MANDIBULAR RECONSTRUCTION WITH TRANSFORMING GROWTH-FACTOR-BETA-1

Hypothesis: Transforming growth factor-beta 1 (TGF-beta 1) plus demine ralized bone matrix (DBM) will reconstruct a critical mandibular defec t devoid of periosteum in a canine model. Study Design: Randomized, bl inded, placebo controlled, prospective animal pilot study. Methods: Ca nine critical mandibular defects devoid of periosteum were reconstruct ed with DBM (group 1, n = 3) and DBM plus TGF-beta 1 (250 mu g TGF-bet a 1/g DBM) (group 2, n = 3). Radiologic, histologic, and biomechanical testing was performed on the test group and control group specimens a t 12 weeks after implantation. Results: A palpable bone bridge was pre sent in the group 2 subjects 5 to 6 weeks after implantation and was n ever present in the group 1 subjects. Radiologic and histologic examin ation at the time of harvest (12 weeks after implantation) demonstrate d a solid bone bridge in the group 2 subjects and a fibrous union in t he group 1 subjects. Group 2 specimens demonstrated failure in four-po int bending testing at an average maximum moment of 9.9 +/- 2.2 N-m. T his value was 9.4% of the maximum moment of the contralateral nonopera ted side. Group 1 specimens were palpably flexible on plate removal an d had a biomechanical strength of 0. The difference in strength betwee n group 1 and group 2 was statistically significant (P < 0.02), suppor ting the hypothesis that the addition of TGF-beta 1 to the DBM carrier resulted in the formation of significantly stronger bone in the criti cal gap. Conclusion: The addition of TGF-beta 1 to DBM results in heal ing of a critical bone defect devoid of periosteum in a higher mammali an model.