Combination of Controlled Release Platelet‐Rich Plasma Alginate Beads and Bone Morphogenetic Protein‐2 Genetically Modified Mesenchymal Stem Cells for Bone Regeneration

Background: Platelet‐rich plasma (PRP) consists of platelet‐derived growth factor and transforming growth factor‐β that increase proliferation of mesenchymal stem cells (MSCs), whereas bone morphogenetic protein‐2 (BMP2) promotes osteogenic differentiation of MSCs. However, the high degradation rate of fibrin leads to the dissociation of cytokines even before the process of bone regeneration begins. To the best of the authors’ knowledge, this is the first study to examine the combined effect of sustained release of PRP from alginate beads on BMP2‐modified MSC osteogenic differentiation in vitro and sustained release of PRP alone on a fracture defect model ex vivo as well as its effect on calvarial suture closure. Methods: After optimizing the alginate concentration for microspheres, the combined osteogenic and mineralization effect of PRP and BMP2 on MSCs was studied. Self‐setting alginate hydrogel carrying PRP was tested on a femur defect model ex vivo. The effect of PRP at day 15 on the closure of the embryonic mouse calvaria sutures ex vivo was also studied. Results: Increase of PRP concentration promoted proliferation of MSCs, and 2.5% to 10% of PRP gradually increased alkaline phosphatase (ALP) activity in the cells in a dose‐dependent manner. Sustained release of PRP and BMP2 demonstrated significantly higher ALP and mineralization activity (P <0.05). Radiographs of alginate hydrogel with PRP‐treated bone demonstrated nearly complete healing of the fracture, and histologic sections of the embryonic calvaria revealed that PRP leads to suture fusion. Conclusion: Sustained release of PRP along with BMP2‐modified MSCs can significantly promote bone regeneration.     

Insulin‐like growth factor‐binding protein‐2 and ‐3 in gingival crevicular fluid

Takenouchi Y, Ohshima M, Yamaguchi Y, Nishida T, Senda N, Idesawa M, Otsuka K, Ito K. Insulin‐like growth factor‐binding protein‐2 and ‐3 in gingival crevicular fluid. J Periodont Res 2010; 45: 803–808. © 2010 John Wiley & Sons A/S Background and Objective: Insulin‐like growth factor‐binding proteins (IGFBPs) are crucial regulators of insulin‐like growth factor (IGF). They enhance or inhibit IGF functions, but also exhibit IGF‐independent effects. In a previous study, we detected, qualitatively, IGFBP‐2 and ‐3 in gingival crevicular fluid using a cytokine antibody array. Here we extended these results using an ELISA to determine the concentrations of IGFBP‐2 and ‐3 in gingival crevicular fluid. In addition, we explored whether the expression of IGFBP‐2 and IGFBP‐3 correlates with periodontal disease severity. Material and Methods: Gingival crevicular fluid samples from 92 sites of 12 patients affected with periodontal disease and from 100 sites of 19 healthy volunteers, were collected, divided into two groups and analyzed by ELISA for IGFBP‐2 and ‐3 expression. The potential correlation among probing depth, gingival index and the concentrations of IGFBP‐2 and ‐3 was analyzed. Results: Positive correlations were observed between the concentration of IGFBP‐2 and probing depth and gingival index, but not for IGFBP‐3. The IGFBP‐2 concentrations at bleeding on probing‐positive sites and at sites with a probing depth of ≥ 4 mm were higher than at bleeding on probing‐negative sites and at sites with a probing depth of ≤ 3 mm. Conclusion: These results indicate that IGFBP‐2 is a potential novel marker for periodontal disease progression. As IGFBP‐2 modulates bone metabolism and cell migration, IGFBP‐2 in the gingival crevicular fluid may reflect periodontal disease activity.     

