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Volume 18 (1999)
- Issue 4 Pages 337-
- Issue 3 Pages 207-
- Issue 2 Pages 137-
- Issue 1 Pages 1-
Volume 18, Issue 1
Displaying 1-13 of 13 articles from this issue
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Part 1 Experimental Composite using Silver-Tin Alloy as Filler and 4-META as Coupling AgentKiyoshi KAKUTA, Somchai URAPEPON, Yukio MIYAGAWA, Hideo OGURA, Chatcha ...1999 Volume 18 Issue 1 Pages 1-10
Published: 1999
Released on J-STAGE: February 12, 2009
JOURNAL FREE ACCESSMetal-resin composites, using metal particles instead of inorganic particles as the filler and 4-META as the coupling agent, were experimentally prepared under 20 different conditions (five different concentrations of 4-META, and four different contents of metal particles). The flexural strength of the prepared metal-resin composites was in the range of about 14.5-61.3MPa. The flexural strength was significantly influenced by the 4-META concentration, the metal particle content and their interaction. The highest strength was estimated at 2-3 mass% of 4-META concentration and 92.0-93.5 mass% metal filler content. The flexural modulus of the metal resin composite ranged approximately from 7.8GPa to 15.5GPa. The flexural modulus of the metal resin composite significantly increased with the metal particle content. The effect of the 4-META concentration on the flexural modulus was not significant.View full abstractDownload PDF (1629K) -
Jiro TANAKA, Kunio ISHIKAWA, Hirofumi YATANI, Atsushi YAMASHITA, Kazuo ...1999 Volume 18 Issue 1 Pages 11-18
Published: 1999
Released on J-STAGE: February 12, 2009
JOURNAL FREE ACCESSIn order to understand the relationship between the durability of adhesive strength in the oral cavity and water absorption, a series of O-methacryloyl-N-acyl tyrosines (MAATY)-2-hydroxyethyl methacrylate (HEMA) bond system samples was prepared and their bonding strength to unetched human dentin was measured as a function of immersion period in water. Also, bulk polymerization was carried out to measure the amount of water absorption as a function of time. All specimens absorbed water suddenly when they were immersed into water. The amount of absorbed water was large when the carbon number in the acyl group was small or the number of carboxylic groups was large. The adhesive strength of the MAATY-HEMA system to unetched dentin decreased significantly when the MAATY-HEMA absorbed a larger amount of water. We concluded, therefore, that preparation of MAATY which absorbs less water may improve durability even when immersed in water.View full abstractDownload PDF (640K) -
Shigeru UNO, Toru TANAKA, Satoshi INOUE, Hidehiko SANO1999 Volume 18 Issue 1 Pages 19-31
Published: 1999
Released on J-STAGE: February 12, 2009
JOURNAL FREE ACCESSThe effect of configuration factor (C-factor) on cavity adaptation was investigated in three compomer and one resin composite restorations. Eighty-four cylindrical dentin cavities (C-factor: approximately 2.5, 3.0 or 4.0) prepared on flat coronal dentin surfaces were filled with the materials in combination with their proprietary adhesive systems. Cavity adaptation was microscopically examined after 15 minutes storage in water at the top surface and at other four sites along the cavity walls. Additionally, indentation testing was performed for each material at 20 minutes and 24 hours after irradiation. Regression analysis revealed no relationship between C-factor and gap dimension in compomer restorations at any of the measuring sites, while a logarithmic relation was found only at the cavity floor of the composite fillings. All materials showed maturation of mechanical properties. The elastic component of the indentation was smaller in compomers than in the composite. It was concluded that C-factor had no influence on the cavity adaptation for compomer restorations. This might be due to reduced stress generation at the bonding interface caused by relatively low mechanical properties immediately after curing, less elasticity, and water absorption in compomers.View full abstractDownload PDF (1139K) -
Hyung-Il KIM, Hyo-Joung SEOL, Dong-Hwa BAE, Ji-Young SHIM, Yukyo TAKAD ...1999 Volume 18 Issue 1 Pages 32-41
Published: 1999
Released on J-STAGE: February 12, 2009
JOURNAL FREE ACCESSThis study describes research with a view to developing a new age-hardenable, high-carat dental gold alloy with better biocompatibility by addition of a small quantity of titanium to gold. The relationship between isothermal age-hardening and phase transformation of the Au-1.6wt% Ti alloy was investigated by means of hardness testing, X-ray diffraction study, scanning electron microscopic observation and energy dispersive spectroscopy. The hardening in the initial stage of ageing seemed to be attributable to the continuous precipitation of the Au4Ti ordered phase in the supersaturated α solid solution matrix. The overaging with softening was attributed mainly to the formation of precipitates at the grain boundaries, which grew to bright lamellae and seemed to be composed of the Au4Ti phase.View full abstractDownload PDF (2142K) -
