Rationale: Several methods have been devised to accelerate the rate of tooth movement during orthodontic treatment which include local administration of cytokines, physical methods and surgical methods. Recently, it has been found that Platelet Rich Plasma (PRP) increases the rate of orthodontic tooth movement. PRP is an autologous concentration of platelets in a small volume of plasma. It has a high concentration of growth factors which include platelet derived growth factors, fibroblast growth factor, vascular endothelial growth factor, epithelial growth factor and few others. These growth factors enhance mitogenesis, angiogenesis, chemotaxis, cell differentiation and bone remodelling.

Aims and Objectives: To evaluate the effect of PRP on rate of tooth movement in canine retraction. Objectives of this study is to evaluate the amount of extraction space closure during canine retraction in experimental and control side and to compare the same.

Setting: Department of Orthodontics and Dentofacial Orthopaedics, PGIDS, Rohtak.

Study Design: Prospective, single blind, split-mouth, randomized clinical study

Time frame: 12 months

Population/participant: Inclusion criteria:- Patients with age between 15-25 years, requiring bilateral extraction of maxillary 1st premolars, with platelet count above 1,00,000 per ml and good oral hygiene. Exclusion Criteria:- Patients with thrombocytopenia (platelet count less than 1,00,000 per ml), clotting or bleeding disorders, systemic diseases, presence of any signs and symptoms of gingival and periodontal diseases, long-term drug history, evidence of bone loss, smoking habit, any untreated carious lesions.

Sample size: a sample size of 12 patients

Method of study: Patients who met the inclusion criteria will be selected for the study. Treatment will be initiated by bonding 0.022” slot MBT straight wire appliance. Space closure will be carried out with 0.017”x 0.025” SS wires using closed coil NiTi springs and Transpalatal Arch- 20gauge(0.9mm) as anchorage unit. 10ml of venous blood sample from each patient will be collected in a sterile test tube. 1ml of 10% Sodium Citrate will be used as anticoagulant. One ml of the whole blood will be sent to the laboratory for the calculation of platelet count. The remaining 9ml of blood will be used for the preparation of PRP. PRP will be prepared by the method of double spin centrifugation. 1ml of PRP will be obtained from which 0.2 ml will be sent to the laboratory for analysis of platelet count and 0.8 ml will be injected submucosally into the buccal vestibular mucosa distal to the canine tooth on the experimental side.

Outcome Measures: The outcome variables will be the rate of canine retraction measured in millimeters.

Statistical Analysis: Data will be checked for normality. If normally distributed then paired t test will be applied. If not normally distributed then wilcoxon signed rank test will be applied.