-
Masahiko NAKAYAMA, John B. MOSER, Evan H. GREENER
1984 Volume 3 Issue 2 Pages
133-138,330
Published: December 25, 1984
Released on J-STAGE: February 12, 2009
JOURNAL
FREE ACCESS
The corrosion and tarnish resistance of two Cu-Al alloys resembling commercial dental alloys of this type have been measured. Corrosion resistance has been found to depend upon chloride ion concentration rather than alloy type, whereas tarnish resistance appears to be a function of alloy composition.
View full abstract
-
Kenzo ASAOKA, Norihiko KUWAYAMA
1984 Volume 3 Issue 2 Pages
139-147,330
Published: December 25, 1984
Released on J-STAGE: February 12, 2009
JOURNAL
FREE ACCESS
Thermal residual stress and deformation of porcelain/alloy restoration, which is a three-layered veneer plate model, were calculated by the theory of statically indeterminate beam and the finite element method. The factors that have the greatest effect on thermal residual stress in the veneer are coefficient of thermal expansion, modulus of elasticity and thickness of the layers. The relation between these factors and thermal residual stress after firing were studied. The effect of physical and mechanical properties of the intermediate oxide layers and the effect of firing two laminated porcelains on metal were examined from these calculating results.
View full abstract
-
Yoshizo OKAMOTO, Takashi HORIBE
1984 Volume 3 Issue 2 Pages
148-162,330
Published: December 25, 1984
Released on J-STAGE: February 12, 2009
JOURNAL
FREE ACCESS
For the purpose of clarifying the color change in porcelains under different firing conditions, we have investigated the properties of porcelain materials, used for firing. Further, porcelain materials fired in a platinum furnace or an infrared furnace were used for analysis of color change.
View full abstract
-
Masataka WADA, Toshi SUGAWARA, Takao HANAWA, Shoji OHKAWA, Seiichiro K ...
1984 Volume 3 Issue 2 Pages
163-169,331
Published: December 25, 1984
Released on J-STAGE: February 12, 2009
JOURNAL
FREE ACCESS
A personal computer program being developed by the authors is introduced. The system requires little maintenance and is suitable for individual laboratories of standard scale. The program is designed for evaluations material nonlinearities using Finite Element Method (FEM) for Computer Aided Engineering (CAE) in dental sphere.
View full abstract
-
Hiroyuki NAKAI, Kazuomi SUZUKI, Masao IRIE, Katsuya NAGAYAMA, Hirokazu ...
1984 Volume 3 Issue 2 Pages
170-192,331
Published: December 25, 1984
Released on J-STAGE: February 12, 2009
JOURNAL
FREE ACCESS
The available low and high copper amalgam alloys were characterized on the basis of their physical properties, as determined by A.D.A. Specification No.1. The effect of mixing time on these properties were also examined. Sufficient mixing following the manufacturer's direction is required for lathe-cut alloys, regardless of the copper content.
View full abstract
-
Takanobu SHIRAISHI, Michio OHTA, Masaji YAMANE
1984 Volume 3 Issue 2 Pages
193-204,331
Published: December 25, 1984
Released on J-STAGE: February 12, 2009
JOURNAL
FREE ACCESS
Ordering process and age-hardening mechanism of CuPd-AuCu pseudo-binary alloys were examined. In alloys with electron-atom ratios (e/a)<0.87, short range ordering was observed in the early stage of aging, thereafter, long range ordering occurred from grain boundaries by heterogeneous ordering mechanism. Age-hardening of these alloys was attained by the increase in volume fractions of CuPd and/or AuCuI phases. On the other hand, in alloys with e/a>0.87, fine domains of AuCuI type superlattice were formed very rapidly in the grain interior. The elastic strain field generated by this reaction caused age-hardening.
View full abstract
-
Masao IRIS, Kazuomi SUZUKI, Hiroyuki NAKAI
1984 Volume 3 Issue 2 Pages
205-209,332
Published: December 25, 1984
Released on J-STAGE: February 12, 2009
JOURNAL
FREE ACCESS
Examination was made on the physical properties of commercially available tannin-fluoride incorporated polycarboxylate and zinc phosphate cements for luting, following immersion in distilled water for up to 12 months. Same cements, containing no fluoride, were used as controls.
View full abstract
-
Shigeki MATSUYA, Yohko MATSUYA, Yasushi YAMAMOTO, Masaji YAMANE
1984 Volume 3 Issue 2 Pages
210-219,332
Published: December 25, 1984
Released on J-STAGE: February 12, 2009
JOURNAL
FREE ACCESS
Erosion of a glass ionomer cement in acetic (AA), lactic (LA), citric (CA) and hydrochloric acids (HA) was investigated by means of chemical analysis, SEM observation and infrared (IR) spectroscopy.The larger stability constants of the complex between the acid anions and Al or Ca, or the lower the pH of the acid solutions, the more Al, Ca, Na, Si and F were leached. SEM observation revealed that the cement matrix dissolved out in 0.01M CA and HA. White precipitates formed in 0.01M CA and HA after immersion of the cement. They were identified as hydrated silicious gels by IR spectroscopy
View full abstract
-
Improvement of its Clinical Application
Michihiko TAKEYA
1984 Volume 3 Issue 2 Pages
220-245,332
Published: December 25, 1984
Released on J-STAGE: February 12, 2009
JOURNAL
FREE ACCESS
The etched enamel and enamel surface after tensile bond test were observed with use of SEM. In addition, the effects of enamel etching on Ca dissolution, surface roughness and tensile bond strength were investigated.
