Platelet-rich fibrin suppresses in vitro osteoclastogenesis

A narrative review on the use of autologous platelet concentrates during alveolar bone augmentation: Horizontal (simultaneous/staged) & vertical (simultaneous/staged)

This review aimed to answer the general question of whether autologous platelet concentrates (APCs, an autologous blood-derivative) can improve the outcome of alveolar bone augmentation. Three clinical scenarios were assessed: horizontal/vertical bone augmentation in combination with implant placement (simultaneous approach), horizontal bone augmentation in a staged approach, and vertical bone augmentation in a staged approach. An electronic literature search strategy was conducted for each review from the outset to July 1st, 2023. The titles and abstracts (when available) of all identified studies were screened and imported into a database. If articles appeared to meet the inclusion criteria or their title and abstract had insufficient data, the full text was obtained to make the final decision. All studies that met the inclusion criteria underwent data extraction. Moreover, the references of the identified papers were screened for additional studies. After title and abstract screening and selection criteria application, 14 clinical studies were included for the qualitative analysis: seven for horizontal/vertical bone augmentation in a simultaneous approach, five for horizontal bone augmentation in a staged approach, and two for vertical bone augmentation in a staged approach. There is scarce literature regarding the added value of APCs in bone augmentation, and most studies had small sample sizes, a lack of standardized protocols, and different outcome variables, which makes comparisons between studies difficult. Out of the 14 studies, four were well-designed randomized clinical trials, where we could find better results for the APCs groups. Most studies, particularly comparative and well-designed studies, demonstrated beneficial and promising results of using APCs in alveolar bone augmentation. However, before high-level evidence-based conclusions can be drawn, more randomized clinical trials must compare the benefits of adding APCs to the gold-standard approach.

Efficacy and safety of a new heterologous fibrin biopolymer on socket bone healing after tooth extraction: An experimental pre-clinical study

AIM

To assess the efficacy of heterologous fibrin biopolymer (HFB) in promoting alveolar bone healing after tooth extraction in rats.

MATERIALS AND METHODS

The upper right incisors of 48 Wistar rats were extracted. Toothless sockets were filled with HFB (HFBG, n = 24) or blood clot (BCG, n = 24). The tooth extraction sites were subjected to micro-computed tomography (micro-CT), histological, histomorphometric and immunohistochemical (for Runt-related transcription factor 2/Runx2 and tartrate-resistant acid phosphatase/TRAP) analyses on days 0, 7, 14 and 42 after extraction.

RESULTS

Socket volume remained similar between days 0 and 14 (69 ± 5.4 mm3), except in the BCG on day 14, when it was 10% lower (p = .043). Although the number of Runx2+ osteoblasts was high and similar in both groups (34 × 102 cells/mm2), the HFBG showed lower inflammatory process and osteoclast activity than BCG at 7 days. On day 14, the number of Runx2+ osteoblasts remained high and similar to the previous period in both groups. However, osteoclast activity increased. This increase was 55% lower in the HFBG than BCG. In the BCG, the presence of an inflammatory process and larger and numerous osteoclasts on day 14 led to resorption of the alveolar bone ridge and newly formed bone. On day 42, numbers of Runx2+ osteoblast and TRAP+ osteoclasts decreased dramatically in both groups. Although the BCG exhibited a more mature cortical bone formation, it exhibited a higher socket reduction (28.3 ± 6.67%) and smaller bone volume (37 ± 5.8 mm3) compared with HFBG (socket reduction of 14.8 ± 7.14% and total bone volume of 46 ± 5.4 mm3).

CONCLUSIONS

HFB effectively suppresses osteoclast activity and reduces alveolar bone resorption compared with blood clot, thus preventing three-dimensional bone loss, particularly during the early healing period. HFB emerges as a promising biopharmaceutical material for enhancing healing processes after tooth extraction.

How to explain the beneficial effects of leukocyte- and platelet-rich fibrin

The survival of an organism relies on its ability to repair the damage caused by trauma, toxic agents, and inflammation. This process involving cell proliferation and differentiation is driven by several growth factors and is critically dependent on the organization of the extracellular matrix. Since autologous platelet concentrates (APCs) are fibrin matrices in which cells, growth factors, and cytokines are trapped and delivered over time, they are able to influence that response at different levels. The present review thoroughly describes the molecular components present in one of these APCs, leukocyte- and platelet-rich fibrin (L-PRF), and summarizes the level of evidence regarding the influence of L-PRF on anti-inflammatory reactions, analgesia, hemostasis, antimicrobial capacity, and its biological mechanisms on bone/soft tissue regeneration.

L-PRF Secretome from Both Smokers/Nonsmokers Stimulates Angiogenesis and Osteoblast Differentiation In Vitro

Leukocyte and Platelet-Rich Fibrin (L-PRF) is part of the second generation of platelet-concentrates. L-PRF derived from nonsmokers has been used in surgical procedures, with its beneficial effects in wound healing being proven to stimulate biological activities such as cell proliferation, angiogenesis, and differentiation. Cigarette smoking exerts detrimental effects on tissue healing and is associated with post-surgical complications; however, evidence about the biological effects of L-PRF derived from smokers is limited. This study evaluated the impact of L-PRF secretome (LPRFS) derived from smokers and nonsmokers on angiogenesis and osteoblast differentiation. LPRFS was obtained by submerging L-PRF membranes derived from smokers or nonsmokers in culture media and was used to treat endothelial cells (HUVEC) or SaOs-2 cells. Angiogenesis was evaluated by tubule formation assay, while osteoblast differentiation was observed by alkaline phosphatase and osterix protein levels, as well as in vitro mineralization. LPRFS treatments increased angiogenesis, alkaline phosphatase, and osterix levels. Treatment with 50% of LPRFS derived from smokers and nonsmokers in the presence of osteogenic factors stimulates in vitro mineralization significantly. Nevertheless, differences between LPRFS derived from smokers and nonsmokers were not found. Both LPRFS stimulated angiogenesis and osteoblast differentiation in vitro; however, clinical studies are required to determine the beneficial effect of LPRFS in smokers.

Platelet-rich fibrin as an autologous biomaterial for bone regeneration: mechanisms, applications, optimization

Platelet-rich fibrin, a classical autologous-derived bioactive material, consists of a fibrin scaffold and its internal loading of growth factors, platelets, and leukocytes, with the gradual degradation of the fibrin scaffold and the slow release of physiological doses of growth factors. PRF promotes vascular regeneration, promotes the proliferation and migration of osteoblast-related cells such as mesenchymal cells, osteoblasts, and osteoclasts while having certain immunomodulatory and anti-bacterial effects. PRF has excellent osteogenic potential and has been widely used in the field of bone tissue engineering and dentistry. However, there are still some limitations of PRF, and the improvement of its biological properties is one of the most important issues to be solved. Therefore, it is often combined with bone tissue engineering scaffolds to enhance its mechanical properties and delay its degradation. In this paper, we present a systematic review of the development of platelet-rich derivatives, the structure and biological properties of PRF, osteogenic mechanisms, applications, and optimization to broaden their clinical applications and provide guidance for their clinical translation.

How to explain the beneficial effects of platelet-rich plasma

Platelet-rich plasma (PRP) is the platelet and leukocyte-containing plasmatic fraction of anticoagulated autologous blood. While evidence supporting the clinical use of PRP in dentistry is low, PRP is widely used in sports medicine, orthopedics, and dermatology. Its beneficial activity is commonly attributed to the growth factors released from platelets accumulating in PRP; however, evidence is indirect and not comprehensive. There is thus a demand to revisit PRP with respect to basic and translational science. This review is to (i) recapitulate protocols and tools to prepare PRP; (ii) to discuss the cellular and molecular composition of PRP with a focus on platelets, leukocytes, and the fibrin-rich extracellular matrix of coagulated plasma; and finally (iii) to discuss potential beneficial effects of PRP on a cellular and molecular level with an outlook on its current use in dentistry and other medical fields.

