Choukroun's Platelet-rich Fibrin Research Articles

Template for Diced Cartilage with Platelet-Rich Fibrin (PRF) in Rhinoplasty: An Easy Solution for Millimetric Camouflage of the Full Dorsal Esthetic Unit.

Dorsal irregularities are one of the most common issues in modern rhinoplasty. Rhinoplasty surgeons propose placing interface grafts lining the hole dorsum to ensure a natural unoperated look. Diced cartilage embedded in Choukroun's platelet-rich fibrin (PRF) scaffold being one of the most recent innovations in the field. However, no method has been described to help with the creation of thin, malleable, and reproductive graft with millimetric precision using that technique. The senior author details his protocol and his experience with a newly developed template for the creation of reproductive grafts with standard size and thickness, using diced cartilage, injectable PRF (iPRF), and advanced PRF (aPRF), for full dorsal camouflage and lining in rhinoplasty. This retrospective case series was conducted to evaluate the results looking at the dorsal esthetic unit at a minimum of 6 months for patients who beneficiated from a millimetric dorsal augmentation from 1 to 2mm using diced cartilage with iPRF and aPRF. The author reports his experience with 54 cases operated from April 2018 to May 2022 using his newly developed template.The template is an innovative technique to allow faster and more reliable fabrication of soft grafts using diced cartilage with both iPRF and aPRF. This novel approach allows for millimetric dorsal augmentation from 1 to 2mm with great precision and high reproductivity with good esthetic outcome.

WOUND MANAGEMENT WITH AND WITHOUT MODIFIED CHOUKROUN'S PLATELET-RICH FIBRIN IN RESCUED FORMOSAN PANGOLINS (MANIS PENTADACTYLA PENTADACTYLA).

Trauma is a key threat to wild Formosan pangolins (Manis pentadactyla pentadactyla) and the most frequent reason for presentation to the rescue center of the Taipei Zoo from 2008 to 2017. Of the 105 cases received during this time, 72% presented for trauma. Among these 76 cases, 72% survived and were returned to the wild. Traditional wound management resulted in healing times from 45 to 410 d. Improvements in the success and duration of wound healing could increase the success rate of pangolin release back to the wild. This case series describes wound management in five cases using either traditional wound management practices (two cases) or modified Choukroun's platelet-rich fibrin (MC-PRF) in an attempt to accelerate the wound-healing process (three cases). MC-PRF is relatively easily obtainable and widely used to promote tissue healing in other species. MC-PRF was applied to the wounds of three pangolins every 1 to 2 wk with satisfactory results. The healing time with MC-PRF were 21, 45, and 51 d, shorter than the 60-98 d seen in the cases of traditional wound management in this series. Given the scarcity of literature on pangolins, these cases evaluating both traditional and MC-PRF wound management practices can serve as examples for other pangolin rescue centers in their treatment of traumatic wounds.

Clinical Management of an Intranasal Abscess in a Captive Elongate Tortoise (Indotestudo elongata) by Using Modified Choukroun's Platelet-Rich Fibrin

An adult male elongate tortoise (Indotestudo elongata) was presented to the Animal Medical Center of Taipei Zoo with an abscess on the tip of its nose. After 43 days of daily debridement and systemic antibiotic administration, we sought an alternative treatment modality due to poor wound management. We developed a novel treatment using platelet-rich fibrin (PRF). There are few studies documenting the benefits of PRF for the management of wounds in reptiles. Most published protocols require the use of specific anticoagulants and methods to prepare PRF; however, we found that a modified Choukroun's PRF was relatively easy to prepare and use for wound treatment of an elongate tortoise. Here, we describe a successful outcome of a chronic, nonresolving facial wound after treatment with modified Choukroun's PRF. To our knowledge, this is the first report of a Choukroun's PRF preparation derived from reptilian blood. We recommend further studies and detailed trials to evaluate the efficacy of this protocol in reptiles.

