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  • 1
    Electronic Resource
    Electronic Resource
    Oxford, UK : Blackwell Publishing Ltd
    Journal of periodontal research 28 (1993), S. 0 
    ISSN: 1600-0765
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Type of Medium: Electronic Resource
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  • 2
    ISSN: 1600-0765
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: The influence of four different dental surfaces, demineralized dentine (DD) and cementum (DC), and nondemineralized dentine (ND) and cementum (NC), on the migration, attachment, and orientation of human gingival fibroblasts (HGF) was tested in an in vitro system. The root surface of porcine teeth was planed using a curette. The cementum was removed from half of the teeth and the roots planed again. Slices of root ∼ 150 μm thick were obtained from the roots. Half of the root slices in each group were partly demineralized in 18% EDTA, pH 7.4. Pairs of root slices were added to each of 20 culture dishes containing 5-day-old confluent cultures of HGF. The attachment of HGF to the four types of attachment surfaces (DD, ND, DC, & NC) and the formation of oriented sheets of cells extending between the periphery of the slices and the bottom of the dish were assessed quantitatively after 1, 3, and 6 days of culture. In a second experiment, 12 cultures comprising demineralized and non-demineralized root slices were examined at 1, 3, and 6 days using SEM. In a third experiment, cultures comprising DC slices were prepared as described and examined for 24 h by time lapse microscopy.It was found, first, that cells started to migrate and attach to the periphery of the slices immediately following the placement of slices. Cellular bridges extending between the attachment surface and the floor of the dish developed during the first 24 h of culture and gradually increased in number and in size throughout the experimental period. Second, partially-demineralized surfaces were more effective in stimulating cell migration and attachment and cell orientation than were non-demineralized surfaces, and demineralized dentine surface were more effective than were demineralized cementum surfaces in this regard. These results further elucidate previous findings regarding the enhancing effect of partial demineralization of dental surfaces on wound healing in vivo and suggest that demineralized dentine may provide the most effective dental surface in this respect.
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    Oxford, UK : Blackwell Publishing Ltd
    Journal of periodontal research 17 (1982), S. 0 
    ISSN: 1600-0765
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: Localized thermal injury was produced in the coronal part of the rat incisor periodontal ligament (PDL). The tooth was cut off at the gingival margin and its pulp removed to a depth of 9 mm from the cut edge. An electrocautery needle was then inserted into the pulp cavity, and a current of two seconds duration was applied. The thermal injury affects primarily PDL vitality, and this is manifested by an eruption slow-down accompanied by typical histological changes. Specimens for histological examination were obtained one, three, and seven days following treatment and compared with the sections prepared from sham operated and control incisors. The mean eruption rate of the cauterized teeth was slower by about 70 % than that in the other two groups. Histological sections of the former incisors revealed well demarcated coagulation necrosis, which was especially pronounced on the first and third post treatment days. Signs of repair in the damaged areas were observed on the seventh day following treatment. The lingual periodontal lesions were infiltrated with fibroblasts and vascular tissue. In some incisors, hard tissue deposits appeared in the tooth-related part of the PDL. The PDL of sham operated or control animals did not exhibit any changes. These experiments demonstrate that isolated damage to the PDL retards tooth eruption, supporting the hypothesis which views the PDL as the prime motor pulling the erupting incisor outward.