Comparative Evaluation of Autologous Platelet‐Rich Fibrin and Platelet‐Rich Plasma in the Treatment of 3‐Wall Intrabony Defects in Chronic Periodontitis: A Randomized Controlled Clinical Trial

Background: The topical use of platelet concentrates is recent, and its efficiency remains controversial. The present study aims to explore the clinical and radiographic effectiveness of autologous platelet‐rich fibrin (PRF) and platelet‐rich plasma (PRP) in the treatment of intrabony defects in patients with chronic periodontitis. Methods: Ninety intrabony defects were treated with either autologous PRF with open‐flap debridement or autologous PRP with open‐flap debridement or open‐flap debridement alone. Clinical and radiologic parameters, such as probing depth (PD), clinical attachment level (CAL), intrabony defect depth, and percentage defect fill, were recorded at baseline and 9 months postoperatively. Results: Mean PD reduction and CAL gain were greater in PRF (3.77 ± 1.19 and 3.17 ± 1.29 mm) and PRP (3.77 ± 1.07 and 2.93 ± 1.08 mm) groups than the control group (2.97 ± 0.93 and 2.83 ± 0.91 mm). Furthermore, significantly greater percentage of mean bone fill was found in the PRF (55.41% ± 11.39%) and PRP (56.85% ± 14.01%) groups compared with the control (1.56% ± 15.12%) group. Conclusions: Within the limit of the present study, there was similar PD reduction, CAL gain, and bone fill at sites treated with PRF or PRP with conventional open‐flap debridement. Because PRF is less time consuming and less technique sensitive, it may seem a better treatment option than PRP. However, long‐term, multicenter randomized, controlled clinical trials will be required to know their clinical and radiographic effects on bone regeneration.     

Antimicrobial Activity of Platelet‐Rich Plasma and Other Plasma Preparations Against Periodontal Pathogens

Background: In addition to releasing a pool of growth factors during activation, platelets have many features that indicate their role in the anti‐infective host defense. The antimicrobial activities of platelet‐rich plasma (PRP) and related plasma preparations against periodontal disease–associated bacteria were evaluated. Methods: Four distinct plasma fractions were extracted in the formulation used commonly in dentistry and were tested for their antibacterial properties against three periodontal bacteria: Porphyromonas gingivalis, Aggregatibacter actinomycetemcomitans, and Fusobacterium nucleatum. The minimum inhibitory concentration of each plasma preparation was determined, and in vitro time‐kill assays were used to detect their abilities to inhibit bacterial growth. Bacterial adhesion interference and the susceptibility of bacterial adherence by these plasma preparations were also conducted. Results: All plasma preparations can inhibit bacterial growth, with PRP showing the superior activity. Bacterial growth inhibition by PRP occurred in the first 24 hours after application in the time‐kill assay. PRP interfered with P. gingivalis and A. actinomycetemcomitans attachment and enhanced exfoliation of attached P. gingivalis but had no influences on F. nucleatum bacterial adherence. Conclusions: PRP expressed antibacterial properties, which may be attributed to platelets possessing additional antimicrobial molecules. The application of PRP on periodontal surgical sites is advisable because of its regenerative potential and its antibacterial effects.     

Crevicular Fluid Growth Factors Release Profile Following the Use of Platelet‐Rich Fibrin and Plasma Rich Growth Factors in Treating Periodontal Intrabony Defects: A Randomized Clinical Trial

Background: The open, usually contaminated nature of periodontal defects could negatively affect availability and activity of platelet concentrate–suggested growth factors (GF). The aim of this study is to test this hypothesis and investigate concentrations of: 1) vascular endothelial growth factor (VEGF) and 2) platelet‐derived growth factor (PDGF‐BB) in gingival crevicular fluid (GCF) from localized intrabony defects treated with platelets rich in growth factors (PRGF) or platelet‐rich fibrin (PRF) compared with a control xenograft defect filling. Methods: Thirty non‐smoking patients suffering severe chronic periodontitis were allocated to this randomized, prospective, single‐masked trial. Each patient had one interproximal defect randomly distributed to: 1) group 1: bone‐substitute grafting control (n = 10); 2) group 2: experimental PRGF (n = 10); or 3) group 3: PRF (n = 10). Clinical parameters were measured at baseline and 6 and 9 months following therapy. GCF samples were obtained on days 1, 3, 7, 14, 21, and 30 after therapy for evaluation of VEGF and PDGF‐BB levels. Results: On days 1, 3, and 7 following surgery, mean levels of VEGF and PDGF‐BB at sites treated with PRGF and PRF were not significantly different versus the control. Levels of PDGF‐BB and VEGF were higher in the PRGF‐treated group, but differences were not significant. Growth factor levels decreased significantly in samples collected on days 14, 21, and 30 with non‐significant differences among the three groups. No significant clinical differences were reported among the three groups during the two observation periods (early period: days 1, 3, and 7; and later period: days 14, 21, and 30). Conclusions: Within the limits of the present study, it can be concluded that PRF and PRGF platelet concentrate failed to augment clinical effects achieved with the xenograft alone in treating intrabony defects. Periodontal defects could not retain extraphysiologic levels of GF suggested to be associated with platelet concentrate.     