Microscopic evaluation of the effect of low-level laser therapy on platelet-rich fibrin: A light microscopic histological study

Background: This study evaluated and compared the concentration of platelets/leukocytes, fibrin matrix, and its distribution in nonlaser-treated platelet-rich fibrin (PRF) and laser-treated PRF. Recently, PRF has been used for regeneration of soft and hard tissue, in periodontics and oral surgery. Low-level laser therapy (LLLT) has been used for many therapeutic purpose of tissue healing. The use of PRF treated with LLLT has shown to enhance better healing potential. Materials and Methods: In this study, we have selected five healthy controls and collected 10 ml of blood from them. All blood samples were centrifuged, and from each blood sample, two PRF clots were formed. A total of ten samples obtained were divided into two groups. Each group had five samples. One group was without LLL treatment (Group I) and other was treated with LLL (Group II). All the ten samples were processed for light microscopic examination. Results: In both the groups, the PRF membrane showed a similar macroscopic structure and microscopic distribution. In the buffy coat region, the concentration of platelets–leukocyte aggregate was little higher in Group I. In Group II, the distribution pattern of fibrin clot was slightly different with that of Group I. Conclusion: The Choukroun's PRF concept leads to specific clot architecture with platelets and fibrin meshwork, especially in the buffy coat region. Changes in the PRF components with LLLT may have an affect the healing and regenerative of soft and hard tissues.

Effect of Choukroun Platelet-Rich Fibrin Combined With Autologous Micro-Morselized Bone on the Repair of Mandibular Defects in Rabbits

The aim of this study was to explore the effect of Choukroun platelet-rich fibrin (PRF) combined with autologous micro-morselized bone on the repair of mandibular defects in rabbits. Thirty-six healthy New Zealand rabbits were selected for the present study. After models of mandibular defects were established, rabbits were randomly divided into Choukroun PRF, autologous micro-morselized bone (autologous), Choukroun PRF combined with autologous bone (combined) and model groups. After the rabbits were sacrificed at 2, 8, and 12weeks postoperatively, their bone formation was assessed by x-ray and scanning electron microscopy, and the histologic changes of the mandibular defect area were detected by hematoxylin and eosin staining. Cone-beam computed tomography was used to observe the size of the change of the mandibular defect area. Bone mineral density (BMD) was analyzed by dual-energy x-ray absorptiometry. The bone defect in the combined group showed better repair, increased bone mineral content, and denser callus than the other groups, and the defect area was filled with mature trabecular bone. In the Choukroun PRF and autologous groups, the defect area was smaller and filled with osteoporotic trabecular bone. A clear mandibular defect area was still observed in the model group. Compared with the other groups, the combined group showed more bone regeneration, more fibrous tissue regeneration, and greater bone maturity at all time points. The combined group had the highest BMD, there was no relevant difference in BMD between the Choukroun PRF and autologous groups, and the model group had the lowest BMD. BMD in all 4 groups increased with time. These findings indicate that Choukroun PRF combined with autologous micro-morselized bone can substantially improve the repair of mandibular defects in rabbits, and the effect is superior to Choukroun PRF or autologous micro-morselized bone alone.

Comparative Evaluation of the Efficacy of Bioactive Ceramic Composite Granules Alone and in Combination with Platelet Rich Fibrin in the Treatment of Mandibular Class II Furcation Defects: A Clinical and Radiographic Study.

Predictable closure of furcation defects with bone grafts, Guided Tissue Regeneration (GTR) and a combination of the two has remained an elusive goal so far. Hence, evaluation of biomimetic agents as candidate technologies for periodontal regeneration merit due consideration. In this study, Choukroun's Platelet Rich Fibrin (PRF), a second generation platelet concentrate, is combined with bone graft to examine if the addition enhances the therapeutic potential of bone graft in the management of Class II furcation defects. To evaluate and compare the clinical effectiveness of Bioactive Ceramic Composite Granules (BCCG) alone and in combination with PRF in the treatment of mandibular Class II furcation defects. Twenty mandibular Class II furcation defects in 16 systemically healthy patients were randomly allocated to test and control groups. Test sites were treated with PRF and bone graft, while control sites were treated with BCCG alone. Soft tissue parameters (probing pocket depth and clinical attachment loss), hard tissue parameters (vertical and horizontal depth of furcation defects) and radiographic parameter (radiographic alveolar bone density) were measured at baseline and six months post surgery. Statistical analysis was performed using Wilcoxon signed rank test for intragroup comparison of parameters and Mann-Whitney U test for intergroup comparison. Statistically significant improvement was observed in the test group compared to the control group with respect to all the measured parameters. However, complete furcation closure was not observed at any of the treated sites. Adjunctive use of PRF with bone graft may be a more effective treatment modality in the management of mandibular Class II furcation defects when compared to bone graft alone.