View full abstract
-
Junzo TAKAHASHI, Masayuki OKAZAKI, Hiroshi KIMURA, Yasuhiro FURUTA, Ka ...
1984 Volume 3 Issue 2 Pages
246-252,333
Published: December 25, 1984
Released on J-STAGE: February 12, 2009
JOURNAL
FREE ACCESS
To evaluate a Ni-43.5wt%Ti alloy as a new alloy for cast clasp, the fatigue properties of its castings were examined and compared with those of Co-Cr and Type IV Au alloys castings. The Ni-Ti alloy was cast into a phosphate-bonded investment mold using an argon-arc melting and pressure casting machine. The Ni-Ti alloy castings showed superelasticity in bending tests. Fatigue tests were carried out by an originally designed machine under bending in one direction on the cantilever at constant set deflection. The fatigue-proof of Ni-Ti alloy was more excellent than those of Co-Cr and Type IV Au alloys.
View full abstract
-
Koh-ichi UDOH, Kunihiro HISATSUNE, Katsuhiro YASUDA, Michio OHTA
1984 Volume 3 Issue 2 Pages
253-261,333
Published: December 25, 1984
Released on J-STAGE: February 12, 2009
JOURNAL
FREE ACCESS
The isothermal age-hardening behaviour in the commercial dental gold alloys containing palladium was studied by means of resistometric, hardness, X-ray and electron microscopy. Drastic overageing occurred following prolonged ageing. The mechanism of the overageing was interpreted as a loss of coherency at the interfaces of the adjacent lamellae which consists of the equilibrium AuCu I ordered phase and the silver-rich α2 phase.
View full abstract
-
Kiyoshi TAJIMA, Hiroshi KAKIGAWA, Yoshio KOZONO, Ichiro HAYASHI
1984 Volume 3 Issue 2 Pages
262-271,333
Published: December 25, 1984
Released on J-STAGE: February 12, 2009
JOURNAL
FREE ACCESS
Oxygen and nitrogen introduced in three Ni-Cr alloy castings were significantly varied according to both different alloys and different melting methods. The arc melting in Ar blow caused significant increases in the amounts of oxygen and nitrogen uptake, which were influenced by alloy composition. The severe gas absorption by the arc melting in Ar blow resulted in the marked occurrence of porosity in the castings of the alloy containing lesser amounts of Cr, Si and/or Mn. No significant variations in hardness of the castings were found due to the differences in melting methods.
View full abstract
-
Minoru KAWAGUCHI, Tadao FUKUSHIMA, Koji MIYAZAKI, Takashi HORIBE, Tets ...
1984 Volume 3 Issue 2 Pages
272-279,333
Published: December 25, 1984
Released on J-STAGE: February 12, 2009
JOURNAL
FREE ACCESS
The eight kinds of aromatic dimethacrylates with different chemical backbones were synthesized and the relationship between the chemical structure and physical properties of these dimethacrylates were investigated.
View full abstract
-
Masaaki NAKAMURA, Hideki DOI, Kazuhiro YOKOYAMA, Haruyuki KAWAHARA
1984 Volume 3 Issue 2 Pages
280-287,334
Published: December 25, 1984
Released on J-STAGE: February 12, 2009
JOURNAL
FREE ACCESS
Experiments were carried out in an in vitro environment by the cell colony forming method in order to study the cytotoxicity to HeLa cells of set specimens of 3 MFRs and 4 composites for core use. In the experiment each of the specimens was extracted in a tissue culture medium for 2 weeks in dynamic environment with a specimen freely moving. With both MFRs and the composites for core use cytotoxicity ranging from moderate to strong was noted initially, followed by subsequent loss of cytotoxicity at the end of experiments, which is quite similar to that of the conventional composites tested earlier.
View full abstract
-
II. Investigation of antibacterial activity and follow-up study on clinical usage
Toshiyuki NAMBU
1984 Volume 3 Issue 2 Pages
288-311,334
Published: December 25, 1984
Released on J-STAGE: February 12, 2009
JOURNAL
FREE ACCESS
The
in vitro antibacterial activity of K-20 prepared by addition of chlorhexidine dihydrochloride to a base sealer was compared with that of a manufactured product. The acute toxicity of K-20 was also investigated in the animals. The results demonstrated that K-20 prevents bacterial propagation without an unfavorable influence on the living tissue.
K-20 was also evaluated clinically in cases of the root canal filling. Ninety three pulpless teeth filled with K-20 and guttapercha points and followed up for more than six months, were successful treated.
View full abstract
-
III. Effects of Physical Properties and Cooling Conditions
Naoyuki KATAKURA, Yoshima ARAKI, Michio KAWAKAMI, Shin KASAHARA
1984 Volume 3 Issue 2 Pages
312-319,335
Published: December 25, 1984
Released on J-STAGE: February 12, 2009
JOURNAL
FREE ACCESS
Thermal stresses in three brands of inlay waxes were numerically analyzed under different cooling conditions using the rheological and thermal properties of waxes. On the basis of this analysis, the shrinkage of the wax pattern was calculated. The larger the stress relaxation of the wax and the higher the ambient temperature, the smaller the thermal stress induced in the wax. The shrinkage of the wax pattern that was restrained by the die was extremely smaller than that of the male portion of the pattern. This indicates that the stress relaxation of the wax contributed greatly to the restriction of shrinkage of the wax pattern at the male portion of the die.
View full abstract