26 participants from the Orthodontic Department at University of Damascus Dental School will be randomly assigned into two groups. In the experimental group, a low level laser with a wave length of 830 nm, output of 150 mw, energy of 2 j per point and application time of 15 seconds per point will be applied on each tooth of the six upper incisors according to this protocol: the root will be divided into 2 halves; gingival and cervical. Laser will be applied in the center of each half from both the buccal and palatal sides which means 4 application points and a total energy of 8 j per each tooth. Control group will undergo typical orthodontic treatment with the laser device applied the same manner but without being turned on (to get the placebo effect for pain reduction effect). This procedure will be repeated after 3, 7, 14 days and each 15 days from the beginning of the second month till the end of the leveling and alignment stage.

The long time needed for orthodontic treatment is considered one of the biggest obstacles which make patients refuse to undergo treatment. It also has many disadvantages including higher caries rates, gingivitis, and root resorption. It also combined commonly with pain, which reducing patient acceptance and cooperation with treatment.

Low level laser therapy in orthodontic has shown pain-reducing effects with an effect in biomodulation which lead to increased orthodontic tooth movement rate and reducing risk of root resorption.

A recent systematic review states that low level laser therapy has shown efficiency in accelerating orthodontic tooth movement, but there is a need for more studies to determine the best protocols regarding energy and frequency. A review of the literature shows that there is no randomized controlled trails evaluating its efficiency in accelerating orthodontic tooth movement in regard of dental crowding cases, which is the main purpose of this study.

Inclusion Criteria:

1. Patients aged between (16 - 24) years.
2. Moderate crowding (3 - 5) mm in the anterior region of the maxillary dental arch with an irregularity index of (7 mm or more) mm according to Little Index with an indication to extract upper two premolars.
3. All upper teeth are existed (except for third molars).
4. Patients have not undergone previous orthodontic treatment.
5. Patients have not undergone any medical treatment that interfere with orthodontic tooth movement (Cortisone, NSAIDs, …).
6. Patient with good oral hygiene (Plaque Index less than 1).

Exclusion Criteria:

1. Any medical condition affecting orthodontic tooth movement.
2. Bad oral hygiene (Plaque Index greater than 1).
3. Any peri-apical lesions developed during treatment.
4. Patient lack of commitment toward follow-up appointments.