Nihon Shishubyo Gakkai kaishi最新文献

The purpose of this study was to clarify the relationship between the lamellar structure and the fibrous components of cementum. Freeze-fracture specimens and ground sections of the human molar cementum were treated with acid- and/or alkaline-solutions, then examined by scanning electron microscopy. Both of the layers of Sharpey (extrinsic) fiber and matrix (intrinsic) fiber were distinguished in freeze-fracture specimens and ground sections, but no lamellar structures appeared. For the first time, the lamellae isolated with narrow grooves were clearly observed on the ground sections that were treated with 5% sodium hypochlorite for 60 min followed by 0.5-1.0 M hydrochloric acid for 30-60 sec. In addition to the two fiber-layer types, the mixed fiber layer containing both components of matrix and Sharpey's fibers was classified, and the lamellar arrangement of matrix fibers was also revealed. When the hypochlorite treatment time was prolonged for 120 min, the lamellar structures were evident. Our results show that those treatments may resolve the regions of physiological hypomineralization related to the incremental lines running parallel to the cemento dentinal junction and the lines of discontinuity of the fibrous components.

It has been supposed that lipopolysaccharide (LPS) derived from the gram negative bacteria of subgingival plaque is one of the important etiologic factors in periodontal disease. The purpose of this study was to detect specifically the LPS from Bacteroides gingivalis (Bg) and to determine the effects of gram-positive bacteria on LPS in culture supernatant of Bg. Enzyme-linked immunosorbent assay was used for specific detection of LPS from Bg. LPS of Bg could be measured in concentrations as low as 4 micrograms/ml. LPS of Bg was not detected in gingival crevicular fluid from periodontal disease patients. There were no significant differences in the concentration of LPS between the culture supernatant of Bg and co-cultivation of Bg and gram-positive bacteria. In this study, gram-positive bacteria had no effects on release and degradation of LPS in the culture supernatant of Bg.

We have established a method to observe circulation in a small area of the human gingiva. Reflected light photo-plethysmographs (RLP) and transilluminated light photo-plethysmographs (TLP) were recorded from healthy gingiva in 2 young adults of twenties. A tungsten-lamp, connected to a stabilized power source, was used to illuminate the gingiva. The reflected or transilluminated light was collected using a fibre-optic bundle. A CdSe photo-conductive cell was used as the photo-detector. The ECG was recorded simultaneously. The results were as follows: 1) RLP and TLP were both synchronous with the heart beat and showed a dicrotic-notched wave form. 2) When the light-collecting fibre was 0.5 mm from the surface of the gingiva, the dicrotic notch with TLP was clearer than that with RLP. 3) When the light-collecting fibre was placed less than 0.5 mm from the gingival surface, clear dicrotic notches were seen in RLP. 4) When the surface of the gingiva was covered with white opaque paint to prevent transilluminated light, definite dicrotic notches were observed with RLP. 5) RLP was produced mainly by the pulsation of the gingival surface, and the pulsatile movement of the tooth had a little effect on RLP. 6) RLP was consisted from the light reflected from the surface of the gingiva and also from the light reflected after penetrating some distance in the gingival tissue.

In an attempt to promote periodontal tissue regeneration following periodontal surgery, an experimental study was conducted by applying the guided tissue regeneration (GTR) technique to a cross-linked atelocollagen membrane. The palatal gingiva of maxillary first molars of rats were dissected and the cementum was removed by curettage. An atelocollagen membrane was implanted into the site of dissection in the experimental group, while the control group received no implant. The wound healing processes in two groups were examined by histopathological methods, including histometric analysis of the cells and histological measurement of the regenerated periodontal tissue, 1, 3, 5, 7, 14 and 21 days, and 1, 2, 3 and 4 months after the implantation. The results were as follows. 1) Implantation of the atelocollagen membrane did not enhance or prolong the inflammatory reaction, indicating possible involvement of inflammatory cells and macrophages in the membrane absorption. 2) In the experimental group, epithelial downgrowth was markedly inhibited and fiber bundles of the gingival connective tissue were clearly arranged vertical to the root surface. 3) The experimental group showed a significant increase in new cementum formation 2 months after surgery compared with the control group. Root resorption was seldom observed in either group during the study period. The above results indicate that the GTR technique using an atelocollagen membrane may provide an effective method to promote periodontal tissue regeneration after periodontal surgery.

