Platelet-rich fibrin (PRF): a second-generation platelet concentrate. Part IV: clinical effects on tissue healing

Platelet-rich fibrin membranes as scaffolds for periosteal tissue engineering

OBJECTIVES

Platelet-rich fibrin (PRF)-based membranes have been used for covering alveolar ridge augmentation side in several in vivo studies. Few in vitro studies on PRF and no studies using human periosteal cells for tissue engineering have been published. The aim is a comparison of PRF with the commonly used collagen membrane Bio-Gide as scaffolds for periosteal tissue engineering.

MATERIAL AND METHODS

Human periosteal cells were seeded on membrane pieces (collagen [Bio-Gide] and PRF) at a density of 10(4) cells/well. Cell vitality was assessed by fluorescein diacetate (FDA) and propidium iodide (PI) staining, biocompatibility with the lactate dehydrogenase (LDH) test and proliferation level with the MTT, WST and BrdU tests and scanning electron microscopy (SEM).

RESULTS

PRF membranes showed slightly inferior biocompatibility, as shown by the LDH test. The metabolic activity measured by the MTT and WST tests was higher for PRF than for collagen (BioGide). The proliferation level as measured by the BrdU test (quantitative) and SEM examinations (qualitative) revealed higher values for PRF.

CONCLUSION

PRF appears to be superior to collagen (Bio-Gide) as a scaffold for human periosteal cell proliferation. PRF membranes are suitable for in vitro cultivation of periosteal cells for bone tissue engineering.

[The use of platelet-rich fibrin membrane in gingival recession treatment]

INTRODUCTION

Fibrin, fibronectin, platelet derived growth factor, and transforming growth factors from platelet concetrate are crucial for tissue reparation and regeneration.

OBJECTIVE

This study was designed to evaluate clinical effectiveness of activated platelet-rich fibrin (PRF) membrane in treatment of gingival recession.

METHODS

19 gingival recessions Miller class I or II were treated with a coronally advanced flap and the PRF membrane (PRF group). Following the elevation of the flap, bone and root surfaces were covered with the PRF membrane. After suturing, the PRF membrane was covered with a coronally advanced flap. In the same patients, 19 other gingival recessions were treated with CTG in combination with the coronally advanced flap (the CTG group). Clinical recordings were made of vertical recession depth (VRD), probing depth (PD), clinical attachment level (CAL) and keratinized tissue width (KTW) before and 12 months after mucogingival surgical treatment. Clinical evaluation of healing events was estimated with recordings of the healing index (HI). Recordings of HI were performed in the 1st, 2nd and 3rd week post-surgically.

RESULTS

Mean root coverage was significant in both groups (the PRF group 79.94% and the CTG group 88.56% %; p < 0.01). The difference between the two tested groups was not statistically significant. Results of the keratinized tissue width showed significant increase (p < 0.05) 12 months after the surgery in both, the PRF and CTG groups. Results of KTW showed statistical significance of recorded differences obtained in the two evaluated groups (p < 0.05). There was no statistical significance in reduction of PD and CAL recorded in the PRF and CTG groups. The values of HI recorded in the 1st and 2nd week postoperatively were significantly enhanced in the PRF group (p < 0.05).

CONCLUSION

Results of this study confirm both procedures as effective with equivalence of clinical results in solving gingival recession problems. The utilization of the PRF resulted in a decreased postoperative discomfort and advanced tissue healing.

Sinus floor augmentation with simultaneous implant placement using Choukroun's platelet-rich fibrin as the sole grafting material: a radiologic and histologic study at 6 months

BACKGROUND

Sinus augmentation with simultaneous implant placement without bone graft material is a hotly debated technique. This technique could be improved and secured by the use of an autologous leukocyte- and platelet-rich fibrin (PRF) (Choukroun's technique) concentrate. The objectives of this study were to assess the relevance of PRF clots and membranes as the sole filling material during a lateral sinus lift with immediate implantation using radiologic and histologic analyses in a case series.