Bone Formation and Maintenance in Oral Surgery: The Decisive Role of the Immune System-A Narrative Review of Mechanisms and Solutions

Based on the evidence of a significant communication and connection pathway between the bone and immune systems, a new science has emerged: osteoimmunology. Indeed, the immune system has a considerable impact on bone health and diseases, as well as on bone formation during grafts and its stability over time. Chronic inflammation induces the excessive production of oxidants. An imbalance between the levels of oxidants and antioxidants is called oxidative stress. This physio-pathological state causes both molecular and cellular damage, which leads to DNA alterations, genetic mutations and cell apoptosis, and thus, impaired immunity followed by delayed or compromised wound healing. Oxidative stress levels experienced by the body affect bone regeneration and maintenance around teeth and dental implants. As the immune system and bone remodeling are interconnected, bone loss is a consequence of immune dysregulation. Therefore, oral tissue deficiencies such as periodontitis and peri-implantitis should be regarded as immune diseases. Bone management strategies should include both biological and surgical solutions. These protocols tend to improve immunity through antioxidant production to enhance bone formation and prevent bone loss. This narrative review aims to highlight the relationship between inflammation, oxidation, immunity and bone health in the oral cavity. It intends to help clinicians to detect high-risk situations in oral surgery and to propose biological and clinical solutions that will enhance patients' immune responses and surgical treatment outcomes.

Comparison between platelet rich fibrin as space filling material versus xenograft and alloplastic bone grafting materials in immediate implant placement: a randomized clinical trial

BACKGROUND

This study aimed to compare the efficacy of different gap filling materials in immediate implant in anterior and premolar regions of maxilla.

MATERIALS AND METHODS

Thirty-six implants were inserted in patients seeking for replacement of non-restorable maxillary anterior and premolar teeth (esthetic zone) by immediate implant. Patients were randomly distributed into three equal groups, twelve implants in each group. Group 1 received Platelet Rich Fibrin (PRF) into the jumping distance, Group 2 received Xenograft into the jumping distance and Group 3 received Alloplastic bone grafting material into the jumping distance. Implant stability by measuring the changes in Resonance Frequency Analysis (RFA), peri-implant pocket depth, marginal bone loss and changes in buccal bone thickness were evaluated during follow up periods. All the clinical and radiographic data were subjected to statistical analysis by One Way ANOVA test and the Post Hoc Tukey test.

RESULTS

This study involved 19 female patients and 17 male patients who received 36 dental implants. There was no significant difference between the study groups regarding implant stability, peri-implant pocket depth and palatal bone loss, while there was a significant difference between PRF Group (Group 1) and the other Groups regarding buccal bone loss and changes in buccal bone thickness.

CONCLUSION

PRF can be used as a gap filling material in conjunction with immediate implant placement, but other bone grafting materials give superior result regarding buccal bone loss and changes in buccal bone thickness.

TRIAL REGISTRATION

The study was listed on www.

CLINICALTRIALS

gov with registration number (NCT05878392) on 26/05/2023. The Institutional Review Board (IRB) of the Faculty of Dentistry, Mansoura University, Mansoura, Egypt, approved the current study in compliance with the seventh revision of the Helsinki Declaration in 2013 (A0103023OS).

Do blood concentrates influence inflammatory signs and symptoms after mandibular third molar surgery? A systematic review and network meta-analysis of randomized clinical trials

OBJECTIVES

To investigate, through a network meta-analysis, the effectiveness of blood concentrates in reducing pain perception, trismus, and edema after mandibular third molar extraction.

MATERIALS AND METHODS

An electronic search was performed in nine databases to locate randomized clinical trials comparing blood concentrate use after mandibular third molar extraction. Two authors selected and extracted the data independently. The individual risk of bias in the studies was assessed with the RoB v2.0 tool. A network meta-analysis compared postoperative pain and trismus scores after applying different blood concentrates, using the mean difference (MD) as an effect estimate. The GRADE approach assessed the certainty of evidence.

RESULTS

Thirty-one randomized clinical trials were included in the review and 18 in the meta-analysis. Leukocyte- and platelet-rich fibrin (L-PRF) was the most used blood concentrate, followed by platelet-rich plasma (PRP). The network meta-analysis, depending on the analyzed period, evaluated up to 1240 surgeries. Among the analyzed blood concentrates, advanced platelet-rich fibrin (A-PRF) performed better among the analyzed blood concentrates, decreasing postoperative pain in 1, 2, 3, and 7 days and reducing trismus up to the inflammatory peak compared to blood clots. Only two studies had a low risk of bias.

CONCLUSIONS

Based on very low certainty of evidence, using concentrates seemed efficient compared to blood clots in reducing pain and trismus after mandibular third molar surgeries. A-PRF decreased postoperative pain throughout the evaluated time and trismus during the acute inflammatory peak.

CLINICAL RELEVANCE

A-PRF after mandibular third molar extractions performed better among the analyzed blood concentrates and seemed efficient in improving postoperative quality by decreasing inflammatory signs and symptoms.

The role and mechanism of platelet-rich fibrin in alveolar bone regeneration

Platelet-rich fibrin (PRF), as an autologous blood preparation, has been receiving increasing attention in recent years and has been successfully applied in various clinical treatments for alveolar bone regeneration in the oral field. This review focuses on analyzing and summarizing the role and mechanism of PRF in alveolar bone regeneration. We first provide a brief introduction to PRF, then summarize the mechanisms by which PRF promotes alveolar bone regeneration from three aspects: osteogenesis mechanism, bone induction mechanism, and bone conduction mechanism, involving multiple signaling pathways such as Smad, ERK1/2, PI3K/Akt, and Wnt/β-catenin. We also explore the various roles of PRF as a scaffold, filler, and in combination with bone graft materials, detailing how PRF promotes alveolar bone regeneration and provides a wealth of experimental evidence. Finally, we summarize the current applications of PRF in various oral fields. The role of PRF in alveolar bone regeneration is becoming increasingly important, and its role and mechanism are receiving more and more research and understanding. This article will provide a reference of significant value for research in related fields. The exploration of the role and mechanism of PRF in alveolar bone regeneration may lead to the discovery of new therapeutic targets and the development of more effective and efficient treatment strategies.

Do autologous platelet concentrates (APCs) have a role in intra-oral bone regeneration? A critical review of clinical guidelines on decision-making process

In the past decades, personalized regenerative medicine has gained increased attention. Autologous platelet concentrates (APCs) such as PRP, PRGF, and L-PRF, all serving as a source of a large variety of cells and growth factors that participate in hard and soft tissue healing and regeneration, could play a significant role in regenerative periodontal procedures. This narrative review evaluated the relative impact of APCs in alveolar ridge preservation, sinus floor augmentation, and the regeneration of bony craters around teeth, both as a single substitute or in combination with a xenograft. L-PRF has a significant beneficial effect on alveolar ridge preservation (bone quality). The data for PRGF are less convincing, and PRP is controversial. L-PRF can successfully be used as a single substitute during transcrestal (≥3.5 mm bone gain) as well as 1-stage lateral window sinus floor elevation (>5 mm bone gain). For PRGF and especially PRP the data are very scarce. In the treatment of bony craters around teeth, during open flap debridement, L-PRF as a single substitute showed significant adjunctive benefits (e.g., >PPD reduction, >CAL gain, >crater depth reduction). The data for PRP and PRGF were non-conclusive. Adding PRP or L-PRF to a xenograft during OFD resulted in additional improvements (>PPD reduction, >CAL gain, >bone fill), for PRGF no data were found. Autologous platelet concentrates demonstrated to enhance bone and soft tissue healing in periodontal regenerative procedures. The data for L-PRF were most convincing. L-PRF also has the advantage of a greater simplicity of production, and its 100% autologous character.

