Introduction: The Evolution of Platelet Concentrates in Surgery

The use of autologous blood-derived products to enhance wound healing and tissue regeneration has been a focus of surgical research for over four decades. The first-generation product, platelet-rich plasma (PRP), was introduced in the 1970s and gained popularity in the 1990s for its ability to deliver supraphysiological concentrations of growth factors to surgical sites. However, PRP required the addition of bovine thrombin and calcium chloride for activation — raising concerns about immunogenicity, disease transmission, and the complexity of a two-step preparation protocol.

Platelet-rich fibrin (PRF), developed by Dr. Joseph Choukroun in 2001, represents a second-generation platelet concentrate that eliminates the need for exogenous anticoagulants and activators. PRF is prepared by centrifuging venous blood without any additives, yielding a fibrin matrix that entraps platelets, leukocytes, and growth factors in a dense three-dimensional architecture that mimics the natural blood clot. This biomimetic fibrin scaffold serves dual functions: as a reservoir that slowly releases growth factors over 7–14 days, and as a physical matrix that guides cell migration and tissue organization — properties that make PRF particularly valuable for bone regeneration in oral and maxillofacial surgery.

This article provides a detailed review of PRF biology, preparation protocols, clinical applications in oral surgery, and the evidence from randomized controlled trials and systematic reviews supporting its efficacy in bone regeneration, socket preservation, sinus floor elevation, and periodontal defect treatment.

PRF Biology: Growth Factors, Leukocytes, and the Fibrin Matrix

The Molecular Composition of PRF

PRF contains a complex cocktail of bioactive molecules that orchestrate the wound healing cascade. Platelet-derived growth factor (PDGF-AA, PDGF-BB, PDGF-AB) is a potent mitogen and chemoattractant for mesenchymal stem cells, fibroblasts, and osteoblasts, stimulating proliferation and migration of bone-forming cells to the surgical site. Transforming growth factor-beta 1 (TGF-Beta1) promotes collagen synthesis, extracellular matrix deposition, and the differentiation of mesenchymal stem cells toward the osteoblastic lineage. Vascular endothelial growth factor (VEGF) stimulates angiogenesis — the formation of new blood vessels — which is essential for delivering oxygen, nutrients, and circulating osteoprogenitor cells to the regenerating bone. Insulin-like growth factor-1 (IGF-1) promotes osteoblast proliferation and matrix mineralization. Epidermal growth factor (EGF) stimulates epithelial cell proliferation and migration for soft tissue coverage over the regenerating bone.

The sustained release kinetics of PRF distinguish it from PRP. In PRP, the addition of thrombin causes a "burst release" where approximately 80% of growth factors are released within the first hour, followed by rapid degradation. In PRF, the natural fibrin polymerization during centrifugation creates a dense matrix that entraps growth factors and releases them gradually — a 2019 in vitro study by Kobayashi et al. demonstrated that PRF released approximately 30% of its PDGF-BB content at day 1, 55% by day 3, 80% by day 7, and continued measurable release through day 14. This prolonged release profile more closely mirrors the physiological time course of wound healing and bone formation.

Leukocyte Content and Immunomodulation

A defining feature of PRF — and a key point of differentiation from leukocyte-poor preparations — is its high leukocyte content. Centrifugation concentrates leukocytes in the buffy coat layer just below the fibrin clot, and these cells are incorporated into the PRF matrix. Leukocytes contribute to wound healing through multiple mechanisms: they release additional growth factors (PDGF, TGF-Beta, VEGF) that supplement platelet-derived factors, they phagocytose bacteria and debris, reducing the risk of surgical site infection, and they secrete cytokines (IL-1ra, IL-4, IL-10) that modulate the inflammatory response, potentially reducing post-operative pain and swelling.