Comparison of Ability of Platelet-rich Fibrin vs CollaPlug in maintaining the Buccal Bone Height of Sockets following Extractions in 20 Patients

ABSTRACT Introduction The preservation of bone volume immediately after tooth removal is necessary to optimize the success of implant placement in terms of esthetics and function. The objectives of this study were to compare the ability of Choukroun's platelet-rich fibrin (PRF) versus CollaPlug (Zimmer) in maintaining the buccal bone height of sockets following extractions in patients. Materials and methods Twenty patients who required tooth extraction and implant placement were enrolled in this study. The patients were randomly divided into two groups. They are group I PRF group and group II CollaPlug group. The vertical buccal crestal bone heights were measured immediately after extraction and 4 months postextraction and implants were placed. Results The buccal crestal bone level in the CollaPlug group had a baseline mean of 4.67 ± 0.54 and a postmean of 6.98 ± 0.60, whereas in the PRF group baseline mean was 5.43 ± 0.47 and postmean was 6.93 ± 0.55. The bone resorption was found in both the groups (2.31 mm for CollaPlug and 1.5 mm for PRF), in agreement with previous studies. However, there was increased bone loss in CollaPlug group compared with PRF group, which was found statistically significant. Conclusion In conclusion, within the limits of the present study, the two tested socket preservation materials seem to be effective in the treatment of extraction sockets, even though the design of the study did not allow us to evaluate to what extent the clinical improvement could be attributed to the PRF per se, since a negative control was not included in this investigation. However, preparation of PRF is not very cumbersome and inexpensive, which makes it a better socket preservation material than CollaPlug. How to cite this article Madhan G, Singh M. Comparison of Ability of Platelet-rich Fibrin vs CollaPlug in maintaining the Buccal Bone Height of Sockets following Extractions in 20 Patients. J Health Sci Res 2017;8(1):1-6.

Advanced Platelet-Rich Fibrin: A New Concept for Cell-Based Tissue Engineering by Means of Inflammatory Cells

Choukroun's platelet-rich fibrin (PRF) is obtained from blood without adding anticoagulants. In this study, protocols for standard platelet-rich fibrin (S-PRF) (2700 rpm, 12 minutes) and advanced platelet-rich fibrin (A-PRF) (1500 rpm, 14 minutes) were compared to establish by histological cell detection and histomorphometrical measurement of cell distribution the effects of the centrifugal force (speed and time) on the distribution of cells relevant for wound healing and tissue regeneration. Immunohistochemistry for monocytes, T and B -lymphocytes, neutrophilic granulocytes, CD34-positive stem cells, and platelets was performed on clots produced from four different human donors. Platelets were detected throughout the clot in both groups, although in the A-PRF group, more platelets were found in the distal part, away from the buffy coat (BC). T- and B-lymphocytes, stem cells, and monocytes were detected in the surroundings of the BC in both groups. Decreasing the rpm while increasing the centrifugation time in the A-PRF group gave an enhanced presence of neutrophilic granulocytes in the distal part of the clot. In the S-PRF group, neutrophils were found mostly at the red blood cell (RBC)-BC interface. Neutrophilic granulocytes contribute to monocyte differentiation into macrophages. Accordingly, a higher presence of these cells might be able to influence the differentiation of host macrophages and macrophages within the clot after implantation. Thus, A-PRF might influence bone and soft tissue regeneration, especially through the presence of monocytes/macrophages and their growth factors. The relevance and feasibility of this tissue-engineering concept have to be proven through in vivo studies.

Effects of Choukroun's platelet-rich fibrin on human gingival fibroblasts proliferation, migration and type I collagen secretion

To investigate the effect of platelet-rich fibrin (PRF) on human gingival fibroblasts (HGF) biological behavior such as proliferation, migration and collagen-I expression. Human healthy gingival tissues were cultured according to the explant technique to obtain primary cultures. PRF was prepared by means of Choukroun's. HGF were co-cultured with PRF membrane originating from the same donor as the explants, divided into three groups, PRF1 group, PRF2 group and blank control group. Methyl thiazolyl tetrazolium (MTT) assay was used for cytotoxicity and cell proliferation study, and enzyme-linked immunosorbent assay (ELISA) for collagen-I (COL-I) secretion study at the 1st, 3rd, 5th day respectively. Eluates from PRF membrane was prepared, and divided into three groups, PRF1 group, PRF2 group and blank control group. Transwell chamber was utilized to determine the effect of PRF membrane eluate on cell migration. The A values of HGF in culture of the PRF1 (0.615 ± 0.036, 0.686 ± 0.006, 0.693 ± 0.004) and PRF2 groups (0.653 ± 0.023, 0.766 ± 0.034, 0.775 ± 0.053) were significantly higher than those of the control cultures (0.514 ± 0.020, 0.544 ± 0.006, 0.545 ± 0.009) (P < 0.01), but the difference between PRF1 and PRF2 group was not significant (P > 0.05). In each group at different time points, the HGF proliferation effect was significantly enhanced with time (P < 0.01). Cell migration test showed that the migration numbers of HGF in PRF1 and PRF2 groups (85.67 ± 2.94, 85.83 ± 1.47) were significantly higher than those of the control group (54.17 ± 2.48) (P < 0.01), but the difference between the two experimental groups was not significant (P > 0.05). COL-I secretion test exhibited that the A values of COL-I in PRF1 (0.184 ± 0.004, 0.200 ± 0.004, 0.204 ± 0.009) and PRF2 group (0.213 ± 0.008, 0.226 ± 0.005, 0.229 ± 0.006) were significantly higher than the A values of the control group (0.174 ± 0.002, 0.184 ± 0.002, 0.186 ± 0.003) (P < 0.01), but the difference between the two experimental groups was not significant (P > 0.05). In each group, the secretion level of COL-I increased significantly with time (P < 0.01). PRF could exert a positive effect on HGF biological behaviour and had clinical application potential in the treatment of gingival recession and in the periodontal tissue engineering when combined with seed cell HGF.