Clinical and Radiographic Evaluation of Autologous Platelet-Rich Fibrin With or Without Demineralized Bone Matrix in the Treatment of Grade II Furcation Defects

Introduction This study aims to differentiate the employment of demineralized bone matrix (DMBM; Osseograft, Advanced Biotech Products (P) Ltd, Chennai, India) and platelet-rich fibrin (PRF) alone to a composite graft consisting of both materials in the surgical actions toward the anomalies of the human periodontal furcation imperfection. Methods In a split-mouth study, 30 patients with mandibular molars affected by the furcation were allocated without conscious choice to test (PRF + DMBM, n = 30) or control (PRF, n = 30) categories. At the starting point, three months after surgery, and six months later, the following modifiable factors were evaluated: probing pocket depth (PPD), full-mouth plaque scores, full-mouth gingival scores, radiographic defect depth, relative vertical clinical attachment level (RVCAL), and relative horizontal clinical attachment level (RHCAL). Results Results at three and six months demonstrated substantial differences between baseline values for both treatment methods in clinical and X-ray imaging appraisal. Nonetheless, the PRF/DMBM group manifests statistically significantly soaring changes observed in comparison to the PRF group. Overall, the probing depth (PD) in the test site was significantly lower than that in the control site, showing a reduction of 68% (95% CI=41%, 95%, p<0.001). Conclusion Clinical indications significantly improved with PRF and DMBM combined instead of PRF alone. On radiographs, the test group also showed higher bone fill.

Histopathological assessment of the preventive effect of leukocyte-platelet-rich fibrin on bisphosphonate-related osteonecrosis of the jaw following dental extraction: An animal study

Background

Leukocyte- and platelet-rich fibrin (L-PRF) could be considered a preventive measure in Bisphosphonate-Related Osteonecrosis of the Jaw (BRONJ). The present experiment aimed to assess the preventive effects of L-PRF on osteonecrosis of the jaw in rats.

Methods

In this interventional animal study with a split-mouth design, 28 rats were randomly allocated to saline (negative control), bisphosphonate (positive control), and Bis + L-PRF (case) groups. Bilateral extraction of maxillary molar teeth was performed followed by random application of L-PRF to one of the extraction sockets treated with Zoledronic acid for four weeks. Clinical occurrence of BRONJ and histopathologic evaluations were done, and data were subjected to the Kruskal-Wallis test, Mann-Whitney U test and exact Fisher test performed using SPSS 25. The significance level was set at 0.05.

Results

The application of L-PRF resulted in a 41.67% reduction in osteonecrosis centers and the number of osteoclast cells. Also, Kruskal Wallis test results showed a significant difference among the three groups regarding the frequency distribution of inflammation severity. However, no significant difference was detected regarding the frequency distribution of the blood vessels (Kruskal Wallis test, P-value = 0.649).

Conclusion

It could be inferred that possible preventive effects on the clinical occurrence of osteonecrosis could be expected from the application of L-PRF.

The Effect of Advanced Platelet-Rich Fibrin in Tissue Regeneration in Reconstructive and Graft Surgery: Systematic Review

This systematic review answered the guiding question using the PICO system: "What are the effects of advanced platelet-rich fibrin (A-PRF) on alveolar ridge preservation and tissue gain in reconstructive and jaw graft surgery?" Searches were performed in the PubMed|MEDLINE, Scopus, Embase, Web of Science, Cochrane Library, and LILACS|bvs databases. In total, 573 articles were found in the initial search, and 564 were evaluated after the removal of duplicates, of which 5 randomized controlled trials met the eligibility criteria and were included 2 studies investigated the effect of A-PRF on the preservation of the bone ridge, 1 study evaluated the tissue repair after tooth extraction with A-PRF, 1 evaluated the peri-implant gap filling with A-PRF-xenograft mixture, and other the A-PRF on the treatment of alveolar osteitis. Advanced-PRF preparation protocol varied between the included studies from 8 to 13 minutes of centrifugation, at 1300 RPM (200 g ). The use of A-PRF provided greater dimensions of height and more favorable maintenance of the ridge profile, probing depth, and gingival margin level after extraction. Advanced-PRF also increased bone density, vital bone, epithelial healing, and control of postoperative pain and swelling after tooth extraction and in the treatment of alveolar osteitis.

Cone-Beam Computed Tomography and Histological Findings for Socket Preservation Techniques Using Different Grafting Materials: A Systematic Review

OBJECTIVE

Socket preservation techniques have been used to maintain the ridge dimension following tooth extraction. The materials used influence the quality and quantity of newly formed bone. Therefore, the aim of this article was to systematically review the literature reporting both histological and radiographic outcomes of socket preservation techniques after tooth extraction in human subjects.

MATERIAL AND METHOD

A systematic electronic search was performed in the electronic databases. English language clinical studies that were published between 2017 and 2022 and included both histological and radiographic findings for the test and control groups. Our primary search produced 848 articles, and of these, 215 were duplicate studies. A total of 72 articles were then eligible for full-text reading.

RESULTS

The review included eight studies that met its inclusion criteria. Three outcomes were compared in the included studies. The percentage of newly formed bone ranged from 21.34 ± 9.14% to more than 50% of new bone formation. The materials that showed more than 50% of newly formed bone formation were demineralized dentin graft, platelet-rich fibrin, freeze-dried bone allograft, corticocancellous porcine, and autogenous bone. Four Studies did not report the percentage of the residual graft materials, while those who reported showed a variable range of a minimum 1.5% to more than 25%. One study did not report the changes in horizontal width at the follow-up period, while other studies ranged from 0.6 mm to 10 mm.

CONCLUSION

Socket preservation represents an efficient technique to preserve the ridge contour with satisfactory newly formed bone in the augmented site and maintaining the vertical and horizontal dimensions of the ridge.

In vitro inflammatory modulation of bioceramic endodontic sealer in macrophages stimulated by bacterial lipopolysaccharide

AIM

To evaluate the effects of AH Plus (Dentsply), Sealer 26 (Dentsply), and Sealer Plus BC (Produtos Médicos e Odontológicos) on cytotoxicity and inflammation in macrophage cultures exposed to bacterial lipopolysaccharide (LPS).

METHODOLOGY

After initial setting, the sealers were conditioned with serum-free culture medium for 24 h (1 ml/cm² ). Macrophages from the RAW 264.7 strain were exposed to sealer extracts in a 1:16 ratio in a culture medium with or without LPS. Cell morphology, viability, mitochondrial activity, oxidative stress and gene expression of interleukin 1β (IL-1β) and tumour necrosis factor-alpha (TNF-α) were evaluated. Data on mitochondrial activity, oxidative stress and TNF-α were analysed using a two-way analysis of variance (anova) test, followed by the Student-Newman-Keuls post-test. IL-1β data were analysed using one-way anova, followed by SNK, and the t-test was used for intragroup comparison. The significance level was set at 5%.

RESULTS

In the absence of LPS, only AH Plus and Sealer 26 showed a reduction in cell density, while in the presence of LPS, Sealer 26 had the lowest density compared to the other groups. In terms of mitochondrial activity, at 24 and 48 h, Sealer Plus BC had significantly higher mean values than Sealer 26 and AH Plus (p < .05). Sealer 26 exhibited the lowest levels of oxidative stress and IL-1β and TNF-α expression, regardless of the presence of LPS (p < .05).

CONCLUSIONS

Although all sealers interfere with the response of macrophages to LPS, contact with epoxy resin-based sealers can impair cell activity in vitro, while bioceramic sealer seems to favour the inflammatory functions of these cells.

Clinical application of platelet-rich fibrin to enhance dental implant stability: A systematic review and meta-analysis

Objective

To investigate the effect of platelet-rich fibrin application on implant stability.

Study design

Five databases, namely, PubMed, Embase, Web of Science, Wiley, and China National Knowledge Infrastructure, were searched for reports published up to November 20, 2022. Randomized controlled trials (RCT), including parallel RCTs and split-mouth RCTs, with at least 10 patients/sites were considered for inclusion.

Results

After screening based on the inclusion criteria, ten RCTs were included. Low heterogeneity was observed in study characteristics, outcome variables, and estimation scales (I² = 27.2%, P = 0.19). The qualitative and meta-analysis results showed that PRF increased the effect of implant stabilizers after implant surgery.

