巻号一覧
19 巻 (2000)
- 4 号 p. 329-
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19 巻, 3 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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Kazuhiro OHMOTO, Hiroshi NAKAJIMA, Jack L. FERRACANE, Hideaki SHINTANI ...2000 年 19 巻 3 号 p. 211-220
発行日: 2000年
公開日: 2009/02/12
ジャーナル フリーThis study examined the relationship between mercury content and mercury evaporation from amalgams during setting. Two different types of commercial high-copper amalgams (single composition and admixed types) were used. Cylindrical specimens of each amalgam were prepared with five different mercury contents according to ADA Specification No.1. Specimens were also prepared by hand condensation. Mercury evaporation from amalgam specimens maintained at 37°C was measured using a gold film mercury analyzer from 10min after the end of trituration until the mercury concentration in air reached an undetectable level. The mercury content more clearly influenced the mercury evaporation from the admixed type amalgam specimens when the mercury content decreased below the manufacturers' recommended trituration conditions. Triturating with less mercury than the manufacturers' recommended amount cannot lower the evaporation of mercury from freshly made amalgam. Proper condensing procedures can minimize the mercury evaporation from the amalgam surface.抄録全体を表示PDF形式でダウンロード (2703K) -
Kyosuke FUKUDA, Takashi NEZU, Yoshihiro TERADA2000 年 19 巻 3 号 p. 221-228
発行日: 2000年
公開日: 2009/02/12
ジャーナル フリーThe interaction between bovine tendon collagen and a series of homologous alcohols were investigated using a differential scanning calorimetry. For all alcoholic substances, as well as 2-hydroxyethyl methacrylate (HEMA), the concentration dependence of the denaturation temperature of collagen was observed, which showed a minimum at 30%. Clearly there are two opposing actions on the stabilization of the collagen structure; destabilization dominates over stabilization at lower concentrations, and vice versa at higher concentrations. The concentration dependence became greater for longer chain alcohols, while it was suppressed by the increased number of OH groups. The chain length-dependent surface tension may be related, which controls the permeation of the additives through the collagen fibers. Overall hydrophobicity, indicated by the hydrophile-lipophile balance (HLB) numbers, suggests the importance of the hydrophobic effect in the interaction of collagen and alcoholic substances, including adhesive monomers such as HEMA.抄録全体を表示PDF形式でダウンロード (816K) -
Taira MIYASAKA, Takaichi YOSHIDA2000 年 19 巻 3 号 p. 229-244
発行日: 2000年
公開日: 2009/02/12
ジャーナル フリーThe mechanical strength of experimental light cure composites containing binary filler mixtures with various combinations of irregular and spherical macrofillers in various mixes, and the microfilled ternary system fillers were measured. The compressive strength of the binary mixtures between different shaped fillers was not related to mixing ratios, although it significantly increased as the filler size decreased. The mixing ratio was immaterial within the irregular filler mixture. The compressive strength of the binary mixtures within the spherical fillers increased as the mixing ratio increased while the filler size was relatively large, then the mixing ratio became insignificant as the filler size decreased under 1.4μm. The compressive strength of the microfilled ternary fillers increased with the decrease in the macrofiller size and with the increase in the mixing ratio. A large diametrical tensile strength was found in several microfilled ternary mixtures containing different shaped macrofillers.抄録全体を表示PDF形式でダウンロード (1712K) -
Yoshiya HASHIMOTO, Masaaki NAKAMURA2000 年 19 巻 3 号 p. 245-262
発行日: 2000年
公開日: 2009/02/12
