A combination of platelet-derived and insulin-like growth factors enhances periodontal regeneration

Abstract The combination of platelet-derived growth factor (PDGF) and insulin-like growth factor one (IGF-1) has previously been shown to enhance repair of soft tissue wounds. Here we report initial observations following application of PDGF and IGF-1 to periodontitis-affected teeth in beagle dogs, 1 μg of PDGF and IGF-1 in an aqueous gel was applied to the root surfaces of test teeth following open flap debridement. Control sites received the gel alone. Block biopsies of the teeth and surrounding bone were taken 2 weeks after treatment. Histologic analyses of control specimens revealed a long junctional epithelial attachment, and no new bone or cementum formation. In contrast, growth factor treated sites exhibited significant amounts of new bone and cementum formation. A nearly continuous layer of osteoblasts lined the newly formed bone, and there was a dense cellular “front” at the coronal extent of the new bone. These preliminary results suggest that in vivo application of the combination of PDGF and IGF-1 may enhance regeneration of the periodontal structures.     

Gene therapy with growth factors for periodontal tissue engineering--a review

The treatment of oral and periodontal diseases and associated anomalies accounts for a significant proportion of the healthcare burden, with the manifestations of these conditions being functionally and psychologically debilitating. A challenge faced by periodontal therapy is the predictable regeneration of periodontal tissues lost as a consequence of disease. Growth factors are critical to the development, maturation, maintenance and repair of oral tissues as they establish an extra-cellular environment that is conducive to cell and tissue growth. Tissue engineering principles aim to exploit these properties in the development of biomimetic materials that can provide an appropriate microenvironment for tissue development. The aim of this paper is to review emerging periodontal therapies in the areas of materials science, growth factor biology and cell/gene therapy. Various such materials have been formulated into devices that can be used as vehicles for delivery of cells, growth factors and DNA. Different mechanisms of drug delivery are addressed in the context of novel approaches to reconstruct and engineer oral and tooth supporting structure.     

Significance of the platelet-derived growth factor in periodontal tissue regeneration

Aim

The aim was to review the significance of the platelet derived growth factor (PGDF) in periodontal tissue regeneration.

Methods and results

Databases were searched using the following terms in different combinations: “growth factors”, “guided bone regeneration”, “guided tissue regeneration”, “periodontal”, “platelet rich plasma” and “platelet derived growth factor”. Titles and abstracts of articles obtained using the above-described criteria were then screened by the authors and checked for agreement. The next step was to hand-search the reference lists of original and review studies that were found to be relevant in the previous step. PDGF has a stimulatory effect on the DNA replication and chemotaxis of osteoblasts, fibroblasts, leukocytes, monocytes, neutrophils periodontal and alveolar bone cells. Proliferation of mesenchymal stem cells is also promoted by supplement treatment with PDGF. PDGF in combination with other growth factors enhances periodontal tissue repair.

Conclusions

The PDGF plays a significant role in periodontal bone and tissue regeneration.     

The effects of short-term application of a combination of platelet-derived and insulin-like growth factors on periodontal wound healing

Polypeptide growth factors are a class of potent natural biologic mediators which regulate many of the activities of wound healing including cell proliferation, migration, and metabolism. Platelet-derived growth factor (PDGF) and insulin-like growth factor-I (IGF-I) have been shown to regulate DNA and protein synthesis in bone cells in vitro and to interact synergistically to enhance soft tissue wound healing in vivo. We have hypothesized that the combination of PDGF and IGF-I may, therefore, enhance regeneration of both the soft and hard tissue components of the periodontium. To test this hypothesis we performed conventional periodontal surgery on all 4 quadrants of the mouth of 13 beagle dogs with naturally occurring periodontal disease. Following flap reflection, degranulation, and root planing, all premolar teeth in 2 quadrants of each dog received a combination of 3 micrograms of recombinant PDGF-B and IGF-I in a methylcellulose gel, while the premolar teeth in the contralateral quadrants received the gel alone. Teeth in 4 additional animals also received 125I-PDGF or 125I-IGF-I in the treated sites. The clearance rate of the 125I-labeled protein, changes in local bone metabolism, and amount of new bone and cementum with inserting collagen fibers were measured. The clearance studies revealed that the half-life of the factors at the site of application was 3.0 hours for IGF-I and to 4.2 hours for PDGF-B. Greater than 96% of the radio-labeled proteins was cleared by 96 hours and no radioactivity was detected 2 weeks after application. There was a significant (P less than 0.01) 2-fold increase in uptake of the bone-seeking radiopharmaceutical Technetium 99-MDP at 2 and 4 weeks in growth factor treated sites compared to controls, indicating that there was increased metabolic activity within the bone at these sites. Computer-aided histologic analyses of biopsies obtained at 2 and 5 weeks post-operatively revealed a significant (P less than 0.01), 5 to 10 fold increase in new bone and cementum in PDGF-B/IGF-I treated sites at both time points compared to controls receiving the placebo gel. The height and total area of new bone continued to increase from 2 to 5 weeks. The new bone underwent a normal maturation process as judged by histologic appearance. A physiologic periodontal ligament space was also formed between the new bone and new cementum. There was no increase in ankylosis in the treated sites.(ABSTRACT TRUNCATED AT 400 WORDS)     