富血小板血浆对人真皮细胞增殖及PDGF、TGF-β和VEGF表达的影响

目的:研究富血小板血浆(PRP)对人真皮成纤维细胞(hFbs)增殖、分化及胞质中PDGF、TGF-β和VEGF表达量的影响。方法:2次离心法制备PRP,成骨诱导条件下hFbs培养液中加入不同浓度PRP于第12天、21天钙-钴法染色,第21天茜素红染色;免疫细胞化学法检测加不同浓度PRP后第4天细胞PDGF、TGF-β和VEGF的表达;碱性磷酸酶染色(ALP)检测细胞活性;CCK-8法检测有和无成骨诱导条件下不同浓度PRP对细胞增殖的影响。结果:茜素红染色显示,2.8%PRP组钙结节形成最明显;钙-钴法染色显示,2.8%PRP组矿化作用最强;免疫细胞化学结果表明PDGF表达存在剂量依赖性,TGF-β和VEGF表达虽无剂量依赖性,但有适宜浓度的要求;ALP染色表明3%PRP组细胞增殖明显,活性最强。CCK-8检测表明各浓度PRP对hFbs均有促增殖作用,PRP加成骨诱导组比单纯PRP组表现出更明显的促增殖作用,其中4.8%PRP促增殖作用最强。结论:适宜浓度的PRP可促进hFbs增殖,但相关因子的表达存在适宜浓度的要求,PRP通过促进细胞增殖,增加相关因子表达促进创伤愈合。     

Activation of human platelet-rich plasmas: effect on growth factors release, cell division and in vivo bone formation

OBJECTIVES: Aims of this controlled study were to determine the effects of activated human platelet-rich plasmas (PRPs) on early and mature bone formation in vivo, and to characterize the effect of PRP activation on growth factors release and endothelial cell division in vitro. MATERIAL AND METHODS: PRPs were prepared from four volunteers with the platelet concentrate collector system (PCCS) system and activated with three concentrations of calcium and thrombin. Platelet-derived growth factor (PDGF)-BB, vascular endothelial growth factor (VEGF), transforming growth factor beta (TGF-beta) and interleukin-1beta (IL-1beta) levels released in supernatants were measured by ELISA, at time 0, 1h, 24h and 6 days following PRP activation. Mitogenic potential of PRP supernatants were tested on endothelial cells in vitro, and the effects of activated human PRPs on bone formation in vivo were measured in athymic rats by micro-CT analyses. RESULTS: Activation of PRPs with calcium and thrombin triggered an immediate release of VEGF, PDGF-BB and TGF-beta and a delayed release of IL-1beta in PRP supernatants. Higher endothelial cell division was observed with supernatants from activated PRPs than from non-activated PRPs. Positive correlations were observed between VEGF levels and endothelial cell division and bone formation. A negative correlation was also found between PDGF-BB concentration and bone formation. However, early and mature bone formations with activated PRPs did not significantly differ from the ones obtained in the control group. CONCLUSIONS: Activation of PRPs with calcium and thrombin regulates growth factors release and endothelial cell division in vitro. However, activated PRPs does not improve the early or mature bone formations in vivo in this athymic rat model.     

