In vitro evaluation of the mitogenic effect of platelet-derived growth factor-BB on human periodontal ligament cells cultured with various bone allografts

BACKGROUND: Several studies have documented the role of growth factors in periodontal regeneration. It has been shown that platelet-derived growth factor (PDGF) is a potent stimulator of human periodontal ligament (PDL) cells. A variety of bone graft materials are used to treat osseous defects caused by periodontal disease. We evaluated the mitogenic effect of PDGF on human PDL cells cultured with different allografts to determine which of the allografts with or without PDGF promoted periodontal regeneration. METHODS: Two human demineralized freeze-dried allografts of cortical (DFDBA) and cancellous (DFBA) bone and a non-demineralized freeze-dried allograft (FBA) from cancellous bone were used alone or supplemented with PDGF-BB. Human PDL cultures were derived from the mid-root of 2 maxillary premolars extracted for orthodontic reasons. Cells were grown separately in 24-well dishes with or without 20 mg of each bone allograft. On day 2 of quiescence, new medium was added with 10 ng/ml of PDGF-BB. DNA synthesis was estimated by measuring [3H] thymidine incorporation to determine the effects of the test agents on cell proliferation. Cells were processed and subjected to scintillation counting after 48 hours of incubation. Counts per minute (cpm/well) were determined for each sample. RESULTS: There was no statistically significant difference (P<0.05) on PDL cell proliferation when the allografts were used alone. PDL cells exhibited significantly greater proliferative responses to the 2 demineralized bone allografts, DFDBA and DFBA, when combined with PDGF-BB. A statistically significant difference on DNA synthesis was noticed when PDGF-BB was added to PDL cells cultured with FBA. PDL cells displayed no significant increase in mitogenic activity when cultured with PDGF-BB alone. CONCLUSIONS: The findings of this study demonstrate the beneficial role of DFDBA, DFBA, and FBA as synergic agents with PDGF-BB to periodontal regeneration. The significant ability of the 2 decalcified bone allografts, DFDBA and DFBA, combined with PDGF to stimulate PDL cell proliferation might be a useful adjunct in the treatment of periodontal defects.     

Growth factors regulate expression of osteoblast-associated genes

BACKGROUND: The goal of periodontal regenerative therapies is to reconstruct periodontal tissues such as bone, cementum, and periodontal ligament cells (PDL). The need to establish predictable treatment modalities is important for reconstruction of these tissues. The aim of this study was to determine the effects of a low molecular extract of bovine bone protein (BP) containing bone morphogenetic proteins (BMPs) 2, 3, 4, 6, 7, 12, and 13, alone or in combination with platelet-derived growth factor (PDGF) and/or insulin-like growth factor (IGF) on osteoblast differentiation in vitro. METHODS: BP, mixed with a collagen matrix, was added to a poly (DL-lactide-co-glycolide) polymer (PLG) and placed at orthotopic sites in the skullcaps of Sprague-Dawleys rats. At day 28, rats were sacrificed for histological analysis. All sites treated with the polymer/BP produced bone while control sites (without BP) showed no bone formation. Having established the biological activity of BP, in vitro studies were initiated using MC3T3-E1 cells, a mouse osteoprogenitor cell line. The ability of BP and other growth factors to alter cell proliferation was determined by Coulter counter, and differentiation was determined by Northern analysis for specific genes. RESULTS: When compared with cells treated with 2% serum alone, PDGF enhanced cell numbers at 10 and 20 ng/ml; IGF produced no significant effect at these doses; and BP at 10 and 20 microg/ml decreased cell proliferation. Northern analysis revealed that PDGF blocked gene expression of osteopontin (OPN) and osteocalcin (OCN), while BP and IGF promoted gene expression of bone sialoprotein (BSP) and OPN. The combination of BP and IGF enhanced expression of OPN beyond that of either BP or IGF alone. PDGF was able to block the effects of IGF on gene expression, but not those of BP. CONCLUSIONS: These results indicate that BP, PDGF, and IGF influence cell activity differently, and thus raise the possibility that combining factors may enhance the biological activity of cells.     

