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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 1
Displaying 1-10 of 10 articles from this issue
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Tohru HAYAKAWA, Kazuyo KIKUTAKE, Kimiya NEMOTO2001 Volume 20 Issue 1 Pages 1-15
Published: 2001
Released on J-STAGE: February 12, 2009
JOURNAL FREE ACCESSThe conformational and quantum analyses of dental adhesive carboxylic acid and carboxylic acid anhydride monomers were preformed. Conformational analyses were carried out by a molecular mechanics calculation. 4-META and 4-AETA showed more compact conformation than 4-MET. Quantum analyses were performed by semi-empirical molecular orbital calculation. 4-MET had a higher dipole moment, polarizability, and HOMO and LUMO energy than 4-META and 4-AETA. The bond lengths and bond orders of the carbonyl groups of the trimellitic acid moiety of 4-MET were different from those of carbonyl groups of the trimellitate anhydride moieties of 4-META and 4-AETA. Oxygen of the methacryloyl or acryloyl groups showed the highest electron densities among the oxygen atoms for all monomers. The superdelocalizabilities of oxygen atoms of the trimellitic acid moiety of 4-MET were greater than that of oxygen of the methacryloyl group. A small change in the bond length of the Ca-O bond showed a large difference in the steric energies of 4-MET/Ca salt.View full abstractDownload PDF (2055K) -
Masayuki HATTORI, Koji HASEGAWA, Masao YOSHINARI, Eiji KAWADA, Yutaka ...2001 Volume 20 Issue 1 Pages 16-23
Published: 2001
Released on J-STAGE: February 12, 2009
JOURNAL FREE ACCESSThe purpose of the present study was to investigate the casting accuracy and the dimensional change of experimental titanium-copper alloys (3.0 and 5.0mass% Cu; hereafter, only “%” will be used) and to compare the findings with those of pure titanium. Castings were made using an argon-arc melting/pressure difference-casting unit. The fit of the metals cast in both full crown and MOD inlay dies was evaluated by measuring the distance between the shoulder margin and the cervical shoulder of the die. The changes in the inner diameter of castings were determined. In addition, surface roughness measurements inside the castings were carried out using a conventional profilometer, and thermal expansion measurements were made on cast cylindrical specimens using a differential dilatometer. There were no significant differences in dimensional change between pure titanium and the titanium-copper alloys. The fit of the titanium-copper alloys was inferior to pure titanium. The results of surface roughness measurements showed significance differences between the roughness of the pure titanium and titanium-copper alloys.View full abstractDownload PDF (739K) -
Tomoyasu ISHIZUKA, Hiroki KATAOKA, Takatomo YOSHIOKA, Hideaki SUDA, Na ...2001 Volume 20 Issue 1 Pages 24-33
Published: 2001
Released on J-STAGE: February 12, 2009
JOURNAL FREE ACCESSThe purposes of this study were to investigate the reliability and efficiency of a new evaluation method for resin bonding to root canal dentin, which measures both marginal adaptation and shear bond strength simultaneously, and to determine the effects of root canal irrigants on resin bonding. A wet bonding system (Single Bond) and a self-etching primer system (Clearfil Mega Bond) were employed; NaClO was used as a root canal irrigant. No gaps or changes in bond strength were observed despite the NaClO treatment when the wet bonding system was employed, while the gap formation ratio increased, and bond strength decreased with longer NaClO treatment time when the self-etching primer system was employed. These findings suggested that this new experimental method was effective for evaluating resin systems to the root canal wall dentin which is affected by irrigation with NaClO.View full abstractDownload PDF (2403K) -
Yukyo TAKADA, Hiroshi NAKAJIMA, Osamu OKUNO, Toru OKABE2001 Volume 20 Issue 1 Pages 34-52
Published: 2001
Released on J-STAGE: February 12, 2009
