Evaluation of the Rate of Maxillary En-masse Retraction Using 0.018-inch Versus 0.022-inch Slot Brackets in Adults

Inclusion Criteria: * Maxillary dentoalveolar protrusion cases that require upper first premolars extraction. * Full permanent dentition (not necessitating third molars). * Good oral hygiene. Exclusion Criteria: * Patients having systemic diseases or on medications that would affect tooth movement. * Active periodontal disease or obvious bone loss in maxillary arch. * Patients with habits that are detrimental to dental occlusion (thumb sucking, tongue thrusting). * Previous orthodontic treatment. * Missing teeth.