生长因子网络调节对骨形成作用的研究：Ⅴ.不同生长因子交互应用对人？…

考察将转化生分子β、胰岛素样生长因子Ⅱ、碱性成纤维细胞生长因子及血小板衍生长性生和茵子４种生长因子两两交互应用对人胚成骨样细胞增殖与分化的影响。方法：在不同的实验间期检测成骨样细胞＾３Ｈ－胸腺嘧啶脱氧苷、＾３Ｈ－脯氨酸的掺入量和碱性磷酸酶的含量。     

The effect of residual calcium in decalcified freeze-dried bone allograft in a critical-sized defect in the Rattus norvegicus calvarium

Demineralized freeze-dried bone allograft (DFDBA), a widely used graft material in periodontal regenerative procedures, is processed with hydrochloric acid in the attempt to expose proteins located within the bone matrixes that are capable of inducing new bone formation. However, the degree of DFDBA demineralization varies between tissue banks, which may have an effect on clinical regeneration. This study uses the critical-sized defect (CSD) model to evaluate the wound-healing response to the residual calcium of donor bone. If the percentage of residual calcium in a graft were demonstrated to significantly enhance wound healing, then periodontal patients may benefit from further standardization of human-allograft processing. Sixty adult, male, Harlan Sprague-Dawley rats (Rattus norvegicus) were randomly and equally divided into 4 test groups (ie, DFDBA at 1%, 2%, and 3% to 6% residual calcium levels and FDBA at 23% residual calcium) and a control group (no allograft). An 8-mm-diameter craniotomy was made in the rat calvarium, and polytetrafluoroethylene membranes with pore sizes of 0.50 microm were placed intracranially and ectocranially. Treatment materials were carefully placed into the CSD with a new sterilized dental amalgam carrier. Tetracycline hydrochloride was injected intraperitoneally for labeling new bone growth, and animals were euthanized 12 weeks postsurgery. As a result, histomorphometric bone fill at 12 weeks showed a statistically significant increase in the 2% DFDBA group as compared to all other groups. The authors conclude that a 2% residual calcium level in human DFDBA appears to significantly (P < or = .05) enhance osseous wound healing in the rat calvarium.     

Use of growth factors to modify osteoinductivity of demineralized bone allografts: lessons for tissue engineering of bone

Biologically active bone graft substitute materials are needed for repair and regeneration of skeletal tissues. Current approaches are focused on the use of osteoinductive agents, including bone morphogenetic proteins (BMP) in combination with biodegradable carriers. Demineralized freeze-dried bone allograft (DFDBA) can provide an osteoconductive surface and, at the same time, function as a time-release carrier for BMP. Donor variability, however, limits the predictability of DFDBA as an osteoinductive material. This article examines the use of growth factors, including platelet-rich plasma, platelet-derived growth factor, enamel matrix derivatives, and BMP-2, to enhance the osteoinductive properties of human DFDBA.     

Effects of TGF-beta1, PDGF-BB, and IGF-1 on the rate of proliferation and adhesion of a periodontal ligament cell lineage in vitro

BACKGROUND: Considering the role of growth factors in periodontal regeneration, the aim of this study was to evaluate the influence of platelet-derived growth factor (PDGF)-BB, insulin-like growth factor (IGF)-1, and transforming growth factor-beta 1 (TGF-beta1), alone or in combination, on the rate of proliferation and adhesion of periodontal ligament (PDL) cells in vitro. METHODS: After establishment and characterization of a primary culture of PDL cells, 72 culture dishes were plated with 10(3) cells distributed among four test groups and a control group. Test groups had PDGF-BB, TGF-beta1, IGF-1, or a combination of all three added to the culture medium, whereas the control group received no growth factor. The samples were counted in triplicate 1, 3, 5, and 7 days after seeding. For the adhesion assay, 14 patients provided 30 root fragments distributed among 10 groups: scaling and root planing (SRP), SRP + growth factors, SRP + citric acid plus tetracycline (CA+T), and SRP + (CA+T) + growth factors. The data were evaluated statistically by analysis of variance complemented by Tukey, Dunnett, and Student-Newman-Keuels methods. RESULTS: Maximum rates of proliferation were observed at day 3 for all groups. TGF-beta1 induced a 344.17% +/- 58.80% increased proliferation rate over control (P < 0.05), followed by the combination (277.5% +/- 29.38%), PDGF-BB (238.79% +/- 5.79%), and IGF-1 (233.16% +/- 19.19%). Groups treated by (CA+T) showed increased numbers of cells attached to root fragments, especially SRP + (CA+T) + combination (13.25 +/- 1.79), with significant differences (P < 0.05) from groups treated only by SRP. CONCLUSION: This combination of growth factors stimulated a mitogenic response and favored the adhesion of PDL cells in vitro, suggesting its possible role in periodontal regeneration.     

