•        This will be an in-vivo study. 24 patients undergoing orthodontic treatment will be selected for the study. Each participant will be treated with fixed pre-adjusted appliance. The study will be carried out in 2 phases.

•        PHASE I :

•         The system used will be metal 0.022 x 0.028” slot MBT bracket system. Trans Palatal Arch (TPA) will be given for anchorage. Leveling alignment will be done with a 0.012-in NiTi archwire, 0.014 in NiTi archwire,0.016 in NiTi archwire according to the requirement of the case. A 0.019×0.025-in SS archwire will be placed for one month for torque expression.

•        PHASE II :

•        Following this, atraumatic extractions of maxillary first premolars will be carried out.

•        This study will be a split-mouth, single blinded, prospective, single centre randomized control study conducted for a period of 4 months (T0, T1, T2, T3, T4).

•        Blood will be drawn before the extraction procedure and sent for centrifugation. Extraction will be carried out atraumatically by a single operator, once we receive the A-PRF and L-PRF.

•        Allocation Method:

•        In the first participant, the sites will be allocated as experimental & control using lottery method.

•        Therefore, one arch of the patient will be packed with A-PRF in the extraction socket on one side and respective control group on opposite side of the same arch. Whereas contralateral arch will be packed with L-PRF in the extraction socket and control group on the opposite side of this arch. Control group will be flushed with saline in extraction socket. Experimental group will be packed with either A-PRF or L-PRF.

•        Hence, each subject will have two experimental and two control quadrants. Experimental groups will be placed diagonal to each other to take care of unequal masticatory forces.

•        In the next patient, the quadrants will be changed going clockwise, so suppose A-PRF was in first quadrant in first patient, the A-PRF site would be in second quadrant in second patient, in third quadrant in third patient and so on. This will be continued till the 24^th patient going in a clockwise circle.

One circle will be completed in 4 patients and similar 6 circles will be completed in 24 patients.

•        L-PRF preparation-Using a 5ml syringe, whole venous blood sample will be drawn quickly from the median cubital vein and placed into two sterile tubes (Bello centrifuge tubes, India) without the use of an anticoagulant. These tubes will then be immediately centrifuged at 2,700 rpm (about 400-g centrifugation force, based on our estimations) for 12 minutes in Centrifugation machine (Labtech Dentifuge, Gujarat, India).   

•          Preparation of A-PRF -After centrifugation in a manner similar to L-PRF, (1500 RPM for 12 minutes) the middle fraction (A-PRF) will be collected.

•        Placement- L-PRF And A-PRF plugs will be placed in the allocated socket using sterile tweezers (GDC, India), and compressed with amalgam condenser. The control group sites will be flushed with saline (Puniska, Gujarat, India). All the sockets will be sutured with 3-0 silk sutures (AQsilk, Karnataka, India)(using simple interrupted suturing technique) to keep the patient blinded about the technique.

•        MEASUREMENTS

•        The patients will start undergoing treatment with fixed appliances. T0 cast will be recorded post extraction and patients will be given 12mm NiTi closed coil spring (G&H, Franklin, USA) for retraction post extraction (150g force) on 0.019×0.025-in SS arch wire. After that, patient will be recalled every month (T1, T2 T3, T4) and study models will be made to check for amount of canine retraction measured from distal surface of canine to mesial surface of 2^nd premolar with the help of Digital Vernier Caliper. (Aerospace, Japan)

•        The velocity will be calculated as follows: v = d/t, where v is the velocity of canine movement, d is the amount of this movement in millimetres, and t is 4 months (i.e. velocity will be measured at T4)