Thirty six patients needs therapeutic extraction of the maxillary first premolars with subsequent retraction of the maxillary canines will be divided randomly into two groups : piezocision group and the ER:yttrium aluminum garnet (YAG) laser group. In each group, piezocision or hard laser-assisted flapless corticotomy will randomly assigned to one side of the maxillary arch at the first premolar region, and the other side served as the control. Canine retraction will be initiated after completion of the leveling and alignment phase via closed nickel-titanium coil springs applying 150 g of force per side, soldered trans-palatal arch will be used as an anchor unit.

Pre- and post distalization dental casts will be evaluated to study rate of canine distalization, canine rotation and anchorage loss over a follow-up period until a Class I canine relationship is achieved. The levels of pain and discomfort will be self-reported using a questionnaire with visual analog scales administered at four assessment times during the first month after the minimally invasive procedure.

One main issue in orthodontics is the prolonged treatment time, leading patients, especially adults, to avoid treatment or seek alternative options such as implants or veneers with less than optimal results.

Therefore, the search for methods that decrease the treatment duration is a main challenge in orthodontic research. Decreased duration of therapy seems to be related not only to better patient compliance, but also to reduced treatment -related root resorption , better periodontal health and lower risk of caries and white spots. Adjunct to the proper selection of brackets, wires, biomechanic systems, force levels, and anchorage systems, an array of novel techniques has been introduced to accelerate orthodontic tooth movement. These techniques can be briefly categorized as surgical and non-surgical. However The surgical approach is the most clinically used and most tested with known predictions and stable results. The invasiveness of surgical procedures, requiring full mucoperiosteal flaps, might have been a drawback for their widespread acceptance among orthodontists and patients. Therefore, more conservative flapless corticotomy techniques have recently been proposed. Although various techniques of flapless corticotomy have been reported to be successful in practice, scientific evidence for their effectiveness so far has been limited to case series and a handful of clinical trials, generally with small groups. Therefore further controlled prospective studies are needed to study the effectiveness of flapless corticotomy in accelerating orthodontic tooth movement .

Inclusion Criteria:

• Adult healthy patients , Male and female , Age range: 15-27 years.

• 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

• Permanent occlusion.

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

• Good oral and periodontal health:

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

Exclusion Criteria:

• Medical problems that affect tooth movement (corticosteroid, nonsteroidal antiinflammatory drugs (NSAIDs), …)

• patients have anti indication for oral surgery ( medical - social - psycho)

• Presence of primary teeth in the maxillary arch

• Missing permanent maxillary teeth (except third molars).

• Poor oral hygiene or Current periodontal disease:

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

• Patient had previous orthodontic treatment