Synergistic effects of dexamethasone on platelet-derived growth factor mitogenesis in vitro.

Platelet-derived growth factor (PDGF) and insulin-like growth factor-I (IGF-I) interact to stimulate proliferation of fibroblasts in culture. Glucocorticoids variably effect the response of cultured fibroblasts to polypeptide growth factors. This study determined the effects of dexamethasone on growth-factor stimulation of gingival, periodontal ligament and pulp fibroblast proliferation in vitro. Cultures of quiescent, low-passage, human fibroblasts were treated for varying periods of time with transforming growth factor-beta 2 (TGF-beta 2), PDGF and IGF-I: (1) alone, (2) in combination with each other, (3) singly plus dexamethasone, (4) in combination plus dexamethasone. Combinations of human, recombinant PDGF and IGF-I (10-1000 ng/ml) induced significantly higher rates of cell proliferation than either factor alone. Dexamethasone at doses ranging from 10(-5) to 10(-8) M substantially enhanced cell proliferation induced by these combinations and by PDGF without IGF-I but not IGF-I alone. By 6 days after a single application, 2-3 times as many cells were present in the PDGF and dexamethasone cultures as compared to PDGF without IGF-I. TGF-beta 2 specifically blocked the effects of dexamethasone added to PDGF-stimulated cells. Collagen and non-collagenous protein synthesis was not affected by the addition of PDGF and IGF-I with or without dexamethasone. These data suggest that dexamethasone may substitute for IGF-I in PDGF stimulation of cell proliferation.     

The effects of varying degrees of allograft decalcification on cultured porcine osteoclast cells

BACKGROUND: Demineralized freeze-dried bone allograft (DFDBA) is widely used in periodontal therapy as a scaffold for new bone formation in periodontal defects. It is demineralized, theoretically, to expose osteoinductive or osteoconductive bone matrix proteins that should facilitate osteogenesis. The degree of DFDBA demineralization varies between tissue banks and may affect clinical regeneration. A 2% residual calcium level in DFDBA has been shown to result in the highest alkaline phosphatase activity levels in cultured human periosteal cells and is optimally osteoinductive or osteoconductive for new bone formation. The purpose of this study was to evaluate the effect of 4 different residual calcium levels in commercially available DFDBA samples on porcine osteoclast activity as measured by resorption on calcium phosphate-coated disks. METHODS: Bone marrow was harvested from the femurs of 3-week-old farm pigs and cultured for 3 weeks. Hematopoietic stem cells were allowed to differentiate into mature active polykaryons displaying genuine osteoclast characteristics. The osteoclast cells displayed a dense actin band inside the margins of the cytoplasm under light microscopy. Culture media was decanted and collagenase added to free the attached cells. Equal cell samples were pipetted onto calcium phosphate-coated disks in 24-well plates. DFDBA samples with 1.44%, 2.41%, and 5.29% residual calcium; FDBA (30% residual calcium); and control cultures without allograft samples were prepared and all samples incubated for 1 week. Cells were fixed and stained for tartrate-resistant acid phosphatase (TRAP), Oregon Green 488-phalloidin, a stain for cytoskeletal proteins, and counterstained with propidium iodide. Specimens were examined by light and fluorescence microscopy using epi-illumination. Calcium phosphate disks were then rinsed in 5% sodium hypochlorite to remove adherent osteoclasts, and substrate surface changes were measured by white light interferometry and image analysis. RESULTS: A higher yield of TRAP-positive cells was produced without DFDBA; however, resorptive activity appears to be significantly increased in the presence of 2.41% residual calcium as compared to all other experimental groups (P<0.0065). CONCLUSION: In this in vitro model, porcine osteoclasts show significantly more resorptive activity as measured on calcium phosphate-coated disks in the presence of 2.41% residual calcium in DFDBA than in other DFDBA residual calcium levels.     

