Dental Materials Journal
Online ISSN : 1881-1361
Print ISSN : 0287-4547
ISSN-L : 0287-4547
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Volume 2, Issue 1
Displaying 1-13 of 13 articles from this issue
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  • Gold Plating Conditions to Denture Base Resin
    Naofumi SHIGETO, Masaru TOKUNAGA, Taizo HAMADA
    1983 Volume 2 Issue 1 Pages 1-9,154
    Published: June 25, 1983
    Released on J-STAGE: February 12, 2009
    DOIhttps://doi.org/10.4012/dmj.2.1
    JOURNAL FREE ACCESS
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    The current density and throwing power of electrogold plating to acrylic resin were determined by the use of the Hull cell test, and the abrasiveness by denture brush and the discoloration by denture cleanser were examined. The gold plating to acrylic resin will be available in dental practice.
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  • Age-hardening Mechanism of Equiatomic AuCu and AuCu-Ag Pseudo-binary Alloys
    Michio OHTA, Takanobu SHIRAISHI, Masaji YAMANE, Katsuhiro YASUDA
    1983 Volume 2 Issue 1 Pages 10-17,154
    Published: June 25, 1983
    Released on J-STAGE: February 12, 2009
    DOIhttps://doi.org/10.4012/dmj.2.10
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    AuCu-Ag pseudo-binary phase diagram was illustrated and the difference in age-hardening mechanism with changes of silver content in the AuCu-Ag pseudo-binary system was studied. In the equiatomic AuCu and low silver alloy, age-hardening was due to the formation of the AuCu I type ordered domains. Growth of the domains caused twinning which resulted in remarkable softening of the alloy. On the other hand, age-hardening in the high silver alloy was attributed to the dual mechanisms of two phase separation and ordering which was initiated by spinodal decomposition.
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  • Change in the Hardness of Dental Amalgams in relation to Time
    Hiroyuki NAKAI, Masao IRIE, Hirokazu HASHIMOTO
    1983 Volume 2 Issue 1 Pages 18-29,154
    Published: June 25, 1983
    Released on J-STAGE: February 12, 2009
    DOIhttps://doi.org/10.4012/dmj.2.18
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    Change in hardness were determined on the various amalgams periodically from one hour to 30 days after mixing. A microvickers hardness tester was applied for this purpose and determination was made at 37°C. Characteristics of several commercial amalgam alloys during hardening were discussed.
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  • Studies on Color Analysis of Dental Porcelains
    II. Effect of Covering Non-precious Alloys with Opaque Porcelain Materials
    Yoshizo OKAMOTO, Takashi HORIBE, Yusuke INOUE, Tomoji MATSUURA, Koichi ...
    1983 Volume 2 Issue 1 Pages 30-47,155
    Published: June 25, 1983
    Released on J-STAGE: February 12, 2009
    DOIhttps://doi.org/10.4012/dmj.2.30
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    We fixed by firing opaque porcelain materials (Uni bond, Vita VMK 68 Paint-on 88) and margin porcelain materials of varying thicknesses on to non-precious alloys (Bio cast of the Co-Cr system, Uni metal of the Ni-Cr-Be system, and Nichrome bond of the Ni-Cr system).
    The effect of covering oxide films with porcelain materials is discussed.
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  • Structural Changes induced by Ageing in Commercial Dental Gold Alloys containing Palladium
    Katsuhiro YASUDA, Kohichi UDOH, Kunihiro HISATSUNE, Michio OHTA
    1983 Volume 2 Issue 1 Pages 48-58,155
    Published: June 25, 1983
    Released on J-STAGE: February 12, 2009
    DOIhttps://doi.org/10.4012/dmj.2.48
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    Age-hardening mechanisrn in a 16K and 14K gold commercial dental alloys was studied by means of electron microscopic observations, electron and X-ray diffraction studies. Metastable AuCu I' phase and equilibrium AuCu I phase were formed by ageing in both alloys. The hardening was due to the introduction of coherency strain at the interface between the AuCu I' ordered platelets and the matrix. The equilibrium AuCu I ordered phase associated with the α2 phase was formed predominantly at the grain boundaries as lamellar structure and they did not contribute to the age-hardening.
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  • ESCA Study on the Oxidized Surface of a Gold Alloy for Porcelain-Metal Bonding
    Hiroki OHNO, Yasuo KANZAWA, Yuro YAMANE
    1983 Volume 2 Issue 1 Pages 59-67,155
    Published: June 25, 1983
    Released on J-STAGE: February 12, 2009
    DOIhttps://doi.org/10.4012/dmj.2.59
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    The surface of gold alloys containing 0.6 Sn and 0.9 In (wt%) for porcelain bonding, oxidized at 1000°C for 30sec to 60min in air was investigated by ESCA. The oxidation states of both Sn and In were determined by comparing the binding energy of photoelectrons with standard samples. A quantitative analysis of Sn, In, and O on the oxidized surface was also performed on the basis of photoelectron intensity of the spectra.
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  • Erosion Behavior of a Zinc Phosphate Cement in Dilute Organic Acid Solutions
    Yohko MATSUYA, Masahiko KODA, Shigeki MATSUYA, Yasushi YAMAMOTO, Masaj ...