Conclusions

The results of the present systematic review and meta-analysis suggest that PRF can increase implant stability after implant surgery. PRF may also have a role in accelerating bone healing and tends to promote new bone formation at the implant site.

Application of biologics for ridge preservation/reconstruction after implant removal

BACKGROUND

The purpose of this review was aimed at providing the rationale supported with a series of cases to apply biologics to enhance orchestrating the healing process at implant removal sites.

SUMMARY

Implant removal is commonly applied on a daily basis, in particular, in cases that exhibit esthetic failures linked to inadequate implant position or in cases of advanced peri-implantitis. Implant removal sites differ substantially from tooth extraction sockets. Implants are ankylosed within the alveolar bone, which therefore have neither mechanoreception nor the elasticity provided by periodontal ligament fibers. As a result, the bone-to-implant contact must be disrupted by means of using a reverse-torque device to minimize trauma. It is possible that the surrounding bone provides limited vascularity, which may interfere with the healing and bone forming process within the socket. Therefore, the use of biologics may enhance this healing and accelerate bone formation in sites where implants are removed due to hopeless functional or esthetic prognoses.

CONCLUSION

The use of biologics, in particular autologous blood-derived products, may enhance and boost the healing process to potentiate bone availability at a later stage during implant placement.

Platelet-Rich Fibrin Reduces IL-1β Release from Macrophages Undergoing Pyroptosis

Background: Pyroptosis is a catabolic process relevant to periodontal disorders for which interleukin-1β (IL-1β) inflammation is central to the pathophysiology of the disease. Despite platelet-rich fibrin (PRF) anti-inflammatory properties and its application to support periodontal regeneration, the capacity of PRF to modulate pyroptosis, specifically the production and release of IL-1β, remains unknown. The question arises whether PRF could regulate IL-1β release from macrophages in vitro. Methods: To answer this question, RAW 264.7 macrophages and primary macrophages obtained from murine bone marrow were primed with PRF before being challenged by lipopolysaccharide (LPS). Cells were then analysed for the pyroptosis signalling components by gene expression analyses and IL-1β secretion at the protein level. The release of mitochondrial reactive oxygen species (ROS) was also detected. Results: PRF lowered the LPS-induced expression of IL-1β and NLRP3 inflammasome, caspase-11 and IL-18 in primary macrophages, and IL-1β and caspase-11 in RAW 264.7 cells. Additionally, PRF diminished the secretion of IL-1β at the protein level in LPS-induced RAW 264.7 cells. This was shown through immunoassays performed with the supernatant and further confirmed by analysing the lysates of permeabilised cells. Furthermore, PRF reduced the ROS release provoked by LPS in RAW 264.7 cells. Finally, to enhance IL-1β release from the LPS-primed macrophages, we introduced a second signal with adenosine triphosphate (ATP). In this setting, PRF significantly reduced IL-1β release in RAW 264.7 cells and a trend to diminish IL-1β release in primary macrophages. Conclusion: These findings suggest that PRF can reduce IL-1β release and, at least in part, inhibit pyroptosis-related factors in LPS-challenged macrophages.

Blood Clots versus PRF: Activating TGF-β Signaling and Inhibiting Inflammation In Vitro

The preparation of platelet-rich fibrin (PRF) requires blood centrifugation to separate the yellow plasma from the red erythrocyte fraction. PRF membranes prepared from coagulated yellow plasma are then transferred to the defect sites to support tissue regeneration. During natural wound healing, however, it is the unfractionated blood clot (UBC) that fills the defect site. It is unclear whether centrifugation is necessary to prepare a blood-derived matrix that supports tissue regeneration. The aim of the present study was to compare lysates prepared from PRF and UBC based on bioassays and degradation of the respective membranes. We report here that lysates prepared from PRF and UBC membranes similarly activate TGF-β signaling, as indicated by the expression of interleukin 11 (IL-11), NADPH oxidase 4 (NOX-4) and proteoglycan 4 (PRG4) in gingival fibroblasts. Consistently, PRF and UBC lysates stimulated the phosphorylation and nuclear translocation of Smad3 in gingival fibroblasts. We further observed that PRF and UBC lysates have comparable anti-inflammatory activity, as shown by the reduction in lipopolysaccharide (LPS)-induced IL-6, inducible nitric oxidase synthase (iNOS) and cyclooxygenase 2 (COX-2) expression in RAW264.7 cells. Moreover, inflammation induced by Poly (1:C) HMW and FSL-1, which are agonists of Toll-like receptor (TLR) 3 and 2/6, respectively, was reduced by both PRF and UBC. PRF and UBC lysates reduced the nuclear translocation of p65 in LPS-induced RAW264.7 cells. In contrast to the similar activity observed in the bioassays, UBC membranes lack the structural integrity of PRF membranes, as indicated by the rapid and spontaneous disintegration of UBC membranes. We show here that the lysates prepared from PRF and UBC possess robust TGF-β and anti-inflammatory activity. However, visual inspection of the PRF and UBC membranes confirmed the negative impact of erythrocytes on the structural integrity of membranes prepared from whole blood. The data from the present study suggest that although both UBC and PRF have potent TGF-β and anti-inflammatory activity, UBC does not have the strength properties required to be used clinically to prepare applicable membranes. Thus, centrifugation is necessary to generate durable and clinically applicable blood-derived membranes.

Fibrinogen Concentrations in Liquid PRF Using Various Centrifugation Protocols

Liquid platelet-rich fibrin (PRF) is produced by fractionation of blood without additives that initiate coagulation. Even though liquid PRF is frequently utilized as a natural source of fibrinogen to prepare sticky bone, the concentration of fibrinogen and the overall amount of "clottable PRF" components have not been evaluated. To this aim, we prepared liquid PRF at 300, 700, and 2000 relative centrifugal force (RCF), for 8 min and quantified the fibrinogen levels by immunoassay. We report here that, independent of the RCF, the fibrinogen concentration is higher in the platelet-poor plasma (PPP) compared to the buffy coat (BC) fraction of liquid PRF and further decreases in the remaining red fraction. We then determined the weight of the clotted PRF fractions before and after removing the serum. The PPP and BC fractions consist of 10.2% and 25.3% clottable matrix suggesting that more than half of the weight of clottable BC is caused by cellular components. Our data provide insights into the distribution of fibrinogen in the different fractions of liquid PRF. These findings suggest that PPP is the main source of clottable fibrinogen, while the BC is more a cell source when it comes to the preparation of sticky bone.

The Evidence-based Effect of Platelet-rich Fibrin in Osteogenesis: A Systematic Review and Meta-analysis

ABSTRACT Background: Platelet Rich Fibrin (PRF) is a growth factor concentration functioning as an initiator of wound healing and bone regeneration, and it is mainly reported in dentistry rehabilitation and rejuvenation. Objective: summarize and analyze the evidence based on the effect of PRF on the bone osteogenesis Methods: A comprehensive search was conducted on the bibliographic databases or Medical Subject Headings in the PubMed. The search was conducted among articles that were published between 2010 and 2021.  Required article information was extracted from each article by abstract and full paper availability that focuses on the Platelet-Rich Fibrin (PRF) And Osteogenesis. We recruited studies with the design was employed clinical trials with in vitro and in vivo approaches. The only study that provided osteogenesis outcome proceeded to the quantitative analysis. Results: Regarding literature search and screening processes, it yielded 24 studies for qualitative assessment and eleven studies for quantitative analysis. Most of the studies performed a combination of PRF with other materials such as Mg ring, BMSCs, Gold nanoparticles, and PDLSCs. It showed that PRF combined with other materials enhanced the osteogenic ability. The assessment of PRF only showed the various result in multiple outcome markers. For the ALP, the mean difference is 1.40 [1.14-1.67] p-value 0.001. It indicates there is a significant effect of PRF application with the increase of ALP. For the RUNX2, there is a significant effect of PRF application with the increase of RUNX2 1.10 [0.93, 1.26]. For OCN, the mean difference of PRF in OCN is 0.77 [0.43, 1.12] p=0.001. It showed a significant effect of PRF application with the increase of OCN. There is also a significant effect of PRF application for TRAP with the declining number of TRAP is -1.59 [-2.96, -0.22] p=0.001. Conclusion: PRF combined with other materials showed more promising results rather than PRF only. Moreover, in the assessment of PRF only, it was found that PRF has a significant effect in accelerating bone osteogenesis. Keywords: PRF, Platelet-Rich Fibrin, Osteogenesis

In Vitro and In Vivo Efficacy of New Composite for Direct Pulp Capping

Objectives

To investigate physicochemical properties, dentin bonding, cytotoxicity, and in vivo pulp response of experimental self-adhesive composites tailored to direct pulp capping.

