EXPERIMENTAL MANDIBULAR REGROWTH BY DISTRACTION OSTEOGENESIS - LONG-TERM RESULTS

The use of gradual distraction to grow bone (distraction osteogenesis) has gained widespread orthopedic acceptance, but has only recently be en applied to craniofacial skeletal defects. The use of bifocal distra ction osteogenesis to fill experimental segmental mandibular defects w ith regenerate bone was recently reported. Though all canines in that study demonstrated normal oromandibular function, they were observed f or only 4 weeks following defect closure. The study that is now report ed describes the long-term (12-month) functional, morphologic, and bio mechanical results when bifocal distraction osteogenesis was applied t o the same model. In this long-term study, three canines had 2.5-cm un ilateral segmental mandibular body defects filled with structurally st able bone using bifocal distraction osteogenesis. These dogs exhibited normal oromandibular function for 1 year following segment regrowth a nd external fixator removal. Macroscopic and histologic evaluation of the regrown segments revealed a re-formation of the cortical and medul lary architecture. Stress testing demonstrated the average ultimate st rength of the regrown segment at 53 MPa, which corresponded to 77%+/-5 .7% of normal mandibular bone. The data suggest that clinical trials a pplying this technique to segmental mandibular reconstruction are warr anted.