JOURNAL FREE ACCESSBinary titanium alloys with the beta-stabilizing elements of Co, Cr, Cu, Fe, Mn and Pd (up to 30%) and Ag (up to 45%) were examined through metallographic observation and X-ray diffractometry to determine whether beta phases that are advantageous for dental use could be retained. Corrosion behavior was also investigated electrochemically and discussed thermodynamically. Some cast alloys with Co, Cr, Fe, Mn, and Pd retained the beta phase, whereas those with Ag and Cu had no beta phase. In some alloys, an intermetallic compound formed, based on information from the phase diagram. The corrosion resistance deteriorated in the TiAg alloys because Ti2Ag and/or TiAg intermetallic compounds preferentially dissolved in 0.9% NaCl solution. On the other hand, the remaining titanium alloys became easily passive and revealed good corrosion resistance similar to pure titanium since their matrices seemed to thermodynamically form titanium oxides as did pure titanium.View full abstractDownload PDF (7913K) -
Satoshi NAKABO, Yasuhiro TORII, Toshiyuki ITOTA, Masahiro YOSHIYAMA, K ...2001 Volume 20 Issue 1 Pages 53-62
Published: 2001
Released on J-STAGE: February 12, 2009
JOURNAL FREE ACCESSThe aim of this study was to regulate fluoride release from restorative resin containing NaF using N-(β-aminoethyl)-γ-aminopropylmethyldimethoxysilane (AMMS) and evaluate factors that regulate fluoride release from the resin. ESCA analysis, FT-IR measurements along with SEM observations demonstrated that a polysiloxane layer was formed on the surface of NaF treated with AMMS. Bis-GMA/TEGDMA resin containing NaF powder treated with AMMS released lower concentrations of fluoride for longer periods when compared with that containing untreated NaF. However, AMMS treatment of NaF was less effective for the regulation of fluoride released from the resin than γ-methacryloxypropyltrimethoxysilane (γ-MPTS) treatment, despite its higher hydrophobic polysiloxane layer formation. These findings may have been caused by the higher density of polysiloxane prepared with γ-MPTS than that prepared with AMMS. The present findings suggested, therefore, that alkoxysilane should be chosen based not only on hydrophobicity but also the density of polysiloxane to effectively regulate fluoride release from the restorative resin containing NaF.View full abstractDownload PDF (1462K) -
Yuro YAMANE, Hiroki OHNO, Kazuhiko ENDO2001 Volume 20 Issue 1 Pages 63-74
Published: 2001
Released on J-STAGE: February 12, 2009
JOURNAL FREE ACCESSThe water durability at adhesion interfaces between 4-META resin and Au-In or Au-Si alloys was investigated by the peeling test and by surface analysis using X-ray photoelectron spectroscopy (XPS) as well as theoretical consideration based on Bolger's acid-base theory. XPS spectra demonstrated that several-nm thick layers of In2O3 and SiO2 were formed on the Au-In and Au-Si alloys. The water durability of the Au-In alloys increased with increases in In content. The Au-Si alloy and quartz glass specimens showed a total absence of water durability. Bolger's theory suggested that the interaction of 4-MET with In2O3 was considered to be ionic and stable in the presence of water while that of 4-MET with SiO2 was due to hydrogen bonds, which can easily be dissociated in the presence of water. These findings suggest that Bolger's theory is useful for evaluating chemical interactions between an adhesive monomer and oxides on a precious metal alloy.View full abstractDownload PDF (1395K) -
Part 2. The Area Ratio Dependence in Five SolutionsMasahiko NAKAYAMA, Nobuo ANDO2001 Volume 20 Issue 1 Pages 75-89
Published: 2001
Released on J-STAGE: February 12, 2009
JOURNAL FREE ACCESSSixteen alloys and five pure metals were used and the open circuit potentials (OCP) and the coupled potentials with titanium were measured in five kinds of solutions. All alloys and metals showed the maximum OCP in 1.3% lactic acid solution, and the minimum in 0.01% sodium sulfide solution. The coupled potential depended on the area ratio (alloy/titanium). This dependence was different in every solution. From the area ratio dependence of the coupled potential, the potassium fluoride solution was thought to be active with pure titanium. In contrast, sodium sulfide solution was thought to be active with the alloys and the metals. The effect of the co-existence of pure titanium was very small in the sodium sulfide solution.View full abstractDownload PDF (1323K) -