Epidermal growth factor released from platelet-rich plasma promotes endothelial cell proliferation in vitro

Bertrand‐Duchesne M‐P, Grenier D, Gagnon G. Epidermal growth factor released from platelet‐rich plasma promotes endothelial cell proliferation in vitro. J Periodont Res 2009; doi: 10.1111/j.1600‐0765.2009.01205.x. © 2009 The Authors. Journal compilation © 2009 Blackwell Munksgaard Background and Objective: The therapeutic benefits of platelet‐rich plasma (PRP) for the promotion of healing and regeneration of periodontal tissues are thought to result from enrichment in growth factors released from platelets. The aim of this study was to evaluate the effects of specific growth factors released from PRP on endothelial cell proliferation. Material and Methods: The levels of vascular endothelial growth factor (VEGF), platelet‐derived growth factor BB (PDGF‐BB), basic fibroblast growth factor (bFGF) and epidermal growth factor (EGF) in supernatants of calcium‐ and thrombin‐activated PRP samples from five donors were quantified by enzyme‐linked immunosorbent assay. Supernatants were treated with neutralizing antibodies specific to each growth factor, and the effects of these treatments on human umbilical vein endothelial cell (HUVEC) proliferation in vitro were determined. The effect of removing EGF from PRP supernatants with antibody‐coated beads on HUVEC proliferation was also tested. Results: Average concentrations of VEGF, PDGF‐BB, bFGF and EGF in PRP supernatants were 189, 27,190, 39.5 and 513 pg/mL, respectively. The addition of EGF neutralizing antibodies to the PRP supernatants significantly reduced HUVEC proliferation (up to 40%), while such an inhibition was not observed following neutralization of the other growth factors. Removal of EGF from PRP supernatants by treatment with antibody‐coated beads also resulted in a significant decrease in HUVEC proliferation. Recombinant EGF increased HUVEC proliferation in vitro in a dose‐dependent manner. Conclusion: This study showed that PRP supernatants are highly mitogenic for endothelial cells and provided evidence that this effect may be due, at least in part, to the presence of EGF. In vivo experiments are needed to confirm the roles of specific growth factors released from PRP in the healing of oral surgical and/or periodontal wounds.     

Platelet‐Rich Plasma Derived From Bone Marrow Aspirate Promotes New Cementum Formation

Background: This study evaluates the influence of platelet‐rich plasma derived from bone marrow aspirate (PRP‐BMA) on the healing of periodontal fenestration defects in rats. Methods: Periodontal fenestration defects were surgically created in the mandibles of 40 rats. The animals were randomly divided into two groups, control and PRP‐BMA, in which defects were filled with blood clot or PRP‐bma, respectively. Animals were euthanized at either 10 or 30 days post‐surgery. Histologic, histometric, and immunohistochemical analyses were performed. Percentage of new bone area (NBA), area of bone trabeculae (ABT), new cementum (NC), and extension of remaining defect were histometrically evaluated. Proliferating cell nuclear antigen (PCNA), bone sialoprotein (BSP), osteocalcin (OCN), and tartrate‐resistant acid phosphatase (TRAP) immunohistochemical staining were performed. Immunolabeled cells were quantified. Data were statistically analyzed (analysis of variance; Tukey, P <0.05). Results: At 10 days, control and PRP‐BMA groups presented similar amounts of NBA and ABT; NC formation was not observed. At 30 days, control and PRP‐BMA groups presented similar amounts of NBA and ABT; the PRP‐BMA group showed NC formation with collagen fibers inserted obliquely or perpendicularly to the root surface. NC formation was not observed in any control group specimen. PRP‐ BMA presented higher numbers of PCNA‐positive and BSP‐positive cells than control at 10 and 30 days post‐surgery. No significant differences in the number of either OCN‐positive or TRAP‐positive cells were observed between groups at 10 or 30 days. Conclusion: PRP‐BMA promoted NC formation with a functional periodontal ligament when applied at experimental periodontal fenestration defects.     

