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Volume 17 (1998)
- Issue 4 Pages 223-
- Issue 3 Pages 163-
- Issue 2 Pages 93-
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Volume 17, Issue 4
Displaying 1-11 of 11 articles from this issue
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Masayuki KON, Youji MIYAMOTO, Kenzo ASAOKA, Kunio ISHIKAWA, Hae-Hyoung ...1998 Volume 17 Issue 4 Pages 223-232
Published: 1998
Released on J-STAGE: February 12, 2009
JOURNAL FREE ACCESSThe purpose of this study was to develop an α-tricalcium phosphate (α-TCP) cement which transforms to hydroxyapatite (HAP) in a relatively short period. We used calcium and phosphate solutions as the liquid phase for the α-TCP cement. The α-TCP powder was first mixed with CaCl2 solution, and then mixed with NaH2PO4 or Na2HPO4 solution for a total powder/liquid ratio of 1.8. The setting time became shorter with the increase in the concentration of calcium and phosphate solutions, reaching 5min, whereas the setting time was longer than 30min when distilled water was used as the liquid phase. X-ray diffraction analysis revealed that the cement was mostly transformed to HAP within 24h when kept in an incubator. We concluded that α-TCP should be mixed with calcium and phosphate solutions since this results in a moderate setting time and fast transformation to HAP even if the method of mixing becomes a little complex.View full abstractDownload PDF (1673K) -
Jiro TANAKA, Kunio ISHIKAWA, Hirofumi YATANI, Atsushi YAMASHITA, Kazuo ...1998 Volume 17 Issue 4 Pages 233-238
Published: 1998
Released on J-STAGE: February 12, 2009
JOURNAL FREE ACCESSWe have prepared various O-methacryloyl-N-acyl tyrosines (MAATY) to reveal the relationship between molecular structure near carboxylic acid and adhesive strength of MAATY-HEMA type adhesive resin to unetched dentin. In this study, we attempted to change the steric hindrance effect without changing the HLB value, i.e., introducing an iso-acyl group instead of n-acyl group into MAATY. O-methacryloyl-N-ethylbutyryl tyrosine (MIHTY) showed significantly lower adhesive strength when compared with O-methacryloyl-N-hexanoyl tyrosine even though both MAATY have the same HLB value. The possible explanation of the significantly different adhesive strength was that the 2-ethylbutyryl group in MIHTY was bulky, resulting in inhibition of the hydrogen bonding of the carboxylic group. The HLB value is independent of the steric effect of molecular structure, and thus the steric factor should be taken into consideration for the explanation of different adhesive strengths within the adhesive monomers having the same HLB value but different molecular structures.View full abstractDownload PDF (574K) -
Setyowati MEIANA, Hidekazu TAKAHASHI1998 Volume 17 Issue 4 Pages 239-252
Published: 1998
Released on J-STAGE: February 12, 2009
JOURNAL FREE ACCESSFatigue strength using the stair-case method and tensile strength of dental gallium alloys after artificial saliva immersion were measured for evaluating the effects of corrosive environment storage on the mechanical properties of the gallium alloys. The fatigue and the tensile strengths of both gallium alloys stored in artificial saliva were significantly decreased after 12-month storage, while those stored in air increased with storage period. The fracture surfaces of the specimens in artificial saliva showed not only metallic luster but also dark areas. In the dark area, the matrix might have dissolved during immersion. These results suggested that the concern over corrosion resistance of gallium alloys still remained.View full abstractDownload PDF (5182K) -
Yoshiharu MUKAI, Kiyoshi TOMIYAMA, Shusaku OKADA, Katsumi MUKAI, Hidey ...1998 Volume 17 Issue 4 Pages 253-263
Published: 1998
Released on J-STAGE: February 12, 2009
