-
Kenzo ASAOKA, Norihiko KUWAYAMA
1986 Volume 5 Issue 2 Pages
145-157,293
Published: December 25, 1986
Released on J-STAGE: February 12, 2009
JOURNAL
FREE ACCESS
Computer calculations were used to simulate the effects of thermal shock on the stresses developed in porcelain-fused-to-metal (PFM) systems. A three-dimensional-finite-element model was employed to first calculate time-dependent temperature distribution in a beam shaped specimen 1.25-2.5×8×20mm. These were then used in a two-dimensional analysis of stresses in a beam consisting of 50 elements. Transient stresses in a beam consisting of 50 elements were calculated for porcelain, porcelain with an opaque layer, and porcelain-opaque-alloy system; the effects of porcelain thickness, thermal expansion coefficients, and quenching temperatures were evaluated. Experimental tests were also conducted for correlation with the theoretical calculations.
Results show that for αm(metal)<αp(porcelain), the highest stresses occur on the surface, and the interface stress is lower than α
m=α
p. When α
m>α
p, the surface stress is lower, and the interface stress is higher than α
m=α
p. When α
p-α
m>2×10
-6°C
-1, cracks are more easily initiated in the porcelain surface rather than the interface. Theory and experiment are in general agreement.
View full abstract
-
Judit VARGA, Hideo MATSUMURA, Eiichi MASUHARA
1986 Volume 5 Issue 2 Pages
158-164,293
Published: December 25, 1986
Released on J-STAGE: February 12, 2009
JOURNAL
FREE ACCESS
The effects of some adhesives on the bonding of amalgam filling to tooth substance were studied. The bonding agents were 4-META resin with adhesive ability derived from the acid anhydride functional group and PANAVIA EX, a composite type adhesive. The sealing and the bonding effects were measured using the dye penetration and shear tests. Both of the adhesive materials had an excellent ability to seal the leakage between the amalgam and the tooth substance.
View full abstract
-
Makiko KAI, Junko SATOU, Naoki SATOU, Hideaki SHINTANI, Michiharu FUJI ...
1986 Volume 5 Issue 2 Pages
165-171,293
Published: December 25, 1986
Released on J-STAGE: February 12, 2009
JOURNAL
FREE ACCESS
Sliding wear tests were performed on 8 different types of composite resins using bovine enamel as the counterface. The wear level of the composites and the effect induced on the bovine enamel by sliding these composites were examined. Filler content and mechanical properties of composite resins were also studied and evaluated in relation to wear. The wear of microfilled resins was less than that of other resins. A positive correlation was observed between the wear of the resin and the wear depth of the bovine enamel. The filler content, the Knoop hardness and the elastic modulus of resin correlated with the wear level.
View full abstract
-
Hiroshi MURAKAMI, Mitsuo KAMIYA, Sekio FUKUYO, Kyoichi HASHIMOTO, Nori ...
1986 Volume 5 Issue 2 Pages
172-177,294
Published: December 25, 1986
Released on J-STAGE: February 12, 2009
JOURNAL
FREE ACCESS
Six kinds of dental implants: Apaceram, Bioceram, Free design blade implant, Shape memory blade implant, Hydroxyapatite-coating blade implant and Vitallium were immersed in three kinds of solutions: Ringer's solution, 1.0% lactate acid solution, and 0.05% HCl solution, for seven days at 37°C. Using an inductively coupled plasma emission spectroscope, the solutions were analyzed. The element solubilities were observed in five kinds of dental implants, except Bioceram.
View full abstract
-
Yoshifumi TAKAHASHI, Tatsushi KAWAI, Norimichi KAWAMURA, Jiro HASEGAWA ...
1986 Volume 5 Issue 2 Pages
178-185,294
Published: December 25, 1986
Released on J-STAGE: February 12, 2009
JOURNAL
FREE ACCESS
Dental amalgam powder consisting of conventional, spherical-shaped alloy was prepared and added to the diet at the rate of 10% or 20% of the weight. An inorganic mercury compound, a solution of 10ppm or 20ppm of mercurous nitrate was also prepared for a comparative study. Five groups of rats were fed the test diet or test solution ad libitum for 8 weeks. Throughout the experiment, all rats were checked for body weight at weekly intervals, and diet consumption was examined at daily intervals. At the end of 8 weeks, the animals were killed, and the mercury content in the brain, liver and kidney was measured with a flameless atomic absorption spectrophotometer. The amalgam powder affected the growth of the rats, and the growth of the kidney tissue of rats was also affected when the rats were fed both mercurous nitrate and amalgam powder. The mercury content was the highest in the kidney, intermediate in the liver and lowest in the brain.
