Mandibular reconstruction with a recombinant bone-inducing factor. Functional, histologic, and biomechanical evaluation.
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.
Toriumi
D M
DM
Department of Otolaryngology-Head and Neck Surgery, University of Illinois College of Medicine, Chicago 60612.
Kotler
H S
HS
Luxenberg
D P
DP
Holtrop
M E
ME
Wang
E A
EA
D000818:Animals; D001696:Biomechanical Phenomena; D001846:Bone Development; D001857:Bone Matrix; D019485:Bone Morphogenetic Proteins; D001860:Bone Plates; D004285:Dogs; D004343:Drug Implants; D006133:Growth Substances / Q000008:administration & dosage; D008334:Mandible / Q000473:pathology / Q000503:physiopathology / Q000601:surgery*; D010865:Pilot Projects; D011183:Postoperative Complications; D011506:Proteins / Q000008:administration & dosage*; D011994:Recombinant Proteins
D019485:Bone Morphogenetic Proteins; D004343:Drug Implants; D006133:Growth Substances; D011506:Proteins; D011994:Recombinant Proteins