JOURNAL FREE ACCESSTo simulate hypersensitive dentin, the smear layer and dentinal plugs of bovine root dentin specimens were removed by immersion in 10% phosphoric acid, polishing with hydroxyapatite particles, and ultrasonic cleansing. The fluoride-tannic acid-lanthanum-apatite (FTLA) group was treated with acidulated phosphate fluoride (APF) containing tannic acid followed by rubbing with a paste of lanthanum chloride (LaCl3) and powdered apatite glass ceramics. The treated specimens were immersed in a remineralizing solution that mimics saliva for 6 weeks. The SEM observations revealed that the treated surfaces of the FTLA group were completely covered with fine spherical compounds and the dentinal tubules were occluded with plugs to a depth of about 3μm. Fluoride and lanthanum were detected to a depth of over 20μm by EPMA observation. After the remineralization, the surface of FTLA-treated specimen did not have any opened tubules and showed a remarkable increase in the number of fine spherical deposits in the dentinal tubules. These results suggest that the reaction products produced by sequential treatment with acidic fluoride and LaCl3 and powdered apatite glass ceramics are able to effectively occlude dentinal tubules.View full abstractDownload PDF (6857K) -
Seiji BAN, Kenji MATSUO, Norihiko MIZUTANI, Haruhiko IWASE, Toshihide ...1998 Volume 17 Issue 4 Pages 264-273
Published: 1998
Released on J-STAGE: February 12, 2009
JOURNAL FREE ACCESSThe microstructure and homogeneity of three commercial dentin and incisal unfired porcelain frits (one conventional and two ultra-low fusing types) fused-to metal were analyzed by X-ray diffractometry, scanning electron microspectroscopy, and wavelength- and energy-dispersive X-ray microspectroscopy. The average contents of tetragonal and cubic leucite for the conventional and one of the ultra-low fusing type frits were 20.1-22.6wt% and 0-2.6wt%, respectively, whereas those of another of the ultra-low fusing type frits were about 11.5-11.6wt% and 2.9-4.6wt%, respectively. The conventional type frits seemed to be admixtures of three kinds of glass frits. One of the ultra-low fusing type frits seemed to be an admixture of four kinds of glass frits. Another ultra-low fusing frits seemed to be only one kind of glass frit dispersed with small size, less than 1μm, leucite crystals. There were no remarkable differences in microstructure and homogeneity between dentin and incisal porcelain frits in each brand.View full abstractDownload PDF (3088K) -
Part I New Precious Metal Alloys with Base Metals for Resin BondingHiroki OHNO, Yuro YAMANE, Kazuhiko ENDO, Yoshima ARAKI, Yoshibumi IIZU ...1998 Volume 17 Issue 4 Pages 275-284
Published: 1998
Released on J-STAGE: February 12, 2009
JOURNAL FREE ACCESSNew dental precious metal alloys for resin bonding without alloy surface modification were developed by adding base metals (In, Zn, or Sn). Before this, binary alloys of Au, Ag, Cu, or Pd containing In, Zn, or Sn were studied for water durability and bonding strength with 4-META resin. The adhesion ability of the binary alloys was improved by adding In equivalent to 15% of Au content, Zn equivalent to 20% of Ag content, and In, Zn, or Sn equivalent to 5% of Cu content. There was no addition effect of the base metals on Pd, however 15% of In addition improved adhesion with Pd-based alloys containing equi-atomic % of Cu and Pd. The alloy surfaces were analyzed by XPS and showed that oxides such as In2O3, ZnO, or SnO play an important role in improving the adhesive ability of the alloys.View full abstractDownload PDF (908K) -
Part II The Relationship between Surface Structure of Au-In Alloys and Adhesive Ability with 4-META ResinHiroki OHNO, Kazuhiko ENDO, Yuro YAMANE, Isao KAWASHIMA1998 Volume 17 Issue 4 Pages 285-293
Published: 1998
Released on J-STAGE: February 12, 2009
JOURNAL FREE ACCESSAdhesion of 4-META to Au-In alloy was improved by adding In equivalent to 15% of Au content. On the basis of the results of Au-In alloys analyzed by XPS, the present study investigated the reason why adhesion of the Au-In alloy was improved. The O 1s spectrum could be separated into three oxygen chemical states, In2O3, chemisorbed H2O, and physisorbed H2O. The amount of chemisorbed H2O decreased remarkably with increasing amount of In. It is considered that the poor adhesive ability of the pure gold and alloys containing only small amounts of In was due to the chemisorbed H2O molecules and insufficient indium oxide on the alloy surface. It was established that excellent adhesion requires an oxide with chemical affinity for 4-META to cover at least 50% of the alloy surface.View full abstractDownload PDF (736K) -
Setsuo SAITO, Toshio ICHIMARU, Yoshima ARAKI1998 Volume 17 Issue 4 Pages 294-300