METHODS

Twenty-five sinus elevations with simultaneous implantation were performed on 20 patients with Choukroun's PRF as the sole filling biomaterial. For each patient, a presurgical exam and a 6-month post-surgical radiologic exam were performed with a panoramic x-ray and three-dimensional volumetric computed radiography (VCR) to evaluate the subsinus residual bone height and the final bone gain around the implants. In nine patients, 6 months after the sinus lift, bone biopsies were collected on the buccal wall of the alveolar ridge at the level of the osteotomy window, and evaluated by histomorphometry.

RESULTS

In this study, 41 implants from three different systems with different screw designs (Biomet 3I Nanotite, MIS Seven, Intra-Lock Ossean) were placed. All implants were inserted in residual bone height between 1.5 and 6 mm (mean +/- SD: 2.9 +/- 0.9 mm). The final bone gain was always very significant (between 7 and 13 mm [mean +/- SD: 10.1 +/- 0.9 mm]). No implant was lost. After radiologic analyses, the position of the final sinus floor was always in the continuation of the end of the implant. All biopsies showed well organized and vital bone.

CONCLUSIONS

From a radiologic and histologic point of view at 6 months after surgery, the use of PRF as the sole filling material during a simultaneous sinus lift and implantation stabilized a high volume of natural regenerated bone in the subsinus cavity up to the tip of the implants. Choukroun's PRF is a simple and inexpensive biomaterial, and its systematic use during a sinus lift seems a relevant option, particularly for the protection of the Schneiderian membrane.

Choukroun's platelet-rich fibrin (PRF) stimulates in vitro proliferation and differentiation of human oral bone mesenchymal stem cell in a dose-dependent way

BACKGROUND

Choukroun's platelet-rich fibrin (PRF) is an autologous leukocyte- and platelet-rich fibrin biomaterial. The purpose of this study was to analyse the in vitro effects of PRF on human bone mesenchymal stem cells (BMSC), harvested in the oral cavity after preimplant endosteal stimulation.

MATERIALS AND METHODS

BMSCs from primary cultures were cultivated with or without a PRF membrane originating from the same donor as for the cells, in proliferation or osteoblastic differentiation conditions. After 7 days, the PRF membranes were removed. A series of cultures were performed using 2 PRF membranes, in order to measure the dose-dependent effect. Cell counts, cytotoxicity tests, alkaline phosphatase (ALP) activity quantification, Von Kossa staining and mineralisation nodules counts were performed at 3, 7, 14, 21 and 28 days. A last independent series was carried on up to 14 days, for a morphological scanning electron microscope (SEM) observation.

RESULTS

PRF generated a significant stimulation of the BMSC proliferation and differentiation throughout the experimental period. This effect was dose-dependent during the first weeks in normal conditions, and during the whole experimentation in differentiation conditions. The cultures without PRF in differentiation conditions did not rise above the degree of differentiation of the cultures in normal conditions with 1 or 2 PRF up to the 14th and 28th day, respectively. The SEM culture analysis at day 14 allowed to show the mineralisation nodules which were more numerous and more structured in the groups with PRF compared to the control groups.

DISCUSSION AND CONCLUSIONS

This double contradictory proliferation/differentiation result may be due to the numerous components of PRF, particularly the presence of leukocytes: any culture with PRF is in fact a coculture with leukocytes. It could be the source of differential geographic regulation processes within the culture. The combination of oral BMSC and PRF might offer many potential clinical and biotechnological applications, and deserves new studies.

Scintigraphic evaluation of osteoblastic activity in extraction sockets treated with platelet-rich fibrin

PURPOSE

To evaluate the effect of platelet-rich fibrin (PRF) on the early bone healing process with bone scintigraphy based on technetium-99m methylene diphosphonate uptake in third molar extraction sockets.

PATIENTS AND METHODS

Fourteen patients with bilaterally soft tissue impacted third mandibular molars were included in the study. The right and left impacted third molars were surgically extracted in the same session. PRF was randomly administered into one of the extraction sockets, whereas the contralateral sockets were left without treatment. Four weeks after surgery, scintigrams were obtained to evaluate scintigraphic differences between PRF-treated and non-PRF-treated sockets. After completion of the clinical study, PRF samples were evaluated by light and scanning electron microscopy.