Materials and Methods

Experimental composites were prepared with beta-tricalcium phosphate and hydroxyapatite nanoparticles adsorbed with simvastatin and glutathione added at 0% (control resin), 1 wt% (Res 1%), and 10 wt% (Res 10%). A commercial light-curable calcium hydroxide (Ca(OH)₂) (Ultra-Blend Plus) was used as control material. The physicochemical properties investigated were flexural strength and modulus, calcium release, and degree of conversion. Dentin bonding was assessed by the push-out test. Proliferation and cell counting assays were performed to evaluate in vitro cytotoxicity using fluorescence microscopy. In vivo pulp capping was performed on molars of Wistar rats, which were euthanized after 14 days and evaluated by histological analysis.

Results

No statistical difference was observed in flexural strength and cell viability (p > 0.05). Res 10% presented higher modulus than control resin and Ca(OH)₂. Also, Res 10% attained statistically higher degree of conversion when compared to other experimental composites. Ca(OH)₂ showed higher calcium release after 28 and 45 days of storage, with no statistical difference at 45 days to Res 10%. All experimental composites achieved significantly higher bond strength when compared to Ca(OH)₂. While no significant difference was observed in the cell proliferation rates, resins at lower concentrations showed higher cell viability. In vivo evaluation of pulp response demonstrated no pulp damage with experimental composites.

Conclusions

The experimental composite investigated in this study achieved adequate physicochemical properties with minor in vivo pulpal inflammation and proved to be a valuable alternative for direct pulp capping.

Synergistic Effect of Biphasic Calcium Phosphate and Platelet-Rich Fibrin Attenuate Markers for Inflammation and Osteoclast Differentiation by Suppressing NF-κB/MAPK Signaling Pathway in Chronic Periodontitis

Background: Periodontitis is characterized by excessive osteoclastic activity, which is closely associated with inflammation. It is well established that MAPK/NF-kB axis is a key signaling pathway engaged in osteoclast differentiation. It is stated that that biphasic calcium phosphate (BCP) and platelet-rich fibrin (PRF) have significant antiostoeclastogenic effects in chronic periodontitis. Objective: We aimed to elucidate the synergetic effect of PRF/BCP involvement of the nuclear factor kappa–light–chain–enhancer of activated B cells (NF-kB) and the mitogen-activated protein kinase (MAPK) signaling pathway in osteoclast differentiation in chronic periodontitis. Methods: We induced osteoclast differentiation in vitro using peripheral blood mononuclear cells (PBMCs) derived from patients with chronic periodontitis. We assessed osteoclast generation by tartrate-resistant acid phosphatase (TRAP) activity, proinflammatory cytokines were investigated by ELISA and NF-κB, and IKB by immunoblot, respectively. MAPK proteins and osteoclast transcription factors were studied by Western blot analysis and osteoclast transcriptional genes were assessed by RT-PCR. Results: The results showed that the potent inhibitory effect of PRF/BCP on osteoclastogenesis was evidenced by decreased TRAP activity and the expression of transcription factors, NFATc1, c-Fos, and the osteoclast marker genes, TRAP, MMP-9, and cathepsin-K were found to be reduced. Further, the protective effect of PRF/BCP on inflammation-mediated osteoclastogenesis in chronic periodontitis was shown by decreased levels of proinflammatory cytokines, NF-kB, IKB, and MAPK proteins. Conclusions: PRF/BCP may promote a synergetic combination that could be used as a strong inhibitor of inflammation-induced osteoclastogenesis in chronic periodontitis.

Osteoclast density is not increased in bone adjacent to radiolucencies (cysts) in juvenile equine medial femoral condyles

BACKGROUND

There is a knowledge gap about how equine MFC subchondral radiolucencies (SR) arise and evolve. Osteoclasts are believed to have a role but have not been studied in situ.

OBJECTIVES

To measure and compare osteoclast density and the percentage of chondroclasts in healthy and MFC SR specimens from juvenile Thoroughbreds.

STUDY DESIGN

Cadaveric study.

METHODS

Medial femoral condyles (MFC) from a tissue bank of equine stifles were studied. Inclusion criteria were MFCs (≤8 months old) with a computed tomography SR lesion and histological focal failure of endochondral ossification (L group). Contralateral, lesion-free, MFCs were a control group (CC). Osteochondral slabs were cut through the lesion (L), a healthy site immediately caudal to the lesion, (internal control; IC) and the contralateral, site-matched controls (CC). Histological sections were immunostained with Cathepsin K for osteoclast counting. Osteoclasts in contact with the growth cartilage (chondroclasts) were also counted. The sections were segmented into regions of interest (ROI) at different depths in the subchondral bone: ROI₁ (0-1 mm), ROI₂ (1-3 mm) and ROI₃ (3-6 mm). Osteoclasts were counted and the bone area was measured in each ROI to calculate their density. Chondroclasts were counted in ROI₁ .

RESULTS

Sections were studied from L and IC (n = 6) and CC sites (n = 5). Osteoclast density was significantly higher in ROI₁ when compared with ROI₃ in all groups. Although higher osteoclast density was measured in ROI₁ in the L group, no significant differences were detected when compared with control ROIs. The proportion of chondroclasts in ROI₁ was lower in the L sections when compared with controls but no significant differences were detected.

MAIN LIMITATIONS

Limited sample size.

CONCLUSIONS

Osteoclasts are important actors in MFC subchondral bone development, digesting both growth cartilage (chondroclasts) and bone, but the pathophysiology of early MFC SRs cannot be explained solely by an increased osteoclast presence in the subchondral bone.

Platelet-Rich Fibrin Decreases the Inflammatory Response of Mesenchymal Cells

Chronic inflammation is a pathological process where cells of the mesenchymal lineage become a major source of inflammatory mediators. Platelet-rich fibrin (PRF) has been shown to possess potent anti-inflammatory activity in macrophages, but its impact on mesenchymal cells has not been investigated. The aim of this study was, therefore, to expose mesenchymal cells to inflammatory cytokines together with lysates generated from liquid platelet-poor plasma (PPP), the cell-rich buffy coat layer (BC; concentrated-PRF or C-PRF), and the remaining red clot layer (RC), following centrifugation of blood. Heating PPP generates an albumin gel (Alb-gel) that when mixed back with C-PRF produces Alb-PRF. Membranes prepared from solid PRF were also subjected to lysis. We report here that lysates of PPP, BC, and PRF decreased the cytokine-induced expression of interleukin 6 (IL6) and nitric oxide synthase (iNOS) in the bone marrow-derived ST2 cells. Consistently, PPP, BC, and PRF greatly decreased the phosphorylation and nuclear translocation of p65 in ST2 cells. The inflammatory response caused by Pam3CSK4 was reduced accordingly. Moreover, PPP, BC, and PRF reduced the enhanced expression of inflammatory mediators IL6 and iNOS in 3T3-L1 pre-adipocyte mesenchymal cells, and iNOS and CCL5 in murine calvarial cells. Surprisingly, PRF lysates were not effective in reducing the inflammatory response of human gingival fibroblasts and HSC2 epithelial cells. The data from the present study suggest that both liquid PRF and solid PRF exert potent anti-inflammatory activity in murine mesenchymal cells.

