The Journal of Nihon University School of Dentistry最新文献

A valuable characteristic of the "IPS Empress" used for producing all ceramic dental restorations is that it is a prefired ceramic ingot. The ingot is heated, softened and press-injected into the cavity, and ceramic restorations are fabricated by the lost wax casting method. The leucite crystal present in the ingot are scattered and distributed into the glassy phase in a more homogeneous manner through this pressing procedure, and the resulting ceramics are of higher flexural strength than conventional ones. The present study was carried out to clarify the microstructure of Empress ceramics by etching, and to observe the etched surface by scanning electron microscopy, in comparison with several other conventional ceramics. It was shown that the form and distribution of the leucite crystals in Empress ceramics are quite different before and after pressing, and that the staining and layering ceramics are also different from conventional ceramics. The method of surface treatment of ceramics prior to etching, such as fracturing or grinding, the kind of etching material used, the concentration and the etching time are important factors for revealing, observing and evaluating the microstructure of ceramics containing leucite crystals.

The treatment of closed jaw locking due to temporomandibular joint (TMJ) arthrosis is described. Conventional mandibular manipulation of the lower and/or upper joint compartments was performed using hydraulic pressure from an imaging X-ray medium. The procedure was used in 40 patients with closed locking (5 acute and 35 chronic). The results of the treatment are evaluated and factors affecting the results are examined. In four of the five patients with acute closed locking, the lock was successfully released after use of the pumping technique on the lower joint compartment. In patients with chronic locking, an average improvement of 6.6 mm in the degree of interincisal opening was observed within 3-4 days of treatment with the pumping technique. In 13 of these patients, satisfactory opening (at least 40 mm) was achieved immediately. All the patients underwent further forward and contralateral manipulation to assist mouth opening, and after a period of 2-3 months 16 patients showed a further average improvement of 5.4 mm in interincisal opening.

Hydroxyproline (Hyp) and total protein levels were studied in gingiva from patients treated with phenytoin (PHT) and cyclosporine-A (CSA). The study included 5 groups of subjects: PHT and CSA groups with and without gingival overgrowth (PHT-GO+), (PHT-GO-), (CSA-GO+), (CSA-GO-), and periodontally healthy controls (C). After taking clinical measurements, gingival samples were harvested by gingivectomy or excising one or two papillae from the posterior areas. The samples were analyzed biochemically. In the PHT groups, both Hyp and total protein levels were significantly higher than in the C group. The differences between the PHT-GO+ and PHT-GO- groups were not statistically significant. In the CSA groups, total protein levels were significantly higher than in controls while no significant difference was found in Hyp levels. The differences between the CSA-GO+ and CSA-GO- groups were not statistically significant. When the PHT and CSA groups were compared, Hyp levels were significantly higher in the PHT-GO+ group than in the CSA-GO+ group. Total protein level differences between the PHT and CSA groups were not statistically significant. Correlations between age, plaque index, gingival overgrowth index, Hyp and total protein levels were analyzed and most were found not to be statistically significant. PHT appears to stimulate both collagen and total protein synthesis in gingiva while CSA seems to have a stronger effect on total protein synthesis. This suggests that the mechanisms underlying PHT- and CSA-induced gingival overgrowth are different and further comparative studies are needed.

The term "choristoma" is used to describe a mass of histologically normal tissue presenting in an aberrant site. A rare case of osseous choristoma of the tongue is presented and the literature is briefly reviewed.

The early replicative phase of Epstein-Barr virus (EBV) was detected by immunohistochemistry, in addition to routine histology with hematoxylin eosin staining, in formalin fixed, paraffin-embedded archive specimens of 97 hyperkeratotic lesions including oral hairy leukoplakia (HL) in order to assess whether EBV is specific to HL, or if it occurs in other hyperkeratotic lesions of the oral mucosa. Monoclonal antibody (MAb) BZ-1 directed against the BZLF-1 gene product of EBV was used for immunostaining by the avidin-biotin peroxidase technique. The reaction was visualized with DAB/H2O2 solution and counterstained with PAS stain to detect any coexisting of hyphae of Candida. Eight lesions were reactive with BZ-1, confirming a diagnosis of HL, although the total number of lesions with koilocytoid features was 33. Seventy percent of the patients with confirmed HL lesions were HIV-seropositive, and 50% of the HL lesions were associated with Candida hyphae. One third of the lesions with koilocytoid features were associated with hyphae of Candida. Only one renal transplant patient had HL, confirmed by a positive BZ-1 reaction, although 60% of the hyperkeratotic lesions showed koilocytoid features in a subgroup of 15 patients with renal transplants.