RESULTS

The average increase in technetium-99m methylene diphosphonate uptake as an indication of enhanced bone healing did not differ significantly between PRF-treated and non-PRF-treated sockets 4 weeks postoperatively (P > .05). Abundant fibrin and inflammatory cells were observed by light microscopic examination of PRF samples. Scanning electron microscopic analysis of PRF revealed the existence of platelet aggregates in a fibrin network and crystalline particles on the outer surface of PRF.

CONCLUSIONS

PRF might not lead to enhanced bone healing in soft tissue impacted mandibular third molar extraction sockets 4 weeks after surgery. PRF exhibits the potential characteristics of an autologous fibrin matrix. However, whether the presence of crystal-like particles on the outer surface of PRF alters bone healing should be investigated further.

The relevance of Choukroun's platelet-rich fibrin and metronidazole during complex maxillary rehabilitations using bone allograft. Part II: implant surgery, prosthodontics, and survival

Extensive bone grafting remains a delicate procedure, due to the slow and difficult integration of the grafted material into the physiological architecture. The recent use of platelet concentrates aims to improve this process of integration by accelerating bone and mucosal healing. Choukroun's platelet-rich fibrin (PRF) is a healing biomaterial that concentrates in a single autologous fibrin membrane, most platelets, leukocytes, and cytokines from a 10-mL blood harvest, without artificial biochemical modification (no anticoagulant, no bovine thrombin). In this second part, we describe the implant and prosthetic phases of a complex maxillary rehabilitation, after preimplant bone grafting using allograft, Choukroun's PRF membranes, and metronidazole. Twenty patients were treated using this new technique and followed up during 2.1 years (1-5 years). Finally, 184 dental implants were placed, including 54 classical screw implants (3I, Palm Beach Gardens, FL) and 130 implants with microthreaded collar (46 from AstraTech, Mölndal, Sweden; 84 from Intra-Lock, Boca Raton, FL). No implant or graft was lost in this case series, confirming the validity of this reconstructive protocol. However, the number of implants used per maxillary rehabilitation was always higher with simple screw implants than with microthreaded implants, the latter presenting a stronger initial implant stability. Finally, during complex implant rehabilitations, PRF membranes are particularly helpful for periosteum healing and maturation. The thick peri-implant gingiva is related to several healing phases on a PRF membrane layer and could explain the low marginal bone loss observed in this series. Microthreaded collar and platform-switching concept even improved this result. Multiple healing on PRF membranes seems a new opportunity to improve the final esthetic result.

The relevance of Choukroun's platelet-rich fibrin and metronidazole during complex maxillary rehabilitations using bone allograft. Part I: a new grafting protocol

Extensive bone grafting remains a delicate procedure, because of the slow and difficult integration of the grafted material into the physiological architecture. The recent use of platelet concentrates aims to improve this process of integration by accelerating bone and mucosal healing. Choukroun's platelet-rich fibrin (PRF) is a healing biomaterial that concentrates in a single autologous fibrin membrane, most platelets, leukocytes, and cytokines from a 10 mL blood harvest, without artificial biochemical modification (no anticoagulant, no bovine thrombin). Whether used as a membrane or as fragments, PRF allows a significant postoperative protection of the surgical site and seems to accelerate the integration and remodeling of the grafted biomaterial. These properties are particularly helpful for vestibular bone grafting on the alveolar ridges. Moreover, it provides a very high quality of gingival maturation.A small quantity of a 0.5% metronidazole solution (10 mg) can also be used to provide an efficient protection of the bone graft against unavoidable anaerobic bacterial contamination. This article describes a new technique of total maxillary preimplant bone grafting using allograft, Choukroun's PRF membranes and metronidazole. This first part focused on the preimplant reconstructive treatment using allogeneic bone granules. PRF membranes are particularly helpful to protect the surgical site and foster soft tissue healing. This fibrin biomaterial represents a new opportunity to improve both the maturation of bone grafts and the final esthetic result of the peri-implant soft tissue.

