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Volume 10 (1991)
- Issue 2 Pages 105-
- Issue 1 Pages 1-
Volume 10, Issue 2
Displaying 1-7 of 7 articles from this issue
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Mamoru OZAKI, Masako SUZUKI, Kazuo ITOH, Sadao WAKUMOTO1991 Volume 10 Issue 2 Pages 105-120,231
Published: December 25, 1991
Released on J-STAGE: February 12, 2009
JOURNAL FREE ACCESSThe possible chemical interaction between synthetic hydroxyapatite or bovine enamel and a functional monomer of 4-methacryloxyethyl trimellitic acid (4-MET) diluted in methyl methacrylate (MMA) was examined by measuring the Raman spectra. It was concluded that the carboxyl group of 4-MET reacted with the calcium in the substrate to form a salt that was detected by the Raman band at around 1, 380cm-1. However, formation of the salt on the surface of the hydroxyapatite (HAP) with the carboxyl group, and polymerization of the 4-MET in the methacryl group near the surface were mutually exclusive reactions for the same 4-MET molecule.View full abstractDownload PDF (1687K) -
Seiichiro FUJISAWA, Yoshinori KADOMA, Yasuo KOMODA1991 Volume 10 Issue 2 Pages 121-127,231
Published: December 25, 1991
Released on J-STAGE: February 12, 2009
JOURNAL FREE ACCESSTo clarify the hemolytic mechanism of Bis-GMA and its related methacrylates, the interaction of five methacrylates (Bis-GMA, MMA, NPGDMA, TEGDMA, and UDMA) with DPPC/Cholesterol (CS) liposomes, as a model for erythrocyte membranes, was studied by 1H-NMR spectroscopy. Exogenous Bis-GMA partitioning into the DPPC/CS liposomes caused disappearances of its proton signals. With NPGDMA, its signals broadened markedly in DPPC/CS liposomes. UDMA partitioning caused changes in chemical shifts to a higher field, whereas MMA and TEGDMA partitioning did not cause any changes in chemical shifts. It was concluded from these observations that Bis-GMA has a stronger interaction with the DPPC/CS liposomes than the other methacrylates used. The high hemolytic activity of Bis-GMA reported previously3, 12) seemed to be due to its migration into the lipid bilayer of phospholipids containing CS in erythrocyte membranes.View full abstractDownload PDF (1126K) -
Kouichi WATANABE, Seigo OKAWA, Osamu MIYAKAWA, Syuji NAKANO, Nobuhiro ...1991 Volume 10 Issue 2 Pages 128-137,231
Published: December 25, 1991
Released on J-STAGE: February 12, 2009
JOURNAL FREE ACCESSThe tracer element molten (TEM) method, which provides titanium flow visualization in a mold cavity, was applied to investigate the flow in a mesh pattern. When a pressure casting machine was used, most of the mesh rods were composed of many solidification layers, which implied that the flow was laminar and almost steady. When a centrifugal casting machine was used, the flow was almost irregular and a stack of solidification layers was observed in only a few segments. These results indicate that the flow was turbulent. In a complicated cavity, such as a mesh pattern, pressure rather than centrifugal force acts as an effective casting force. Therefore, in such a cavity, favorable castability can be achieved with high pressure and laminar flow.View full abstractDownload PDF (5246K) -
Toshiyuki NAMBU, Chuji WATANABE, Yoshiaki TANI1991 Volume 10 Issue 2 Pages 138-148,232
Published: December 25, 1991
Released on J-STAGE: February 12, 2009
JOURNAL FREE ACCESSIn an attempt to evaluate the influence of water on the mechanical properties of composite resin, the transverse strengths of 15 commercially available composites were determined in water at 37°C and compared with the strength measured in air after storage in water for periods of 1 day to 3 months. Some of the composites, including two which contained a blend filler, showed remarkable reduction of transverse strength when measured in air, according to the procedures specified in ISO 4049, in comparison with transverse strength measured in water. The change of water content in the material can predominantly affect the mechanical behavior of composite resin.View full abstractDownload PDF (2444K) -
Choltacha HARNIRATTISAI, Hiroyasu HOSODA1991 Volume 10 Issue 2 Pages 149-164,232
Published: December 25, 1991
Released on J-STAGE: February 12, 2009
JOURNAL FREE ACCESSThe purpose of this study was to investigate pulpal response and bacterial invasion associated with five dentin bonding systems placed in cavities without an enamel margin. Two hundred and twenty-four dentin margin cavities were created by removing the surrounding marginal enamel of class V cavities in monkey teeth. These cavities were restored with a resin composite using various current dentin bonding systems. All of the dentin bonding systems showed odontoblastic layer changes to varying degrees, and slight to moderate inflammation at the initial stage. With the lapse of time, the degree of inflammation tended to decrease markedly, except for those cases in which bacteria were present. The result of SA/Photo Bond corresponded to that of the glass ionomer cement (negative control). Accordingly, this study suggests that a good bond and adaptation between resin and dentin should be obtained for eliminating pulpal irritation, even in the dentin cavity.View full abstractDownload PDF (5267K) -
Tohru HAYAKAWA, Kozo HORIE1991 Volume 10 Issue 2 Pages 165-171,232
Published: December 25, 1991
Released on J-STAGE: February 12, 2009
JOURNAL FREE ACCESSSeven types of amide monomers, methacryloyl tyrosine amide (MTYA), p-methacryloxybenzamide (p-MBA), p-methacryloxybutoxybenzamide (p-MBBA), o-methacryloxybutoxybenzamide (o-MBBA), p-methacryloxybutoxy phenylpropionamide (p-MBPPA), 3, 5-dimethacryloxybenzamide (3, 5-DMBA), and 3, 5-di (methacryloxybutoxy) benzamide (3, 5-DMBBA), were prepared for use as bonding agents. The monomers were dissolved in HEMA. Bovine enamel was etched with 40% phosphoric acid, and bovine dentin was etched with 10% citric acid before being primed with MTYA·G·H. The tensile bond strengths between bovine enamel or dentin and experimental adhesives were measured after one day immersion in water at 37°C. HEMA was used as a control adhesive.
When bonding to etched enamel, the bond strengths of composite resins with o-MBBA and 3, 5-DMBA were significantly higher than those with HEMA. The bond strengths of composites with MTYA, p-MBA, p-MBBA, 3, 5-DMBBA and p-MBPPA were almost the same as those with HEMA. When bonding to dentin, the bond strengths of composite resin with MTYA and p-MBBA were significantly higher than those with HEMA.View full abstractDownload PDF (3028K) -
Osamu OKUNO, Shin ISHIKAWA, Florentina Takako IIMURO, Yohsuke KINOUCHI ...1991 Volume 10 Issue 2 Pages 172-184,233
Published: December 25, 1991
Released on J-STAGE: February 12, 2009
JOURNAL FREE ACCESSThe purpose of this study was to develop a small cup type yoke magnetic attachment sealed from oral fluid. The magnetic device forms a closed circuit between the magnet, yokes, and keeper. A3.2mmφ×1.4mm SmCO5 magnet was put into a cup yoke of 447J1 stainless steel and covered by 447J1 stainless steel disk yoke with a 316L stainless steel ring. To protect the magnet from corrosion, the connection was sealed by laser welding. The optimum dimensions were figured out by a finite element method. The performance of the magnetic attachment was investigated. As a result, a magnet device 4.4mm in diameter and 2.1mm in height was developed. The breakaway retention when the keeper touched it was 341 gf on average.View full abstractDownload PDF (3740K)
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