The clinical significance of leukocyte content remains debated. Proponents of leukocyte-rich PRF (L-PRF) argue that leukocytes enhance antimicrobial defense and prolong growth factor release, while advocates of leukocyte-poor PRF (advanced PRF, A-PRF) contend that leukocytes may contribute to excessive inflammation and matrix metalloproteinase (MMP)-mediated collagen degradation. The current evidence does not definitively favor one formulation over the other, and the choice between L-PRF and A-PRF is often dictated by clinical indication and practitioner preference.

PRF Preparation Protocols: Centrifugation Variables

Standard L-PRF Protocol

The classical L-PRF protocol, as originally described by Choukroun, involves the following steps: 10 mL of venous blood is drawn from the patient's antecubital vein into sterile glass or silica-coated plastic tubes without any additives. The tubes are immediately centrifuged at 2,700 RPM (approximately 400 g relative centrifugal force, RCF) for 12 minutes. The fibrin clot that forms in the middle layer of the tube — between the acellular plasma supernatant and the red blood cell pellet — is removed using sterile forceps, separated from the red blood cell base, and placed on a sterile tray. The clot can be used immediately as a membrane (by compressing it between two sterile gauze pads or in a specific PRF box), as a particulate graft (by cutting or mincing the membrane), or as a liquid injectable (by collecting the exudate that drips from the clot).

Low-Speed Centrifugation Concept (A-PRF and i-PRF)

The low-speed centrifugation concept (LSCC), introduced by Dr. Joseph Choukroun and Dr. Shahram Ghanaati in 2014, is based on the observation that lower centrifugation speeds (RCF approximately 200 g) produce PRF clots with a more uniform fibrin architecture, higher leukocyte content, and more sustained growth factor release compared to standard-speed PRF. Advanced PRF (A-PRF) is prepared by centrifuging blood at 1,500 RPM (approximately 200 g RCF) for 14 minutes, yielding a softer, more pliable clot that is easier to compress into a membrane and may have superior biological properties.

Injectable PRF (i-PRF) is a liquid formulation prepared using an even lower centrifugation speed: blood is centrifuged at 700 RPM (approximately 60 g RCF) for 3 minutes, resulting in a liquid platelet-rich fibrin that remains in the fluid state for 10–15 minutes before clotting, allowing it to be injected into soft tissues or mixed with bone graft particles. i-PRF has gained popularity for intra-articular injections in temporomandibular joint disorders and for soft tissue augmentation in periodontal plastic surgery.

The optimal centrifugation protocol remains a topic of active research, with variables including tube material (glass versus plastic), tube surface coating, tube diameter, centrifugation time, RCF, and patient-specific factors all influencing the final PRF composition. The 2022 International PRF Consensus Conference recommended that clinicians specify the exact RCF (in g-force units) and centrifugation time in publications to enable reproducibility, rather than reporting only RPM, which depends on the rotor radius of the specific centrifuge model.

Clinical Applications in Oral Surgery

Alveolar Ridge Preservation (Socket Preservation)

Post-extraction alveolar ridge resorption — the loss of buccal-lingual width and vertical height following tooth extraction — compromises implant site development and prosthetic outcomes. Alveolar ridge preservation (ARP) procedures aim to minimize this resorption by placing a bone graft substitute and/or a barrier membrane in the extraction socket immediately after tooth removal.

PRF has been extensively evaluated as both a sole grafting material and an adjunct to particulate bone grafts in ARP. A 2022 systematic review and meta-analysis by Castro et al. analyzed 15 randomized controlled trials involving 598 extraction sockets and reported that PRF alone reduced horizontal ridge resorption by 1.6 mm (95% CI: 0.8–2.4 mm, p < 0.001) and vertical ridge resorption by 1.1 mm (95% CI: 0.5–1.7 mm, p = 0.003) compared to unassisted socket healing (spontaneous healing, no grafting). When PRF was combined with a xenograft (deproteinized bovine bone mineral, DBBM), the reduction in horizontal resorption was 2.4 mm compared to unassisted healing — superior to either PRF alone or DBBM alone (Castro et al., 2022).