In vitro effects of Choukroun's PRF (platelet-rich fibrin) on human gingival fibroblasts, dermal prekeratinocytes, preadipocytes, and maxillofacial osteoblasts in primary cultures

OBJECTIVES

The objective of this study was to analyze the effects of Choukroun's PRF (platelet-rich fibrin), a leucocyte and platelet concentrate clinically usable as fibrin membrane or clot, on human primary cultures of gingival fibroblasts, dermal prekeratinocytes, preadipocytes, and maxillofacial osteoblasts.

STUDY DESIGN

For the proliferation study, these cells were cultivated with or without a PRF membrane originating from the same donor as for the cells. For osteoblasts and fibroblasts, dose-dependent effect was assessed (using 2 membranes). Cell counts and cytotoxicity tests were performed at 3, 7, 14, and 21 days, and even 28 days for osteoblasts. More osteoblast cultures were prepared in differentiation conditions according to 3 modalities (without PRF, with PRF, with PRF the first day and differentiation medium applied only after the first week of culture). Osteoblast differentiation was analyzed using Von Kossa staining and alkaline phosphatase, DNA and total cell proteins dosage.

RESULTS

PRF induced a significant and continuous stimulation of proliferation in all cell types. It was dose dependent during all the experiment with osteoblasts, but only on day 14 with fibroblasts. Moreover, PRF induced a strong differentiation in the osteoblasts, whatever the culture conditions. The analysis of osteoblast cultures in differentiation conditions with PRF, using light and scanning electron microscopy, revealed a starting mineralization process in the PRF membrane itself after 14 days. Moreover, PRF leucocytes seemed to proliferate and interact with osteoblasts.

CONCLUSIONS

Cultures with PRF are always cocultures with leucocytes. These "chaperone leucocytes" could be the source of differential geographic regulation within the culture and explain the double contradictory effect proliferation/differentiation observed on osteoblasts.

Clinical evaluation of a modified coronally advanced flap alone or in combination with a platelet-rich fibrin membrane for the treatment of adjacent multiple gingival recessions: a 6-month study

BACKGROUND

The aim of this study was to determine whether the addition of an autologous platelet-rich fibrin clot (PRF) to a modified coronally advanced flap (MCAF) (test group) would improve the clinical outcome compared to an MCAF alone (control group) for the treatment of multiple gingival recessions.

METHODS

Twenty subjects, presenting three adjacent Miller Class I or II multiple gingival recessions of similar extent on both sides of the mouth, were enrolled in the study. The mean recession value at baseline was 2.9 +/- 1.1 mm for test sites and 2.5 +/- 0.9 mm for control sites. Each patient was treated on both sides by an MCAF technique; the combination treatment (with a PRF membrane) was applied on the test side. Probing depth (PD), recession width, clinical attachment level (CAL), keratinized gingival width, and gingival/mucosal thickness (GTH) were measured at baseline and at 6 months post-surgery. Gingival recession was measured at baseline and at 1, 3, and 6 months post-surgery.

RESULTS

Mean root coverage after 1, 3, and 6 months was 81.0% +/- 16.6%, 76.1% +/- 17.7%, and 80.7% +/- 14.7%, respectively, at the test sites and 86.7% +/- 16.6%, 88.2% +/- 16.9%, and 91.5% +/- 11.4%, respectively, at the control sites. Differences between the two groups were statistically significant at 3 and 6 months. At 6 months, complete root coverage was obtained at 74.6% of the sites treated with the control procedure but at only 52.2% of the experimental sites. At 6 months, the increase in GTH was statistically significant when comparing the test sites (from 1.1 +/- 0.3 mm at baseline to 1.4 +/- 0.5 mm at 6 months) to the control sites (from 1.1 +/- 0.3 mm at baseline to 1.1 +/- 0.3 mm at 6 months). In the case of PD, there was no significant difference between the two groups at 6 months, but a significant CAL gain in favor of the control group was observed at that time.