Neuropeptides modulate RANKL and OPG expression in human periodontal ligament cells

Neuropeptides, such as substance P (SP) and calcitonin gene-related peptide (CGRP), may be associated with bone remodeling in response to mechanical stress during orthodontic tooth movement. To investigate this hypothesis, we examined the effects of neuropeptides on the expression of receptor activator of nuclear factor κB ligand (RANKL) and osteoprotegerin (OPG) in human periodontal ligament (PDL) cells under compression in vitro. PDL cells were subjected to compressive force (2.0 g/cm²) continuously in the presence or absence of SP or CGRP for 2–4 days. The expression of the SP receptor, neurokinin 1-receptor (NK₁-R), in PDL cells was confirmed by RT–PCR and immunofluorescent staining. The effects of neuropeptides (SP and CGRP) on the expression of RANKL and OPG mRNA were determined using RT–PCR. PDL cells constitutively expressed NK₁-R on both the mRNA and protein levels. Compressive force decreased OPG mRNA expression and increased RANKL mRNA expression. In the presence of neuropeptides, the OPG level decreased synergistically with compression. Neuropeptides stimulated RANKL expression without compression, whereas they decreased RANKL mRNA expression with compression. These results indicate that PDL cell compression induces the up-regulation of RANKL and down-regulation of OPG, whereas neuropeptides suppress the RANKL expression induced by compression. Therefore, the neuropeptides SP and CGRP may modulate bone remodeling by PDL cells during orthodontic tooth movement.     

牛血小板衍化生长因子对人牙周膜成纤维细胞的生物学效应

目的：观察在牛血小板衍化生长因子作用下人牙周膜成纤维细胞ＤＮＡ和胶原蛋白合成的情况。方法：采用体外细胞培养技术和核素掺入法。结果：２０ｎｇ／ｍｌ～６０ｎｇ／ｍｌ牛血小板衍化生长因子可明显促进人牙周膜成纤维细胞ＤＮＡ合成，４０ｎｇ／ｍｌ浓度使细胞ＤＮＡ合成在２４ｈ达最高峰；对细胞的胶原蛋白合成无明显促进作用。结论：牛血小板衍化生长因子对人牙周膜成纤维细胞ＤＮＡ合成有促进作用，在牙周组织的创伤修复中可能起重要作用。     

正畸牙移动过程中血小板源性生长因子-BB在牙周组织中的表达

目的观察正畸牙移动过程中血小板源性生长因子（platelet—derived growth factor,PDGF）．BB在牙周组织中的表达分布情况,探讨其与牙周组织改建的关系。方法36只Wistar大鼠随机分为加力1d、3d、7d、14d、21d组及对照组。建立正畸牙移动模型,采用苏木素-伊红染色和免疫组化法,对PDGF—BB半定量、定位分析。结果PDGF-BB主要定位于成纤维细胞、成骨细胞、破骨细胞、血管内皮细胞,施力后表达显著增强,压力侧加力第7天达峰值,张力侧加力第14天达峰值,此后表达下降。结论PDGF-BB作为局部调控因子参与了正畸牙周组织改建过程。     

