巻号一覧
17 巻 (1998)
- 4 号 p. 223-
- 3 号 p. 163-
- 2 号 p. 93-
- 1 号 p. 1-
17 巻, 1 号
選択された号の論文の10件中1～10を表示しています
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Tsuneo IMAI, Kazuo ITOH, Chihiro TANI, Atsufumi MANABE, Takashi YAMASH ...1998 年 17 巻 1 号 p. 1-10
発行日: 1998年
公開日: 2009/02/12
ジャーナル フリーThe effectiveness of newly developed commercial dentin bonding systems (SB, MB II and KB) was evaluated by measuring the contraction gap width of a resin composite restored into a cylindrical dentin cavity prepared in an extracted human molar and by measuring the tensile bond strength to the flat dentin surface. In addition, calcium loss during dentin conditioning was analyzed using electron microanalyses. An experimental dentin bonding system composed of EDTA conditioning, GM solution priming and a bonding agent containing 10-MDP was employed as a control in which it was presumed that contraction gap formation was prevented completely. However, gap formation was observed using the three commercial simplified dentin bonding systems. SEM observation showed that the gap was formed between the resin composite and the top surface of the dentin cavity wall indicating that the fracture occurred at the adhesive interface, but never inside the dentin nor inside the resin composite.抄録全体を表示PDF形式でダウンロード (2369K) -
Kyo-Han KIM, Kenzo ASAOKA, Kenichi YOSHIDA1998 年 17 巻 1 号 p. 11-20
発行日: 1998年
公開日: 2009/02/12
ジャーナル フリーTo develop a suitable heating program for the investments which affect the casting accuracy/defects of prostheses, a probable microstructural change of the gypsum-bonded investments related to the transition of refractory particles during thermal processing was inspected by the measurement of acoustic emission (AE) signals. Gypsum-bonded cristobalite and quartz investment molds were used. AE measurements were carried out for the specimens in an electric furnace that was heated/cooled at a constant rate. For the heating process of the cristobalite investment, high AE activities were detected in the temperature range where the cristobalite was transformed. However, the AE signals detected were low for the second run of the heating and cooling processes. Even in the heating process, significant AE signals were not detected for the quartz investment. For cristobalite investment molds, micro-cracks are initiated and developed in relation to the transition of cristobalite particles in the mold. This leads to deterioration of the mechanical properties of the cristobalite investment at high temperatures (melt-pouring), and may affect the fitness of cast prostheses.抄録全体を表示PDF形式でダウンロード (1560K) -
Jian WU, Kazuo ITOH, Takashi YAMASHITA1998 年 17 巻 1 号 p. 21-30
発行日: 1998年
公開日: 2009/02/12
ジャーナル フリーThe efficacy of a commercial total-etch wet-bonding dentin bonding system and the effect of conditioning using 10% phosphoric acid both on the Ca-content in the substrate dentin and on the efficacy of the experimental contraction gap-free dentin bonding system were evaluated by measuring the wall-to-wall polymerization contraction gap width of a commercial light-activated resin composite filled into a cylindrical cavity prepared in extracted human dentin. The Ca-content in the dentin was measured with an EDS. Complete marginal adaptation was obtained only in the experimental contraction gap-free dentin bonding system group. The Cacontent in the dentin was rapidly reduced by the 10% phosphoric acid conditioning. It was concluded that the dentist should not decalcify the dentin cavity wall possibly by using a dentin conditioner such as 10% phosphoric acid because the resin composite paste is apt to separate easily from the decalcified dentin cavity wall during polymerization.抄録全体を表示PDF形式でダウンロード (1647K) -
Masahiro IIJIMA, Kazuhiko ENDO, Hiroki OHNO, Itaru MIZOGUCHI1998 年 17 巻 1 号 p. 31-40
発行日: 1998年
公開日: 2009/02/12
ジャーナル フリーThe corrosion behavior of three Ni-Ti alloys with compositions as commercial super-elastic orthodontic wires was investigated using polished plate specimens. Corrosion resistance was estimated by potentiodynamic polarization measurement in 0.9% NaCl and 1% lactic acid solutions and analysis of released metals by atomic absorption spectrophotometry. The influence of Cr and Cu addition on the structure of the surface oxide film was examined by X-ray photoelectron spectroscopy (XPS). Addition of 0.19at% Cr had little effect on the structure of the oxide films and the corrosion resistance of the Ni-Ti alloys. For Ni-Ti-5Cu-0.3Cr alloy, the metallic Cu was enriched at the alloy/oxide film interface, resulting in increased susceptibility to pitting corrosion above+1000mV. However, the passive current density and the amount of released Ni were not significantly increased by the addition of Cu. The study showed that small amounts of Cr and Cu added to change the super-elastic characteristics do not change the corrosion resistance of the Ni-Ti alloy freely immersed in simulated physiological environments.抄録全体を表示PDF形式でダウンロード (1544K) -
Fumiaki KAWANO, Takao HANAWA, Masayuki KON, Kenji OKA, Yoritoki TOMOTA ...1998 年 17 巻 1 号 p. 41-50
発行日: 1998年
公開日: 2009/02/12
ジャーナル フリーResidual stress in the surface of dental porcelain was estimated using laser Raman spectroscopy. Sixteen different magnitudes of residual stress were generated in commercial porcelain disks by tempering, ion exchange, and slow cooling. The specimens were analyzed using a laser-Raman spectrometer with an Ar+ laser. The Raman shift of the largest peak near 500cm-1 originating from silica was used as an indicator of the level of residual stress. For comparison, the residual stress in the specimen was estimated by the indentation micro-fracture method. The Raman shift of the porcelain increased with increasing residual stress at 3.7×10-2cm-1/MPa (R2=0.89). The increase in the Raman shift corresponded to the increase in compressive stress. In addition, the value of full width at half maximum on the peak corresponded to the residual stress (-1.57×10-1cm-1/MPa: R2=0.82). These results revealed that the increase of residual stress in porcelain clearly appears on the Raman spectrum as an increase in the Raman shift. It is thus feasible to estimate residual stress in porcelain by laser-Raman spectroscopy.抄録全体を表示PDF形式でダウンロード (1047K) -