In Search of a Consensus Terminology in the Field of Platelet Concentrates for Surgical Use: Platelet-Rich Plasma (PRP), Platelet-Rich Fibrin (PRF), Fibrin Gel Polymerization and Leukocytes

In the field of platelet concentrates for surgical use, most products are termed Platelet-Rich Plasma (PRP). Unfortunately, this term is very general and incomplete, leading to many confusions in the scientific database. In this article, a panel of experts discusses this issue and proposes an accurate and simple terminology system for platelet concentrates for surgical use. Four main categories of products can be easily defined, depending on their leukocyte content and fibrin architecture: Pure Platelet-Rich Plasma (P-PRP), such as cell separator PRP, Vivostat PRF or Anitua's PRGF; Leukocyteand Platelet-Rich Plasma (L-PRP), such as Curasan, Regen, Plateltex, SmartPReP, PCCS, Magellan, Angel or GPS PRP; Pure Plaletet-Rich Fibrin (P-PRF), such as Fibrinet; and Leukocyte- and Platelet-Rich Fibrin (L-PRF), such as Choukroun's PRF. P-PRP and L-PRP refer to the unactivated liquid form of these products, their activated versions being respectively named P-PRP gels and L-PRP gels. The purpose of this search for a terminology consensus is to plead for a more serious characterization of these products. Researchers have to be aware of the complex nature of these living biomaterials, in order to avoid misunderstandings and erroneous conclusions. Understanding the biomaterials or believing in the magic of growth factors ? From this choice depends the future of the field.

In Vitro Effects of Choukroun's Platelet-Rich Fibrin Conditioned Medium on 3 Different Cell Lines Implicated in Dental Implantology

The aim of this work was to determine the relevance of Choukroun's platelet-rich fibrin (PRF) in dental implantology by determining the in vitro effects of soluble factors released by PRF clot. We used 3 different cell lines implicated in dental implantology: osteoblast, keratinocyte, and fibroblast. Cellular viability, cell proliferation, and gene expression were analyzed using PRF conditioned medium. Three different cells lines were used: SaOS2 (osteoblast), MRC5 (fibroblast), and KB (epithelial cell). The sulforhodamine B assay showed a significant increase in cell number for the undiluted and 1:3 diluted conditioned medium after 24 and 48 hours. There was no effect for the 1:9 dilution. Cell cycle analysis by flow cytometry confirmed the viability test results. After 48 hours, PRF conditioned medium induced gene expression in osteoblasts. Expression of osteopontin and osteocalcin, late osteogenic markers, was observed using reverse transcriptase-polymerase chain reaction (RT-PCR). This study establishes a model to evaluate, in vitro, the effects of soluble growth factors released by PRF clot. Our work confirmed PRF is useful in stimulating tissue healing and bone regeneration. This work should recommend Choukroun's PRF in numerous implantology clinical applications.