Effectiveness of treating segmental bone defects with a synergistic co-delivery approach with platelet-rich fibrin and tricalcium phosphate

Several studies have applied tricalcium phosphate (TCP) or autografts in bone tissue engineering to enhance the clinical regeneration of bone. Unfortunately, there are several drawbacks related to the use of autografts, including a risk of infection, blood loss, limited quantities, and donor-site morbidities. Platelet-rich fibrin (PRF) is a natural extracellular matrix (ECM) biomaterial that possesses bioactive factors, which can generally be used in regenerative medicine. The goal of the present investigation was to develop osteoconductive TCP incorporated with bioactive PRF for bio-synergistic bone regeneration and examine the potential biological mechanisms and applications. Our in vitro results showed that PRF plus TCP had excellent biosafety and was favorable for initiating osteoblast cell attachment, slow release of bioactive factors, cell proliferation, cell migration, and ECM formation that potentially impacted bone repair. In a rabbit femoral segmental bone defect model, regeneration of bone was considerably augmented in defects locally implanted by PRF plus TCP according to radiographic and histologic examinations. Notably, the outcomes of this investigation suggest that the combination of PRF and TCP possesses novel synergistic and bio-inspired functions that facilitate bone regeneration.

Management of internal inflammatory root resorption using injectable platelet-rich fibrin revascularization technique: a clinical study with cone-beam computed tomography evaluation

OBJECTIVES

The current study evaluated clinically and radiographically the management of internal inflammatory root resorption (IIRR) in permanent anterior teeth with or without periapical lesions using injectable platelet-rich fibrin (i-PRF) regenerative approach.

METHODS

Ten systemically healthy patients, with thirteen anterior mature teeth diagnosed with IIRR were selected for the study. At the first visit, the tooth was anesthetized, access cavity opened, root canals were mechanically prepared then medicated with calcium hydroxide and temporarily sealed. After 2-4 weeks, regenerative endodontic procedures were performed by preparing and applying i-PRF inside the canal, then a freshly prepared PRF membrane was placed over it. White mineral trioxide aggregate was placed over the PRF matrix, and the tooth was restored with a glass ionomer cement base and resin composite restoration. The patients were recalled for clinical and radiographic evaluation and follow-up every 3 months for 12 months. Cone-beam computed tomography (CBCT) imaging was performed preoperatively and after 12 months.

RESULTS

Clinical evaluation results showed resolution of signs and symptoms through the follow-up period in all of the cases. Both CBCT imaging readings of IIRR lesions and periapical lesions revealed a volumetric significant difference (p = 0.00) between the preoperative and the 12-month follow-up period.

CONCLUSIONS

Usage of i-PRF could arrest and allow for healing of IIRR in permanent mature teeth and allow for periapical healing with successful clinical results.

CLINICAL RELEVANCE

i-PRF revascularization technique proved to be a successful REP in the treatment of the IIRR, reducing the number of appointments and increasing patient compliance.

Microstructural features of subchondral radiolucent lesions in the medial femoral condyle of juvenile Thoroughbreds: A microcomputed tomography and histological analysis

BACKGROUND

The aetiology of equine medial femoral condyle (MFC) subchondral bone radiolucencies (SR) is unknown.

OBJECTIVES

Characterise the microstructural structural features of MFC SR in juvenile Thoroughbreds with microcomputed tomography (μCT) and histology.

STUDY DESIGN

Cross-sectional post-mortem study.

METHODS

Distal femurs were collected at post-mortem. Conventional tomodensitometry was employed to scout for MFCs with and without SR lesions (SR+ and SR-, respectively). Group 1 were CT MFC SR+ and Group 2 age-matched SR- controls. Both underwent μCT and histological analysis. Group 3 CT MFC SR- foals, <6 months, were selected to search for chondronecrosis. Histological sections, processed from the lesion (Group 1) and a corresponding site in Groups 2 and 3, were assessed for chondronecrosis, fibrin, fibroplasia and osteochondral separation. Group 3 sections were surveyed for chondronecrosis alone.

RESULTS

A total of 178 femurs from 89 Thoroughbreds were harvested. Of these horses 19.1% (95% CI: 10.9%-27.3%) were CT MFC SR+ (17/23; 7.46 ± 4.36 months) and met the inclusion criteria for Group 1. Group 2 included 30 CT MFC SR- specimens (5.00 ± 2.73 months) and Group 3 had 44 CT MFC SR- s (2.68 ± 1.74 months). SR were located axially in foals <7 months of age, and centrally thereafter. All SRs had areas of thickened cartilage on histology and separation at the osteochondral junction containing fibrin (acute event) and fibroplasia (chronicity) in 73.9% (17/23; 95% CI: 56%-91.9%). In Group 1 specimens, chondronecrosis was present in 82.6% (19/23; 95% CI: 67.1%-98.1%) but four MFC SR+ had no evidence of chondronecrosis. Chondronecrosis was not detected in the Group 3 foal MFCs.

MAIN LIMITATIONS

No longitudinal follow-up.

CONCLUSIONS

The absence of chondronecrosis, pathognomic of osteochondrosis, in four MFC SR+s and in all of the CT MFC SR- foals suggests that osteochondrosis is not the cause, or the only cause, of these lesions and favours trauma as an alternate aetiological hypothesis.

Effect of different platelet-rich fibrin matrices for ridge preservation in multiple tooth extractions: A split-mouth randomized controlled clinical trial

AIM

To evaluate dimensional changes in the alveolar ridge and bone structure after tooth extraction when L-PRF or A-PRF+ was used in comparison to unassisted socket healing.

MATERIALS AND METHODS

Twenty patients in need of at least three tooth extractions in the aesthetic zone were included. L-PRF, A-PRF+ or control was randomly assigned, leaving one empty socket/edentulous site between conditions. CBCT scans were obtained immediately after tooth extraction and after 3 months of healing. Horizontal and vertical dimensional changes of the ridge and socket fill were calculated. Histological and micro-CT analysis of bone biopsies were used to evaluate post-surgical bone structural healing.

RESULTS

Mean horizontal and vertical changes at 1-mm below the crest (buccal and palatal side) were similar for the three sites (p > 0.05). For the socket fill, L-PRF (85.2%) and A-PRF+ (83.8%) showed superior values than the control (67.9%). The histological and radiological analysis reported more newly formed bone for the PRF groups, without any significant differences between both.

CONCLUSIONS

PRF matrices failed to reduce the dimensional changes after multiple tooth extractions in the premaxilla. After 3-month healing, both PRF matrices showed radiographically a significant superiority for the socket fill. Histologically, they seemed to accelerate new bone formation.

Liquid PRF Reduces the Inflammatory Response and Osteoclastogenesis in Murine Macrophages

Macrophage activation and osteoclastogenesis are hallmarks of inflammatory osteolysis and may be targeted by the local application of liquid platelet-rich fibrin (PRF). Liquid PRF is produced by a hard spin of blood in the absence of clot activators and anticoagulants, thereby generating an upper platelet-poor plasma (PPP) layer, a cell-rich buffy coat layer (BC; termed concentrated-PRF or C-PRF), and the remaining red clot (RC) layer. Heating PPP has been shown to generate an albumin gel (Alb-gel) that when mixed back with C-PRF generates Alb-PRF having extended working properties when implanted in vivo. Evidence has demonstrated that traditional solid PRF holds a potent anti-inflammatory capacity and reduces osteoclastogenesis. Whether liquid PRF is capable of also suppressing an inflammatory response and the formation of osteoclasts remains open. In the present study, RAW 264.7 and primary macrophages were exposed to lipopolysaccharides (LPS), lactoferrin, and agonists of Toll-like receptors (TLR3 and TLR7) in the presence or absence of lysates prepared by freeze-thawing of liquid PPP, BC, Alb-gel, and RC. For osteoclastogenesis, primary macrophages were exposed to receptor activator of nuclear factor kappa B ligand (RANKL), macrophage colony-stimulating factor (M-CSF), and human transforming growth factor-β1 (TGF-β1) in the presence or absence of PPP, BC, Alb-gel, RC lysates and hemoglobin. We show here that it is mainly the lysates prepared from PPP and BC that consistently reduced the agonist-induced expression of interleukin 6 (IL6) and cyclooxygenase-2 (COX2) in macrophages, as determined by RT-PCR and immunoassay. With respect to osteoclastogenesis, lysates from PPP and BC but also from RC, similar to hemoglobin, reduced the expression of osteoclast marker genes tartrate-resistant acid phosphatase (TRAP) and cathepsin K, as well as TRAP histochemical staining. These findings suggest that liquid PRF holds a potent in vitro heat-sensitive anti-inflammatory activity in macrophages that goes along with an inhibition of osteoclastogenesis.

