60 patients needed therapeutic extraction of the maxillary first premolars with subsequent retraction of the maxillary canines were divided to randomly three groups:

(1) PRP group: Received PRP injections, (2) I-PRF group: Received I-PRF injections, (3) Control group: conventional treatment with no injections. TPAs were used as an anchor unit. Coil springs were used to distalize the upper canines on 0.019 x 0.025-inch stainless archwires. Alginate impressions and dental casts of the maxillary arch were done at five-time points over a 4-month follow-up period. The amount of canine movement, canine rotation, and anchorage loss were measured on three-dimensional digital models superimposed on the rugae area.

One of the most important goals of orthodontic treatment is to decrease the treatment time via achieving faster tooth movement chiefly in adults. Adults have more bone density and less bone turnover than adolescence, which may be linked to potential root resorption, periodontal problems, and white spot lesions.

Approaches to reduce orthodontic treatment time included surgical and non-surgical techniques. Non-surgical approaches such as systemic and local administration of chemical substances, low-level laser therapy, vibrations, and pulsed electrical stimulation therapy still need more studies to determine their safety and effectiveness.

Surgical procedures such as corticotomy, corticision, and micro-osteoperforations have

, in general high success rates, but they rely on incurring an injury to bone tissues. The latter has been linked to the regional acceleratory phenomenon (RAP). But the invasive nature of these procedures, associated risks of loss of alveolar bone and gingival recession, and the help needed from another specialist limit its routine application. Recently, the possibility of using platelet-based preparations from the patient's blood to accelerate orthodontic tooth movement like platelet-rich plasma (PRP) and platelet-rich fibrin (PRF) has grown. PRF represents the second generation of biological materials derived from blood. It is obtained through a centrifuge of the patient's blood without adding any additives to the tube. The variety of growth factors in PRP and PRF may have the ability to stimulate the activation of osteoblasts and osteoclasts together, which supports the idea that PRP could affect orthodontic tooth movement The study sample consisted of 60 patients and was calculated using (G-power sample size calculator), depending on the rate of canine retraction with a study power of 90%.

After ensuring the patient's compliance with the terms and conditions of this study, the purpose and methods of the study were explained to the patients using Information Sheet. In case of approval to participate, the patients were asked to sign the informed consent. Extra & Intra-oral photographs, impressions and clinical examinations were made.

Canine retraction was initiated after completion of the leveling and alignment phase via closed nickel-titanium coil springs applying 150 g of force per side at the same time.

Inclusion Criteria:

1. both male and female subjects
2. 18-25 years old
3. Class II Division 1 malocclusion, treated with extraction of the maxillary first premolars
4. Full permanent dentition
5. Good general and oral health

Exclusion Criteria:

1. extreme skeletal class II malocclusion, overjet > 10 mm ANB>7◦
2. diseases and medications that were likely to affect bone biology
3. poor oral hygiene
4. previous orthodontic treatment
5. smoking
6. coagulation disorders, or being treated with anticoagulants