Periodontal tissue engineering after tooth replantation

Background: Blood‐derived products, platelet‐poor plasma (PPP) and platelet‐rich plasma (PRP), constitute an approach in the enhancement of tissue healing. PRP has also been used as a scaffold for bone marrow stem cells in tissue engineering. This study evaluates the effect of PPP, calcium chloride–activated PRP (PRP/Ca), calcium chloride– and thrombin‐activated PRP (PRP/Thr/Ca), and bone marrow mononuclear cells and PRP/Ca (BMMCs/PRP/Ca) on the healing of replanted dog teeth. Methods: After 30 minutes of extraction, teeth were replanted with 1) no material (control); 2) PPP; 3) PRP/Ca; 4) PRP/Thr/Ca; or 5) BMMCs/PRP/Ca. Histologic, histomorphometric, and immunohistochemical analysis was assessed 120 days after replantation. Data from histomorphometric analysis were analyzed statistically (analysis of variance, Tukey; P <0.05). Quantitative immunohistochemical analysis was analyzed by Kruskal‐Wallis and Dunn post hoc test (P <0.05). Results: Flow cytometry analysis showed 55.98% of CD34⁺ and 32.67% of CD90/Thy‐1 for BMMCs sample. BMMCs/PRP/Ca presented the largest areas of replacement resorption characterized by osseous ingrowth into cementum (P <0.05), with intense immunomarcation for tartrate‐resistant acid phosphatase. The PRP/Ca group also showed areas of replacement resorption with significant immunomarcation for osteopontin. PRP/Thr/Ca presented no replacement resorption. PPP showed areas of inflammatory resorption, with immunomarcation for tartrate‐resistant acid phosphatase. Conclusions: The results suggest that platelets activated with thrombin play an important role in the healing of tissues after tooth replantation. Additional studies are necessary to test other materials, because PRP/Ca did not present an appropriate scaffold for undifferentiated cells in the treatment of avulsed teeth.     

Optimized Platelet‐Rich Fibrin With the Low‐Speed Concept: Growth Factor Release,Biocompatibility, and Cellular Response

Background: Over the past decade, use of leukocyte platelet‐rich fibrin (L‐PRF) has gained tremendous momentum in regenerative dentistry as a low‐cost fibrin matrix used for tissue regeneration. This study characterizes how centrifugation speed (G‐force) along with centrifugation time influence growth factor release from fibrin clots, as well as the cellular activity of gingival fibroblasts exposed to each PRF matrix. Methods: Standard L‐PRF served as a control (2,700 revolutions per minute [rpm]‐12 minutes). Two test groups using low‐speed (1,300 rpm‐14 minutes, termed advanced PRF [A‐PRF]) and low‐speed + time (1,300 rpm‐8 minutes; A‐PRF+) were investigated. Each PRF matrix was tested for growth factor release up to 10 days (eight donor samples) as well as biocompatibility and cellular activity. Results: The low‐speed concept (A‐PRF, A‐PRF+) demonstrated a significant increase in growth factor release of platelet‐derived growth factor (PDGF), transforming growth factor (TGF)‐β1, epidermal growth factor, and insulin‐like growth factor, with A‐PRF+ being highest of all groups. Although all PRF formulations were extremely biocompatible due to their autogenous sources, both A‐PRF and A‐PRF+ demonstrated significantly higher levels of human fibroblast migration and proliferation compared with L‐PRF. Furthermore, gingival fibroblasts cultured with A‐PRF+ demonstrated significantly higher messenger RNA (mRNA) levels of PDGF, TGF‐β, and collagen1 at either 3 or 7 days. Conclusions: The findings from the present study demonstrate modifications to centrifugation speed and time with the low‐speed concept favor an increase in growth factor release from PRF clots. This, in turn, may directly influence tissue regeneration by increasing fibroblast migration, proliferation, and collagen mRNA levels. Future animal and clinical studies are now necessary.     

