INTRODUCTION
Healing is a complex process that involves cellular organization, chemical signals, and the extra-cellular matrix for tissue repair. Platelets play a very important role in both tissue hemostasis and wound healing. Upon activation, platelets release various growth factors that stimulate cellular growth, proliferation, healing, and cellular differentiation.[1] Various bioactive surgical additives are developed to regulate the inflammation and increase the speed of healing process.[2]
One of the latest innovations in advanced surgical dentistry is the use of platelet concentrates for in vivo tissue engineering applications. Two types of such platelet concentrates are available: (1) platelet-rich plasma (PRP) and (2) platelet-rich fibrin (PRF). These are concentrated suspension of growth factors found in platelets that act as bioactive surgical additives when applied locally to induce wound healing.[3]
First introduced by Whitman et al.[4] in 1997, the use of PRP in oral surgical procedures proved to enhance cellular proliferation but also carried potential risk due to generation of antibodies against factors V, XI, and thrombin, leading to coagulopathies that may endanger life.[3]
PRP was developed by Dohan et al.[2] in 2001 and was classified as a second-generation platelet derivative. Unlike PRP, PRF strictly being an autologous fibrin matrix contains a large quantity of platelets and leukocytes with a simpler preparation technique that avoids artificial or exogenous biochemical modifications such as the use of anticoagulants or bovine thrombin or other jellifying agent.[5]
CLASSIFICATION OF PLATELET-RICH FIBRIN PRODUCTS
Dohan Ehrenfest et al.[6] classified PRF into two types according to the leukocyte content:
- Pure PRF or leukocyte-poor PRF
- Leukocyte-rich PRF (also called advanced PRF or Choukroun's PRF).
BIOLOGIC PECULIARITY OF PLATELET-RICH FIBRIN
PRF being a second-generation platelet concentrate enhances the healing process of tissue, thereby increasing predictability. The constituent elements of PRF include platelets, leukocytes, and fibrin matrix.[7] The biologic role of PRF in aiding the healing mechanism has been summarized in [Flowchart 1].
The various cytokines[8] that are involved in PRF are:
- Transforming growth factor-β
- Platelet-derived growth factor
- Vascular endothelial growth factor
- Insulin growth factor-1
- Fibroblast growth factor
- Epidermal growth factor.
PROTOCOLS FOR PLATELET-RICH FIBRIN PREPARATION
Though the classical method for preparation of PRF was given by Dr. Choukroun, the present technique for PRF preparation is legitimized by the French Health Ministry. Currently, PRF is prepared without any use of anticoagulant or bovine thrombin. A PRF with standard quality and quantity of the fibrin matrix, leukocytes, platelets, and growth factors demands a standard protocol for preparation. The armamentarium for preparation of PRF includes a PC-02 table centrifuge and a blood collection kit that contains in it a 24G butterfly needle and 9-ml blood collection tubes. The collected patient's blood sample in 10-ml tubes that is devoid of any anticoagulant is centrifuged immediately at a rate of 3000 rpm for 10 min.[9] The time lapse between blood collection and centrifugation is an important parameter deciding the success and clinical outcome of PRF. The centrifugation process causes blood to contact with the test tube wall, leading to activation of platelets and initiation of coagulation cascade. The resultant product after centrifugation process consists of three layers: the uppermost layer of acellular platelet-poor plasma, middle layer of PRF clot, and red blood cells (RBCs) at the bottom of the test tube. The fibrin clot that is formed is collected from the test tube and any remaining RBCs that are attached to it are discarded. Squeezing of the fluid out from the fibrin clot gives a PRF membrane.[6]
USES OF PLATELET-RICH FIBRIN IN ADVANCED SURGICAL DENTISTRY
Periodontal regeneration
Local application of growth factors promotes periodontal regeneration and healing. The use of PRF in the treatment of intrabony defects has shown significant clinical benefits. Yuchao et al.[10] showed that the use of PRF as the sole grafting material seems to be an effective modality of regenerative treatment for periodontal intrabony defects. PRF could serve as a resorbable membrane for guided bone regeneration, preventing the migration of nondesirable cells into bony defect and providing a space that allows the immigration of osteogenic and angiogenic cells, and permits the underlying blood clot to mineralize.[11] The concept of “natural bone regeneration” was proposed by Simonpieri et al.[12] which includes regeneration of gingival tissue and bone volume through PRF membrane.
