Hard tissue response to anterior tooth retraction

Aim: The purpose of this study was to investigate skeletal and dental changes during anterior tooth retrac-tion as well as upper lip response to this orthodontic treatment. Materials and Methods: Pretreatment and post treatment lateral cephalograms of ۱۵ post-pubertal female patients (mean age ۱۸.۲) with class II division I malocclusion or bialveolar protrusion who required upper first premolar (P۱) extraction were evaluated using a series of ۵ linear and ۹ angular measurements. All the cases were treated using combination edgewise technique. Point A displacement was then analyzed, and then the effect of orthodontic correction was determined using single variant regression analysis. Results: On average, the maxillary incisors retraction was found to be ۴.۸mm which cause significant changes in SNA angle due to backward and downward movement of point A. Conclusion: Preoral region hard tissue changes can be produced by surgical intervention, growth, ortho-pedic forces, and orthodontic movement of teeth. According to this study point A movement in post-puber-tal patients is possible but it seems surgical intervention is inevitable in severe cases. Also palatal and occlusal plane rotation occur consequent to the tooth retraction. (IJO ۲۰۰۶; ۱: ۴۸ - ۵۲ )