The goal of this clinical trial is to assess the effect of Low Level Laser Therapy (LLLT) on Upper Incisor Crowding using Clear Aligner Treatment (CAT).

The goal of this clinical trial is to assess the effect of Low Level Laser Therapy (LLLT) on Upper Incisor Crowding using Clear Aligner Treatment (CAT) on healthy patients (16-23 years old) with complete set of dentition and Angle class I. The main questions to answer are:

1. Evaluate rate of Upper Incisor Decrowding using CAT and LLLT
2. Does LLLT affect pain during CAT?

Researchers will compare CAT with LLLT to CAT without LLLT to see if the LLLT will accelerate Orthodontic Tooth Movement.

Participants will:

• Change to a new aligner every 7 days.
• Visit the clinic every week for checkup.
• Log in pain scores every 6, 24, 48 and 72 hours after delivery of new aligners.

Inclusion Criteria:

1. Patients age ranging from 16-23 years old with Angle class I malocclusion and upper anterior crowding.
2. Healthy, compliant and internally motivated patient.
3. Full set of maxillary permanent dentition except third molar.

Exclusion Criteria:

1. Previous orthodontic treatment.
2. Any systemic diseases that could interfere with orthodontic treatment.
3. Gross gingival or periodontal problems