ジャーナル フリーTwenty-eight chemicals used as dental materials and bisphenol-A related chemicals were diluted with DMSO to concentrations ranging from 10-7 to 10-3M and tested for estrogenicity. Bisphenol-A (BPA), bisphenol-F (BPF) and bisphenol-A-bischloroformate (BPACF) showed estrogenic activity using the yeast two-hybrid system, and BPA, BPF, BPACF and bisphenol-S (BPS) showed estrogenic activity using the fluorescence polarization system. However, none of the remaining chemicals and none of the dental materials showed any activity at concentrations between 10-7 and 10-3M. Although BPA, BPF, BPACF, bisphenol-A-dimethacrylate and BPS showed estrogenic activity in the E-screen test, the remaining chemicals did not. Thus, most of the chemicals showed consistent results, either positive or negative, by the three testing methods, while two chemicals showed conflicting results. Further studies, together with in vivo and epidemiological examinations, are required. Elucidation of the structure-activity relationships of these chemicals is also needed to estimate the estrogenicity of a chemical from its structure.抄録全体を表示PDF形式でダウンロード (1676K) -
Yohji IMAI, Mariko WATANABE, Ayumi OHSAKI2000 年 19 巻 3 号 p. 263-269
発行日: 2000年
公開日: 2009/02/12
ジャーナル フリーThe purpose of this study was to examine the quality of commercially available Bis-GMA because concerns about Bis-GMA and Bis-GMA-based resins have been recently expressed in dentistry. Four major components and bisphenol A, which is a compound of recent controversy, were quantitatively analyzed using high performance liquid chromatography (HPLC) in three commercial Bis-GMA and six Bis-GMA-based composite resins. The contents of genuine Bis-GMA, Iso-bis-GMA, Bis-GMA-H, and Bis-GMA-M as well as the total content of the four monomers were 45.7-57.5%, 19.9-26.2%, 1.8-5.0%, 0.6-15.0% and 83.7-85.6% in the commercial Bis-GMAs, or 3.8-9.1%, 1.7-4.3%, 0.1-0.5%, 0.1-2.0% and 5.8-14.0% in composite resins, respectively. There were some differences in the composition of the major components between domestic and foreign materials. Bisphenol A contents in the unpolymerized composite resins were 1.5-10.2μg/g resin.抄録全体を表示PDF形式でダウンロード (717K) -
Katsunori HAOKA, Taro KANNO, Yukyo TAKADA, Kohei KIMURA, Osamu OKUNO2000 年 19 巻 3 号 p. 270-282
発行日: 2000年
公開日: 2009/02/12
ジャーナル フリーMagnetic attachments have been used in clinical dental practice, but there is some difficulties associated with removable bridges. One possible solution is to make whole bridges of Pt-Fe magnet alloys and its abutment out of magnetic stainless steel by casting. In terms of castability and magnetic properties, the promising composition of the Pt-Fe-Nb magnet alloy is Pt-30.0 mass% Fe-0.6 mass% Nb and Pt-30.0 mass% Fe-0.5 mass% Nb-0.03 mass%Si. In the present study, the corrosion resistance of these alloys was investigated based on the elusion test, electrochemical behavior and surface characterization by EPMA analysis. The released elements from the Pt-Fe-Nb magnets were mainly Fe ions in quantities similar to that of stainless steel for biomedical use, and the Pt-Fe-Nb magnet alloy, the Pt-Fe-Nb-Si magnet alloy and platinum resembled each other in electrochemical behavior. The present findings suggest, that the Pt-Fe-Nb magnet alloy provides excellent corrosion resistance and has important clinical dental applications.抄録全体を表示PDF形式でダウンロード (4234K) -
Part 1. Setting Time and Compressive StrengthAkira NAKAI2000 年 19 巻 3 号 p. 283-293
発行日: 2000年
公開日: 2009/02/12
ジャーナル フリーThis study was carried out to develop a new titanium casting investment consisting of calcia as the refractory material and a cold-curing resin system as the binder. The setting time of the investment was investigated under different N, N-dimethyl-p-toluidine (DMPT) contents in methyl methacrylate monomer (MMA) and benzoyl peroxide (BPO) contents in calcia without any sintering agent. The effects of the sintering agents, which were calcium fluoride (CaF2) and calcium chloride (CaCl2), on the compressive strength of the investments were investigated at room temperature before and after heating to two different temperatures. The shortest setting time (68 minutes) of the investment was obtained at 0.37 DMPT/BPO (1.5vol%/1.0 mass%) ratio by mass. The highest strength (16.5MPa) was obtained from the investment which contained 2 mass% CaF2 and was heated to 1, 100°C. It was found that the developed calcia investment containing 2 mass% CaF2 has a possibility for use in titanium castings.抄録全体を表示PDF形式でダウンロード (1124K) -