Porcine fetal enamel matrix derivative enhances bone formation induced by demineralized freeze dried bone allograft in vivo

BACKGROUND: Embryonic enamel matrix proteins are involved in the formation of acellular cementum during development of the periodontal attachment apparatus, suggesting that these proteins might be used clinically to promote periodontal regeneration. At present, it is unknown if these proteins are osteoinductive, osteoconductive, or osteopromotive. To address this question, we examined the ability of a commercially prepared embryonic porcine enamel matrix derivative to induce new bone formation in nude mouse calf muscle, or to enhance the bone induction ability of a demineralized freeze-dried bone allograft (DFDBA). METHODS: Porcine fetal enamel matrix derivative (EMD) was implanted bilaterally in the calf muscle of 4 male Nu/Nu mice per treatment group (N = 8 implants): 2 mg EMD alone; 4 mg EMD alone; inactive human DFDBA alone; inactive DFDBA + 2 mg EMD; inactive DFDBA + 4 mg EMD; active DFDBA alone; active DFDBA + 2 mg EMD; and active DFDBA + 4 mg EMD. Implants were harvested after 56 days and examined histologically for bone induction using a semi-quantitative score and histomorphometrically for area of new bone, cortical bone, bone marrow, and residual DFDBA. RESULTS: Implants containing inactive DFDBA, 2 mg EMD, 4 mg EMD, and inactive DFDBA + 2 or 4 mg EMD did not induce new bone. Active DFDBA and active DFDBA + 2 mg EMD induced new bone to a similar extent. In contrast, active DFDBA + 4 mg EMD resulted in enhanced bone induction, area of new bone, and cortical bone. Residual DFDBA was also increased in this group. CONCLUSIONS: EMD is not osteoinductive. However, it is osteopromotive, due in part to its osteoconductive properties, but a threshold concentration is required.     

Effects of growth factors on temporomandibular joint disc cells

The effects of growth factors on cartilaginous tissues are well documented. An exception is the temporomandibular joint (TMJ) disc, where data for growth factor effects on proliferation and biosynthesis are very limited. The purpose of this study was to quantify proliferation of and synthesis by TMJ disc cells cultured in monolayer with either platelet derived growth factor-AB (PDGF), basic fibroblast growth factor (bFGF) or insulin-like growth factor-I (IGF), at either a low (10 ng/ml) or high (100 ng/ml) concentration. Proliferation was assessed with a DNA quantitation technique, collagen synthesis was measured via a hydroxyproline assay, and GAG synthesis was determined with a dimethylmethylene blue dye binding assay at 14 days. Overall, the most beneficial growth factor was bFGF, which was most potent in increasing proliferation and GAG synthesis, and also effective in promoting collagen synthesis. At the high concentration, bFGF resulted in 96% more cells than the control and 30 to 45% more cells than PDGF and IGF. PDGF and bFGF were the most potent upregulators of GAG synthesis, producing 2-3 times more GAG than the control. IGF had no significant effect on GAG production, although at its higher concentration it increased collagen production by 4.5 times over the control. Collagen synthesis was promoted by bFGF at its lower concentration, with levels 4.2 times higher than the control, whereas PDGF had no significant effect on collagen production. In general, higher concentrations increased proliferation, whereas lower concentrations favoured biosynthesis.     

