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Volume 20 (2001)
- Issue 4 Pages 247-
- Issue 3 Pages 195-
- Issue 2 Pages 127-
- Issue 1 Pages 1-
Volume 20, Issue 3
Displaying 1-5 of 5 articles from this issue
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Taro INOUE, Ai INOUE, Masuo ASAI, Yutaka KOMASA2001 Volume 20 Issue 3 Pages 195-205
Published: 2001
Released on J-STAGE: February 12, 2009
JOURNAL FREE ACCESSThe present study was undertaken to evaluate the clinical applicability of cast CP titanium crowns fabricated with sintered molds. To this end, the dimensional changes and accuracy of fit of cast CP titanium crowns, manufactured under varying mold firing temperatures, were examined. Molds were fired at 7 temperatures.
The outer height of the crown and outer width of the occlusal surface decreased under all sets of firing conditions. The outer width of the cervical part tended to increase at firing temperatures of 1, 200, 1, 300 and 1, 400°C. The inner widths of the occlusal surface and cervical part tended to increase under all sets of firing conditions. In the analysis of the fit of crowns, floating (gained latitude) was observed under all sets of conditions. However, the amount of floating was significantly smaller when the firing temperature was 1, 200, 1, 300 or 1, 400°C than when it was 800, 900, 1, 000 or 1, 100°C.View full abstractDownload PDF (1564K) -
Jiro TANAKA, Toshiaki HASHIMOTO, Jeffrey W. STANSBURY, Joseph M. ANTON ...2001 Volume 20 Issue 3 Pages 206-215
Published: 2001
Released on J-STAGE: February 12, 2009
JOURNAL FREE ACCESSThe properties of dental matrix resins have been improved by synthesis of new monomers. However, except for improvements in water-resistance, monomers with better mechanical properties than Bis-GMA and UDMA could not being synthesized. Changing the point of emphasis, we tried to improve the mechanical properties controlling the matrix resin higher structure using noncovalent bonds. We prepared a matrix resin structured by UDMA, which is a high viscosity base monomer with imino groups, and by a low viscosity acidic monomer with carboxyl groups, which permits noncovalent bonds such as hydrogen bonds or electrostatic interaction with imino groups. The maximal mechanical strength for matrix resins structured by UDMA and an acidic monomer was obtained with a composition of imino groups and carboxyl groups at a ratio of 1:1. This mechanical strength value was higher than those obtained with UDMA resin or with a Bis-GMA/TEGDMA/UDMA resin with typical composition. The improvement in mechanical properties may be due to the complex based on noncovalent bonds, between the imino groups of UDMA and the carboxyl groups of the acidic monomers.View full abstractDownload PDF (896K) -
Takanobu NISHINO, Takeshi ASAO, Hiroshi NAGAMATSU, Tatsuro KOJO, Hiros ...2001 Volume 20 Issue 3 Pages 216-226
Published: 2001
Released on J-STAGE: February 12, 2009
JOURNAL FREE ACCESSThe wearing behaviors of a hybrid composite resin for crown and bridge (ES) were examined using a two-body impacting-sliding wear test with a porcelain (PO), Au-Ag-Pd alloy (PD), direct restorative composite resin (CR) and tooth enamel (TO). Although PO was the hardest of all, it showed the largest wear together with ES in the combination of ES-PO, which was probably initiated from the superficial destruction by their impact. The wear in ES-PD was the second largest. It was noted in this combination that the surface of ES was partially contaminated by scraped thin layers of PD to a degree distinguished by the naked eye. The mutual wears of the components were relatively low in the combination of ES with CR, TO or ES itself. It is suggested from these findings that the hybrid composite resin may be useful as an alternative to porcelain for posterior crown and bridge unless it opposes porcelain or alloys.View full abstractDownload PDF (2272K) -
Suchit Poolthong, Toshiko Mori, Michael V. Swain2001 Volume 20 Issue 3 Pages 227-236
Published: 2001
Released on J-STAGE: February 12, 2009
JOURNAL FREE ACCESSA nano-indentation test was applied to determine elastic modulus (E) and hardness (H) of dentin. Three spherical indenters with nominal radii of 20, 5 and 1μm were used and load/partial-unload cycles were repeated. Each cycle provided E and contact pressure or Meyer's hardness. The plot of contact pressure versus penetration depth was converted into a normalized indentation stress-strain relationship, which was used to select the optimum maximum indentation force for each indenter. The results were compared with those determined by the conventional triangular pyramidal (Berkovich) indenter technique. The comparable E value, irrespective of radius, was 19.5-20.9GPa and the 1μm indenter was able to provide E values of peritubular (28.0GPa) and intertubular dentin (14.9GPa). The H values generated with the Berkovich indentation technique were comparable to those determined by the spherical indenter technique at indentation strains of 0.9 and 0.5 for the 1 and 5μm indenters.View full abstractDownload PDF (1523K) -
Seiichiro FUJISAWA, Norihisa OKADA, Eitoku MURAOKA2001 Volume 20 Issue 3 Pages 237-242
Published: 2001
Released on J-STAGE: February 12, 2009
JOURNAL FREE ACCESSThe purpose of this study was to evaluate the histopathological effect of eugenol and bis-eugenol on oral mucous membranes at the tissue organ level. Oral mucous membranes of mice were applied with three reagents, eugenol, bis-eugenol, and aceton (as the control). The control group showed a normal architecture. The eugenol group showed severe hyperkeratosis, parakeratosis, cellular edema, pachy chronic inflammation, pleomorphism and hyperchromatism of basal layer cells, indicating high mitotic activity. Comparatively, the bis-eugenol group showed mild hyperkeratosis, parakeratosis, however, the shape or arrangement of basal layer cells were normal. Bis-eugenol was considerably less toxic than eugenol.View full abstractDownload PDF (3017K)
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