الفهرس 
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Abstract
The aim of this study was to evaluate the orthodontic tooth movement during en-masse retraction of maxillary anterior teeth with and without the injection of platelet-rich plasma.
Twenty patients with age range 18-25 years were enrolled in this randomized controlled clinical trial over a duration of twelve months. They were classified into two groups; group I: Control, group II: Platelet rich plasma (PRP) injection. In both groups extraction of the maxillary first premolars and retraction of the maxillary anterior teeth on two self-drilling miniscrews was done. The six anterior teeth were retracted by Niti coil spring on crimpable hooks placed distal to the upper lateral incisors.
In both groups, orthodontic records were taken and digital 3D models and CBCT were obtained pre and post en-masse retraction. The 3D digital models were obtained by scanning the stone casts using 3-Shape R-750 scanner (3shape A/S. Copenhagen, Denmark). Skeletal, dental and soft tissue measurements were taken from CBCT while the rate of en-masse retraction, I intercanine width, intermolar width and canine rotation were calculated from digital models.
Two Hubit self-drilling mini-implants (Hubit Orthodontics, Gyeonggi, South Korea) were inserted buccally in the mucogingival junction between the maxillary second premolar and first molar (right and left- handed screws, 1.6 mm diameter and 8 mm length). Six millimeter length hooks (Jiscop, Korea) were crimped onto 0.017” × 0.025” stainless steel wire distal to the lateral incisors and the six anterior teeth were ligated together.
En-masse retraction was carried out over a period of 12 months using closed NiTi coil springs (Jiscop, Korea) and a consistent force of 200 gram/side as measured by strain gauge.
The follow up of patients was carried out every 4 weeks. At each visit, the appliance was checked to ensure that there were no loose wires or debonded brackets and that there was an adequate mini-implant stability. Oral hygiene instructions were reinforced, a consistent retraction force was ensured and the closed coil spring was changed when necessary. After retraction, finishing and detailing were carried out.
In conclusion, within the limitations of this study it could be observed that PRP was effective in accelerating the rate of tooth movement during en-masse retraction without affecting significantly the canine rotation. Furthermore, the administration of PRP had no contribution to any of the dental, skeletal or soft tissue outcomes of the applied treatment mechanics.