As mononuclear phagocytes have been implicated as important cellular elements in the process of bone resorption, we decided to study the relevancy of macrophage (M phi) activities to bone resorption. In this study, we investigated the phagocytic activity and activities of lysosomal enzymes of peritoneal resident M phi from rats fed a high-sucrose diet (Diet 2000) to appreciate the effects of Diet 2000 on systemic and local factors. Minkin et al. have postulated that bone-derived chemotactic factors were released from foci undergoing resorption. And so, we examined the effects of the supernatant from alveolar bone cultures (Bone-sup) prepared from rats fed Diet 2000 on the activities of glycogen induced peritoneal M phi. As a result we observed mild alveolar bone resorption with slight inflammation when the rats were fed Diet 2000 for six months. In the periodontal tissue, we found inflammatory cell infiltration, destruction of the periodontal ligament, and lacunae in the alveolar bone due to resorption. The phagocytic activity of M phi treated with Bone-sups was suppressed before the periodontal tissue, which is inflammatory condition such as alveolar bone resorption. Furthermore the phagocytic activity of resident M phi taken from rats on the Diet 2000 was suppressed. After one month of the Diet 2000, the activity of acid phosphatase (AcP), a lysosomal enzyme of M phi, was suppressed, but by six months it was enhanced. The activity of beta-N-acetyl-D-glucosaminidase (NAG), another lysosomal enzyme of M phi, was suppressed over the total period of Diet 2000 before the periodontal tissue was destroyed. These findings suggest that the capacity for defense against infection by M phi is suppressed when periodontitis is initiated by Diet 2000 feeding and that M phi activities are influenced by some factors elaborated by cells in the alveolar bone.

Local and systemic administrations of tetracycline have been used in human periodontal treatment for conditions including juvenile periodontitis and rapidly progressive periodontitis, although microbiological effects of the treatment have not been clear. The effect of systemic oral administration of tetracycline on subgingival bacteria in experimental periodontal disease in hamsters as an animal model has not yet been reported. The aim of this study was to investigate changes in subgingival bacteria and bone resorption at the lower left first molar, and supragingival plaque formation on the lower right first molar in animals with (TC group) or without (Diet-2000 group) systemic oral administration of tetracycline hydrochloride 25 mg/kg/day in 20-day-old golden hamsters that mere fed a high sucrose diet (Diet-2000). Experimental periods were established as 15, 29, 43, 57, and 71 days. Supragingival plaque formation on the lingual surface on the lower right first molar in the Diet-2000 group gradually increased with time; that in the TC group was scarce and was not increased with time. Bone resorption at the lower left first molar in the Diet-2000 group proceeded rapidly with time, while that in the TC group was scarce. Total number of bacteria from subgingival plaque on the lower left first molar in the Diet-2000 group increased rapidly with time, but that in the TC group did not vary at all with time. Actinomyces (Actinomyces naeslundii and Actinomyces viscosus) and Bacteroides (Bacteroides capillosus and Bacteroides ruminicola subsp. ruminicola) in the Diet-2000 group increased with time; those in the TC group decreased with time. A remarkable difference in IgG titers to Bacteroides asaccharolyticus was not observed in the Diet-2000 and the TC groups. These results suggest that systemic oral administration of tetracycline hydrochloride on experimental gingivitis in golden hamsters causes the total number of subgingival bacteria to be confined, and to be decreased species of Actinomyces (Actinomyces naeslundii and Acinomyces viscosus) and Bacteroides (Bacteroides capillosus and Bacteroides ruminicola subsp. ruminicola), leading to the inhibition of bone resorption and supragingival plaque formation. It is suggested that Bacteroides asaccharolyticus is not a pathogen concerned in experimental periodontal disease in hamsters, because the antibody titer was not elevated in the Diet-2000 group.

This study was carried out in order to determine the efficacy of CaO-P2O5-MgO-SiO2-CaF system glass ceramics, which are made as implant materials, for treatment of furcation lesions. Glass ceramic granules were implanted in artificial class II furcation bony defects in monkeys. As controls, non-implanted sites were preserved. Radiographic and various clinical examinations were performed before surgery and at 0, 2, 4 and 8 weeks after implantation. Two, 4 and 8 weeks after implantation, two monkeys were sacrificed and the mandibles were sectioned for histopathological observation. The results obtained were as follows; 1. During the experiment, no clinical problems or abnormal response at the sites of glass ceramic implantation were observed. 2. In clinical observation, no remarkable differences were obtained between control sites and implanted sites. 3. Two and 4 weeks after surgery, remarkable regeneration of bone was shown in the implanted sites. However 8 weeks after surgery, the difference between implanted and control sites was not so clear.