动情周期不同阶段正畸牙移动影响牙周组织胰岛素样生长因子表达的研究

目的探讨正畸力对牙周组织胰岛素样生长因子（IGF）表达的影响,从体内实验角度阐明雌激素和应力对局部骨改建的调控途径和机制。方法建立在Wistar雌性大鼠动情周期不同阶段给予正畸加力的实验模型,采用核酸原位杂交技术检测雌性大鼠动情周期不同阶段牙周组织中IGF mRNA的表达变化。采用SPSS 11.0软件包,单因素方差分析法（one way ANOVA）比较动情周期同一阶段加力实验组与对照组差异,Student- Newman- Keuls（S- N- K）法进行同一组内动情周期不同阶段各亚组间的两两比较。结果正畸牙移动使处于动情周期不同阶段的雌性大鼠牙周组织中的IGF mRNA含量增加,其中IGF- Ⅰ mRNA的表达在动情期最低,而动情前期最高（P<0.05）;而IGF- ⅡmRNA的表达在动情周期中没有明显规律。结论IGF- Ⅰ不仅可以在应力反应中由骨形成细胞在局部合成,而且还与动情周期的全身激素状态有关,而IGF- Ⅱ则是对应力发生反应的一种局部生长因子。     

牛血小板衍化生长因子对人牙周膜成纤维细胞超微结构的影响

目的：对经牛血小板衍化生长因子作用的人牙周膜成纤维细胞超微结构进行观察。方法：透射电镜观察。结果：发现细胞超微结构发生了明显的变化，包括粗面内质网扩张和增多，发达的线粒体与大量的多聚核糖体形成，胞核增大，核内常染色质增多等。结论：牛血小板衍化生长因子可促进人牙周膜成纤维细胞ＤＮＡ、ＲＮＡ、蛋白质合成旺盛，代谢、增殖活跃。提示这些变化可能与细胞在该因子作用下生物学功能增强有密切关系。     

Specific pro-apoptotic fibronectin fragments modulate proteinase expression in periodontal ligament cells

BACKGROUND: During inflammation and periodontal disease, the extra-cellular matrix protein fibronectin (FN) is degraded into fragments whose activities differ from those of the intact molecule. In periodontal ligament cells in vitro, some fragments elevate the expression of matrix metalloproteinases and serine proteinases, while others induce apoptosis through a mechanism regulated by caspase proteases and specific signaling pathways. In this study, we investigated whether the pro-apoptotic V+H- fibronectin fragment modulates proteinase expression as part of the apoptotic mechanism in periodontal ligament cells. The importance of this study is that a structurally similar fibronectin fragment found in vivo (40-kDa) is associated with periodontal disease status. However, the recombinant V+H- FN protein which is structurally and functionally similar to the in vivo 40-kDa fragment was chosen as the focus of these studies over the in vivo fragment because of the ability to readily produce and purify large quantities of recombinant fragments for detailed studies. Thus, findings from this study relate to our understanding of how the extracellular matrix of the periodontal ligament in an inflamed environment may contribute to periodontal disease and its progression. METHODS: We used substrate zymography, reverse zymography, proteinase inhibitors, and partial sequencing to investigate whether the pro-apoptotic V+H- fibronectin fragment modulates proteinase expression as part of this apoptotic mechanism. RESULTS: Incubation with the V+H- fragment reduced the expression of all gelatinolytic proteinases and inhibitors commonly expressed by periodontal ligament cells. In the presence of caspase inhibitors, inhibitors known to suppress apoptosis, however, the reduced proteinase profile was rescued, showing that caspase inhibitors were able to reverse the reduced proteinase profile and indicating that caspase-mediated pathways are pertinent to fibronectin-fragment-mediated matrix metalloproteinase expression. In addition, the V+H- fragment also triggered the expression of a unique high molecular weight gelatinolytic proteinase of approximately 200 kDa. This proteinase was a serine proteinase, whose identity is not known. CONCLUSION: These findings suggest that matrix-degrading proteinases may be involved in apoptosis as part of a unique mechanism of periodontal tissue breakdown, in which novel proteinases may help execute the dissolution of the extracellular matrix.     