View full abstract
-
Seiichiro FUJISAWA, Yoshinori KADOMA
1986 Volume 5 Issue 2 Pages
186-192,294
Published: December 25, 1986
Released on J-STAGE: February 12, 2009
JOURNAL
FREE ACCESS
The interaction of photoinitiators (benzil: BZ, camphoroquinone: CQ and 9-fluorenone: 9F plus 2-(dimethylamino) ethyl methacrylate: DM) with dimyristoyl phosphatidylcholine (DMPC) and dipalmitoyl phosphatidylcholine (DPPC) liposomes was investigated by the application of differential scanning calorimetry (DSC), to clarify their hemolytic activity1). The DSC data showed that the photoinitiators, when irradiated, caused large changes in the phase transition properties of the liposomes which were characterized by a shift of the phase transition temperature (T) to a lower temperature, a decrease in the enthalpy (ΔH), and a decrease in the height/half-height width (H/HHW) of cooperativity in an endothermic peak.
Paticularly, interactions of aromatic ketones (BZ/DM and 9F/DM) with the liposomes was markedly higher than that of aliphatic ketones (CQ/DM) during irradiation. The surface active complexes between photosensitizer (BZ, CQ and 9F) and the reducing agent (DM), which are formed during irradiation promoted a T shift and decrease in the ΔH and H/HHW value. Therefore, the surface active complexes probably cause the hemolysis during irradiation.
View full abstract
-
II. Effects of Test Conditions
Seiji BAN, Masahiko IWAI, Jiro HASEGAWA
1986 Volume 5 Issue 2 Pages
193-201,295
Published: December 25, 1986
Released on J-STAGE: February 12, 2009
JOURNAL
FREE ACCESS
The pH changes of small amounts of test solutions which were in contact with luting cement surfaces during setting were determined using a flat combination electrode. The effects of 1) time intervals between the start of mixing and water contact, 2) different compositions of test solutions and 3) different types of filter were examined. The results showed that the initial rate of pH change for each cement became slower as the time interval between start of mixing and water contact increased. Polycarboxylate cement was the least acidic and showed the highest neutralization rate for each test solution. For both NaHCO
3 solution and human saliva, the initial rate of pH change of each cement was lower than that for other test solutions such distilled water, NaCl solution and albumin solution. Additionally, the pH change of the test solution varied with the type of filter placed between the cement surface and the pH-sensitive surface of the electrode.
View full abstract
-
III. pH Change and Setting Reaction of Zinc Phosphate Cements
Seiji BAN, Jiro HASEGAWA, Alton M. LACY
1986 Volume 5 Issue 2 Pages
202-210,295
Published: December 25, 1986
Released on J-STAGE: February 12, 2009
JOURNAL
FREE ACCESS
The effects of various additives on pH and rates of setting reactions of a commercial zinc phosphate cement system were examined. While the addition of various organic materials to the cement powderproduced no effect on the pH changes, addition of both calcium oxide and calcium hydroxide to the cement powder increased the neutralization rate of water in contact with the cement surface when compared with the unaltered cement. The addition of both magnesium oxide and magnesium hydroxide was effective in raising the initial pH of the cement. The addition of aluminum ion to the cement liquid retarded the setting reaction and delayed the neutralization of the cement when compared with cement liquid which contained no cation additives. Zinc ion showed a similar effect. There was a positive correlation between pH change and viscosity change for each cement during setting. X-ray diffraction and infrared spectroscopy suggest that the addition of zinc ion to the cement liquid induces the formation of hydrated zinc phosphate (Hopeite) during setting, while the addition of aluminum ion probably forms an amorphous phosphate without Hopeite.
View full abstract
-
Experimental Evidence of the Deterioration of Bonding Ability due to Adsorbed Water on the Oxide Layer
Hiroki OHNO, Yoshima ARAKI, Masahiro SAGARA, Yuro YAMANE
1986 Volume 5 Issue 2 Pages
211-216,296
Published: December 25, 1986
Released on J-STAGE: February 12, 2009
JOURNAL
FREE ACCESS
The effect of a several-molecule thick layer of water adsorbed on the oxide layer was examined for a Co-Cr alloy and 18-8 stainless steel. The alloys were dehydrated by heating to 700°C at 1×10
-6 Torr after oxidizing at 500°C in air. Dental adhesive resin containing 4-META was bonded to these alloy surfaces in an atmosphere with no water vapor. In both alloys, the bonding ability for the dehydrated surface is superior to those for the as-heated surface at 500°C. Deterioration of bonding ability between the resin and the alloys due to the adsorbed water on the oxide layer was proved experimentally.
View full abstract
-
II. Synthesis and Adhesiveness of Monomers that have Amide Groups
Tohru HAYAKAWA, Hiroshi ENDO, Masahiro NAGASHIMA, Masashi YUDA, Kozo H ...
