Aim: To study the relationship between incisor retraction and soft tissue profile alterations and to identify and quantify the parameters that influence it. Methods: Pre- and posttreatment lateral cephalograms of 37 Class I and Class II Division 1 Iranian females in whom at least one maxillary premolar was bilaterally extracted were analyzed and compared. Results: Significant positive correlations were found between retraction of the maxillary and mandibular incisors and posterior movement of the upper lip (r = 0.53, P < .001), the lower lip (r = 0.63, P < .001), thickness increase of the upper (r = 0.59, P < .001) and lower (r = 0.69, P < .001) lip, increase of the soft tissue lower anterior face height (r = 0.81, P < .001) and lower soft tissue component (r = 0.49, P < .001), and an increase of the nasolabial angle (r = 0.43, P < .01). The ratio of maxillary incisor to upper lip retraction was 2:1. Conclusion: In Iranian girls, a strong correlation exists between anterior tooth retraction and the position and configuration of both lips. World J Orthod 2010;11:262–268.
Key words: prediction, profile, incisor retraction, lip position, extraction therapy