    1983 Volume 2 Issue 1 Pages 68-75,156
    Published: June 25, 1983
    Released on J-STAGE: February 12, 2009
    DOIhttps://doi.org/10.4012/dmj.2.68
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    The erosion of a zinc phosphate dental cement was studied in 0.001M/1 and 0.01M/1 acetic, lactic and citric acid solutions. The greatest erosion was noted in the citric acid solution. Zn/P2O5 ratios in the acid solutions were very high and the solutions tended to be neutralized during immersion, indicating that Zn2+ ion was eluted from unreacted cement powder in preference to a binding matrix. At the cement surfaces, hopeite crystals were observed and they showed different morphologies among the acids.
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  • Erosion Process of Polycarboxylate Cements in Organic Acids
    Shigeki MATSUYA, Masahiko KODA, Yohko MATSUYA, Yasushi YAMAMOTO, Masaj ...
    1983 Volume 2 Issue 1 Pages 76-85,156
    Published: June 25, 1983
    Released on J-STAGE: February 12, 2009
    DOIhttps://doi.org/10.4012/dmj.2.76
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    The amounts of Zn and Mg eluted from the zinc polycarboxylate cement into acetic, lactic and citric acids increased with an increase in the formation constant of the acid-Zn or -Mg complexes. The erosion process consisted of two processes, namely, dissolution of the unreacted cement powder and decomposition of the matrix. The matrix was remarkably eroded by 0.01M citric acid which formed stable complexes with Zn and Mg. Erosion of the matrix took place with the exchange reaction between H+ ion in the acid and Zn2+ or Mg2+ in the matrix.
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  • A Multivariate Analysis of Mechanical Factors Influencing the Accuracy of Dental Castings
    Sadami TSUTSUMI, Masahiro FUKUMA, Kazuo IDA
    1983 Volume 2 Issue 1 Pages 86-99,156
    Published: June 25, 1983
    Released on J-STAGE: February 12, 2009
    DOIhttps://doi.org/10.4012/dmj.2.86
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    The effects of some mechanical factors on the dimensional changes of dental castings were examined experimentally and analytically. Multivariate analysis using the Hayashi's multidimensional quantification theory-I was useful to evaluate the effects of the factors individually and quantitatively.
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  • Long-term Biocompatibility Test of Composite Resins and Glass Ionomer Cement (in vitro)
    Masaaki NAKAMURA, Haruyuki KAWAHARA, Koichi IMAI, Susumu TOMODA, Yoshi ...
    1983 Volume 2 Issue 1 Pages 100-112,157
    Published: June 25, 1983
    Released on J-STAGE: February 12, 2009
    DOIhttps://doi.org/10.4012/dmj.2.100
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    In order to examine long-term biocompatibility of restorative dental materials, three composite resins and one glass ionomer cement were tested. Hardened specimen was immersed in extraction medium (MEM) for a unit period of two weeks, after which extraction was continued in the same manner for twenty weeks. Extraction was carried out by gyration at 200rpm at 37°C that allowed the specimens to move freely, thus making the extracting environment much closer to a clinical situation. Each extract obtained was used for cell colony formation of HeLa S3 cells. Cell colony forming rates were utilized as biocompatibility measure in vitro. As a result, it was found that initial cytotoxicity of the materials tested ranged from moderate to marked levels at the 2nd week in the dynamic experimental environment. This was followed by none to weak cytotoxicity toward the end of the experiments. Importance of in vitro simulation experiments of a clinical situation and the establishment of an in vitro long-term biocompatibility testing were discussed.
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  • A proposition for long-term biocompatibility test of dental materials in vitro
    Masaaki NAKAMURA, Hideki KODA, Haruyuki KAWAHARA
    1983 Volume 2 Issue 1 Pages 113-123,157
    Published: June 25, 1983
    Released on J-STAGE: February 12, 2009
    DOIhttps://doi.org/10.4012/dmj.2.113
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    The importance of establishing a testing method for long-term biocompatibility of dental materials can not be overemphasized, since the materials remain in the living system for a long period of time once inserted. Unfortunately, the current testing methods lay greater stress on shorter testing periods than on longer ones. In addition, none of them include testing in an environment simulating the oral cavity. The present study incorporated to some degrees these two essential factors, i.e. long-term test and oral simulation. Standardization of each step was made and satisfactory results were obtained.
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  • A New Method for Measuring the Wear of Composite Restorative Materials
    Yoshiaki TANI, Katsumi SUZUKI, Shigeki YUASA
    1983 Volume 2 Issue 1 Pages 124-133,158
    Published: June 25, 1983
    Released on J-STAGE: February 12, 2009
    DOIhttps://doi.org/10.4012/dmj.2.124
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    A new glass beads abrasion test for composite restorative materials is presented. After testing all of the conventional composites showed much higher wear in volume loss than the microfilled resins. The amalgam was similar to the microfilled resin in wear. The results obtained by toothbrushing abrasion conflicted with those obtained by the glass beads abrasion. These results in combination with SEM studies suggest that there was a close parallel between the results of the glass beads abrasion and clinical findings.
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  • DENTAL MATERIALS AND DEVICES IN JAPAN 1981-1982
    KAZUO IDA, D. Eng.
    1983 Volume 2 Issue 1 Pages 134-145
    Published: June 25, 1983
    Released on J-STAGE: February 12, 2009
    DOIhttps://doi.org/10.4012/dmj.2.134
    JOURNAL FREE ACCESS
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