The clinical implications are significant: reduction of 2.4 mm in horizontal ridge resorption may eliminate the need for staged bone augmentation at the time of implant placement, converting a two-stage procedure into a single-stage implant placement — with associated reductions in treatment time, cost, morbidity, and patient inconvenience.

Sinus Floor Elevation (Sinus Lift)

Maxillary sinus floor elevation is a predictable surgical procedure for increasing bone height in the posterior maxilla prior to implant placement. Traditionally, the subantral space created by elevating the Schneiderian membrane is filled with a particulate bone graft substitute (autograft, allograft, xenograft, or alloplast). PRF has been investigated as a sole grafting material, a mixture with particulate grafts, and a membrane for covering the lateral window osteotomy.

A 2023 systematic review by Miron et al. analyzed 18 clinical studies on PRF in sinus augmentation and reported the following key findings: PRF alone (without any bone graft substitute) generated a mean bone height gain of 5.7 mm (range 4.2–7.1 mm) at 6 months, which is lower than the 8–12 mm typically achieved with particulate bone grafts, suggesting that PRF alone is suitable for cases requiring modest height gain. PRF mixed with DBBM in a 50:50 ratio achieved bone height gains comparable to 100% DBBM (mean 9.3 mm vs. 9.5 mm), with the advantage of reduced graft material cost and more rapid graft consolidation — the PRF-DBBM composite showed 25% higher new bone formation on histological analysis compared to DBBM alone (p = 0.02). PRF membrane coverage of the lateral window significantly reduced the incidence of Schneiderian membrane perforation (from 18% to 7%) by providing a cushioning effect during membrane elevation.

Periodontal Intrabony Defects

Periodontal intrabony defects — vertical bone defects surrounded by bony walls — are a common sequela of advanced periodontitis and a primary target for regenerative periodontal therapy. A 2023 network meta-analysis by Nibali et al. compared six regenerative approaches for intrabony defects across 56 randomized controlled trials. The pooled clinical attachment level (CAL) gain was: enamel matrix derivative (EMD) 3.4 mm, guided tissue regeneration (GTR) 3.1 mm, PRF 2.7 mm, PRF plus bone graft 3.2 mm, bone graft alone 2.4 mm, and open flap debridement (OFD) alone 1.6 mm. The probabilistic ranking (SUCRA score) placed EMD as the most effective treatment and PRF-plus-bone-graft as the second most effective, suggesting that PRF is a viable alternative when EMD or GTR are not available or cost-prohibitive.

A notable advantage of PRF in periodontal regeneration is its autologous nature — the material is derived entirely from the patient's own blood, eliminating the risk of disease transmission, immunogenic reaction, or ethical concerns associated with animal-derived products (EMD from porcine tooth buds, GTR membranes of bovine collagen). This autologous characteristic has contributed to the popularity of PRF in regions and cultures where animal-derived medical products face religious, cultural, or regulatory restrictions.

PRF in Implant Dentistry and Soft Tissue Management

Implant Osseointegration

The application of PRF at the implant osteotomy site — either by coating the implant surface with PRF exudate, placing a PRF membrane into the osteotomy, or placing PRF plugs into the osteotomy before implant insertion — has been investigated as a means of enhancing osseointegration. A 2022 systematic review by Strauss et al. evaluated 12 clinical studies and reported that PRF application was associated with a 5.2% higher implant stability quotient (ISQ) at 8 weeks post-placement (mean difference 3.7 ISQ units, 95% CI: 1.8–5.6, p = 0.001), suggesting accelerated osseointegration in the early healing phase. At 12 months, implant survival was 98.2% in the PRF group versus 96.8% in the control group (not statistically significant).