    Type of Medium: Electronic Resource
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  • 4
    Electronic Resource
    Electronic Resource
    Copenhagen : Munksgaard International Publishers
    Journal of periodontal research 36 (2001), S. 0 
    ISSN: 1600-0765
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: Growth factors are known to play a major role in the regeneration of the periodontium. Basic fibroblast growth factor (bFGF) is a polypeptide growth factor considered to have a role in chemotaxis and mitogenesis of periodontal ligament (PDL) cells. The aim of this study was to assess the effect of bFGF on the transcription level of tropoelastin. As known controls, we assessed the transcription levels of collagen type I, collagen type III and the housekeeping gene, actin. Initially, PDL cells were cultured without bFGF for 3, 7 and 14 days. At each time point, total RNA was extracted and the levels of transcription were assessed by semiquantitative reverse transcription polymerase chain reaction (RT-PCR) assay. The results showed that tropoelastin mRNA is transcribed in PDL cells and its levels increased from minimal amounts by day 3 to maximal amounts by day 14 of culture. We further examined the effect of the addition of 10 ng/ml bFGF to the culture media by day 14. The results showed that the addition of bFGF suppressed the transcription level of tropoelastin. At that time, as expected, a decrease in collagen type I transcription level was shown, while the transcription level of collagen type III was not affected. The findings that elastin is transcribed in vitro by PDL cells, but only negligibly in vivo, imply mechanisms that downregulate or even shut down the expression of the elastin gene in the functioning PDL. Basic FGF might be one of the cytokines involved in control of elastin expression in vivo.
    Type of Medium: Electronic Resource
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  • 5
    Electronic Resource
    Electronic Resource
    Oxford, UK : Blackwell Publishing Ltd
    Journal of periodontal research 24 (1989), S. 0 
    ISSN: 1600-0765
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: The capacity of collagen membranes to prevent the apical migration of epithelium and to support new connective tissue attachment was assessed in experimental perodontal defects in dogs. Experimental periodontal defects were produced in 8 mongrel dogs by removing the alveolar bone and the periodontal ligament over the most coronal 5 mm of the labial aspect of the maxillary canines. Experimental defects associated with the right canine and its surrounding bone were covered by collagen membranes prepared by air drying gels of rat type I fibrillar collagen. Flaps were repositioned and sutured. The contralateral control defects were sham-operated without using collagen membranes. Animals were killed, 10 and 30 days after surgery, 4 at each time point. The experimental and control sites were processed for histologic and histomorphometric evaluation. At 10 d, the average distance between the apical margin of the epithelium and the apical level of the defect (EA) sites was 3.20±0.55 mm for the experimental sites and 0.73±0.18 mm for the controls. The experimental root surfaces apical to the epithelium and the collagen membranes were covered by connective tissue cells. At 30 d, the EA for experimental and control sites were 2.55±0.36 mm and 0.47±0.30 mm, respectively. In the experimental sites healing by long junctional epithelium was observed in the coronal 40% of apicoocclusal dimension of the defect and new connective tissue attachment with inserting fibers in the apical 55% of the defect length. No new bone formation was observed. In the control sites, pocket formation was found in the most coronal one-third of the defect. Healing by long junctional epithelium was found in the most apical two-thirds of the defect. Collagen membrane remnants were not identified at 30 d. These results indicate that collagen membranes have the capacity to partially prevent epithelial apical migration and to support new connective tissue attachment formation in experimental periodontal defects in the dog.
    Type of Medium: Electronic Resource
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  • 6
    Electronic Resource
    Electronic Resource
    Oxford, UK : Blackwell Publishing Ltd
    Journal of periodontal research 22 (1987), S. 0 
    ISSN: 1600-0765
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: Collagen membranes were interposed between full thickness periodontal flaps and denuded root surfaces of right upper canines in 3 mongrel dogs; the left canines were sham-operated without the use of collagen membranes. Animals were killed 10 d after surgery. Tissue blocks were removed, and experimental and control sites were processed for histometric and histologic examination. The results indicate that collagen membranes: (i) prevent apical migration of the epithelium during initial stages of healing; and (ii) are colonized by connective tissue cells and incorporated within the healing connective tissue.