血小板衍化生长因子-BB和碱性成纤维细胞生长因子对人牙周膜细胞增殖的影响

目的探讨重组人血小板衍生生长因子（rhPDGF）-BB和重组人碱性成纤维细胞生长因子（rh—bFGF）对人牙周膜细胞（PDLC）增殖的影响。方法原代培养人PDLC,应用甲噻唑四唑氮（MTT）比色和流式细胞仪检测rh-PDGF-BB和rh-bFGF单独及联合作用下细胞的增殖能力和增殖指数。结果rhPDGF-BB和rh-bFGF联合作用后,PDLC增殖能力提高,活性增强。其中,10μg&#183;L^-1的rhPDGF—BB加10μg&#183;L^-1的bFGF为最佳显效质量浓度,第3天为最佳显效时间。结论PDGF—BB和bFGF联合能更显著促进人PDLC的增殖并且具有明显的协同效应。     

血小板衍生生长因子-BB、转化生长因子-β1联合应用对大鼠正畸牙牙周膜中整合素β3表达的影响

目的 观察大鼠正畸牙局部联合应用血小板衍生生长因子-BB（PDGF-BB）和转化生长因子-β1（TGF-β1）后正畸牙牙周膜中整合素 β3表达的变化。方法 按随机数字表法,将 32只大鼠随机均分为4组。建立大鼠上颌第一磨牙近中移动正畸模型,隔日于施力磨牙颊侧牙龈黏膜下分别注射1%PBS、10 ng PDGF-BB、5 ng TGF-β1、10 ng PDGF-BB和5 ng TGF-β1叠加剂量,注射体积均为0.1 mL。加力10 d后处死动物,取左上颌第一磨牙及其牙周组织,用免疫组织化学方法检测牙周组织中整合素 β3的表达,进行阳性表达区域平均光密度值测量,对测量结果行方差分析,服从正态分布,再行组间t检验统计学分析。结果 各实验组压力侧牙周膜细胞中整合素β3的表达强度均高于对照组（P<0.01）,其中PDGF-BB+TGF-β1组与TGF-β1组或PDGF-BB组比较差异均有统计学意义（P<0.01）。实验组张力侧牙周膜细胞中整合素β3的表达强度均高于对照组（P<0.05）,其中PDGF-BB+TGF-β1组整合素β3表达强度较强,与TGF-β1或PDGF-BB组比较差异无统计学意义（P>0.05）。结论 局部联合应用外源性PDGF-BB和TGF-β1对大鼠正畸牙牙周组织中整合素β3的上调作用较单独运用PDGF-BB或TGF-β1组强,二者联合应用有协同效应,共同促进了正畸牙周组织改建。     

Human periodontal fibroblast response to enamel matrix derivative, amelogenin, and platelet-derived growth factor-BB

BACKGROUND: The ideal goal of clinical therapy in periodontal defects is regeneration of all lost structures. For regeneration to occur, cell proliferation, migration, and extracellular matrix synthesis are prerequisites. Attempts at regeneration of periodontal defects by guided tissue regeneration using bone grafts and membranes have not always yielded predictable results. Recently, attempts at engineering the defects using various materials have shown promising results. Two such approaches have been used to regenerate periodontal defects, one using extracellular matrix such as enamel matrix proteins and the other using growth factors. However, to our knowledge, no study has looked at combining these two approaches to achieve potentially even greater regeneration. METHODS: Primary human periodontal ligament (PDL) fibroblasts were explanted, and alkaline phosphatase (ALK PHOS) activity was determined. Phenotypically different cell lines were incubated for 1, 3, 6, and 10 days in 0.2% fetal bovine serum (FBS) media containing different concentrations of either enamel matrix derivative (EMD), amelogenin, platelet-derived growth factor-BB (PDGF-BB), EMD+PDGF-BB, or amelogenin+PDGF-BB. A culture of 0.2% FBS alone served as a negative control, and a culture of 10% FBS served as a positive control. Cell proliferation was measured using a Coulter counter to determine the cell number. The effects on a wound-fill model were evaluated by scraping a 3-mm wide cell-free zone in PDL monolayers across the diameter of the tissue-culture plate and determining PDL cell migration into the cell-free zone using computer assisted histomorphometry. RESULTS: Compared to the control, only EMD+PDGF-BB significantly increased PDL cell proliferation in an ALK PHOS (-) cell line (P<0.001), and EMD alone, EMD+PDGF-BB, and amelogenin+PDGF-BB significantly increased PDL cell proliferation in an ALK PHOS (+) cell line (P<0.001) with EMD+PDGF-BB showing a trend for greater proliferation than either PDGF or EMD alone. Individually, EMD and amelogenin had no significant effect on PDL cell proliferation. In the wound-fill experiment, all factors and their combinations except amelogenin significantly enhanced cell migration compared to the control (P<0.05) at the wound edge. In addition, EMD+PDGF-BB had additive effects on the ALK PHOS (-) cell line at the wound edge. At the center of the wound, neither EMD nor amelogenin had a significant wound-fill effect. However, the combination of EMD+PDGF-BB additively increased wound fill for both ALK PHOS (+) and ALK PHOS (-) cells. CONCLUSIONS: The combination of EMD and PDGF-BB produces greater proliferative and wound-fill effects on PDL cells than each by themselves. If these combined effects can be translated clinically, one may see greater regeneration in periodontal defects with this combination. However, amelogenin does not have significant effects on PDL cell proliferation or migration by itself. This may suggest that either another enamel matrix component in EMD may be responsible for some of its clinical effects, or that amelogenin alone may not trigger the regenerative potential of periodontal tissues and that it requires a combined interaction with other enamel matrix components of EMD to direct the regenerative process.     

