matrix and marrow cells (group 3), the matrix with 100 µg of bone growth factor mixture (group 4), or the matrix with bone growth factor mixture and marrow cells (group 5). Animals were killed after 8 weeks, and the nondemineralized specimens were processed histologically. Specimens from group 1 were not processed because there was no grossly appreciable bone regeneration. Stereologic techniques were used to determine and compare the volume fractions and volume estimates of mature bone, new bone, osteoid, marrow, remaining cement, and fibrous tissue in each defect. Results  Volumes of mature bone, new bone, and remaining cement did not differ significantly among the groups ( P = .30 for mature bone, P = .17 for new bone, and P = .34 for cement). However, group 4 and 5 specimens contained significantly more osteoid and larger marrow spaces than did the group 2 and 3 specimens ( P P Conclusion  The synthetic bone substitute containing bone growth factor mixture was effective in stimulating new bone and osteoid development in the rat mandibular model.