Published: 1998
Released on J-STAGE: February 12, 2009
JOURNAL FREE ACCESSTo clarify the factors determining the dimensional stability of alginate impressions during immersion in disinfectant and fixing solution, thè weight change of impressions in solutions of glutaraldehyde (GA), NaClO, Na2SO4, K2SO4, CaCl2 and ZnSO4 was measured. In the nonelectrolytic solution, GA, the weight decreased in proportion to concentration, possibly due to the gradient of osmotic pressure between the impression and solution. In monovalent metallic salt solutions the weight change decreased with increased concentration. Especially at lower concentrations the rate of weight loss was high. A chemical action of the solution might also be involved, in addition to the osmotic pressure difference. The weight loss in divalent metallic salt solutions was greater than in monovalent solutions, implicating crosslinking reactions between the impression and solution.View full abstractDownload PDF (676K) -
Min YAN, Hidekazu TAKAHASHI1998 Volume 17 Issue 4 Pages 301-313
Published: 1998
Released on J-STAGE: February 12, 2009
JOURNAL FREE ACCESSThe purpose of this study was to improve the characteristics of gypsum-bonded alumina investments using magnesia and potassium sulfate as chemical additives. Magnesia content improved fluidity, delayed setting reaction, increased green strength, and decreased setting expansion, when mixed with distilled water. When the investment was mixed with potassium sulfate, the setting time and setting expansion were reduced, and the thermal expansion increased, however, the green strength decreased. Therefore, the investment with a small amount of magnesia mixed with potassium sulfate was considered a suitable composition, having adequate setting behavior, enough green strength and sufficient compensate expansion for casting.View full abstractDownload PDF (3141K) -
Seiichiro FUJISAWA, Yoshinori KADOMA, Shigeru ITO1998 Volume 17 Issue 4 Pages 314-320
Published: 1998
Released on J-STAGE: February 12, 2009
JOURNAL FREE ACCESSTo clarify the interaction mechanism of biological activities induced by camphorated phenol (CP), the interactions between CP and phospholipid liposomes [dipalmitoyl phosphatidylcholine (DPPC) liposomes, dimyristoyl phosphatidylcholine (DMPC) liposomes and DMPC/dilauloyl phosphatidylethanolamine (DLEA) liposomes] were studies by DSC and NMR spectroscopy. CP exhibited a larger DSC phase transition properties [shift of phase transition temperature to a lower temperature and decrease in Height/Half-Height Width (H/HHW) of DSC peak)] than phenol in the various liposome systems. It was concluded from the NMR studies that CP is highly incorporated into the DPPC bilayer, the 1H and 13C signals of phenol in a complex between phenol and camphor being markedly broadened but shielded in the presence of DPPC liposomes. It was clear that CP is incorporated as a complex into the lipid bilayers.View full abstractDownload PDF (603K) -
Mizuho KUSUNOKI, Kazuo ITOH, Hisashi HISAMITSU, Sadao WAKUMOTO1998 Volume 17 Issue 4 Pages 321-327
Published: 1998
Released on J-STAGE: February 12, 2009
JOURNAL FREE ACCESSThe dentin cavity adaptation and setting characteristics of four commercial compomers were evaluated by measuring the wall-to-wall contraction gap width in the cylindrical dentin cavity and measuring the compressive strength for a maximum of 14 days after setting. The dentin cavity wall was pretreated by the dentin adhesives according to each manufacturer's instructions or the experimental contraction gap-free dentin bonding system. Complete marginal integrity was obtained in only one compomer and two resin composites which were combined with the experimental dentin bonding system. The compressive strength of two resin composites and two compomers ten minutes after setting was comparable to that after 14 days which indicated that the compomers exhibited setting characteristics as rapidly as the resin composite. It was concluded that a high efficacy dentin bonding system is required for commercial compomers to prevent gap formation during irradiation caused by the rapid setting shrinkage.View full abstractDownload PDF (763K)
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