Platelet‐Rich Plasma,Low‐Level Laser Therapy,or Their Combination Promotes Periodontal Regeneration in Fenestration Defects: A Preliminary In Vivo Study

Background: This study histomorphometrically analyzes the influence of platelet‐rich plasma (PRP), low‐level laser therapy (LLLT), or their combination on the healing of periodontal fenestration defects (PFDs) in rats. Methods: PFDs were surgically created in the mandibles of 80 rats. The animals were randomly divided into four groups: 1) C (control) and 2) PRP, defects were filled with blood clot or PRP, respectively; 3) LLLT and 4) PRP/LLLT, defects received laser irradiation, were filled with blood clot or PRP, respectively, and then irradiated again. Animals were euthanized at either 10 or 30 days post‐surgery. Percentage of new bone (NB), density of newly formed bone (DNB), new cementum (NC), and extension of remaining defect (ERD) were histomorphometrically evaluated. Data were statistically analyzed (analysis of variance; Tukey test, P <0.05). Results: At 10 days, group PRP presented ERD significantly lower than group C. At 30 days, group PRP presented NB and DNB significantly greater than group C. Groups LLLT, PRP, and PRP/LLLT showed significant NC formation at 30 days, with collagen fibers inserted obliquely or perpendicularly to the root surface. NC formation was not observed in any group C specimen. Conclusions: LLLT, PRP, or their combination all promoted NC formation with a functional periodontal ligament. The combination PRP/LLLT did not show additional positive effects compared to the use of either therapy alone.     

Platelet‐Derived Growth Factor Promotes Periodontal Regeneration in Localized Osseous Defects: 36‐Month Extension Results From a Randomized,Controlled, Double‐Masked Clinical Trial

Background: Recombinant human platelet‐derived growth factor (rhPDGF) is safe and effective for the treatment of periodontal defects in short‐term studies up to 6 months in duration. We now provide results from a 36‐month extension study of a multicenter, randomized, controlled clinical trial evaluating the effect and long‐term stability of PDGF‐BB treatment in patients with localized severe periodontal osseous defects. Methods: A total of 135 participants were enrolled from six clinical centers for an extension trial. Eighty‐three individuals completed the study at 36 months and were included in the analysis. The study investigated the local application of β‐tricalcium phosphate scaffold matrix with or without two different dose levels of PDGF (0.3 or 1.0 mg/mL PDGF‐BB) in patients possessing one localized periodontal osseous defect. Composite analysis for clinical and radiographic evidence of treatment success was defined as percentage of cases with clinical attachment level (CAL) ≥2.7 mm and linear bone growth (LBG) ≥1.1 mm. Results: The participants exceeding this composite outcome benchmark in the 0.3 mg/mL rhPDGF‐BB group went from 62.2% at 12 months, 75.9% at 24 months, to 87.0% at 36 months compared with 39.5%, 48.3%, and 53.8%, respectively, in the scaffold control group at these same time points (P <0.05). Although there were no significant increases in CAL and LBG at 36 months among all groups, there were continued increases in CAL gain, LBG, and percentage bone fill over time, suggesting overall stability of the regenerative response. Conclusion: PDGF‐BB in a synthetic scaffold matrix promotes long‐term stable clinical and radiographic improvements as measured by composite outcomes for CAL gain and LBG for patients possessing localized periodontal defects ( ClinicalTrials.gov no. CT01530126).     

Healing of Fresh Frozen Bone Allograft with or without Platelet‐Rich Plasma: A Histologic and Histometric Study in Rats

Purpose: This study histomorphometrically analyzed the effect of autogenous platelet‐rich plasma (PRP) on healing of fresh frozen bone allograft (FFBA) in bony defects in rat calvaria. Materials and Methods: A 5 mm–diameter defect was created in the calvarium of 30 rats. Animals were divided into three groups: C (defect was filled by blood clot only), FFBA (defect was filled with 0.01 mL of FFBA), and FFBA/PRP (defect was filled with 0.01 mL of FFBA combined with 100 µL of PRP). All animals were euthanized at 30 days postoperatively. Histomorphometry and histology analyses were performed. Data were statistically analyzed (analysis of variance, Tukey, p < .05). Results: FFBA had a statistically smaller new bone area than groups FFBA/PRP and C. No statistically significant differences were observed between groups FFBA and FFBA/PRP with regard to remaining bone graft particle area. Conclusion: It can be concluded that (1) PRP improved the incorporation of FFBA, increasing the amount of new bone formed; (2) PRP has not influenced the resorption of nonviable particles of the FFBA; and (3) presence of remaining FFBA particles might have accounted for the smaller amount of new bone observed in group FFBA when compared with control group.     