Porphyromonas gingivalis lipopolysaccharide modulates the responsiveness of human periodontal ligament fibroblasts to platelet-derived growth factor

Lipopolysaccharides (LPS) prepared from periodontopathic bacteria have been known to induce various biological responses which may lead to periodontal tissue breakdown. The purpose of this study was to determine if Porphyromonas gingivalis LPS could affect cellular functions of human periodontal ligament fibroblasts (HPLF). We showed here the responsiveness of cultured HPLF to platelet-derived growth factor (PDGF)-BB, a growth factor for mesenchymal cells, in the presence of P. gingivalis LPS. DNA synthesis of HPLF was enhanced in a dose-dependent manner when LPS were co-incubated for 48 h; thereafter, it decreased to the baseline level within 24 h incubation. The stimulating effect of PDGF-BB was further enhanced by the pretreatment of HPLF with LPS (10 μg/ml) for 48 h. The binding assay of [¹²⁵I] PDGF-BB and the flow cytometric assay using rabbit antiserum to human PDGF receptor (PDGF-R) β-type indicated that this enhancement was due to the increase of the number of PDGF-R β-type on HPLF. Immunoprecipitation using antiserum to human PDGF-R β-type also showed that the synthesis of PDGF-R β-type was augmented in the LPS-treated HPLF. These results indicate that P. gingivalis LPS stimulate cellular proliferation and responsiveness to PDGF-BB of cultured HPLF. These cellular reactions may be mediated by PDGF-BB binding, followed by increased synthesis of the receptor protein.     

Gene expression of growth differentiation factors in the developing periodontium of rat molars

Growth and differentiation factors (GDF) 5, 6, and 7 are known to play roles in tendon and ligament formation, and are therefore probably involved in the formation of periodontal ligament. In this study, we sought to determine temporal and spatial expression of GDF-5, -6, and -7 mRNA in developing periodontal tissue of rat molars using in situ hybridization. GDF gene expression in the periodontal ligament was first detected in cells associated with the initial process of periodontal ligament fiber bundle formation. Gene signals were also detected in cells located along the alveolar bone and cementum surfaces, the insertion sites of periodontal ligaments, during the course of root formation. GDF expression in these cells were down-regulated after completion of root formation. Our results appeared to suggest the involvement of GDF-5, -6, and -7 in the formation of the dental attachment apparatus.     

Vascular endothelial growth factors and progression of periodontal diseases.

BACKGROUND: Tissues become hemorrhagic and edematous coincident to periodontal diseases; however, there is little information concerning the biologic mechanisms which may produce these changes. Vascular endothelial growth factor (VEGF) is a macromolecule which enhances blood vessel growth and permeability. However, there is no information concerning gingival VEGF concentrations within normal or diseased gingiva. The purpose of this study was to assess changes in gingival concentrations of VEGF during initiation and progression of periodontal diseases and compare them to changes in the number of blood vessel profiles and concentration of recognized markers of periodontal disease severity (interleukin-6[IL-6]). METHODS: Normal (non-hemorrhagic gingiva adjacent to a < or =3 mm gingival sulcus) and inflamed gingiva (hemorrhagic gingiva adjacent to a < or =3 mm, 4 to 6 mm, or >6 mm periodontal pocket) were studied. VEGF and IL-6 concentrations were assessed by ELISA and the number of blood vessels determined by histomorphometric techniques. Data were placed into one of the following groups: < or =3 mm, normal; < or =3 mm, diseased; 4 to 6 mm, diseased; and >6 mm, diseased. These groups were compared by factorial ANOVA and Scheffe comparisons. In addition, groups were compared by simple and multiple regression and regression ANOVA to determine possible correlations between them. RESULTS: VEGF and IL-6 concentrations were significantly lower within normal than within diseased gingiva. The number of blood vessel profiles and mean IL-6 concentrations were highest in diseased tissues adjacent to >6 mm sulci and were significantly correlated with sulcular depth (P <0.001). In contrast, VEGF concentrations were highest within diseased gingiva adjacent to 4 to 6 mm periodontal pockets (P <0.001) and were not correlated with sulcular depth. CONCLUSIONS: VEGF may be a factor in initiation and progression of gingivitis to periodontitis, possibly by promoting expansion of the vascular network coincident to progression of the inflammation.     