Students vs. DentistsHidehiko SANO, Nobuharu KANEMURA, Michael F. BURROW, Norimichi INAI, T ...1998 年 17 巻 1 号 p. 51-58
発行日: 1998年
公開日: 2009/02/12
ジャーナル フリーThe purpose of this study was to evaluate the operator variability of two dentin bonding systems. Fourteen undergraduate students and ten dentists of different levels of clinical experience were selected. Tensile bond strengths between resin composite and bovine dentin using dentin adhesive systems (Clearfil Liner Bond II: LB II; Scotchbond Multi-Purpose: MP) bonding systems showed a large scatter among students and dentists. The dentists group demonstrated no statistically significant differences for mean bond strengths between LB II and MP. The student group recorded a statistically greater bond strength using LB II . The mean coefficient of variation of the dentists group showed no statistically significant difference between LB II and MP, however that of the students group was lower with LB II. When using MP, the dentist group demonstrated a lower coefficient of variation than that of the student group. In order to obtain optimal bonding performance, or when beginning the use of a new system, the operator should be aware of the technique sensitivity of some adhesive systems and sensitivity to operator variability.抄録全体を表示PDF形式でダウンロード (852K) -
Shinichi UKON, Makoto FUJITA, Masanobu HAYAKAWA, Atsushi TAKAMI, Masah ...1998 年 17 巻 1 号 p. 59-67
発行日: 1998年
公開日: 2009/02/12
ジャーナル フリーThis study was carried out to determine the design and thickness of the cervical margin of a castable ceramic restoration from the point of view of its castability. Castability of castable ceramics was lower compared to Ag-Pd-Au and Co-Cr alloy with the use of the mesh pattern and rod patten test (p<0.05). It was more dependent on the pattern thickness than alloys (p<0.05), and perfect reproducibility with non-measurable variability could be estimated to reach 1.0mm thickness of the original pattern (p<0.001). Marginal shape was certainly more reproducible in a right angle shoulder than in 30, or 45 degree bevels (p<0.05). From these results, it is suggested that a right angle shoulder margin with 1.0mm thickness is more suitable to castable glass ceramic restoration than any other design.抄録全体を表示PDF形式でダウンロード (2419K) -
Young-gill KIM, Susumu HIRANO, Tadashi HIRASAWA1998 年 17 巻 1 号 p. 68-76
発行日: 1998年
公開日: 2009/02/12
ジャーナル フリーThe physical properties and shear bond strength of two resin-modified glass-ionomers: RMGIs (FJL and VT) and as a control, a conventional glass-ionomer: CGI (FJ), were evaluated. Ninety percent of the setting shrinkage under dry conditions and nominal hygroscopic expansion in water during 360h occurred within the first 24h. The nominal hygroscopic expansion of CGI was 0.38% while the RMGIs demonstrated over 1%, but considering the setting shrinkage the total hygroscopic expansion of CGI and the RMGIs were over 7 times and about 2.5 times, respectively. The thermal expansion of the RMGIs after water immersion was greater than that under dry condition. In contrast, FJ demonstrated expansion less than under dry condition. There was no significant difference between FJL and VT (P<0.05) as regard water absorption. The shear bond strength of the RMGIs to enamel and dentin were superior to FJ, except for VT to dentin.抄録全体を表示PDF形式でダウンロード (944K) -
Masao IRIE, Hiroyuki NAKAI1998 年 17 巻 1 号 p. 77-82
発行日: 1998年
公開日: 2009/02/12
ジャーナル フリーThe flexural properties, flexural strength, flexural modulus and modulus of resilience, of four commercially available compomers, and one resin-modified glass ionomer cement and one microfilled resin comosite (as controls) immediately after light-activation and after 1 week of water storage were tested to assess the mechanical properties. The water swelling after storage in water was also tested to assess the characteristics in water of compomers. The flexural test showed compomers to be statistically stronger and more resilient than the resin-modified glass ionomer cement or the microfilled composite, when tested immediately after light-activation and after 1 week of water storage. Water swelling of compomers was statistically less than the resin-modified glass ionomer cement after 1 week of water storage.抄録全体を表示PDF形式でダウンロード (605K) -
Miwako OHBA, Atsufumi MANABE, Kazuo ITOH, Hisashi HISAMITSU, Sadao WAK ...1998 年 17 巻 1 号 p. 83-88
発行日: 1998年
公開日: 2009/02/12
ジャーナル フリーThe effects of 2-hydroxyethyl methacrylate (2-HEMA) both in the primer and in the commercial dentin bonding agent on the efficacy of the dentin bonding system was evaluated by measuring the polymerization contraction gap width of a commercial resin composite restored in a cylindrical dentin cavity prepared in an extracted human molar. Contraction gap formation was prevented in the group of the EDTA-conditioning followed by glyceryl mono-methacrylate, ethylene glycol and 1, 6-hexanediol priming regardless of the 2-HEMA content in the dentin bonding agent containing 10-methacryloxydecyl dihydrogen phosphate. However, gap formation could not be prevented completely by the 2-HEMA priming. Therefore, it was possible to conclude that 2-HEMA was neither essential in the primer nor in the dentin bonding agent because of its low bonding efficacy and the resulting side effects on skin tissue as a delayed allergic reaction.抄録全体を表示PDF形式でダウンロード (696K)
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