This study aims to estimate the levels of pain and discomfort associated with the en-masse retraction of the six upper anterior teeth and assisted by either conventional or flapless corticotomy.

Thirty-four adult patients exhibiting class П division 1 malocclusion will be randomly allocated to either the conventional corticotomy group or the flapless corticotomy group, and they will be treated by extraction of maxillary first premolars with applying mini-screws between maxillary second premolar and first molar as temporary skeletal anchorage devices (TSADs). The levels of pain and discomfort will be rated after 24 hours of corticotomy (T1), four days (T2), seven days (T3), 14 days (T4) and after 28 days of corticotomy, by asking the patients to fill in a questionnaire for assessing levels of pain and discomfort.

Increasing the treatment duration is one of the most important difficulties facing the orthodontist. Several therapeutic procedures accompanying orthodontic treatment have been introduced in order to reduce the treatment duration and the most important one is the corticotomy. Although traditional corticotomy proved to be effective in accelerating different types of tooth movement, it is considered aggressive in nature. Hence, there is an interest to develop minimally invasive surgical techniques. These techniques include the flapless corticotomy using the piezosurgery device.

In flapless corticotomy group, 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 second premolars. The incisions will be 5 mm long and started 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.

In traditional corticotomy group, a full-thickness mucoperiosteal flap will be elevated, extended from the distal side of the second premolar on the right side to the same position on the left side without performing any vertical releasing incisions. The full-thickness flap will be extended 3 mm above the root apices, from the buccal and palatal sides. Then, one vertical incision between the roots of upper anterior teeth and two vertical incisions in the site of first premolar extraction will be made by the piezosurgery knife. The vertical incisions will be connected by a horizontal incision using the piezosurgery knives. The vertical incisions will be 3 mm in depth, starting 2-3 mm apical to the alveolar crest, and extending 3 mm beyond the root apices. The interrupted technique of suturing will be done using a non-absorbent 3-0 black silk.

The levels of pain and discomfort will be rated after 24 hours of corticotomy (T1), four days (T2), seven days (T3), 14 days (T4) and after 28 days of corticotomy, by asking the patients to fill in a questionnaire based on the Visual Analogue Scale (VAS), and patient's responses will be obtained regarding their feelings of pain, discomfort, swelling, mastication and swallowing difficulties, jaw movement restriction, satisfaction and recommend the procedure to a friend.

Inclusion Criteria:

1. Age range between 18 and 30 years.
2. Class II division 1 malocclusion requiring extraction of upper first premolars.
3. Mild to moderate skeletal class II malocclusion.
4. Normal or excessive anterior facial height.
5. No or mild crowding (tooth-size arch-length discrepancy ≤3 mm).
6. Overjet >5 mm and <10 mm.
7. Completion permanent dentition (regardless of third molars).
8. No previous orthodontic treatment.
9. No drug use or systematic disease that would affect the bone and tooth movement rate.
10. Healthy periodontium and good oral hygiene.

Exclusion Criteria:

1. Patients with previous orthodontic treatment.
2. Patients with severe skeletal dysplasia in all three dimensions.
3. Patients suffer from systemic diseases or syndromes
4. Patients on medication for systemic disorders, pregnancy or steroid therapy.
5. Patients showing any signs of active periodontal disease
6. Patients with severe crowding (≥ 3.5 mm) in maxillary arch
7. Patients with missing or extracted teeth in maxillary arch except third molar.