The present study was undertaken to determine the biocompatibility of a newly-developed CaO-P2O5-MgO-SiO2-CaF system glass ceramic tooth implant. Two adult male monkeys were selected and 12 weeks after extraction of M1 and P1, 8 glass ceramic teeth were implanted into alveolar bone. At 1 week after implantation, 6 teeth were allowed occlusal function, and 2 teeth were left free from occlusion as control teeth. The implants were observed for 4-12 weeks and examined histopathologically. The results were as follows: 1. Seven implanted teeth were well maintained clinically, and only one tooth was lost after 5 weeks. 2. In histopathological observation, implanted teeth were surrounded by bone, and connected by bonyankylosis. At cervix of dental implant, connective tissue as also attached firmly to implanted tooth surfaces and epithelial attachment was observed. 3. Although these implants were allowed occlusal function at an early stage (1 week after implantation), osteogenesis around implants was not disturbed. These results suggest that the new glass ceramic implant has good biocompatibility and is useful as an implant tooth.

The aim of this study is to determine the process of periodontal tissue regeneration and the metabolic activity of osteoblasts after implantation of bone ceramic and collagen gel compound materials (BC). Bone defects were artificially prepared in the alveolar septa of the bilateral upper first and second molars of Wistar rats. Subsequently, BC were implanted into the defective sites on the left side, and the gingival flaps were closed. At the defective sites on the right side, as a control, gingival flaps were closed without implantation. Rats were sacrificed 1, 3, 5, 7 or 14 weeks after implantation, and prepared tissue sections were observed both pathologically and autoradiographically using 3H-Proline. The results obtained were as follows: Pathological Findings One week after BC implantation, inflammatory cellular infiltration of the surrounding gingival connective tissue was relatively mild. Three weeks after implantation, BC were present in fibrous connective tissues, and some directly bound to the marices of regenerated bone. Observation 5 weeks after implantation revealed that BC had become embedded in the regenerated bone matrices and that there was giant cell reaction to foreign bodies at the margin of BC located in connective tissue. BC were directly bound to the regenerated bone matrices without intermediary fibrous tissues 7 and 14 weeks after implantation. Connective tissues showed high grade regeneration of collagen fiber bundles, in an arrangement that tended to be fixed in mesial and distal directions. Autoradiographic Findings There was no uptake of 3H-Proline into the regenerated bone matrices or the gingival connective tissue surrounding BC, while uptake of 3H-Proline into the entire area around the root apex and in the vicinity of the alveolar septum was observed with time (weeks) after BC implantation. These results suggest that BC provide nuclei for bone regeneration through inclusion in newly-generated periodontal bone tissue, although it is difficult to produce definite induction of bone tissue by BC alone. It is also apparent that these are useful bone implantation materials for restoration of the physiological morphology of alveolar bone in periodontal surgical treatment.

We have previously reported that the sonicate extrast from Actinomyces viscosus T 14 V (Av. sup) causes polyclonal B cell activation (PBA) in murine splenic B cells without any T cell assistance. However, there are some reports describing T cell dependency of PBA induced by A. viscosus in human peripheral blood B cells, and it is still controversial whether or not A. viscosus has the capability of exhibiting PBA without the help of T cells. In this report, we examined PBA in human peripheral blood B cells using the same Av. sup which induced T cell independent PBA in murine splenic B cells. The PBA was evaluated in terms of immunoglobulin (Ig) production by means of micro-ELISA method and cell proliferation by incorporation of 3H-TdR after incubation of cells for 5 or 7 days with Av. sup. Human peripheral blood B cells were highly purified by the following methods; The peripheral blood was collected by venipuncture and the peripheral blood mononuclear cells were harvested using gradient centrifugations. These cells were passed through a Sephadex G-10 column, and T cells were eliminated by rosette formation with sheep red blood cells. B cells were highly purified from these T cell-depleted cell populations by panning method with anti-human Ig antibody coated dishes followed by complement-dependent cytotoxisity using monoclonal antibody cocktails consisting of OKT 3, OKT 4 and OKT 8. These highly purified B cells could not respond to T cell mitogens such as PHA.(ABSTRACT TRUNCATED AT 250 WORDS)