Evaluation of effect of bracket slot system on the quality and quantity of tooth movement during leveling and alignment stage

Inclusion Criteria:

• An age range from14 to18 years. All permanent teeth are erupted(3rd molar not included).
• Angle class I malocclusion with normal facial proportions.
• Moderate to severe crowding in the lower dental arch asassessed by lett irregularity Index that require treatment with fixed appliance using extraction approach.
• There is no previous orthodontic treatment.

Exclusion Criteria:

• Poor oral hygiene or periodontally compromised teeth.
• Craniofacial anomalies or previous history of trauma, bruxism, or Parafunctions.
• Uncooperativepatient.