Bovine-derived bone protein extract in the treatment of mandibular Class II furcations

This study was an initial evaluation of the use of a bovine-derived bone protein (BP) extract that contains various growth factors combined with decalcified freeze-dried bone allograft (DFDBA) as regenerative treatment for class II mandibular furcations. Twenty-five patients were divided into 5 groups according to the dosage of BP present per mg of DFDBA to be grafted: (1) 0.00 microgram/mg, (2) 3.13 micrograms/mg, (3) 6.25 micrograms/mg, (4) 12.5 micrograms/mg, and (5) 25.0 micrograms/mg. Surgical exploration of the furcation defects was performed followed by grafting with BP/DFDBA. Results at 6 months showed that attachment gain in the treated furcation areas was greatest in Groups 4 and 5, suggesting that BP has the potential to increase the effects of DFDBA in gaining clinical attachment in mandibular class II furcations.     

Histologic comparison of healing after tooth extraction with ridge preservation using mineralized versus demineralized freeze-dried bone allograft

Background: Allografts, such as demineralized freeze‐dried bone allograft (DFDBA) and mineralized freeze‐dried bone allograft (FDBA) are commonly used by clinicians for ridge preservation procedures. The primary objective of this study is to histologically evaluate and compare the healing of non‐molar extraction sockets grafted with DFDBA versus FDBA for ridge preservation. The secondary aim of this study is to compare dimensional changes in ridge height and width after grafting with these two materials. Materials: Forty patients were randomly divided into two groups of 20. Extraction sockets were filled with either FDBA or DFDBA. To minimize variables associated with the organ donor and with tissue processing, all of the graft material was procured from a single donor; the only difference in the two materials was the percentage mineralization of the final bone graft. A 2‐mm‐diameter core biopsy was taken from each grafted site ≈19 weeks after grafting. Histomorphometric analysis was performed to determine percentage of vital bone, residual graft particles, and connective tissue (CT)/other non‐bone components. Results: There were no significant differences when comparing changes in alveolar ridge dimensions of the two groups. There was no significant difference in percentage CT/other between groups. DFDBA had a significantly greater percentage of vital bone at 38.42% versus FDBA at 24.63%. The DFDBA group also had a significantly lower mean percentage of residual graft particles at 8.88% compared to FDBA at 25.42%. Conclusion: This study provides the first histologic and clinical evidence directly comparing ridge preservation with DFDBA versus FDBA in humans and demonstrates significantly greater new bone formation with DFDBA.     

Effects of demineralized freeze-dried bone allograft on gene expression of osteoblastlike MG63 cells

Demineralized freeze-dried bone allograft (DFDBA) is widely used in periodontal regeneration procedures as a scaffold for new bone formation in periodontal defects. How this biomaterial alters osteoblast activity to promote bone formation is poorly understood. We therefore attempted to address this question by using microarray techniques to identify genes that are differently regulated in osteoblasts exposed to DFDBA. By using DNA microarrays containing 20,000 genes, the authors identified in an osteoblastlike cell line (MG-63) cultured with DFDBA (Allogro, Dentsply/Friadent-Ceramed) several genes whose expression was significantly up-regulated or down-regulated. The differently expressed genes cover a broad range of functional activities: (1) cell cycle regulation, (2) immunity, (3) vesicular transport, (4) production of cytoskeletal elements, and (5) bone remodeling. The data reported are, to the authors' knowledge, the first genetic portrait of DFDBA effects. They can be relevant to a better understanding of the molecular mechanism of bone regeneration and as a model for comparing other materials with similar clinical effects.     

