Inclusion Criteria:  Class I malocclusion with moderate crowding (between 4-6 mm of tooth-size-arch-length-discrepancy). Good oral hygiene and periodontal health. No severe skeletal discrepancy. Normal proclination for the upper and lower incisors.  Exclusion Criteria:  Bimaxillary dentoalveolar severe protrusion. Need for extraction. Previous orthodontic treatment. Subject with psychological abnormalities. congenitally missing or extracted teeth (except for the third molars). history of previous trauma to the maxillofacial region or surgical interventions.