Treatment of intrabony periodontal defects with platelet-rich plasma versus platelet-poor plasma combined with a bovine-derived xenograft: a controlled clinical trial

Background: The purpose of this study is to assess the healing outcomes of intrabony defects after treatment with platelet‐rich plasma (PRP) versus platelet‐poor plasma (PPP) combined with bovine‐derived xenograft (BDX). Methods: Using a split‐mouth design, a total of 79 intrabony defects with an intrabony component of ≥3 mm in 20 patients were treated either with PRP/BDX (group 1) or PPP/BDX (group 2). At baseline and 12 months after surgery, plaque and sulcus bleeding indices, probing depth (PD), relative attachment level, recession, and probing and radiographic bone levels were recorded. Results: After 12 months, groups 1 and 2 presented a mean PD reduction of 3.87 ± 0.86 and 3.76 ± 0.80 mm, recession of 1.35 ± 0.68 and 1.58 ± 0.54 mm, attachment gain of 2.51 ± 0.97 and 2.18 ± 0.87 mm, clinical bone gain of 2.18 ± 0.86 and 2.09 ± 0.89 mm, and radiographic bone gain of 2.11 ± 0.87 and 2.19 ± 0.96 mm, respectively. Intergroup differences were found to be insignificant. Conclusions: Within its limits, these results suggest that the outcomes of the treatment after PRP/BDX and PPP/BDX applications in intrabony defects are similar. When the platelet counts are taken into consideration, PPP seems to demonstrate similar clinical efficacy as the PRP.     

Platelet‐Derived Growth Factor‐BB Release Profile in Gingival Crevicular Fluid After Use of Marginal Periosteal Pedicle Graft as an Autogenous Guided Tissue Membrane to Treat Localized Intrabony Defects

Background: The aim of this study is to evaluate levels of platelet‐derived growth factor‐BB (PDGF‐BB) in gingival crevicular fluid (GCF) during the early stages of healing for sites treated by marginal periosteal pedicle (MPP) graft as an autogenous guided tissue membrane compared to that of the control open flap debridement (OFD). Methods: Fifteen non‐smoking patients (13 males and 2 females) with severe chronic periodontitis participated in this prospective, controlled, masked trial. Each subject contributed matched pairs of 2‐ or 3‐walled intrabony interproximal defects in premolar or molar teeth. Interproximal contralateral defects were randomly assigned to either the MPP group 1 or control OFD group 2. GCF samples were collected at 1, 3, 7, 14, and 30 days after surgery. PDGF‐BB in the GCF samples was measured using a human PDGF‐BB enzyme‐linked immunosorbent assay kit. Results: In both MPP and OFD, PDGF‐BB concentrations peaked in the samples obtained during the early postoperative days (days 2 and 3) and decreased sharply in the samples obtained 7, 14, and 30 days post‐surgery. Conclusion: Periosteal coverage of periodontal defects is not associated with a significant increase in PDGF‐BB levels.     

Platelet‐Rich Plasma–Assisted Guided Bone Regeneration for Ridge Augmentation: A Randomized,Controlled Clinical Trial

Background: Platelet‐rich plasma (PRP) contains a number of biologically active growth factors, and previous studies have reported conflicting ridge augmentation results. The primary aim of this randomized, controlled, masked, clinical trial was to determine if PRP combined with a rapidly resorbing cancellous allograft would enhance the regenerative result compared with an allograft without PRP. Methods: Thirty‐two patients with an edentulous ridge defect were sequentially entered into the study; four were excluded from data analysis. Fourteen patients received a cancellous allograft (CAN group) and the other 14 received a cancellous allograft mixed with PRP (PRP group). All 28 grafted sites were covered with a resorbable polylactide membrane. After elevation of a full‐thickness flap, horizontal ridge dimensions were measured with a digital caliper at the crest and 5 mm apical to the crest. Vertical ridge dimensions were measured from a tooth‐supported stent. All sites were reentered at 4 months, and a trephine core was obtained for histologic analysis before implant placement. Results: The crestal ridge width for the CAN group had a mean gain of 2.0 ± 1.2 mm, whereas the PRP group gained 2.9 ± 1.0, and the difference was statistically significant between groups (P <0.05). The percent vital bone was 36% ± 14% for the CAN group compared with 51% ± 15% for the PRP group and was statistically significant between groups (P <0.05). Loss of augmented ridge width was 34% ± 17% for the CAN group and 28% ± 17% for the PRP group (P >0.05). Conclusion: These clinical and histologic findings suggest that PRP enhanced bone regeneration and resulted in increased horizontal bone gain and percentage vital bone.     