    Type of Medium: Electronic Resource
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  • 7
    ISSN: 1600-0765
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Type of Medium: Electronic Resource
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  • 8
    Electronic Resource
    Electronic Resource
    Oxford, UK : Blackwell Publishing Ltd
    Journal of periodontal research 29 (1994), S. 0 
    ISSN: 1600-0765
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: In the context of cellular origins, ondotogenic epithelium and oral epithelium are the sources for junctional epithelium during development and during wound healing respectively. In contrast, both odontogenic and non-odontogenic mesenchyme contain the progenitors for gingival fibroblasts in developing tissues while in wounded tissues, gingival fibroblasts are derived from gingival connective tissues and comprise a heterogeneous population of cells with diverse properties and functions. Periodontal ligament, bone and cementum cell populations apparently originate from dental follicle progenitor cells during development, but during wound healing derive from ancestral cells in periodontal ligament and bone. Cellular differentiation in developing periodontium is governed in part by epithelial-mesenchymal interactions that generate specific signals which regulate selective cell populations in time and space. On the other hand, differentiation during wound healing and regeneration is regulated by a vast array of extracellular matrix informational molecules and by cytokines that induce both selective and non-selective responses in the different cell lineages and their precursors. Further, several important signalling systems are irretrievably lost after development is complete. Thus, in the context of cellular origins and differentiation, developing and wounded periodontal tissues exhibit fundamental differences. Future prospects for improved healing and regeneration of periodontal tissues may derive from identification and isolation of informational molecules that are stored in connective tissue matrices. These molecules and elucidation of their functions may open new perspectives in our understanding of the biology of periodontal wound healing and may provide novel approaches to periodonlal regeneration.
    Type of Medium: Electronic Resource
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  • 9
    ISSN: 1600-0765
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: Mouse monoclonal anti-fibronectin antibodies and rabbit affinity-purified actin antibodies were used with gold-labelled secondary antibodies to study the distributions of fibronectin and actin within the periodontal tissues of the rat. Following perfusion fixation, demineralization, and embedding in glycolmethacrylate, sections 70–80 nm thick were obtained from the gingiva, periodontal ligament and the supporting bone of the first and second mandibular molars. In both gingiva and periodontal ligament, fibronectin was located over the collagen fibers and at certain sites at the cell-collagen interface. In addition, unbanded fibrillar material 10–20 nm thick was decorated by fibronectin antibodies. Actin was localized primarily in the peripheral cytoplasm and at the cell-extracellular matrix interface. Labelling for actin was detected at a few sites within the extracellular matrix. In double labelling experiments, fibronectin and actin were observed to co-distribute at cell-matrix interfaces. These data support the concept that fibronectin within the dense connective tissue of the rat gingiva and periodontal ligament, as in other soft connective tissues, may mediate the interaction between different components of the extracellular matrix and between these components and the cell membrane. In addition, they strengthen the hypothesis that actin filaments may be active in vivo in the formation of cell-matrix contacts, and that actin and fibronectin may form fibronexus-like structures similar to those described for fibroblasts in culture.
    Type of Medium: Electronic Resource
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  • 10
    ISSN: 1600-0765
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: Background:  The aim of orthodontic treatment is to relocate teeth abnormally positioned in the jaws. This is achieved by application of continuous force on the tooth, which is immediately being sensed by the periodontal ligament (PDL), bone and the gingiva. Since the bony response is mediated by the PDL, tooth movement is primarily a PDL phenomenon.Objectives:  Thus, the purpose of the present study was to evaluate the direct effect of force (excluding the in vivo tissue response) on the molecular level of matrix metalloproteinase-1 (MMP-1) and collagen type-I (Col-I) in human PDL fibroblasts.Methods:  PDL cell culture flasks were centrifuged for 10, 20, 30, 60, 90 and 120 min by horizontal microplate rotor. The effect of force on mRNA levels of β-actin, MMP-1, Col-I, tissue inhibitors-1 and -2 (TIMPs) genes was analyzed by RT-PCR.Results:  The results showed that force had no effect on the mRNA levels of β-actin during the first 90 min of application of force, indicating for the first time the use of β-actin gene as an internal invariant control. It increased the mRNA levels of MMP-1 while almost no effect on Col-I and TIMPs was observed.Conclusions:  The results indicate that PDL remodeling following application of orthodontic force could be partly attributed to the direct effect of the force on MMP-1 gene expression in fibroblasts.
    Type of Medium: Electronic Resource
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