Treatment of periodontal intrabony defects using bovine porous bone mineral and guided tissue regeneration with/without platelet-rich fibrin: a randomized controlled clinical trial

BACKGROUND

To investigate the regenerative effect of adjunctive use of guided tissue regeneration (GTR), bovine porous bone mineral (BPBM), and platelet-rich fibrin (PRF) in intrabony defects.

METHODS

Fourteen participants were enrolled, and for each patient their left and right two sides were randomized to the test group or control group. Only the worst intrabony defect on each side was analyzed. The test group received GTR, BPBM, and PRF, whereas the control group received only GTR and BPBM. The PRF used in the trial was fluid PRF, which combined with the BPBM to form a BPBM-PRF complex. The patients were followed up by clinical and radiographic evaluation for 24 months after surgery.

RESULTS

Probing depth (PD) in the test group was significantly less than that in the control group at 12 and 24 months after surgery, and the mean difference was ≈ 0.5 to 0.7 mm. Clinical attachment level (CAL) gain in the test group was ≈ 0.9 mm higher than that in the control group at 6 months after surgery, and the difference reached 1.0 to 1.1 mm 12 and 24 months after surgery. None of the other clinical or radiographic parameters differed significantly between the two groups at any time-point after the surgery.

CONCLUSION

Compared with GTR and BPBM, the combination of GTR and BPBM-PRF complex is more effective clinically, and results in better clinical outcomes.

A clinical and radiographic study of implants placed in autogenous bone grafts covered by either a platelet-rich fibrin membrane or deproteinised bovine bone mineral and a collagen membrane: a pilot randomised controlled clinical trial with a 2-year follow-up

Purpose

To compare the survival and clinical performance of implants placed in sites previously augmented with autogenous bone grafts covered by either a platelet-rich fibrin (PRF) membrane (PRF group) or a standard procedure (gold standard) involving coverage of the autogenous bone graft with deproteinised bovine bone mineral and a resorbable collagen membrane (control group).

Methods

A total of 27 partially edentulous patients (test n = 14, control n = 13) with indication for staged lateral bone block augmentation and dental implant placement were included. Twenty-four months after crown placement (range: 14–32 months), patients were recalled for a final clinical and radiographic follow-up. Outcome measures were implant survival, implant crown survival, clinical parameters of the implant, peri-implant marginal bone level, marginal bone level of adjacent tooth surfaces, biological and technical complications and patient-related outcome measures.

Results

Two implants were lost in the control group (85% survival rate); none were lost in the PRF group (100% survival rate). None of the 26 initially placed implant crowns were lost, but one implant and therefore one implant crown were lost after 20 months. Consequently, the definitive implant crown survival was 92% (95% confidence interval (CI): 73–110%) in the control group and 100% in the PRF group. No statistical difference in implant survival rate (p = 0.13) or implant crown survival was seen between the groups (p = 0.28). The mean marginal bone level at the follow-up was 0.26 mm (95% CI: 0.01–0.50 mm) in the PRF group and 0.68 mm (95% CI: 0.41–0.96 mm) in the control group. The difference between the groups was − 0.43 mm (95% CI: − 0.80 to − 0.05 mm, p = 0.03), which was statistically significant (p = 0.03). Both groups demonstrated similar healthy peri-implant soft tissue values at the final follow-up.

Conclusion

Although the current study is based on a small sample of participants, the findings suggest that the methodology of the PRF and the control group approach can both be used for bone augmentation with a similar outcome. A significant, but clinically irrelevant, higher peri-implant marginal bone level was registered in the PRF group than in the control group. Patients in both groups were highly satisfied with the treatment.

Trial registration

ClinicalTrials.gov Identifier: NCT04350749. Registered 17 April 2020. Retrospectively registered.

Relative Centrifugal Force (RCF; G-Force) Affects the Distribution of TGF-β in PRF Membranes Produced Using Horizontal Centrifugation

Solid platelet-rich fibrin (PRF) is produced with centrifugation tubes designed to accelerate clotting. Thus, activated platelets may accumulate within the fibrin-rich extracellular matrix even before centrifugation is initiated. It can thus be assumed that platelets and their growth factors such as transforming growth factor-β (TGF-β) are trapped within PRF independent of their relative centrifugal force (RCF), the gravitation or g-force. To test this assumption, we prepared PRF membranes with tubes where clotting is activated by a silicone-coated interior. Tubes underwent 210 g, 650 g and 1500 g for 12 min in a horizontal centrifuge. The respective PRF membranes, either in total or separated into a platelet-poor plasma and buffy coat fraction, were subjected to repeated freeze-thawing to prepare lysates. Gingival fibroblasts were exposed to the PRF lysates to provoke the expression of TGF-β target genes. We show here that the expression of interleukin 11 (IL11) and NADPH oxidase 4 (NOX4), and Smad2/3 signaling were similarly activated by all lysates when normalized to the size of the PRF membranes. Notably, platelet-poor plasma had significantly less TGF-β activity than the buffy coat fraction at both high-speed protocols. In contrast to our original assumption, the TGF-β activity in PRF lysates produced using horizontal centrifugation follows a gradient with increasing concentration from the platelet-poor plasma towards the buffy coat layer.

Effect of melatonin versus injectable platelet rich fibrin on critical wound healing in submandibular salivary glands of diabetic rats

Background

Diabetes mellitus (DM) has harmful effects on body organs, including submandibular salivary glands (SMGs). It impairs wound healing process that follow sialoadenectomy. Yet there is no complete cure to diabetes, the available medications tend to control the side effects of DM or manage insulin resistance. Herein we tried to investigate the possible effects of injectable platelet rich fibrin (i-PRF) and melatonin on wound healing in diabetic rats.

Material and methods

Surgical defects were created in SMGs of 30 rats after confirmation of DM induction. Then rats were randomly and equally allocated into three groups. Group I served as control group; group II received topically applied i-PRF, and group III received topically administrated melatonin. After 28 days all rats were euthanized, and SMGs were processed for histological and biochemical analysis.

Results

Both i-PRF and melatonin caused significant reduction of malondialdehyde (P < 0.0001) and caspase-3 (P < 0.001) and significant increase in vascular endothelial growth factors (P = 0.001,0.009 respectively) that increased SMGs regenerative capacity when compared to diabetic group. Melatonin showed superior results regarding the histomorphological structure of SMGs.

Conclusion

Melatonin and i-PRF can be possible candidates for improvement of wound healing events in SMGs of diabetic rats.

Platelet-Rich Fibrin Can Neutralize Hydrogen Peroxide-Induced Cell Death in Gingival Fibroblasts

Hydrogen peroxide is a damage signal at sites of chronic inflammation. The question arises whether platelet-rich fibrin (PRF), platelet-poor plasma (PPP), and the buffy coat can neutralize hydrogen peroxide toxicity and thereby counteract local oxidative stress. In the present study, gingival fibroblasts cells were exposed to hydrogen peroxide with and without lysates obtained from PRF membranes, PPP, heated PPP (75 °C for 10 min), and the buffy coat. Cell viability was examined by trypan blue staining, live-dead staining, and formazan crystal formation. Cell apoptosis was assessed by cleaved caspase-3 Western blot analysis. Reverse transcription-quantitative polymerase chain reaction (RT-PCR) was utilized to determine the impact of PRF lysates on the expression of catalase in fibroblasts. It was reported that lysates from PRF, PPP, and the buffy coat—but not heated PPP—abolished the hydrogen peroxide-induced toxicity in gingival fibroblasts. Necrosis was confirmed by a loss of membrane integrity and apoptosis was ruled out by the lack of cleavage of caspase-3. Aminotriazole, an inhibitor of catalase, reduced the cytoprotective activity of PRF lysates yet blocking of glutathione peroxidase by mercaptosuccinate did not show the same effect. PRF lysates had no impact on the expression of catalase in gingival fibroblasts. These findings suggest that PRF, PPP, and the buffy coat can neutralize hydrogen peroxide through the release of heat-sensitive catalase.

