This study aimed to evaluate the levels of pain, discomfort, and functional impairment associated with traditional corticotomy and flapless corticotomy in the retraction of upper anterior teeth.

40 patients requiring extraction of maxillary first premolars and maximum anchorage to retract the upper anterior teeth will participate in the study. They will be divided randomly into two groups: flapless corticotomy (20 patients) and traditional corticotomy (20 patients).

A corticotomy is the cutting of the bone that involves cortical bone only, leaving intact the medullary vessels and periosteum. It offers an advantage to adult patients in reducing orthodontic treatment time. The definition of traditional corticotomy is: elevating full-thickness periodontal flaps from a coronal approach, and vertical corticotomies are made between the teeth extending from 2-3 mm apical of the alveolar crest to 2 mm beyond the tooth apices and connected by a horizontal corticotomy; this process is done on both the labial and palatal aspects.

The definition of flapless corticotomy is a minimally invasive version of corticotomy, using a piezotome to inflict bone injury. This technique entails labial and palatal interproximal piezoelectric micro-incisions into the cortical bone without reflecting periodontal flaps.

Before enrolling each subject into the study, they will be examined completely to determine the orthodontic treatment plan. The operator will inform them about the aim of the study and ask them to provide written informed consent.

Self-drilling titanium mini-implants (1.6mm diameter and 8mm length) will be used. they will be inserted between the maxillary second premolar and first molar at approximately 8-10mm above the archwires at the mucogingival junction and will be checked for primary stability (mechanical retention). Then the maxillary first premolar will be extracted. The maxillary arch will be leveled and aligned. The rectangular stainless steel archwires (0.019" × 0.025") with anterior 8mm height soldered hooks distal to the lateral incisors will be inserted.

The surgery will be carried out under local anesthesia. The traditional corticotomy will be handled by the same maxillofacial surgeon, and the flapless corticotomy will be handled by the same orthodontist.

For traditional corticotomy, incisions in the mesial aspect of one-second premolar to the mesial surface of the contralateral second premolar will be placed, and a full-thickness flap will be elevated 3 mm above the apical region of the tooth. piezoelectric under copious irrigation will make vertical and horizontal cuts (only cortical surface). The vertical cuts will be between the dental roots in the interdental cortical surfaces, stopping 2 mm short of the alveolar crest occlusally. The horizontal cut will connect the vertical cuts 2 mm beyond the root apex. These cuts will be performed from the mesial aspect one-second premolar to the mesial surface of the contralateral second premolar involving the anterior. Similarly, a palatal flap incision will be raised immediately for doing the same vertical and horizontal cuts in the superficial surface of the palatal bone.

For the flapless corticotomy, the depth of gingival tissue will be determined through bone sounding using a periodontal probe. A scalpel will be used to make the incisions through the gingiva, 4mm below the interdental papilla, to preserve the coronal attached gingiva. These vertical incisions will be placed from the mesial aspect of the one-second premolar to the mesial surface of the contralateral second premolar on the labial and palatal aspects of the maxilla through the gingiva and the underlying bone. A piezo-surgery knife will be used to create the cortical alveolar incisions to a depth of 1 mm within the cortical bone.

The surgical procedure will be performed, and (250-300) g force will be applied on each side (3-4 days) after corticotomy using two Nickle-Titanium (NiTi) springs attached between the mini-implants and the soldered hooks in a direction approximately parallel to the occlusal plane for conducting an en-masse retraction. The force level will be measured every 2 weeks after the corticotomy. Retraction will be stopped when a class I canine relationship is achieved, and a good incisor relationship will be obtained.

Inclusion Criteria:

1. Adult healthy patients

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. Previous orthodontic treatment