Platelet Rich Fibrin in the revitalization of tooth with necrotic pulp and open apex

Regeneration of pulp-dentin complex in an infected necrotic tooth with an open apex is possible if the canal is effectively disinfected. The purpose of this case report is to add a regenerative endodontic case to the existing literature about using Platelet Rich Fibrin (PRF). A nine year old boy who accidently broke his immature maxillary central incisor tooth, developed pulpal necrosis with apical periodontitis. After the access cavity preparation, the canal was effectively irrigated with 20 ml of 5.25% sodium hypochlorite solution and 10ml of 0.2% chlorhexidine solution and dried with paper points. Triple antibiotic paste was placed inside the canal and left for 21 days. 12 ml of whole blood was drawn from the patient's right antecubital vein and centrifuged for 10 minutes to obtain the Choukroun's PRF. After the removal of the triple antibiotic paste, the PRF was placed into the canal till the level of cementoenamel junction and 3mm of grey MTA was placed directly over the PRF clot. The setting of MTA was confirmed 3 days later and the tooth was double sealed with GIC and Composite restoration. After 1 year the clinical examination revealed negative responses to percussion and palpation tests. The tooth responded positively to cold and electric pulp tests. Radiographic examination revealed continued thickening of the dentinal walls, root lengthening, regression of the periapical lesion and apical closure. On the basis of the results obtained in our case report we conclude that revitalization of necrotic infected immature tooth is possible under conditions of total canal disinfection and PRF is an ideal biomaterial for pulp-dentin complex regeneration.

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.

Restoration of peri-implant defects in immediate implant installations by Choukroun platelet-rich fibrin and silk fibroin powder combination graft

The objective of this study was to determine the capability of silk fibroin powder as a biomaterial template for the restoration of peri-implant defects when mixed with Choukroun platelet-rich fibrin (PRF) in vivo. Ten New Zealand white rabbits were used for this study. Using a trephine bur (diameter 7.0 mm), 2 monocortical defects were prepared. Subsequently, 2 dental implants were installed into the tibia (diameter 3.0 mm, length 10.0 mm). In the experimental group, the peri-implant defect was filled with a combination graft of silk fibroin powder and Choukroun PRF. The control was left in an unfilled state. The animals were killed at 8 weeks. Subsequently, a removal torque test and a histomorphometric analysis were done. The removal torque for the experimental group was 30.34 +/- 5.06 N.cm, whereas it was 21.86 +/- 3.39 N.cm for the control. The difference between the 2 groups was statistically significant (P = .010). Mean new bone formation was 51.93 +/- 27.90% in the experimental group and 11.67 +/- 15.12% in the control (P = .003). Mean bone-to-implant contact was 43.07 +/- 21.96% in the experimental group and 15.37 +/- 23.84% in the control (P = .002). A peri-implant defect can be successfully repaired by the application of Choukroun PRF and silk fibroin powder.

A combination graft of low-molecular-weight silk fibroin with Choukroun platelet-rich fibrin for rabbit calvarial defect

The objective of this study was to determine the capabilities of silk fibroin as a biomaterial template for bone formation when mixed with Choukroun platelet-rich fibrin (PRF) in vivo. Ten New Zealand white rabbits were used for this study and bilateral round shaped defects were formed in the parietal bone (diameter 9.0 mm). The silk fibroin was digested by acid and made into powder (molecular weight <1.0 kDa). The right side (experimental group) received the silk fibroin plus platelet-rich fibroin and the left side (control group) did not receive a graft. Animals were killed at 6 weeks and 12 weeks. The specimens were examined by microscopic computerized tomography (micro-CT). Subsequently, they underwent decalcification and were stained for histologic analysis. There was no significant difference between groups at 6 weeks after operation. In the micro-CT results, however, tissue mineral content in the experimental group at 12 weeks after operation was 132.09 +/- 4.41 and that in the control group was 126.42 +/- 6.62 (P = .011). Tissue mineral density in the experimental group was 2,088.88 +/- 648.34, and that in the control group was 2,029.72 +/- 668.22 (P = .013). The results of the histomorphometric analysis were in accordance with the micro-CT results. The total new bone was 49.86 +/- 7.49% in the control group at 12 weeks after the operation and 59.83 +/- 10.92% in the experimental group (P = .021). A combined application of Choukroun PRF with acid-digested silk fibroin showed more rapid bone healing than unfilled control.

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

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. 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. 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. 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.

Letter to the Editor: Re: “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”

Choukroun's platelet-rich fibrin (PRF) is a fibrin biomaterial with a specific composition, three-dimensional architecture, and associated biology. This letter highlights some key issues related to the use of this complex material during periodontal surgery. First, a reproducible protocol for the production of PRF membranes must be followed to control the quantity and quality of the fibrin matrix, leukocytes, platelets, and growth factors. Second, its use in periodontology must follow two principles founded on tissue-engineering basic rules and classical periodontal concepts. Using this two-principle safe protocol, the use of PRF in periodontal surgery leads to a significant improvement during the early healing phase and to a thick and stable final remodeled gingiva.

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

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. 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. 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. 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.

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.