Surgical modification technique try to get bodily movement during upper canine retraction.

I- Original surgical technique (Liou and Huang technique, 1998) :

On the conventional surgical side, (the control side), the intersepital bone was undermined by two vertical cuts on the mesio-buccal and mesio-palatal line angles of the first premolar socket. They were connected at the base of the socket by an oblique cut. The surgical round bur was held parallel to the long axis of the canine and moved buccolingually, while shaving the interseptal bone buccolingual (back-and-forth) shaving movements were reduced the thickness of the interseptal bone by approximately 1 mm

II- Modified surgical technique:

In the surgical modification side, (the experimental side), intra-alveolar mesio-buccal and mesio-palatal cuts and interseptal bone shaving were done by surgical round bur and copious irrigation, without the oblique cut since it was done blindly in the original surgical technique. A buccal semilunar flap was opened on the apical area of canine-premolar region. The surgical pin helped also in location of the point of initial drilling of the apical horizontal cut from buccal approach, when the surgical pin's socket arm rested on the depth of the socket, the vestibular arm marked the point of access. It also estimated mesiodeistal extension of the apical horizontal cut. The apical horizontal cut was started from the socket apex to half way of the interseptal bone mesiodistally as an extension and for the depth, Mallet and Chisel were used from the cortical bone to reach the mesio-palatal cut. The flap was sutured. This surgical modification step provided more predictability and safer surgery than the blind oblique cut in the original surgical technique.

Inclusion Criteria:

1. Orthodontic patients needed extraction of upper first premolars, with age range from 18 - 25 years old.
2. All patients were medically free. (See Appendix II)
3. No previous orthodontic treatment.
4. Adequate oral hygiene and periodontally healthy teeth.
5. The canines were almost leveled and aligned.
6. Maximum anchorage requirements.
7. Healthy canines; no deep carious lesions, no endodontic lesions, no root canal treatment, nor internal or external root resorption.
8. All patients were informed of the procedure and signed the consents.

Exclusion Criteria:

Exclusion Criteria

Subjects were excluded from the study when:

1. They failed to keep several consecutive appointments.
2. Oral hygiene was subjectively judged as deteriorating during the preliminary stages of patient preparation.
3. Compliance with the instructions provided was inadequate.