The Influence of PRP on Early Bone Formation in Membrane Protected Defects. A Histological and Histomorphometric Study in the Rabbit Calvaria

Background: Platelet rich plasma (PRP) has been proposed to be a useful adjunct to bone grafting. Purpose: The aim of the present study was to assess new bone formation in bone regeneration procedures using platelet rich plasma (PRP) alone or in combination with autogenous bone. Materials and Methods: Four surgically created, monocortical defects 5 mm in diameter in the calvariae of 15 New Zealand rabbits were grafted with a coagulum‐filled control, PRP, particulated autogenous bone alone (A), or combined with PRP (A‐PRP). Results: Mean platelet concentration of 1,761,930 ± 680,200/µl was achieved (5.30 ± 2.63 × fold of baseline). Animals were sacrificed 1, 2, and 4 weeks later. Histomorphometric analysis showed no statistical difference for total new bone formation at any time point, however, a detailed analysis revealed a statistically significant higher percentage of lamellar bone than woven bone for the autogenous bone group at 2 weeks; all other groups demonstrated equal percentages of either bone type. At 4 weeks, all groups revealed a statistically greater component of lamellar bone over woven bone. Graft resorption rate was similar for both A and A‐PRP. PRP platelet concentration was significantly positively correlated with TGF‐beta1 but not with PDGF‐AB. Conclusions: Within the limits of the chosen animal model, this study demonstrated that PRP during early healing, whether alone or mixed with autogenous bone, did not lead to greater bone remodelling, as compared to coagulum. In contrast, autogenous bone alone demonstrated accelerated bone remodelling at 2 weeks.     

富血小板血浆影响正畸牙齿移动效率的研究进展

富血小板血浆(PRP)是一种从自体血液中提取的血小板浓缩物,含有丰富的细胞因子和生长因子,其中血小板衍生生长因子、转化生长因子β、血管内皮生长因子主要对成骨细胞和破骨细胞的活性产生影响,促进骨重建过程。正畸牙的移动效率受到骨重建的影响,故局部注射PRP将是加速正畸牙齿移动效率的新方向。该文主要对PRP在正畸治疗中加速正畸牙移动效率的相关实验及其基础研究进行了综述,有助于进一步探讨PRP应用于临床治疗中加速正畸牙移动效率的可行性。     

Influence of antiplatelet substances on platelet-rich plasma.

PURPOSE: Platelets containing a number of growth factors (platelet-derived growth factor [PDGF], transforming growth factor-beta [TGF-beta], etc) can be obtained in high concentrations through centrifugal separation and are used in clinical applications as platelet-rich plasma (PRP). However, only a few studies have been conducted on the growth factors present in PRP. In this study, we focused on the concentrations of growth factors in PRP and clarified the influence of using antiplatelet substances in the process of platelet concentration to improve the concentration rate of growth factors in PRP. MATERIALS AND METHODS: We made platelet pellets from whole blood obtained from humans with or without some antiplatelet substances (prostaglandin E1, aspirin, apyrase). Platelet pellets were resuspended in phosphate-buffered saline as platelet resuspensions. We measured PDGF and TGF-beta1 concentrations in the samples. In measurements, we had the samples treated to release growth factors from platelets to measure accurate concentrations. RESULTS: PDGF and TGF-beta1 were concentrated to a mean of over 400% in the samples with antiplatelet substances as compared with the samples without antiplatelet substances. CONCLUSIONS: The antiplatelet substances were effective for efficiently concentrating growth factors in platelets.