1986 Volume 5 Issue 2 Pages
217-224,296
Published: December 25, 1986
Released on J-STAGE: February 12, 2009
JOURNAL
FREE ACCESS
The synthesis and adhesiveness of monomers that have amide groups as hydrophilic groups,
i.e. 4-methacryloxybenzamide (MBA) and 4-methacyloylphenylpropionamide (MPPA) are reported.
MBA was prepared from the reaction of p-hydroxybenzamide with methacryloyl chloride in an alkaline solution. MPPA was prepared from the reaction of p-hydroxyphenylpropionamide with methacryloyl chloride in trifluoroacetic acid.
The bovine enamel and dentin were etched by a 10% citric acid -3% FeCl
3 (10-3) solution. The monomers were dissolved in MMA, and the adhesiveness of MMA and O-methacryloyl tyrosine amide (MTYA) were also tested. The tensile bond strengths (MPa) after 1 day at 37°C water were measured. They were MMA: 11.1±5.3 (enamel), 5.7±2.8 (dentin); MBA/MMA: 12.1±6.0 (enamel), 12.3±4.0 (dentin); MPPA/MMA: 11.8±2.5 (enamel), 12.1±3.5 (dentin); and MTYA/MMA: 11.8±3.5 (enamel), 14.1±6.1 (dentin).
View full abstract
-
Akihiko SHIMIZU, Takashi UI, Masahiro KAWAKAMI
1986 Volume 5 Issue 2 Pages
225-232,296
Published: December 25, 1986
Released on J-STAGE: February 12, 2009
JOURNAL
FREE ACCESS
The bovine enamel and dentin samples ground flat with a series of emery papers were pretreated with fluoride either before or after etching, and several of the dentin samples were lined with glass ionomer cement. Adhesive resin cement, Panavia or Super-Bond, was applied on the enamel and dentin samples, and then amalgam was placed on these samples.
The highest bond strength between amalgam and enamel was 90kg/cm
2 for Panavia, and 102kg/cm
2 for Super-Bond. These values were obtained by the pretreatment with Ag(NH
3)
2F. The bond strength between amalgam and the dentin treated with fluoride or the etching agent was 13-17kg/cm
2 for Panavia, and 23-65kg/cm
2 for Super-Bond. The bond strength between amalgam and lined dentin was 41-46kg/cm
2 when Panavia was used. The bond strength tended to be increased by the fluoride treatment prior to etching.
We suppose that the adhesion technique for amalgam would be clinically valuable.
View full abstract
-
Yoshiaki TANI, Toshiyuki NAMBU, Takao MAKISHIMA
1986 Volume 5 Issue 2 Pages
233-236,297
Published: December 25, 1986
Released on J-STAGE: February 12, 2009
JOURNAL
FREE ACCESS
This study evaluated the effects of the pretreatment of the cavity on microleakage of the composite resin restorations with dentin margins. The labial surfaces of bovine teeth were ground until the dentin was exposed. Two standardized round cavities were prepared side by side. Four kinds of cleaning agents; 3% aluminum lactate, 10% ascorbic acid, 10% citric acid and 10% phosphoric acid were applied for 60 seconds to one of the two cavities. The other was left without cleaning. After bonding, a composite resin was inserted into cavity. The restored teeth were thermocycled, prior to immersion in dye for 24 hours.
The dentin bonding agent singly could not prevent dye penetration at the cervical dentin margin, and prior to bonding the pretreatment of dentin with some cleaning agents was effective for decreasing microleakage.
View full abstract
-
Compatibility with Cast Metal Core
Yoshio KOZONO, Kiyoshi TAJIMA, Hiroshi KAKIGAWA, Ichiro HAYASHI, Yuji ...
1986 Volume 5 Issue 2 Pages
237-245,297
Published: December 25, 1986
Released on J-STAGE: February 12, 2009
JOURNAL
FREE ACCESS
Pure titanium was applied to the prefabricated post and its compatibility with cast metal core was examined in comparison with those of the commercially available prefabricated posts of Ni-Cr alloy and 18-8 stainless steel.
The mechanical properties of the titanium post were comparable to those of Type III gold alloy. Although Ni-Cr and 18-8 stainless steel were subjected to annealing during the casting process of the core showing marked decrease in hardness and tensile strength, the titanium post had already annealed during the working process and showed no significant changes in properties when heat-treated up to 1, 000°C. The core alloys exhibited excellent castability against the titanium post, and pure titanium seemed to be applicable to a prefabricated post for the cast metal core if the core could be cast in the neighborhood of 1, 000°C at most.
View full abstract
-
Part 1 Setting Characteristics of UV and Visible Light-activated Composite Resins
Hiroyuki ARIKAWA, Koichi FUJII, Takahito KANIE, Yasuhiro TABATA, Jun-i ...
