Enhancement of bone formation by bone morphogenetic protein-2 during alveolar distraction: an experimental study in sheep.
BACKGROUND
The purpose of this study was to perform alveolar ridge augmentation by distraction osteogenesis (DO) and to enhance bone regeneration through the use of recombinant human bone morphogenetic protein-2 (rhBMP-2), followed by implant placement.


METHODS
Alveolar segmental osteotomy was performed in the mandible of 10 sheep followed by placement of 1.5 mm alveolar distraction devices. The study group was injected on the fifth day of distraction with a single dose of 10 microg rhBMP-2. Only distraction was performed in the control group.


RESULTS
A mean alveolar augmentation of 12 mm was achieved. After 12 weeks of consolidation, the distraction devices were removed and biopsies were taken for histological and immunohistochemical characterization and morphometry of the newly formed bone. Titanium threaded cylindrical implants were then placed in the newly augmented bone. Radiological evaluation showed lifting of the transport segment and integration of the implants within both the transport segment and the regenerated bone. The histological study demonstrated that the association of DO and BMP resulted in increased trabecular bone size and volume (32.2%+/-0.95% versus 18.6%+/-0.71%; P <1 x 10(-17) after 24 days of lengthening and 63.8%+/-1.89% versus 42.5%+/-1.33%; P<1 x 10(-15) after 12 weeks of consolidation) and increased numbers of proliferating cell nuclear antigen stained cells (0.7+/-0.04 versus 0.47+/-0.04; P<1 x 10(-10)) compared with the DO only group.


CONCLUSIONS
Alveolar distraction augments atrophic alveolar ridge and creates new bone that permits implant placement. rhBMP-2 enhances bone quality and may shorten the consolidation period of distraction allowing for earlier implant placement.
Rachmiel
Adi
A
Department of Oral and Maxillofacial Surgery, Rambam Medical Center, Haifa, Israel. adi_rach@netvision.net.il
Aizenbud
Dror
D
Peled
Micha
M
D016301:Alveolar Bone Loss / Q000188:drug therapy*; D000540:Alveolar Ridge Augmentation / Q000379:methods; D000818:Animals; D055396:Bone Morphogenetic Protein 2; D019485:Bone Morphogenetic Proteins / Q000627:therapeutic use*; D015921:Dental Implants; D010012:Osteogenesis / Q000187:drug effects*; D019857:Osteogenesis, Distraction / Q000295:instrumentation / Q000379:methods*; D010865:Pilot Projects; D012756:Sheep; D014025:Titanium / Q000627:therapeutic use; D016212:Transforming Growth Factor beta / Q000627:therapeutic use*
C525718:BMP2 protein, human; D055396:Bone Morphogenetic Protein 2; D019485:Bone Morphogenetic Proteins; D015921:Dental Implants; D016212:Transforming Growth Factor beta; D014025:Titanium