Part 1 Effects of Pd and Cu Contents, and Addition of Ga or Sn on Physical Properties and Bond with Ultra-low Fusing CeramicShin-ichi GOTO, Yukio MIYAGAWA, Hideo OGURA2000 年 19 巻 3 号 p. 294-306
発行日: 2000年
公開日: 2009/02/12
ジャーナル フリーAg-Pd-Au-Cu quaternary alloys consisting of 30-50% Ag, 20-40% Pd, 10-20% Cu and 20% Au (mother alloys) were prepared. Then 5% Sn or 5% Ga was added to the mother alloy compositions, and another two alloy systems (Sn-added alloys and Ga-added alloys) were also prepared. The bond between the prepared alloys and an ultra-low fusing ceramic as well as their physical properties such as the solidus point, liquidus point and the coefficient of thermal expansion were evaluated. The solidus point and liquidus point of the prepared alloys ranged from 802°C to 1142°C and from 931°C to 1223°C, respectively. The coefficient of thermal expansion ranged from 14.6 to 17.1×10-6/°C for the Sn- and Ga-added alloys. In most cases, the Pd and Cu contents significantly influenced the solidus point, liquidus point and coefficient of thermal expansion. All Sn- and Ga-added alloys showed high area fractions of retained ceramic (92.1-100%), while the mother alloy showed relatively low area fractions (82.3%) with a high standard deviation (20.5%). Based on the evaluated properties, six Sn-added alloys and four Gaadded alloys among the prepared alloys were suitable for the application of the tested ultra-low fusing ceramic.抄録全体を表示PDF形式でダウンロード (2352K) -
Kouichi WATANABE, Seigo OKAWA, Mitsugu KANATANI, Syuji NAKANO, Osamu M ...2000 年 19 巻 3 号 p. 307-316
発行日: 2000年
公開日: 2009/02/12
ジャーナル フリーAlthough titanium has been widely used in prosthetic appliances, such as cast removable partial denture frameworks, high quality castings are still difficult to obtain. This study proposes a new partition technique using a metal foil for improving castability of a two-chamber pressure casting unit. The metal foil was formed beforehand to bring it in contact with the mold crucible wall so that no clearance was left behind it. Using this formed foil, the mold cavity can be completely isolated from the upper chamber and can be maintained in a vacuum even after the rupture of the foil. Accordingly, a large casting force is generated very quickly, and as a result, castability is expected to be significantly improved. This expectation was confirmed by the experiments using wax patterns including thin plate and mesh plate.抄録全体を表示PDF形式でダウンロード (4320K) -
Linlin HAN, Neamat ABU-BAKR, Akira OKAMOTO, Masaaki IWAKU2000 年 19 巻 3 号 p. 317-325
発行日: 2000年
公開日: 2009/02/12
ジャーナル フリーThe purpose of the present study was to determine the resin-dentin Interface conditions in Wet vs. Dry Dentin. Dentin disks were prepared from extracted human premolars. Sectioned dentin surfaces were used for SEM studies of wet vs. dried acid-etched dentin. These specimens were cut perpendicular to the surface into two equal halves. One-half of the sectioned specimen was observed by SEM in three treatment groups and the other half was observed for micromorphological differences in the resin-dentin interface using Wavelength Dispersive X-ray Spectrometer (WDX). SEM photomicrographs of the dentin surface showed the collapse of collagen fibrils in the demineralized layer and enlargement of the tubule orifices. A collagen rich layer approximately 8-10μm thick (WDX) was observed at the resin-dentin interface when treated with the conventional dry-bonding technique. Dentin surfaces treated by the wet-bonding technique (SB), as observed by SEM, showed an uncollapsed collagen layer, while the collagen-rich layer was approximately 1-2μm thick (WDX). The present findings suggest that moist bonding is required for optimum infiltration of adhesive resin into the demineralized layer.抄録全体を表示PDF形式でダウンロード (2379K)
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