Sixty patients who need extraction-based treatment of the maxillary first premolars with subsequent retraction of the maxillary anterior teeth will be divided randomly into three groups: piezocision group, piezocision with low-level laser therapy group, and control group. In each group, after the levelling and alignment phase is completed, the rectangular stainless steel archwires (0.019" × 0.025") will be inserted, then after two weeks, the en masse retraction will be started via closed nickel-titanium coil springs applying 250 g of force per side. For anchorage, mini implants will be inserted between the second premolars and the first molar on each side.

Regarding the Piezocision, vertical soft-tissue incisions will be made on the buccal and palatal gingiva. One incision will be made between the roots of the six upper anterior teeth, and two incisions will be made between the upper canines and the second premolars. The incisions will be 5 mm long and start 4 mm apical to the interdental papilla. Then a piezosurgery knife will be inserted to perform the cortical alveolar incisions with 3-mm in-depth and 8 mm in length. No suturing will be needed.

Regarding the piezocision with the later application of low-level laser therapy (LLLT):

After six weeks of piezosurgery, a diode laser (wavelength: 810 nm and exposure time of 10 seconds\point) 10 seconds per point will be applied on each tooth of the six maxillary anterior teeth according to this protocol: the root will be divided theoretically into two halves; gingival and cervical, and the laser will be applied in the center of each half from both buccal and palatal sides which means four application points and total energy of 16 Joules per tooth. LLLT irradiation will be performed in the sixth week after the onset of mass retraction (day 0). After that, irradiation is repeated on days 3, 7, and 14, then every two weeks, until the class I canine relationship is achieved and/or spaces lateral to incisors are closed

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. The patient had previous orthodontic treatment