In Vitro Evaluation of Demineralized Freeze‐Dried Bone Allograft in Combination With Enamel Matrix Derivative

Background: Preclinical and clinical studies suggest that a combination of enamel matrix derivative (EMD) with demineralized freeze‐dried bone allograft (DFDBA) may improve periodontal wound healing and regeneration. To date, no single study has characterized the effects of this combination on in vitro cell behavior. The aim of this study is to test the ability of EMD to adsorb to the surface of DFDBA particles and determine the effect of EMD coating on downstream cellular pathways such as adhesion, proliferation, and differentiation of primary human osteoblasts and periodontal ligament (PDL) cells. Methods: DFDBA particles were precoated with EMD or human blood and analyzed for protein adsorption patterns via scanning electron microscopy. Cell attachment and proliferation were quantified using a commercial assay. Cell differentiation was analyzed using real‐time polymerase chain reaction for genes encoding Runx2, alkaline phosphatase, osteocalcin, and collagen 1α1, and mineralization was assessed using alizarinred staining. Results: Analysis of cell attachment revealed no significant differences among control, blood‐coated, and EMD‐coated DFDBA particles. EMD significantly increased cell proliferation at 3 and 5 days after seeding for both osteoblasts and PDL cells compared to control and blood‐coated samples. Moreover, there were significantly higher messenger ribonucleic acid levels of osteogenic differentiation markers, including collagen 1α1, alkaline phosphatase, and osteocalcin, in osteoblasts and PDL cells cultured on EMD‐coated DFDBA particles at 3, 7, and 14 days. Conclusion: The results suggest that the addition of EMD to DFDBA particles may influence periodontal regeneration by stimulating PDL cell and osteoblast proliferation and differentiation.     

Effect of platelet-rich plasma on bone growth and osseointegration in human maxillary sinus grafts: three bilateral case reports

Platelet-rich plasma is an autologous product that is derived from whole blood through the process of gradient density centrifugation. The proposed value of this product in dental implantology and in bone augmentation procedures lies in the ability to incorporate high concentrations of the growth factors PDGF TGF-beta1, TGF-beta2, and IGF as well as fibrin, into the graft mixture. Research has shown an increased bone maturation rate and improved bone density when this product, or its recombinant growth factors, is added to small bony defects or to larger defects that use autogenous bone as the grafting material. This study tested the efficacy of platelet-rich plasma in three bilateral sinus graft cases with grafts of anorganic bovine bone that contained minimal or no autogenous bone. Histomorphometric analysis indicated that the addition of platelet-rich plasma to the grafts did not make a significant difference either in vital bone production or in interfacial bone contact on the test implants.     

The effects of growth factors on DNA synthesis, proteoglycan synthesis and alkaline phosphatase activity in bovine dental pulp cells.

Platelet-derived growth factor (PDGF), insulin-like growth factor-I and -II (IGF-I and -II), acidic fibroblast growth factor (aFGF), basic fibroblast growth factor (bFGF) and epidermal growth factor (EGF) stimulated [125I]-deoxyuridine incorporation about 13, 6.2-, 4.6-, 3.8-, 3.1- and 1.2-fold, respectively, above control values at a concentration of 50 ng/ml. Transforming growth factor-beta (TGF-beta) decreased incorporation about 30% at the same dose. aFGF, IGF-I, IGF-II, bFGF and TGF-beta increased [35S]-sulphate incorporation 231, 71, 64, 42 and 39%, respectively, in proliferating cells, while EGF, IGF-I, TGF-beta and PDGF decreased incorporation about 30%, and aFGF increased incorporation 80% in stationary-stage culture. TGF-beta, PDGF, aFGF and bFGF caused 65-40% inhibition of alkaline phosphatase activity in proliferating and stationary cultures. These findings suggest that the proliferation of pulp cells may be stimulated mainly by PDGF and IGF-I, and the production of extracellular matrix proteoglycan may be enhanced by aFGF, IGF-I and IGF-II. Furthermore, TGF-beta, PDGF, aFGF and bFGF may regulate the differentiation of pulp cells into odontoblasts.     

