Long-term mandibular skeletal and dental effects of standard edgewise treatment

Introduction: The purpose of this investigation was to examine the effect of Tweed edgewise treatment on the expression of mandibular growth in the horizontal direction through maintenance of vertical control. Methods: We studied 36 patients who had 4 premolars extracted during treatment. Pretreatment, posttreatment, and postretention records of these patients were matched by age (+/- months), sex, malocclusion, and treatment interval (+/- months) to untreated controls from the Bolton-Brush Growth Study Center, Cleveland, Ohio. The cephalograms of the 2 samples were traced, digitized, and analyzed by descriptive cephalometric analysis and detailed regional superimposition. Results: Tweed edgewise treatment can prevent clockwise rotation but was not observed to enhance the normal forward rotation of the mandible. The mandible did not rotate forward in the treated patients who underwent a greater chin advancement. Conclusions: The pattern of skeletal change was favorable both during treatment and in later years. A feature of this effect was an improved pattern of mandibular growth displacement, when mandibular change was compared with maxillary change.