The effects of platelet-derived growth factor-BB on periodontal cells in an in vitro wound model

BACKGROUND: Platelet-derived growth factor (PDGF-BB) has been shown to enhance periodontal regeneration. Principles of guided tissue regeneration dictate that one of the goals of therapy is to modulate the wound healing processes to favor repopulation of the wound with cells derived from the periodontal ligament rather than from the gingival tissues. Using an in vitro wound model, gingival fibroblasts (GF) have been shown to fill a wound space significantly faster than periodontal ligament cells (PDL). There are no data reported directly comparing the response of these 2 cell types to PDGF-BB within such a wound model. Therefore, the aims of this research were: 1) to characterize both the proliferative and wound fill (WF) effects of PDGF-BB within an in vitro model and 2) to compare specific growth factor effects between GF and PDL. METHODS: Primary cultures of both human PDL and GF were derived from explanted tissues and passaged to 12-well tissue culture plates. Triplicate cultures of both cell types were grown to confluence and in vitro wounds were mechanically created, removing a 3 mm wide band of the cell layer across the diameter of the wells. The wells were then incubated for 2, 6, and 9 days in media containing 0.1% fetal bovine serum (FBS) and 1 of 5 concentrations of PDGF-BB. At each time point, cells were pulsed with 5-bromo, 2-deoxyuridine (BrdU) fixed, and nuclei were stained to measure BrdU incorporation (as a measure for proliferation). Cells were counter-stained with cytoplasmic stain to measure cell number. Quantitative analyses within the wound boundaries, marginally (area of interest [AOI] 1) and centrally (AOI 2), were accomplished using computer-assisted histomorphometry. RESULTS: PDL exhibited a significantly greater proliferative response to PDGF-BB in both AOI when compared to GF (P <0.0001). The PDL exhibited increased levels of proliferation at concentrations of PDGF-BB greater than or equal to 10 ng/ml. By contrast, GF displayed no increase in proliferation in response to stimulation with PDGF-BB at any of the concentrations tested when compared to negative controls. The wound fill (WF) responses to PDGF-BB were similar between PDL and GF, with both cell types responding in an all or none fashion when measured at day 2, and in a concentration-dependent manner at later time points. The only significant difference in WF between PDL and GF occurred in AOI 2 in negative control medium (0 ng/ml of PDGF-BB), with GFs having greater (P <0.01) levels of WF over the 9 days. CONCLUSION: The findings from this study demonstrate differing effects of PDGF-BB on the proliferation of PDL and GF in this in vitro model. These results suggest that there may be cell-specific differences critical to periodontal wound healing that may be exploited in the development of new therapies.     

Clinical results using recombinant human platelet-derived growth factor and mineralized freeze-dried bone allograft in periodontal defects

Human studies have demonstrated the safety and effectiveness of highly purified recombinant human platelet-derived growth factor-BB (rhPDGF-BB) in combination with osteoconductive matrices for the treatment of moderate to severe periodontal intrabony defects. These study results, together with binding and release characteristics for rhPDGF-BB with different matrices, provide clear evidence that demineralized freeze-dried bone allograft and beta-tricalcium phosphate (beta-TCP) each can be combined with rhPDGF-BB to promote significant improvements in clinical, radiographic, and histologic parameters. The purpose of the current case series was to determine the clinical and radiographic regenerative potential of rhPDGF-BB-enhanced mineralized freeze-dried bone allograft (FDBA) for the treatment of severe periodontal intrabony defects. Clinical reentry and radiographs at up to 11 months showed complete bone fill in these challenging cases, indicating that rhPDGF combined with FDBA provides excellent clinical results.