Hard tissue response to anterior tooth retraction

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.
Pretreatment and post treatment lateral cephalograms of 15 post-pubertal female patients (mean age 18.2) with class II division I malocclusion or bialveolar protrusion who required upper first premolar (P1) extraction were evaluated using a series of 5 linear and 9 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.
On average, the maxillary incisors retraction was found to be 4.8mm which cause significant changes in SNA angle due to backward and downward movement of point A.
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 2006; 1: 48 - 52 )