1986 Volume 5 Issue 2 Pages
246-251,297
Published: December 25, 1986
Released on J-STAGE: February 12, 2009
JOURNAL
FREE ACCESS
The setting times of 18 commercial light-activated composite resins were measured using an oscillating rheometer, and the effects of specimen thickness, exposure time and distance from the fiber tip of light curing unit to the specimen on the setting time were examined. In addition, the curing shrinkage in the direction of tooth axis and the effect of inorganic filler content on the curing shrinkage were evaluated.
The setting times for specimens of maximum depths of cure recommended by the manufacturers were in the range 0.9-2.5min. These values varied with the thickness of the specimen, exposure time and distance from the fiber tip of light curing unit to the specimen. The curing shrinkage in the direction of tooth axis for a 2.5mm specimen was in the range 1.5-2.8%.
View full abstract
-
Part 2 Physical and Mechanical Properties of UV and Visible Light-activated Composite Resins
Koichi FUJII, Kazuhiko GINYA, Hiroyuki ARIKAWA, Takahito KANIE, Kazuhi ...
1986 Volume 5 Issue 2 Pages
252-259,298
Published: December 25, 1986
Released on J-STAGE: February 12, 2009
JOURNAL
FREE ACCESS
Physical and mechanical properties of 18 commercial light-activated composite resins were measured and the correlation between their properties was discussed. Hardness of the material, which was polymerized in accordance with the manufacturer's recommendation, increased considerably after exposure to light and reached approximately constant values after 24 hours. Hardness and elastic modulus were strongly dependent upon the filler fraction. On the other hand, there was no significant correlation between filler fraction and compressive strength. Most of the curing shrinkage was brought together at the bottom part of the cavity, as the light-activated composite resins polymerized from the surface exposed to light.
The resistance to toothbrush abrasion increased according to the increase of inorganic filler content level.
View full abstract
-
Kazuo ITOH, Toshio YANAGAWA, Sadao WAKUMOTO
1986 Volume 5 Issue 2 Pages
260-266,298
Published: December 25, 1986
Released on J-STAGE: February 12, 2009
JOURNAL
FREE ACCESS
Adaptation to dentin cavity wall of three marketed and eight experimental composites was investigated by measuring polymerization contraction in cylindrical dentin cavities and by SEM observation. The cavity adaptation of light cured composites was always inferior to that of the chemically cured composite and, in the experimental composites, the optimum filler content was obtained.
These facts indicate that cavity adaptation is affected significantly by the flow of the composites from the free surface into the cavity during polymerization.
View full abstract
-
Koichi MATSUDA, Yuji IBARAKI, Hideyuki SAKAI, Hirokata SHIMOKOBE
1986 Volume 5 Issue 2 Pages
267-275,299
Published: December 25, 1986
Released on J-STAGE: February 12, 2009
JOURNAL
FREE ACCESS
Corrosion behavior of dental amalgams and their phases was investigated by means of an electrochemical method and surface analysis by electron probe X-ray microanalyzer. The tin and tin-containing intermetallic compounds had an anodic and two cathodic current peaks with nearly identical potentials. The γ
2 phase had the highest peak current. Polarization curves of the dental amalgams showed two anodic current peaks (1a and 2a) and three or four cathodic current peaks in the range of potential from -1.5V to +0.5V.
On the basis of the equilibrium petential, the peaks 1a and 1c were thought to be due to the formation and reduction of divalent tin salt. The peaks 2a and 2c were considered to be due to the formation and reduction of quadra-valent tin salt. A Sn-Cl rich cluster was observed on the sample of the conventional amalgam after the anodic polarization.
View full abstract
-
Effect of Various Mordants on Bonding to Dentin
Yusuke INOUE, Tadao FUKUSHIMA, Koji MIYAZAKI, Takashi HORIBE
1986 Volume 5 Issue 2 Pages
276-282,299
Published: December 25, 1986
Released on J-STAGE: February 12, 2009
JOURNAL
FREE ACCESS
The bond strength of glass ionomer cement to dentin treated with cleanser and subsequently mordants was measured to develop the best treating system. Also, the effect of the chosen system on the bonding of five other cements to dentin was investigated.
The bond strength of glass ionomer cement to dentin subjected to 37°C water immersion for 1 day was improved by using 0.5M maleic acid and three mordants containing Fe (III) ion. Particularly, 10% FeCl
3⋅6H
2O and 10% FeNH
4 (SO
4)
2⋅12H
2O solutions greatly improved the bonding.
Although the bond strength of three other polycarboxylate-based cements such as polycarboxylate and glass ionomer cements was improved using 0.5M maleic acid and 10% FeNH
4(SO
4)
2⋅12H
2O, that of two resin cements to dentin was not improved.
View full abstract
-
1986 Volume 5 Issue 2 Pages
e1
Published: 1986
Released on J-STAGE: February 12, 2009
JOURNAL
FREE ACCESS
