Evolution: Mandibular Distraction
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Karp and coworkers conducted a similar experimental study with a more comprehensive analysis of distraction regenerates at different stages of formation (Karp et al., 1990, 1992). Ten days after a periosteal-preserving corticotomy, unilateral mandibular lengthening began at a rate of 1 mm per day for 20 days, followed by an 8 week consolidation period. Histomorphologically, the distraction gap can be represented by four zones: 1) a central zone of fibrous tissue, 2) a zone of extending bone formation, 3) a zone of bone remodeling, and 4) a zone of mature bone.

Collectively, these studies provided a scientific basis for the clinical adaptation of the distraction osteogenesis technique to the craniofacial complex. Since then, distraction osteogenesis for gradual mandibular lengthening and/or widening has received the majority of clinical attention.

FIG. 2.6.6, 2.6.7. Radiograph of a dog mandible after 20 mm of osteodistraction (left). Note radiolucent interzone in the middle of the distraction regenerate. Diagram of zonal structure of distraction regenerate (right). Reproduced with permission from Karp N, Thorne CH, McCarthy JG, Sisson GA. Bone lengthening in the craniofacial skeleton. Ann Plast Surg 1990;24(3):231-237 and from Karp NS, McCarthy JG, Schreiber JS, Sissons HA, Thorne CH. Membranous bone lengthening: A serial histological study. Ann Plast Surg 1992;29:2-7.

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