Sinus lift
A sinus floor elevation is a technique to increase the residual bone height of the posterior edentulous maxilla. Boyne and James[13] in the 1980s performed sinus augmentation with autogenous bone grafts by the lateral window technique which was later developed by Tatum et al.[14] PRF can be used in sinus lift procedures in two ways, either as fragments mixed with different bone substitutes such as autogenous bone, graft, xenogeneic, allogeneic, and some artificial materials or as a sole filling material.[15]
Gingival recession
Coronally advanced flap procedure, with subepithelial connective tissue, is the most predictive plastic procedure. Recently, PRF has been used along with conventional order to improve the efficiency of the root coverage treatments and reduce the morbidity of the techniques.[16] According to Aroca et al.,[17] use of PRF membrane showed an increase in the width of keratinized gingiva at the test sites at 6 months compared to the modified coronally advanced flap alone.
Perio-endo lesions
Perio-endo lesions develop by either periodontal lesion spreading apically with an already existing periapical lesion or an endodontic lesion combining with an existing periodontal lesion. The prognosis of a true combined perio-endo lesion is often poor or even hopeless, especially if it is chronic in nature. The prognosis of such affected tooth can be improved by increasing the bony support through bone grafting and guided tissue regeneration and the application of polypeptide growth factors to the surgical wound.[18] El-Sharkawy et al.[19] suggested the administration of PRF along with tissue regeneration methods for the repair of intrabony defects, furcations, and periapical cystic cavities.
ADVANTAGES OF USING PLATELET-RICH FIBRIN
Literature reports the following advantages[20] related to the use of PRF:
- Simplified preparation and efficient technique
- Accelerates the healing rate of the grafted bone
- It is available through autologous blood sample
- Minimal blood manipulation
- It can be used solely or in combination with other grafts
- The natural fibrin framework with growth factors within imparts prolonged activity that stimulates tissue regeneration effectively
- It circumvents the addition of external thrombin as polymerization is a completely natural process, thus refraining from any risk of immunological reaction
- When used along with bony grafts, it is a quick as well as an economical alternative when compared with recombinant growth factors.
DISADVANTAGES OF USING PLATELET-RICH FIBRIN
PRF may present some disadvantages[20] as follows:
- Being autologous in nature, the final amount available is very less
- The blood collection time and its transference for the centrifuge greatly affects the success of PRF
- Clot polymerization requires the need of using a glass-coated tube
- It becomes very difficult to store PRF after preparation and it shrinks
- Dehydration causing shrinkage and alteration in structural integrity of PRF demands its immediate use after preparation
- Manipulation of PRF requires clinical experience.
OTHER CLINICAL APPLICATIONS
The literature reports some other possible applications of PRF such as:
- To enhance healing of the donor site post harvesting of free gingival graft
- For pulp revascularization and dentinogenesis of a necrotic tooth
- To preserve height of the alveolar ridge after extraction of multiple teeth
- After transalveolar extraction procedure
- As an adjuvant to healing of orofacial fractures
- For peri-implant bone regeneration
- Bone reconstruction of large surgical defects after oral cancer therapy
- To fill the defects created after removal of cystic pathologies
- As an additive to promote healing after ablative surgical treatment of oral mucosal lesions
- For tissue volumerization
- Autologous fat transfer procedures
- For the treatment of articular cartilaginous defects of temporomandibular joint
- Mineralized PRF can be used for bone replacement procedures
- In localized osteitis.
CONCLUSION
Various experimental as well as clinical results favor the use of PRF alone or along with other biomaterials, without any conflicting findings. It shows promising outcome both in medical as well as dental fields with several advantages and many indications. However, some of the aspects of its uses, especially in dentistry, should be explored more with more clinical uses, especially after ablative surgery for the treatment of large oral cancers. In the current scenario, PRF seems to be a minimally invasive technique that comes with low risk factors and clinically satisfactory results.
Financial support and sponsorship
Nil.
Conflicts of interest
There are no conflicts of interest.
REFERENCES
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