DISTRACTION OF OEOGENESIS
One nesv approach to correction of deficiencies in the mandible and the maxilla involves the use of distraction osteogenesis (DO). When correcting deformities associatcd with these deficiencies, the conventional osteotomy techniques have several potential limitations (described
previously in this chapter). When large skeletal movements are required, the associatedsoft tissue often cannot adapt to’ the acute changes and stretching that result from the surgical repositioning of bony segments. This
failure of tissue adaptation results in several problems, including surgical relapse, potential excessive loading of the T~IJ structures, and increased severity of neurosensory loss as a result of stretching of nerves. In some cases
tile amount of movement is so large that the ·gaps crcatcd require bone grafts harvested from secondary surgical sites such as the iliac crest.
In the case atma~dibalar deficiency, the initial surgical procedure involves performing an osteotomy and placement of the distraction appliance. After a latency period of 7 days, the distraction occurs with a rate and
rhythm of 1 mm per day (completed by activating the appliance 0.5, mm twice each day). Once this distraction is complete the appliance is left is place for the consolidation. phase, which is usually two or three times the
amount of time required for the distraction phase. The appliance is then removed, and’ active orthodontic treatment continues. Fig. 25-32 on pages 597 through 599 demonstrates a case of DO of the mandible.