TGFβ activity released from platelet-rich fibrin adsorbs to titanium surface and collagen membranes

Platelet-rich fibrin (PRF) contains a broad spectrum of bioactive molecules that can trigger several cellular responses. However, these molecules along with their upstream responses remain mostly uninvestigated. By means of proteomics we revealed that PRF lysates contain more than 650 proteins, being TGF-β one of the few growth factors found. To uncover the major target genes regulated by PRF lysates, gingival fibroblasts were exposed to lysates obtained from PRF membranes followed by a whole genome array. We identified 51 genes strongly regulated by PRF including IL11, NOX4 and PRG4 which are characteristic TGF-β target genes. RT-PCR and immunoassay analysis confirmed the TGF-β receptor I kinase-dependent increased expression of IL11, NOX4 and PRG4. The PRF-derived TGF-β activity was verified by the translocation of Smad2/3 into the nucleus along with the increased phosphorylation of Smad3. Considering that PRF is clinically used in combination with dental implants and collagen membranes, we showed here that PRF-derived TGF-β activity adsorbs to titanium implants and collagen membranes indicated by the changes in gene expression and immunoassay analysis. Our study points towards TGF-β as major target of PRF and suggest that TGF-β activity released by PRF adsorbs to titanium surface and collagen membranes

Histology of augmented autogenous bone covered by a platelet-rich fibrin membrane or deproteinized bovine bone mineral and a collagen membrane: A pilot randomized controlled trial

OBJECTIVES

This study aimed to evaluate histologic and histomorphometric bone characteristics with a focus on vitality after lateral alveolar ridge augmentation using an autogenous bone graft as a block covered by either a platelet-rich fibrin (PRF) membrane (test group) or a standard procedure involving coverage of the bone block with a deproteinized bovine bone mineral and a resorbable collagen membrane (control group).

MATERIAL AND METHODS

A total of 27 (test = 14, control = 13) partially edentulous patients with indication for bone block augmentation before implant installation were included. For analyses, a biopsy of augmented bone was retrieved six months after bone grafting.

RESULTS

Histologic evaluation of augmented bone revealed a predominance of non-vital bone toward the periosteum and few localized areas of vital bone in the center of the graft in both groups. In contrast, augmented bone toward the native bone demonstrated extensive bone remodeling in both groups. Histomorphometric analyses demonstrated a mean of 14% vital bone, 80% non-vital bone, 5% soft tissue, and 1% blood vessels in the test group. In the control group, the corresponding shares were 14% vital bone, 63% non-vital bone, 22% soft tissue, and 1% blood vessels. We observed no significant differences between the groups (p > .05).

CONCLUSION

In conclusion, a comparable low bone vitality of augmented bone was observed in the PRF and in the control group. Consequently, the present study could not verify the potential beneficial effect of a PRF membrane on bone vitality of an autogenous bone graft used as a block.

Effect of platelet-rich fibrin on cell proliferation, migration, differentiation, inflammation, and osteoclastogenesis: a systematic review of in vitro studies

Objective

To systematically assess the effects of platelet-rich fibrin (PRF) on in vitro cellular behavior.

Methods

A systematic electronic search using MEDLINE database was performed. In vitro studies using PRF were considered and articles published up to June 31, 2018 were screened. Eligible studies were selected based on the use of human PRF.

Results

In total, 1746 titles were identified with the search terms, from these 37 met the inclusion criteria and were chosen for data extraction. In addition, 16 new studies, mainly published in 2019, were also included in the analysis resulting in 53 studies. No meta-analysis could be performed due to the heterogeneity of study designs. Included studies show that PRF enhances proliferation, migration, adhesion, and osteogenic differentiation on a variety of cell types along with cell signaling activation. Furthermore, PRF reduces inflammation, suppresses osteoclastogenesis, and increases the expression of various growth factors in mesenchymal cells.

Summary and conclusions

Despite some notable differences of the studies, the overall findings suggest a positive effect of PRF on cell proliferation, migration, adhesion, differentiation, and inflammation pointing towards a therapeutic potential in regenerative dentistry.

Clinical relevance

PRF serves as a reservoir of bioactive molecules to support wound healing and bone regeneration. Although the cellular mechanisms by which PRF supports the clinical outcomes remain unclear, in vitro research provides possible explanations. This systematic review aims to provide an update of the existing research on how PRF affects basic physiological processes in vitro. The overall findings suggest that PRF induces cell proliferation, migration, adhesion, and differentiation along with possessing anti-inflammatory properties further supporting its therapeutic potential in wound healing and bone regeneration.

Platelet-rich fibrin suppresses in vitro osteoclastogenesis

Background

Platelet‐rich fibrin (PRF) membranes can preserve alveolar ridge dimension after tooth extraction. Thus, it can be presumed that PRF suppresses the catabolic events that are caused by osteoclastic bone resorption.

Methods

To address this possibility, we investigated the impact of soluble extracts of PRF membranes on in vitro osteoclastogenesis in murine bone marrow cultures. Osteoclastogenesis was induced by exposing murine bone marrow cultures to receptor activator of nuclear factor kappa B ligand (RANKL), macrophage colony‐stimulating factor (M‐CSF) and transforming growth factor‐beta 1 (TGF‐β1) in the presence or absence of PRF. Osteoclastogenesis was evaluated based on histochemical, gene expression, and resorption analysis. Viability was confirmed by formation of formazan crystals, live‐dead staining and caspase‐3 activity assay.

Results

We report here that in vitro osteoclastogenesis is greatly suppressed by soluble extracts of PRF membranes as indicated by tartrate‐resistant acid phosphatase (TRAP) staining and pit formation. In support of the histochemical observations, soluble extracts of PRF membranes decreased expression levels of the osteoclast marker genes TRAP, Cathepsin K, dendritic cell‐specific transmembrane protein (DCSTAMP), nuclear factor of activated T‐cells (NFATc1), and osteoclast‐associated receptor (OSCAR). PRF membranes, however, cannot reverse the process once osteoclastogenesis has evolved.

Conclusion

These in vitro findings indicate that PRF membranes can inhibit the formation of osteoclasts from hematopoietic progenitors in bone marrow cultures. Overall, our results imply that the favorable effects of PRF membranes in alveolar ridge preservation may be attributed, at least in part, by the inhibition of osteoclastogenesis.

Anti-inflammation effects of injectable platelet-rich fibrin via macrophages and dendritic cells

Immune response to implantation materials plays a critical role during early local inflammation and biomaterial-induced regeneration or restoration. A novel platelet concentrate termed i-PRF (injectable platelet-rich fibrin) has recently been developed without any additives by low centrifugation speeds. To date, scientists have investigated the capability of releasing growth factors to improve regeneration but have ignored whether i-PRF can inhibit the inflammatory effect around the wound. The present study investigated the anti-inflammation effects of i-PRF on immune response-related cells, especially macrophages and dendric cells. We found that i-PRF reduced pro-inflammatory M1 phenotype of macrophages and activated dendritic cells around muscle defect that was injected with bacterial suspension. Moreover, in vitro experiments showed similar results. i-PRF deleted inflammatory response caused by lipopolysaccharide to some extent. We determined that TLR4, an activator of inflammatory stimulation and p-p65, a key factor belongs to classical inflammatory related NF-κB signal pathway, can be inhibited by use of i-PRF. Results indicate the potential anti-inflammatory role of i-PRF during regeneration and restoration.