54 patients who need extraction-based treatment of the maxillary first premolars with subsequent retraction of the maxillary canines will be divided randomly into three groups in this trial. The prolonged duration of the treatment period can cause many side effects such as white spots, caries, periodontal diseases, and pain and discomfort. So many efforts have been made to reduce the treatment time. Many procedures have been introduced to accelerate orthodontic tooth movement, which can category as surgical or non-surgical. Piezocision is a minimally invasive surgical method for accelerating orthodontic tooth movement and shortening treatment time. Low-level laser therapy (LLLT) is one of the physical acceleration methods that have contributed to decreasing treatment time.

There are three groups:

The first group (control group): the canine retraction in this group will be performed in conventional method.

The second group (Experimental group): the canine retraction in this group will be performed in association with piezocision.

The third group (Experimental group): the canine retraction in this group will be performed in association with low-level laser therapy.

Closed nickel-titanium coil springs applying 150 g of force per side will be used for retraction of the upper canine.

Regarding the Piezocision, three vertical incisions will be made (3-mm depth and 8-10 mm length) after anesthesia. The cuts will be performed mesial and distal the upper canine as well as at an equal distance from the upper canine and 2nd premolar.

Regarding the low-level laser therapy (LLLT): GaALAs diode laser (wavelength: 810 nm and exposure time of 10 seconds\point) will be applied around the upper canine in 10 sites from buccal and palatal. The middle of the extraction site will be also irradiated in 4 sites (2 buccally and 2 palatally). The LLLT will be applied 5 times in the first month of canine retraction. After that, until the class I canine relationship will be achieved, the irradiation will be repeated every two weeks.

The levels of pain and discomfort will be self-reported using a questionnaire with visual analog scales administered at five evaluation times during the first month of canine retraction.

Inclusion Criteria:

1. Adult healthy patients, Male and female, Age range: 17-28 years.

2. Class II Division 1 malocclusion :

   • Mild/moderate skeletal Class II (sagittal discrepancy angle ≤7)
   • Overjet ≤10
   • Normal or excessive facial height (Clinically and then cephalometrically assessed using these three angles: mandibular/cranial base angle, maxillary/mandibular plane angle, and facial axis angle)
   • Mild to moderate crowding ≤ 4

3. Permanent occlusion.

4. Existence of all the upper teeth (except third molars).

5. Good oral and periodontal health:

   • Probing depth < 4 mm
   • No radiographic evidence of bone loss.
   • Gingival index ≤ 1
   • Plaque index ≤ 1

Exclusion Criteria:

1. Medical problems that affect tooth movement (corticosteroid, nonsteroidal anti-inflammatory drugs (NSAIDs), …)

2. Presence of primary teeth in the maxillary arch

3. Missing permanent maxillary teeth (except third molars).

4. Poor oral hygiene or Current periodontal disease:

   • Probing depth ≥ 4 mm
   • radiographic evidence of bone loss
   • Gingival index > 1
   • Plaque index > 1

5. Patient had previous orthodontic treatment