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October 1991

Mandibular Reconstruction With a Recombinant Bone-Inducing Factor: Functional, Histologic, and Biomechanical Evaluation

Author Affiliations

From the Division of Facial Plastic and Reconstructive Surgery, the Department of Otolaryngology—Head and Neck Surgery (Drs Toriumi and Kotler), University of Illinois College of Medicine, Chicago; and Genetics Institute, Cambridge, Mass (Ms Luxenberg and Drs Holtrop and Wang).

Arch Otolaryngol Head Neck Surg. 1991;117(10):1101-1112. doi:10.1001/archotol.1991.01870220049009

• Bone morphogenetic protein–2 (BMP-2) is a human recombinant bone-inducing factor that stimulates bone formation within 14 days. Twenty-six dogs underwent reconstruction of 3-cm full-thickness mandibular defects. After stabilizing the defects with stainless steel reconstruction plates, test implants composed of inactive dog bone matrix carrier and human recombinant BMP-2 were placed in defects of 12 animals (group 1). Control implants (carrier without BMP-2) were used in 10 animals (group 2), and no implants were placed in mandibular defects of four animals (group 3). Animals were killed at 3 and 6 months. The reconstructed segments were evaluated by roentgenography, analysis of functional stability, histology, histomorphometry, and analysis of biomechanical strength using three-point bend testing. In group 1, reconstruction plates were removed at 10 weeks because stiff, noncompressible mineralized bone formed across the defects, allowing the animals to chew a solid diet. The defects from groups 2 and 3 showed minimal, if any, bone formation and remained grossly unstable, prohibiting plate removal or advancement to a solid diet. Histomorphometric analysis at 6 months revealed that 68% of the group 1 implants were replaced by mineralized bone, whereas mineralized bone occupied less than 4% of the implants in groups 2 and 3. Biomechanical testing at 6 months revealed that the average bending strength of the reconstructed hemimandibles (expressed as a percentage of the contralateral hemimandible) was 27% for group 1 and 0% for group 2. The biomechanical strength of the defects reconstructed with BMP-2 increased significantly from 3 to 6 months and was related to degree of mineralization and thickness of bone bridging the defect.

(Arch Otolaryngol Head Neck Surg. 1991;117:1101-1112)