VECTOR OF DEVICE PLACEMENT AND TRAJECTORY OF MANDIBULAR DISTRACTION

The role of preoperative planning, the geometric changes, and the long -term effects of mandibular distraction have not been previously repor ted. This study included 10 patients who underwent unilateral (5 patie nts) or bilateral (5 patients) mandibular distraction. Preoperative, p ostdistraction, and yearly radiographs (panoramic, posteroanterior, an d lateral cephalograms) were reviewed. Postdistraction follow-up range d from 12 to 70 months. Postdistraction, the mandibles showed evidence of anticipated growth without relapse. This growth rate was variable and dependent on the genetic program of the native bone. Previously re ported improvement in temporomandibular joint morphology was maintaine d in the long term. The resulting shape of the neomandible was most in fluenced by the vector of placement of the distraction device. When pl aced vertically, ramal elongation was observed. When placed horizontal ly, anterior projection of the mandibular body occurred. When placed o bliquely, ramal and body elongation occurred with preservation of the genial angle. After 2 to 5 years of follow-up, continued growth of the neomandible was observed.