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Establishment of Experimental Periapical Inflammatory Lesions in Mice
Get PDFapplication/pdfAbstract: Although studies on the formation of apical periodontitis have somehow been carried out but detailed cellular dynamics remain unclear. We recently established an experiment that could easily be performed using ddY mice. First, under general anesthesia using isoflurane inhalation, the coronal portion of the maxillary first molar was penetrated using a round bur and drill with water irrigation causing pulp exposure until the root apex. Micro computed tomography (R_mCT) was taken over time during observation. Four weeks later, R_mCT confirmed the presence of a radiolucent image at the apex of the tooth, which was then removed for histological examination. The results showed that granulation tissue with fibrosis had gradually formed at the periphery of the abscess. The present method confirmed the effectiveness of the experimental mode to exmine the formation of chronic inflammatory lesions at the root apex.journal articl
Production and enzymatic properties of a prolyl tripeptidyl peptidase of Streptococcus anginosus
Get PDFapplication/pdfStreptococcus anginosus is considered to be implicated in the etiology of oral infectious diseases as well as abscess formation in various body sites. We investigated the production and the enzymatic properties of PTP of S. anginosus NCTC 10713. This enzyme was found only in cell extract and active on tripeptide substrates containing proline residue at P1 position, particularly H−Ala−Ala−Pro−p−nitroanilide. The enzyme was produced by all 8 species of tested streptococci, indicating occurrence of this enzyme is rather ubiquitous within streptococci. This PTP was purified to homogeneity from the cell extract by the procedures including ammonium sulfate precipitation, chromatography, gel filtration and electrophoresis. The enzyme was inhibited by serine enzyme inhibitors and chelating reagents, indicating this PTP is a serine metalloenzyme with a molecular mass of 66 kDa. The enzyme was active against H−Ala−Ala−Pro−p−nitroanilide and H−Ala−Phe−Pro−p−nitroanilide in neutral pH solutions. The activity was completely lost by heating at 50°C for 10min.journal articl
CONTENTS
Get PDF9784905130062application/pdfEditor, Toshiyuki KawakamiLanguage Editor, David M Carlsonviii, 232 p. ill. (some col.)boo
Chapter 4 : Injury and the Recovery Reaction due to the Penetration of Material into the Mandibular Canal
Get PDF9784905130062application/pdfA root canal filling material paste, mainly made of calcium hydroxide and iodoform with the addition of silicone oil, was experimentally introduced into the mandibular canals of dogs. The tissue reactions to the paste were examined by radiography, histopathology, and electron microscopy. The examination results showed that the paste was phagocytosed by macrophages and, in general, was gradually resorbed by the passage of time. The paste was also found to cause heterotopic calcification and/or bone formation within the limited area of original penetration. The histopathological tissue changes of the alveolar nerve tissue were also examined. No injury-related histopathological change was observed as long as the injected paste did not contact alveolar nerve tissue, but tissue damage was observed at sites of direct contact. After removal of degenerated nerved debris by macrophages and Schwann cells, the persisting external membrane or “Schwann tubes” appeared to provide a scaffold for axonal regeneration and Schwann cell proliferation.Editor, Toshiyuki KawakamiLanguage Editor, David M Carlsonviii, 232 p. ill. (some col.)boo
Application of Sintered Titanium Dioxide to Biomaterials:Sintering Temperature of Anatase-Type TiO2 and Cell Proliferation of L929 Cells
Get PDFapplication/pdfThe purpose of this study was to create biomaterials from anatase-type titanium dioxide (TiO2). TiO2 is known for photocatalysis and osteogenesis. In order to apply this function to orthodontic brackets and coating materials for implants, the relationship between sintered temperature and cell proliferation was examined. In addition, sintered temperature, crystal structure and the surface properties of sintering bodies were investigated.Experimental Method: We began by pressure-molding anatase-type TiO2 powder and sintering it at temperatures of 700, 800, 900, 1,000, 1,100, 1,200 and 1,300℃ to produce sintered bodies for use as samples. We then used surface roughness, x-ray diffraction and scanning electron microscopy to observe the surface properties and texture. Moreover, we seeded the samples produced at each of the sintering temperatures with L929 mouse fibroblast cells in order to evaluate the cytocompatibility in terms of cell proliferation.Results: For the samples sintered at 700℃, only the crystalline phase of anatase-type TiO2 was confirmed, but for the samples sintered at 800℃ or 900℃ the crystalline phase of anatase-type TiO2 and in some cases rutile-type TiO2 crystalline phases were confirmed. At sintering temperatures of 1,000℃ or higher, all samples were transformed into rutile-type TiO2. In the test of cytocompatibility, the samples of anatase-type TiO2 sintered at 700℃ were found to have reduced cell counts after 24 to 96 hours of incubation compared to those immediately after being placed in the incubator (0 hour). However, the samples sintered at 800℃ or higher than 900℃ whereby the samples were transformed to rutile-type TiO2 showed remarkable cell proliferation even after time had passed.journal articl