Effects of Local Application of Platelet Rich Fibrin on Postoperative Sequelae after Surgical Removal of Impacted Lower Third Molars

Aims: The goals of this research was to evaluate the effects of Platelet Rich Fibrin (PRF) in reducing postsurgical complications as pain, swelling, and trismus after surgical extraction of impacted lower third molars. Materials and Methods: A total of 44 patients who fulfilled the inclusion criteria were chosen to take part in this research. Postoperative pain was assessed using a numerical rating scale (NRS). Facial swelling was measured by a modification of tape measure method. To assess trismus, the maximal interincisal mouth opening was measured by using a digital caliper scale (electronic vernier). Results: In the Platelet Rich Fibrin PRF group; the results showed a significant difference of levels of pain experienced (NRS) in the 1 st postoperative day in comparison to the control group. In regard to post-operative swelling; a significant decrease in the 3 rd postoperative day was observed in comparison to the control group. With regard to trismus; no significant differences between groups regarding interincisal mouth opening was noticed. Conclusions: The application of PRF reduces the severity of the immediate postoperative sequelaes.


INTRODUCTION
Platelet rich fibrin (PRF) clots, were developed by Choukroun et al. (6) . Platelet rich fibrin consists of a polymerized fibrin matrix in a trimolecular system containing platelets, leukocyte, cytokines, and circulating stem cells (7) . Such a complex makes PRF a curative biomaterial that favors soft tissue and bone regeneration (8) . Several studies have shown that PRF has facilitated the healing of wounds such as following the removal of cysts, sinus augmentations and periodontal defects (6,9,10) .
The goal of this clinical trial was to investigate whether there is any beneficial value of local application of platelet rich fibrin clot on the postoperative swelling, pain, and trismus.

Patient selection:
The study was a randomized, blinded, 3-Pregnant and lactating women.

Marouf IS., Rejab AF
4-Patients that fulfilled the demands, but at surgery the procedure take more than one hour time.

Study design
In order to minimize differences, all patients were operated by the same oral surgeon with a standardized surgical technique and equipment. Patients were divided randomly into 2 groups: study group and control group.
In the study group (22 patients) platelet rich fibrin clot applied into the socket, and in the control group (22 patients) nothing was applied into the socket.

Preparation of PRF
Prior to giving anesthesia, 2 tubes of ten ml  The tubes were placed in a tube rack, allowing the formed clot to mature for approximately 4-8 minutes (11) . The middle layer (PRF clot) was removed using sterile tweezers and separated by scissors from the underlying red corpuscular base, as shown in Figure (

Marouf IS., Rejab AF
Five different measurements were recorded. All measurements were taken before operation and on the 1 st , 3 rd , and 7 th days after operation (13) , as shown in Figure (4).

Statistical analysis
Statistical analysis was carried out using Social    (7) . PRF acts as a scaffold that is able to guide epithelial cell migration and in carrying cells involved in tissue regeneration (17,18) .
An essential coagulation glycoprotein called (thrombospondin-1) and three main growth factors involving vascular endothelial growth factor (VEGF), transforming growth factor β-1, platelet-derived growth factor (PDGF) are released from PRF for 1 week duration after application (19) . In addition to these, PRF also secrete other types of factors of growth including epidermal growth factor, fibroblast growth factor, and three substantial proinflammatory cytokines-IL-1b, IL-6, and TNF-α which is obtained with a simple centrifugation procedure. These constituents make PRF a curative biomaterial that enables optimal healing through the fast and effective regeneration of hard and soft tissues (6,19,20) .
Contrasting results regarding the clinical efficacies of PRF in oral surgical procedures have been reported in different clinical procedures (8,(21)(22)(23) .
The purpose of the current study was to On the contrary, Ozgul et al. (26) conducted a study to assess the efficacy of PRF in the healing process by assessing changes in pain and swelling following third molar al. (19) placed PRF in extraction sockets following extraction and concluded that despite pain was less in the study side compared to control side, yet there was no statistical significance.
Most of the surgical procedures induce odema. Swelling usually reaches its maximum at 1-2 days after the surgery; it begins to subside on the third or fourth day and usually ends on the first week (27) . In this study, swelling was significant at the 3 rd postoperative day only. Ozgul et al. (26) study results indicated that PRF was more effective in reducing swelling in the third day after surgery. Kumar et al. (20) also reported that use of PRF in extraction socket resulted in reduction of odema after 1 st postoperative day.
In contrast to this, Bilginylar et al. (28) found no differences in swelling between PRF and control groups. They attributed that for using a tape measure for measuring variations in swelling. In support to this, Ogundipe et al. (29) used PRP gel after extraction of third molar and noticed that PRP reduced pain, swelling, and trismus compared to control group but the differences were statistically significant only for postoperative pain and was not significant for postoperative swelling.

CONCLUSIONS
PRF appears to be effective in reducing postoperative swelling and pain following third molar removal. However, the effects were significant for few postoperative days.