Hiroki OHNO, Kazuhiko ENDO, Yuro YAMANE, Isao KAWASHIMA2001 Volume 20 Issue 1 Pages 90-102
Published: 2001
Released on J-STAGE: February 12, 2009
JOURNAL FREE ACCESSThree precious metal alloys, Type IV gold alloy, 14K gold alloy, and silver-based alloy, were treated with different surface modifications including a metal primer (VBATDT) application, a SiOX coating method, high-temperature oxidation, modification method with a liquid Ga-Sn alloy, and tin electroplating. Then thin PMMA films were bonded with a resin containing 4-META. Water durability at the adhesion interface was evaluated after water immersion, followed by thermal cycling used liquid nitrogen. The weakest zone at the interface was investigated using XPS only for the Ag-Pd alloy specimens that had been surface-treated with aspolishing, adhesive primer, and the SiOX coating method, since peeling of the PMMA film on the surface of specimens surface-treated by other methods was not observed. Metal elements were detected from the resin side at the adhesion interface. The chemical states of Cu in the resin before argon ion etching were characterized as metal oxides and/or states of chemical interaction with 4-META, VBATDT, or SiOX.View full abstractDownload PDF (1421K) -
Masahiro IIJIMA, Kazuhiko ENDO, Hiroki OHNO, Yasuyuki YONEKURA, Itaru ...2001 Volume 20 Issue 1 Pages 103-113
Published: 2001
Released on J-STAGE: February 12, 2009
JOURNAL FREE ACCESSThe corrosion behaviors of a commercial Ni-Ti alloy orthodontic wire and a polished plate with same composition in 0.9% NaCl and 1% lactic acid solutions were examined using an electrochemical technique, an analysis of released ions, and a surface analysis by X-ray photoelectron spectroscopy (XPS). The effect of polishing the wire on the corrosion was also examined. The XPS analysis demonstrated the presence of a thick oxide film mainly composed of TiO2 with trace amounts of Ni hydroxide, which had formed on the wire surface during the heat treatment and subsequent pickling processes. This oxide layer contributed to the higher resistance of the as-received wire to both general and localized corrosion in 0.9% NaCl solution, compared with that of the polished plate and the polished wire. The thick oxide layer, however, was not stable and did not protect the orthodontic wire from corrosion in 0.1% lactic acid solution.View full abstractDownload PDF (2352K) -
Fluoride Release, Fluoride Uptake and Acid Resistance of Tooth StructuresLinlin HAN, Neamat ABU-BAKR, Akira OKAMOTO, Masaaki IWAKU2001 Volume 20 Issue 1 Pages 114-122
Published: 2001
Released on J-STAGE: February 12, 2009
JOURNAL FREE ACCESSThe objectives of this study, were to evaluate the fluoride release from fluoridate adhesive resin cement, fluoride uptake into surrounding tooth structures and the effect of their acid resistance. Several specimens were prepared using a plastic ring mould, from extracted human premolars, and prepared from enamel and dentin of the central area of the buccal surface of bovine teeth. The fluoride release rate of fluoridate adhesive resin cement (PN 200) per day was higher than other materials during the 7-day study period. Fluoride released and fluoride uptake by tooth structures was higher in the fluoridate adhesive resin cement. WDX analysis showed the fluoride concentration on dentin contact area was higher than that of enamel after 60 days of immersion in deionized water. The calcium release values were similar for enamel and dentin plates in the various test materials. The present findings indicated the important enhancement of tooth structure acid resistance by fluoridate material.View full abstractDownload PDF (1888K)
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