CONCLUSIONS

MCAF is a predictable treatment for multiple adjacent Miller Class I or II recession-type defects. The addition of a PRF membrane positioned under the MCAF provided inferior root coverage but an additional gain in GTH at 6 months compared to conventional therapy.

Slow release of growth factors and thrombospondin-1 in Choukroun's platelet-rich fibrin (PRF): a gold standard to achieve for all surgical platelet concentrates technologies

Platelet concentrates for surgical topical applications are nowadays often used, but quantification of the long-term growth factor release from these preparations in most cases is impossible. Indeed, in most protocols, platelets are massively activated and there is no significant fibrin matrix to support growth factor release and cell migration. Choukroun's platelet-rich fibrin (PRF), a second generation platelet concentrate, is a leucocyte- and platelet-rich fibrin biomaterial. Here, we show that this dense fibrin membrane releases high quantities of three main growth factors (Transforming Growth Factor b-1 (TGFbeta-1), platelet derived growth factor AB, PDGF-AB; vascular endothelial growth factor, VEGF) and an important coagulation matricellular glycoprotein (thrombospondin-1, TSP-1) during 7 days. Moreover, the comparison between the final released amounts and the initial content of the membrane (after forcible extraction) allows us to consider that the leucocytes trapped in the fibrin matrix continue to produce high quantities of TGFbeta-1 and VEGF during the whole experimental time.

Osteotome sinus floor elevation using Choukroun's platelet-rich fibrin as grafting material: a 1-year prospective pilot study with microthreaded implants

OBJECTIVES

The aim of this prospective study was to document, radiographically, changes in the apical bone levels on microthreaded implants placed in subsinus residual bone height, according to a bone-added osteotome sinus floor elevation technique with platelet-rich fibrin (PRF) as grafting material.

STUDY DESIGN

Implants were placed using PRF as grafting material in the bone-added osteotome sinus floor elevation (BAOSFE) technique. The survival rate at abutment tightening (6 to 12 weeks of healing) and at 1 year was calculated. The radiographic analysis determined on consecutive radiographs: 1) the mean residual bone height (RBH) under the maxillary sinus at implant placement; and 2) the change in endosinus bone level. Mean and standard deviation were used to assess the endosinus bone changes in the mesial and distal implant sides at 1 year.

RESULTS

Between December 2004 and June 2005, 20 consecutive patients were included in the study after bone height measurement by periapical radiographs. Patients included 14 women (70%) and 6 men (30%) with a mean age of 54.8 +/- 11.1 years, range 35 to 73 years; they were treated with 35 Astra Tech implants (Astra Tech Dental Implant System; Astra Tech, Mölndal, Sweden) fulfilling the inclusion criteria. The mean healing time before abutment tightening was 8.3 +/- 1.4 weeks (range 6-12 weeks); by this time, 1 implant was mobile and was removed. At 1 year, all implants were clinically stable and the definitive prostheses were in function, resulting in a survival rate of 97.1%. Nineteen implants (55%) were 11 mm long, 6 implants (17%) were 9 mm, 5 implants (14%) were 8 mm, and 5 implants (14%) were 13 mm. The RBH was measured after implant placement on the radiographs on both implant sides. The mean RBH was 6.5 +/- 1.7 mm: 6.3 +/- 1.3 on the mesial side and 6.7 +/- 2.0 mm on the distal side. Measurements of the changes in the endosinus level on the mesial and distal sides showed that all implants gained endosinus bone. The mean endosinus gain was 3.2 +/- 1.5 mm: 3.5 +/- 1.4 mm on the mesial side and 2.9 +/- 1.6 mm on the distal side. The lowest bone gain was 0.9 mm and 0.1 mm on the mesial and distal sides, respectively. The highest gain was 5.8 mm and 5.2 mm on the mesial and distal sides, respectively.

CONCLUSIONS

The BAOSFE procedure with PRF as grafting material can lead to an endosinus bone gain. Despite a limited RBH, a healing period of 2-3 months was found to be sufficient to resist a torque of 25 N.cm applied during abutment tightening. At 1 year, formation of a new recognizable bone structure delimiting the sinus floor was identified radiologically and led to a predictable implant function.