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Volume 9 (1990)
- Issue 2 Pages 129-
- Issue 1 Pages 1-
Volume 9, Issue 2
Displaying 1-10 of 10 articles from this issue
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Tohru HAYAKAWA, Isao SHIBUYA, Kiyoyuki TAKAHASHI, Kozo HORIE1990 Volume 9 Issue 2 Pages 129-135,277
Published: December 25, 1990
Released on J-STAGE: February 12, 2009
JOURNAL FREE ACCESSNew dentin etchants AC (ammonium citrate) were examined. The pH of the AC solution was 7.3∼7.4, and the concentration of the solutions varied from 5% to 30%. The etching of a 10% AC solution was the most effective in improving the adhesion between the composite resin and dentin among the AC solutions employed when MTYA·G·H was used as a dentin primer. The smear layer was removed and the tubules were not generally opened with AC etching. The bond strengths to dentin etched with 10% AC were comparable with those to dentin etched with neutralized 0.5M EDTA or EDTA 3-2. The bond strengths increased with primers MTYA·H and MTYA·G·H, in that order.View full abstractDownload PDF (2547K) -
Seiichiro FUJISAWA, Yoshinori KADOMA, Yasuo KOMODA1990 Volume 9 Issue 2 Pages 136-146,277
Published: December 25, 1990
Released on J-STAGE: February 12, 2009
JOURNAL FREE ACCESSTo clarify the mechanism of interaction of dental adhesive monomers with biological membranes at the molecular level, we studied the interaction of methacryloyloxydecyl dihydrogen phosphate (MDP) and methacrylic acid (MAA) with the dipalmitoylphosphatidylcholine (DPPC) liposome system using NMR and DSC. MDP-DPPC interaction became apparent through broadening of the DPPC phase transition as pH decreased, finally the enthalpy of MDP-DPPC (1:1 mol ratio) reduced to zero at pH 2.5. Proton chemical shifts of MDP enhanced shielding and proton signals due to the phosphatidylcholine polar group (O-CH2-CH2-N bond) of DPPC were observed. MAA-DPPC interaction was smaller than that of MDP-DPPC, even at low pH. It was concluded that the strong hemolytic activity of MDP may be due to its interation with the phospholipid bilayers of erythrocyte membranes.View full abstractDownload PDF (1422K) -
Atsufumi MANABE, Tokuji HASEGAWA, Hisashi CHIGIRA, Kazuo ITOH, Sadao W ...1990 Volume 9 Issue 2 Pages 147-152,228
Published: December 25, 1990
Released on J-STAGE: February 12, 2009
JOURNAL FREE ACCESSThe side effects of dentin primer applications on soft tissue were examined pathologically. Of the 4 experimental dentin primers tested, dimethylaminoethyl methacrylate (DMAEM) and glutaraldehyde (GLU) caused irritation to the skin of rabbits whereas hydroxyethyl methacrylate (HEMA) and glyceryl methacrylate (GM) caused only insignificant changes in the substrate. It was concluded that an aqueous solution of GM can be used clinically because of its low irritation to skin and high bonding efficacy, as previously reported, though possible irritation to pulp tissues should perhaps still be investigated. The mechanisms of irritation to operator fingertips caused by repeated direct contact with dentin primers containing HEMA remain unknown.View full abstractDownload PDF (3025K) -
Seiji BAN, Yosifumi TAKAHASHI, Hiroaki TANASE, Jiro HASEGAWA1990 Volume 9 Issue 2 Pages 153-162,228
Published: December 25, 1990
Released on J-STAGE: February 12, 2009
JOURNAL FREE ACCESSThe heat curing behavior of light-cured restorative composite resins, light-cured crown and bridge veneering resins, pure dimethacrylate monomers, Bis-GMA monomers containing various initiators, and monomer mixtures were investigated by slow heating at a constant rate with differential scanning calorimetry (DSC) without any light irradiation -the so-called dynamic DSC measurement. Some of the lightcured restorative composite resins and the light-cured crown and bridge veneering resins showed a sharp exothermic peak due to heat curing. Pure TEDMA also showed a sharp exothermic peak, whereas the BisGMA monomers containing catalysts for light curing showed no exothermic peak. It seems that heat curing behavior of light-cured composite resins depends not on the decomposition of camphorquinone, but on that of the monomer itself.View full abstractDownload PDF (2284K) -
Reiko SUDA, Yoshiaki ANDOH, Manabu SHIONOME, Kohji HASEGAWA, Kazuo ITO ...1990 Volume 9 Issue 2 Pages 163-166,228
Published: December 25, 1990
Released on J-STAGE: February 12, 2009