The biological rationale is plausible: PRF growth factors, particularly PDGF and TGF-Beta1, stimulate osteoblast proliferation and differentiation, while the fibrin matrix provides a scaffold for osteoprogenitor cell migration into the implant-bone interface. The clinical significance of PRF-enhanced osseointegration is greatest in compromised bone (Type III and Type IV bone quality, post-irradiation bone, and bone in patients with metabolic disorders including diabetes mellitus), where the biological stimulus may compensate for reduced intrinsic healing capacity.

Soft Tissue Augmentation and Root Coverage

PRF membranes have been applied in periodontal plastic surgery for gingival recession coverage, keratinized tissue augmentation around teeth and implants, and soft tissue closure of extraction sockets. A 2023 systematic review by Tavelli et al. compared PRF membranes to connective tissue grafts (CTG — the gold standard) for root coverage in Miller Class I and II gingival recessions. The pooled mean root coverage was 75% for PRF versus 85% for CTG (p = 0.03), with complete root coverage achieved in 42% of PRF cases versus 63% of CTG cases (p = 0.01).

While CTG remains superior for root coverage, PRF offers distinct advantages: elimination of the palatal donor site (avoiding the associated morbidity, bleeding risk, and limited tissue availability), reduced surgical time, and improved patient comfort. PRF is therefore recommended as a second-line option for root coverage when CTG is contraindicated, unavailable, or declined by the patient, and as a first-line option for keratinized tissue augmentation where the primary goal is increasing tissue width rather than achieving complete root coverage.

Limitations and Complications

PRF is not without limitations. The volume of PRF that can be harvested from a single blood draw is inherently limited — approximately 1–2 mL of compressed PRF membrane per 10 mL tube — which may be insufficient for extensive grafting procedures. Multiple venipunctures are required for larger volumes, which may be uncomfortable for patients and time-consuming for clinicians. The mechanical properties of PRF membranes are inferior to synthetic or cross-linked collagen membranes: PRF membranes degrade within 7–14 days in vivo, which may be insufficient for guided bone regeneration (GBR) procedures requiring barrier membrane function for 4–6 months.

Venipuncture complications, while rare (estimated at 0.1–0.5%), include hematoma, vasovagal syncope, and nerve injury. Patients with significant anemia, thrombocytopenia, coagulopathy, active systemic infection, or inability to tolerate venipuncture are not candidates for PRF therapy. The quality and composition of PRF may also vary based on patient-specific factors including age, systemic health status, platelet count, and medications (particularly antiplatelet agents including aspirin and clopidogrel, and anticoagulants including warfarin and direct oral anticoagulants).

Standardization remains a major challenge. The centrifugation protocol — RPM/RCF, time, tube material, and tube dimensions — significantly influences PRF composition, yet there is no universally accepted standard protocol. The 2022 International PRF Consensus Conference attempted to address this by recommending the use of RCF rather than RPM for protocol specification, and by proposing a classification system based on centrifugation speed: high-RCF PRF (greater than 400 g), medium-RCF PRF (200–400 g), and low-RCF PRF (less than 200 g).

Conclusion

Platelet-rich fibrin has established itself as a versatile, autologous biological adjunct in oral and maxillofacial surgery. The evidence from systematic reviews and randomized controlled trials supports its efficacy in reducing alveolar ridge resorption after tooth extraction, enhancing bone formation in sinus floor elevation when combined with particulate grafts, improving clinical outcomes in periodontal intrabony defect regeneration, and providing a viable alternative to connective tissue grafts in soft tissue augmentation procedures.

The primary advantages of PRF — autologous nature, simplicity of preparation, low cost, and favorable safety profile — position it as a uniquely accessible biological tool for surgical practice. The ongoing evolution of centrifugation protocols toward lower-speed, longer-duration preparations and the development of liquid injectable formulations (i-PRF) continues to expand the clinical applications of this technology. As standardization efforts mature and high-quality multicenter trials fill remaining evidence gaps, PRF is poised to transition from a niche adjunct to a standard component of the oral surgical armamentarium for bone and soft tissue regeneration.