Michihiro NAGAMINE, Nasman NUR ALIM, Toshiyuki ITOTA, Yasuhiro TORII, ...1999 Volume 18 Issue 1 Pages 42-53
Published: 1999
Released on J-STAGE: February 12, 2009
JOURNAL FREE ACCESSA new fluoride releasing resin-ionomer cement was used for bonding of gallium alloy restorations in vitro. Etching, priming, and fluoride releasing resin-ionomer cement were used in the experimental group (ARG), prior to placement of the gallium alloy restorations. Three different controls were used: gallium alloy only (G), no etching, fluoride releasing resin-ionomer cement, gallium alloy (RG), etching, priming, non-fluoride cement and gallium alloy (ACG). The mean shear bond strengths of ARG group to enamel and dentin were higher than those of the three control groups. Artificial secondary caries lesions around the restorations in the experimental group and the control groups were produced, using a strep. mutans culture. The microradiographs were examined for presence of a caries inhibition zone near the restoration. Caries inhibition zones were clearly detected around RG and ARG, but not around G and ACG. The results indicate that the fluoride releasing resin-ionomer cement provided good adhesion and caries inhibition in enamel and dentin.View full abstractDownload PDF (1549K) -
Seiichiro FUJISAWA, Shigeru ITO1999 Volume 18 Issue 1 Pages 54-62
Published: 1999
Released on J-STAGE: February 12, 2009
JOURNAL FREE ACCESSOur objective was to determine whether high-resolution proton-nuclear magnetic resonance (500MHz) could be utilized for detection of ionic binding interaction of the 4-META resin system with calcium derived from hydroxyapatite. The stability of 4-META in aqueous medium was studied, findings indicated that 4-META was rapidly converted to 4-MET, a hydrate product of 4-META in 10% D2O/DMSO-d6. The 1H-NMR signals of the methacryloyloxyethoxy group of 4-MET remained intact following the addition of both monocalcium phosphate (MCP) and dicalcium phosphate dihydrate (brushite) solution, whereas those of its trimellitic portion were markedly shifted upfield depending on the phosphate concentration. The shielding effect followed by upfield shifts was due to the localization of electron density surrounding the carboxylate anions that were dissociated by the interaction with calcium counter cation. The shielding effect of 4-MET with brushite was larger than that with MCP. An ionic interaction of 4-MET derived from 4-META with calcium was demonstrated.View full abstractDownload PDF (851K) -
Young-gill KIM, Susumu HIRANO1999 Volume 18 Issue 1 Pages 63-75
Published: 1999
Released on J-STAGE: February 12, 2009
JOURNAL FREE ACCESSThe effects of the C-value (bonded surface area/unbonded surface area) and the volume of the cavity on the volumetric dimensional changes [volumetric setting shrinkage (VSS) and volumetric hygroscopic expansion (VHE)] of a resin-modified glass-ionomer (RMGI) filled in experimental cylindrical cavities were evaluated.
The VSS and the VHE rate decreased with increasing C-value. There was a high inverse regression between the cavity C-value and volumetric dimensional changes, but a low regression between cavity volume and volumetric dimensional changes. Therefore, it was thought that greater contraction stress would remain in high C-value cavities than low C-value cavities during the setting process. It was also confirmed that the volumetric dimensional changes of RMGI in cavity were influenced primarily by the cavity C-value.View full abstractDownload PDF (1678K) -
Sakari HIKAGE, Atushige SATO, Shiro SUZUKI, Charls F. COX, Kunihiko SA ...1999 Volume 18 Issue 1 Pages 76-86
Published: 1999
Released on J-STAGE: February 12, 2009
JOURNAL FREE ACCESSThe purpose of the this study was to evaluate the cytotoxicity of dental resin monomers in the presence of a rat liver S9 mix containing cytochrome P 450 enzymes. JTC-12 cells derived from a monkey kidney were seeded on a 96-well multi-well-plate at 9×103 cells per well. After cultivation, the S9 mix was added to the wells as an S9 mix group (+S9), and PBS- was added to the other wells as a none-S9 mix group (-S9), then 7 different concentrations of various monomers were added to each well. All the specimens were cultured for another 24hrs. The cell survival ratios (CSR) were calculated by using a neutral red cytotoxicity assay.