In this study the authors set out to investigate the stress distribution around the chin due to articulation, and to discuss whether the calculated stresses can cause bone remodeling. A finite element model of facial soft tissue was constructed and movements related to the articulation of the five basic Japanese vowel sounds were reproduced individually on the model. The stress distribution of each vowel depended on the shapes formed by the lips and the degree of mandibular opening. Stresses increased with the strain on the soft tissue of the lips. It seemed unlikely that the calculated stress alone was sufficient to produce a hypertrophic increase in modeling. However, it seemed that muscle forces might produce an effective strain load with a range sufficient to cause bone remodeling by accumulation of stresses around the chin.

Two cases of either peripheral odontogenic fibroma (POF) (WHO type) or peripheral ameloblastoma are reported. Their immunohistochemical characteristics were investigated in an attempt to clarify their histogenesis. The results showed that the epithelial component of this neoplasm tended to retain its distinct odontogenic character and expressed a keratin profile different from that of the overlying oral epithelium from which both cases most probably originated. The connective tissue element of these tumors was vimentin-positive and S-100 protein negative, confirming their mesodermal nature but precluding the possibility of ectomesenchymal derivation. No reactivity for desmin was noted.

Ehlers-Danlos syndrome (EDS), a group of rare, autosomal dominantly inherited connective tissue dysplasias, characterized mainly by abnormal collagen synthesis, has been shown to exhibit extensive heterogeneity with at least 11 clinical entities differentiated by their clinical, biochemical, and genetic features. Of these, Type VIII EDS is of special interest from a dental viewpoint, due mainly to the resulting fragility of the oral mucosa and blood vessels, and an aggressive type of periodontitis causing severe loss of alveolar bone; all of these clinical manifestations of the entity make it necessary to exercise care during the dental treatment procedures. Here we present a case of EDS Type VIII with typical clinical findings, together with details of the dental treatment modalities, placing emphasis on surgical methods.

Levels of serum IgG against Porphyromonas gingivalis cell sonicate were determined in patients with rheumatoid arthritis (RA) (n = 25), rapidly progressive periodontitis (RPP)(n = 25) and adult periodontitis (AP)(n = 15) and controls (HP)(n = 10) utilizing the ELISA technique. Comparison between groups showed no significant differences between the HP and RA groups and also between the RPP and AP groups. The increased levels of IgG in the RPP and AP groups were comparable. Significant differences in IgG levels were noted between HP and RPP (p<0.05) and between HP and AP (p<0.01). The differences between RA and RPP and between RA and AP were highly significant (p<0.0001). Thus it was revealed that the serum levels of IgG against P. gingivalis in RPP and AP patients were elevated, whereas the levels in RA patients were comparable to those in controls.

An epithelial Madin-Darby canine kidney (MDCK) cell line was grown in two kinds of standard media and a medium conditioned by MRC-5 embryonic lung cells, and temporo-regional differences in cell proliferation were examined by immunohistochemical detection of incorporated bromodeoxyuridine (BrdU). MRC-5-conditioned medium is known to contain scatter factor, which induces scattering of MDCK cells. In a proliferation assay, the BrdU labeling index (percentage ratio of BrdU-positive to total nuclei) was highest in day 2 cultures in the standard media, but on day 3 in the conditioned medium. MDCK cells in the standard media formed multiple epithelial sheets by day 2. In the conditioned medium, however, epithelial sheet formation was retarded and observed only after day 3. Once epithelial sheets had formed, cells close to the edge of the sheet were more proliferative than those distant from the edge in both standard and conditioned media. These findings suggest that proliferation of MDCK cells is suppressed during the scattering induced by the conditioned medium, and that their DNA synthesis becomes most active when cell scattering has ceased and epithelial sheets have begun to form.