Gingival matrix collagen in chronic periodontitis

Cellular and collagen reference values of gingival and periodontal ligament tissues in rats: a pilot study

Reference data are lacking on the periodontal ligament and the gingival tissue of the rat model, which would be useful for studies of new medical or biomaterial periodontal treatments. The objective of the current study was to propose cellular and collagen reference values of gingival and periodontal ligament tissues in rat, using a simple and reliable quantitative method after decalcification. Mandibular samples of ten adult Sprague-Dawley rats were used. Mild decalcification was carried out using ethylenediaminetetraacetic acid (EDTA) to preserve the morphology of tissues. Half of the samples were decalcified and the other half were not. The gingiva and the periodontal ligament were analyzed. Descriptive histology and computer-assisted image analysis were performed. The data showed that qualitatively, cellular and extracellular matrix morphologies were well preserved compared to non-decalcified periodontal soft tissue biopsies. Histomorphometrically, constitutive cellularity and the total amount of native collagen, collagen directionality and collagen anisotropy in both experimental conditions did not significantly differ. Taken together, these results suggested that EDTA decalcification did not negatively affect the studied endpoints. Moreover, this mild decalcification method allowed in situ maintenance of the periodontal soft and hard tissue integrity. The structural and compositional computerized assessment performed in the healthy periodontal soft tissue could provide reference values that will be required for future assessment on the effects of pathological, reparative and regenerative processes in rat periodontal soft tissues.

Effects of a bleaching agent on human gingival fibroblasts

Mild oxygenating agents generating low concentrations of hydrogen peroxide (H2O2) are effective alternatives to heat-activated 30% H2O2 in bleaching discolored, vital teeth. There are concerns about possible pathological effects of long-term exposure to bleaching agents, and irritation and ulceration of the gingiva and other oral soft tissues can occur. The objective of this study was to determine the effect of one of these agents on gingival fibroblasts in vitro. Microscopic examination revealed that concentrations of 0.05% to 0.025% of the agent appeared to kill most of the cells. At concentrations of 0.025% to 0.017% some morphological changes were noted; the cells appeared normal at concentrations of < or = 0.0125%. The agent significantly (P < or = 0.002) decreased proliferation (measured by incorporation of [3H]-thymidine into cellular DNA) at concentrations as low as 0.006%. The agent also had a dose-dependent effect on fibronectin production, measured by ELISA, causing significant (P < or = 0.03) decreases at concentrations as low as 0.017%. The agent significantly decreased the production of types I (P < or = 0.01) and III (P < or = 0.04) collagens (measured by ELISA) at concentrations as low as 0.0125%. Type V collagen was not detected under any conditions. Catalase, which catalizes the breakdown of H2O2, abolished toxic effects of a 0.05% solution. The results show that in vitro, the agent is toxic to human gingival fibroblasts, inhibiting several cellular functions.(ABSTRACT TRUNCATED AT 250 WORDS)

Immunohistochemical localization of collagenous components in healthy periodontal tissues of the rat and marmoset (Callithrix jacchus). I. Distribution of collagen types I and III

The distribution of collagen types I and III was demonstrated in healthy periodontal tissues of the rat and marmoset using immunofluorescent localization after decalcification of the maxillae and mandiblae in 0.2 N HCl. An intense fluorescence in the alveolar bone and cementum matrix, as well as in the soft periodontal tissue, was demonstrated with anti-collagen type I antibodies. In the gingival connective tissue and in the periodontal ligament thick fibers of collagen type I could be observed. The fluorescent reaction in the rat periodontal ligament was not strong in comparison to the marmoset periodontal ligament. Sharpey's fibers, inserting into the cementum and alveolar bone, were also stained. On the other hand, collagen type III could not be demonstrated in the hard periodontal tissues, but could be in the bone marrow stroma and the incremental lines as well as around the Sharpey's fibers of the cementum, in accordance to previous studies. In the gingival connective tissue a strong staining was evident, especially near the basement membrane. The periodontal ligament showed an intense fluorescence that was, in some areas, continuous with Sharpey's fibers inserting into the cementum. The distribution of collagen types I and III was demonstrated with immunohistochemical techniques in the rat and marmoset periodontium. These results provide necessary information on healthy tissues that will be required for future studies on the effects of pathological, reparative and regenerative processes.

Immunohistochemical localization of collagenous components in healthy periodontal tissues of the rat and marmoset (Callithrix jacchus). II. Distribution of collagen types IV, V and VI

The immunohistochemical distribution of collagen types IV, V and VI has been demonstrated in healthy periodontal tissues of rats and marmosets following decalcification of the maxillae and mandibulae in 0.2 N HCl. An intense fluorescence with anti-collagen type IV antibodies was demonstrated in the basement membranes of the epithelium and of the blood vessels and nerves. In the alveolar bone stroma and in the periodontal ligament (PL) collagen type IV was present only in the basal membranes of the blood vessels and nerves. In comparison, collagen type V was observed in a fibrillar pattern in the gingival connective tissue, as well as the PL. In the PL, type V collagenous fibers demonstrated a parallel distribution with stronger fluorescence near the cementum surface. Collagen type VI could be demonstrated in fine fibers present in the gingival connective tissue and the PL. Blood vessels and nerves were not stained in the marmoset, but were in the rat, where a localization of collagen type VI was demonstrated in these areas. Alveolar bone and cementum, as well as the Sharpey's fibers embedded in these tissues, were not stained with antibodies against collagen type V and type VI, but a pericellular localization of these collagenous components could be observed. Collectively, these results provide basic information on the relative distribution of different collagen types in normal tissues of rats and marmosets that will be required for future studies on the effects of pathological, reparative and regenerative processes.

Immunohistochemical distribution of the collagen types IV, V, VI and glycoprotein laminin in the healthy rat, marmoset (Callithrix jacchus) and human gingivae

The purpose of this study was to demonstrate the localization of collagen types IV, V and VI as well as the glycoprotein laminin in biopsies of healthy rat, marmoset (Callithrix jacchus) and human gingivae. The slices, after the use of indirect immunofluorescence (incubation with antibodies against these extracellular matrix components), showed the same distribution with the anti-type IV and laminin antibodies on the basement membranes of the epithelium, blood vessels and nerves. Collagen type V, as a filamentous, and collagen type VI, as microfibrillar components, were localized in a similar pattern in the different species. In contrast to the other species, collagen type VI could not be found near the basement membranes of vessels and nerves of the marmoset gingiva. This result shows differences between human and monkey tissues, but not between rat and human gingivae, and conforms the heterogeneity of collagen type VI in the various cell and tissue types.

Isolation and partial characterization of bovine gingival AB collagen

Limited proteolysis with pepsin solubilized 25% of the insoluble gingival matrix as mainly soluble collagenous material. Fractional salt precipitation at neutral pH resulted in the separation of types III and I at 1.8 and 2.6 M NaCl, respectively. In addition, a collagenous fraction accounting for 2% of the solubilized collagen and precipitating at 4.5 M NaCl was shown to be identical with type V collagen. Isolation and partial characterization of the constituent-alpha-chains of the 4.5 M PPT by gel filtration, ion exchange and hydroxylapatite chromatography as well as disc electrophoresis showed that gingival type V collagen contains alpha A and alpha B chains in a ratio alpha B/alpha A of 1.73-1.8. Electron microscopic examination of ATP-precipitates showed that this collagen type gave only one kind of SLS aggregates with asymmetric band pattern characteristically different from that of type I collagen. The data provide evidence that gingival AB collagen is a heteropolymer in which the alpha A and alpha B chains are assembled in the same macromolecule in a 1:2 ratio.