CSR for 50μg/mL of Bis-GMA/S9 mix was 92.6% while for none-S9 mix it was 6.6%. The values of CSR for UDMA, Bis-MPEPP, EGDMA, TEGDMA, DMAEM, 4-META and HEMA exhibited a reduction in cytotoxicity in the presence of the S9 mix. There were significant differences between +S9 and -S9 for respective monomers (p<0.05). However, there were no significant differences between +S9 and -S9 for MMA (p<0.05).View full abstractDownload PDF (902K) -
Effect of Carboxyl Group in O-Methacryloyl-N-Acyl Tyrosines on Adhesiveness to Unetched Human DentinJiro TANAKA, Kunio ISHIKAWA, Hirofumi YATANI, Atsushi YAMASHITA, Kazuo ...1999 Volume 18 Issue 1 Pages 87-95
Published: 1999
Released on J-STAGE: February 12, 2009
JOURNAL FREE ACCESSWe have reported that the carboxylic group plays an important role in the adhesion of methacryloyl amino acid-2-hydroxyethyl methacrylate type restorative resin to dentin surfaces. However, our study so far has been limited to the methacryloyl amino acid that has only one carboxylic acid. In this investigation, three new O-methacryloyl-N-acyl tyrosines (MAATY) that have one or two carboxylic groups in the acyl group, and thus two or three carboxylic groups in MAATY, were prepared and evaluated for their bond strength to unetched dentine. Higher bond strength was observed when the MAATY contained larger number of carboxylic acid groups. Factor analysis of the bonding strength revealed that the hydrogen bond ability of the carboxylic acid and the hydrophile-lipophile balance (HLB) affected the bond strength.View full abstractDownload PDF (670K) -
Barbara H. MILLER, Margaret WOLDU, Hiroshi NAKAJIMA, Toru OKABE1999 Volume 18 Issue 1 Pages 96-107
Published: 1999
Released on J-STAGE: February 12, 2009
JOURNAL FREE ACCESSThis study investigated the physical and mechanical properties and the microstructure of four different gallium alloys. For all gallium alloys, the compressive strengths measured at one hour (86-223MPa) and 24 hours (265-286MPa) after specimen preparation were found to be well within the range exhibited by many high-copper amalgams. The creep values and dimensional change of the gallium alloys were comparable to those of leading amalgams, except for the dimensional change value of one alloy. The set gallium alloys consisted of a multi-phase structure including β-Sn, CuGa2, In4Ag9, Ag72Ga28, and Ga5Pd (except for one product that did not contain Pd) that was more complicated than the structure of dental amalgams. Although the gallium alloys had physical and mechanical properties comparable to those of high-copper amalgams, the microstructure, coupled with the instability of the element gallium itself, could make these materials more prone to corrosive attack compared to amalgams.View full abstractDownload PDF (2736K) -
Masao IRIE, Kazuomi SUZUKI1999 Volume 18 Issue 1 Pages 108-115
Published: 1999
Released on J-STAGE: February 12, 2009
JOURNAL FREE ACCESSThis study evaluated the effect of primer on shear bond strength and marginal gaps of six new compomers immediately after light-activation. A resin-modified glass ionomer cement, a conventional glass-ionomer cement and a microfilled composite were used for comparison. The marginal gap widths of each of the four compomers and a microfilled composite used with the primer were significantly smaller compared with those used without the primer. The bond strength values of five compomers used with the primer were significantly higher than those used without the primer. The bond strength of conventional glass-ionomer was not affected by the primer (or the conditioner).View full abstractDownload PDF (785K) -
Atsufumi MANABE, Kazuo ITOH, Chihiro TANI, Hisashi HISAMITSU, Sadao WA ...1999 Volume 18 Issue 1 Pages 116-123
Published: 1999
Released on J-STAGE: February 12, 2009
JOURNAL FREE ACCESSThe objective of the present study was to understand the role of the functional monomers in dentin bonding agents of an experimental dentin bonding system by measuring the wall-to-wall contraction gap and tensile bond strength measurement. The efficacy of three commercial dentin bonding agents after using EDTA for conditioning and GM for priming was evaluated by measuring the contraction gap of the resin composite in a cylindrical dentin cavity, and by measuring the tensile bond strength of the composite to a flat dentin surface. The effect of the functional monomers was demonstrated by the contraction gap measurement alone. The value of the contraction gap was significantly different between the commercial dentin bonding agents and these agents without functional monomers (p<0.05). It was concluded that the functional monomers were essential to obtaining the marginal integrity of the resin composite in the dentin cavities.View full abstractDownload PDF (909K) -
Satoshi IMAZATO, Hisashi TARUMI, Setsuko KATO, Noboru EBI, Atsushi EHA ...1999 Volume 18 Issue 1 Pages 124-132
Published: 1999
Released on J-STAGE: February 12, 2009
JOURNAL FREE ACCESSIn this study, water sorption of resins and composites containing Bis-GMA and TEGDMA in various proportions were measured, and the influence of degree of conversion and the hydrophobicity of the material on the water sorption characteristics of Bis-GMA/TEGDMA resins were evaluated. Unfilled resins and composites containing Bis-GMA/TEGDMA, with a ratio of 1/1, 2/1, or 3/1 by weight, were prepared and cured. Water uptake and the degree of conversion of each specimen were determined, and the hydrophobicity was compared by measuring the contact angle of water. Both unfilled resins and composites containing Bis-GMA/TEGDMA in the ratio of 1/1 showed significantly greater water uptake than the others. The degree of conversion of the specimens increased as the proportion of TEGDMA was increased, and no inverse relationship was found between the water sorption and the degree of conversion. In contrast, the contact angle of the 1/1-specimen was less than the others, demonstrating significant correlation with the water uptake. These findings indicate that Bis-GMA/TEGDMA resins showed the greatest water uptake at the ratio of 1/1, and the water sorption characteristic was not influenced by the degree of conversion but mainly by the hydrophobicity of the material.View full abstractDownload PDF (906K)
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