Effect of Early Versus Late Premolar Extraction on Orthodontic Tooth Movement

The goal of this randomized controlled trial is to evaluate whether the timing of premolar extraction affects the rate of orthodontic space closure during en-masse anterior retraction. The study will also assess gingival cleft formation, mesial movement of the upper first molars, ease and duration of premolar extraction, and patient-reported pain and anxiety. The main question it aims to answer is: Does early versus late premolar extraction affect the rate of orthodontic space closure? Researchers will compare two groups of patients. In the early extraction group the maxillary first premolars will be extracted before or within one week of start of fixed orthodontic treatment. In the late extraction group, the premolars will be extracted after alignment and immediately before the start of space closure. Participants will: * Receive fixed orthodontic treatment and bilateral extraction of the maxillary first premolars. * Be randomly assigned to either the early-extraction or late-extraction group. * Undergo orthodontic alignment followed by en-masse anterior retraction. * Have dental impressions/digital models obtained at the start of retraction and at 3 and 6 months to measure orthodontic tooth movement and space closure. * Be assessed for gingival clefts and mesial movement of the upper first molars. * Have the ease and duration of their premolar extraction recorded and report their pain and anxiety associated with the extraction procedure.