Mandibular reconstruction using bone morphogenetic protein 2: long-term follow-up in a canine model

Area of Science:

• Biomaterials Science
• Regenerative Medicine
• Oral and Maxillofacial Surgery

Background:

• Critical-size mandibular defects pose significant reconstruction challenges.
• Bone morphogenetic proteins offer potential for enhanced bone regeneration.

Purpose of the Study:

• To evaluate bone resorption and stability after reconstructing canine mandibular defects using recombinant human bone morphogenetic protein 2 (rhBMP-2) with a bioerodible carrier.
• To assess the long-term integration and functional capacity of rhBMP-2-induced bone.

Main Methods:

• Surgically created 3-cm mandibular defects in nine dogs were reconstructed using rhBMP-2 with a bioerodible carrier or carrier alone (control).
• Defects were stabilized with titanium plates, which were removed after 10 weeks in test animals.
• Bone density, height, and area density were assessed via roentgenography and histomorphometry over 30 months.

Main Results:

• rhBMP-2 induced significant bone formation, comparable to host bone by 3 months, with no bone formation in controls.
• Early localized cortical thinning and height reduction were observed, but stabilized by 11 months.
• Bone area density increased over 30 months, indicating successful integration and stability.

Conclusions:

• rhBMP-2 in a bioerodible carrier effectively induces new bone formation in critical-size mandibular defects.
• The newly formed bone integrates with host bone, providing a stable union capable of withstanding masticatory forces.
• While early resorption occurs, rhBMP-2-induced bone demonstrates long-term stability and increased density.