Contour and volume assessment of repairing mandibular osteoperiosteal continuity defects in sheep using recombinant human osteogenic protein 1.

BACKGROUND: This study describes the contour and volume of reconstructed mandibles using recombinant human osteogenic protein 1.
MATERIAL AND METHODS: The investigation was conducted on six adult sheep, where a unilateral 35 mm parasymphyseal osteoperiosteal continuity defect of the mandible was created. Recombinant human osteogenic protein 1 and type-I collagen (as carrier) were applied to the defects. Radiographic and ultrasonographic examinations were carried out at day 1 of the surgery and 2, 4, 8, and 12 weeks following the surgery. The animals were then sacrificed 3 months after the operation. Postmortem CT-scan was performed for volumetric, cross-sectional area, height and width measurements.
RESULTS: Ultrasound was more efficient than radiographs in demonstrating early callus formation at 2 weeks, while radiographic evidence of bone formation was consistently detectable only after 4 weeks. Using the combination of recombinant human osteogenic protein type 1 and type-I collagen resulted in twice the volume, cross-sectional surface area, and height when compared with those of the corresponding region of the contra-lateral non-operated side of the mandible.
CONCLUSION: Within 3 months, recombinant human osteogenic protein type 1 on type-I collagen carrier failed to restore the original contour and volume of mandibular osteoperiosteal continuity defects.