Clinical evaluation of demineralized freeze-dried bone allograft and enamel matrix derivative versus enamel matrix derivative alone for the treatment of periodontal osseous defects in humans

BACKGROUND: A recent study suggests that the addition of enamel matrix derivative to demineralized freeze-dried bone allograft may enhance osseoinduction. The purpose of this study was to evaluate the use of demineralized freeze-dried bone allograft (DFDBA) in combination with enamel matrix derivative (EMD + DFDBA) compared to enamel matrix derivative (EMD) alone in the treatment of human intrabony periodontal defects. METHODS: Forty patients with a total of 67 sites (intrabony defect > or = 3 mm deep) were selected to participate in this single-masked, parallel design, randomized, controlled clinical trial. Each subject received either EMD alone (34 sites) or in combination with DFDBA (33 sites). Soft tissue measurements included probing depth (PD), clinical attachment level (CAL), and recession. Hard tissue measurements included defect depth, alveolar crestal resorption, and defect morphology. Following 6 months of healing, all soft tissue measurements were repeated. Forty-nine sites (EMD + DFDBA = 26 sites, EMD alone = 23 sites) were surgically reentered. Statistical analyses were performed using unpaired and paired Student t tests. RESULTS: Analyses showed a significant improvement in soft tissue parameters for both treatment groups (P < 0.001) as compared to preoperative measurements. There were no statistical differences between treatment groups. The probing depth reduction (PDR) for the EMD + DFDBA was 3.6 +/- 0.2 mm, while the EMD alone had a PDR of 4.0 +/- 0.3 mm. The CAL gain for the EMD + DFDBA group was 3.0 +/- 0.3 mm and 3.2 +/- 0.3 mm for the EMD alone group. The mean value for bone fill in the EMD + DFDBA group was 3.7 +/- 0.2 mm (74.9%), while the EMD alone group demonstrated a mean bone fill of 2.6 +/- 0.4 mm (55.3%). While there were no significant differences between the two treatments with regards to soft tissue measurements, the combination of EMD + DFDBA therapy yielded statistically significant improvements in bone fill, crestal resorption, and percentage of sites gaining greater than 50% and 90% bone fill when compared to EMD alone (P < 0.001). CONCLUSION: The results of this study indicate that there may be an enhancement of hard tissue parameters when enamel matrix derivative is added to demineralized freeze-dried bone allograft.     

Implications of minocycline, platelet-derived growth factor, and transforming growth factor-beta on inflammatory repair potential in the periodontium.

BACKGROUND: Semisynthetic tetracyclines used in the adjunctive treatment of inflammatory periodontal disease enhance collagen expression in induced periodontal lesions of rats. Polypeptide growth factors regulate key cellular events in tissue repair. The physiologically active androgen 5 alpha-dihydrotestosterone (DHT) stimulates bone and connective tissue turnover. It was relevant to study the effects of transforming growth factor beta (TGF-beta)/platelet-derived growth factor (PDGF) and minocycline alone and in combination on the formation of biologically effective androgens which can influence repair. METHODS: Confluent monolayer cultures of human gingival fibroblasts of the fifth through the ninth passage were incubated in Eagle's minimum essential medium, with 14C-testosterone/14C-4-androstenedione in the presence or absence of optimal concentrations of TGF-beta/PDGF/minocycline (M), alone and in combination. At the end of a 24-hour incubation period, the medium was analyzed for steroid metabolites and quantified using a radioisotope scanner. RESULTS: The androgen substrates 14C-testosterone (14C-T) and 14C-4-androstenedione (14C-4-A) were metabolized to DHT and 4-androstenedione/testosterone respectively. There were significant increases in the formation of DHT from 14C-T in response to M, TGF-beta, and PDGF, alone and in combination (13 to 48%), compared with controls (n = 4; P<0.01). The yields of 4-androstenedione were also greater in response to these agents (31%; 3-fold). When 14C-4-A was used as substrate, there were 21 to 80% increases in the formation of DHT in response to these agents alone and in combination (n = 4; P<0.01). CONCLUSIONS: The biologically effective androgen metabolites formed in response to minocycline, TGF-beta, and PDGF can contribute to reparatory events in the inflamed periodontium. Judicious, adjunctive usage of the chemically-modified tetracyclines in the treatment of periodontal diseases can obviate the risk of microbial resistance, with potential applications of their anti-inflammatory and proanabolic effects in regenerative technology.