JOURNAL FREE ACCESSThe sedative effect of the dentin primer, 35% hydroxyethyl methacrylate (HEMA) solution, on dentin hypersensitivity was clinically evaluated. Exposed root surfaces of teeth were cleaned with neutralized 0.5mol/L EDTA and treated with 35% HEMA solution followed by the application of a commercial dentin bonding agent. The extent of sedation was estimated by comparison of the responses before and after treatment to irritation by a cold water spray, compressed air blast and scratching with an explorer. The degree of the response to these irritations was decreased significantly upon the combined application of HEMA and commercially available dentin bonding agents though it was still ineffective in nearly 30% of the 48 cases tested.View full abstractDownload PDF (2315K) -
Yohji IMAI, Takahiro AKIMOTO1990 Volume 9 Issue 2 Pages 167-172,229
Published: December 25, 1990
Released on J-STAGE: February 12, 2009
JOURNAL FREE ACCESSThe hydrodynamic theory is generally accepted as an explanation of hypersensitive dentin and suggests that occlusion of exposed dentinal tubules should result in a reduction of hypersensitivity. We tried to block tubules by in situ precipitation of insoluble calcium phosphate. Calcium phosphate crystals precipitated in situ on patent dentin surfaces and formed in the tubules immediately upon serial application of sodium phosphate and calcium chloride solutions, thus occluding the tubules. The size of crystals, their degree of coverage, and the thickness of the precipitate depended on the method of application and concentration of the solutions. The application of 5% disodium phosphate solution followed by rubbing with 10% calcium chloride solution resulted in immediate relief from dental hypersensitivity in 84% of patients treated.View full abstractDownload PDF (3443K) -
Masayuki TAIRA, Kunio WAKASA, Masao YAMAKI, Akira MATSUI1990 Volume 9 Issue 2 Pages 173-180,229
Published: December 25, 1990
Released on J-STAGE: February 12, 2009
JOURNAL FREE ACCESSTo evaluate the effect of the diamond grit size of commercial dental diamond points on the dental cutting, we conducted weight-load cutting tests on bovine enamel and glass-ceramic typodont teeth using 3 different diamond grit sizes and air-bearing and ball-bearing air-turbine driven handpieces. With the transverse load applied on the diamond point varied between 20 and 80g, we measured rotational cutting speed and cutting volume. Generally, increases in applied load caused decreases in rotational cutting speed and increases in cutting volume. The intensity of this trend, however, differed between grit sizes. Regular grit diamond points most strongly showed this tendency, while super-fine grit diamond points were least affected. Fine grit diamond points behaved in a manner similar to regular grit points.View full abstractDownload PDF (1941K) -
Masayuki KON, Kunio ISHIKAWA, Norihiko KUWAYAMA1990 Volume 9 Issue 2 Pages 181-192,230
Published: December 25, 1990
Released on J-STAGE: February 12, 2009
JOURNAL FREE ACCESSZirconia dispersed composite porcelains with glass and aluminous porcelain as matrix were prepared as models of dental porcelains. The bending strength and fracture toughness of the composite porcelains were examined. The bending strength and fracture toughness of composite porcelains containing 50wt% zirconia were 20 to 80% greater than in glass alone. However, bending strength and fracture toughness decreased upon the addition of zirconia at more than 50wt%. Moreover, in the case of aluminous porcelain as matrix, fracture toughness increased to a maximum value of 2.6MPa⋅m1/2 by addition of 23wt% zirconia, twice the toughness of glass alone. On the other hand, no increase of bending strength was observed in this case. Deflection and bowing of cracks as well as microcracking effects were related to these increases of mechanical properties in zirconia dispersed composite porcelains.View full abstractDownload PDF (3607K) -
Kenzo ASAOKA, Masayuki KON, Norihiko KUWAYAMA1990 Volume 9 Issue 2 Pages 193-202,230
Published: December 25, 1990
Released on J-STAGE: February 12, 2009
JOURNAL FREE ACCESSChanges in the viscosity of dental porcelain as a function of temperature are the controlling factor determining incompatible stresses in porcelain-fused-to-metal restorations. A new method was used to estimate viscosity using a viscoelastic analytical model that considers the relation between the heating rate and deformation temperature (Td) of dental porcelain with stress applied during heating. The activation energy of viscous flow and the viscous constant in the Arrhenius equation were calculated for six kinds of commercial body and opaque porcelains. The effect of the heating rate on the instantaneous coefficient of thermal expansion was also measured. Tg onset was graphically determined using data on thermal deformation and agreed well with the strain point as defined by viscosity. The data gathered in this study was also compared to the experimental results of previous works by others.View full abstractDownload PDF (2302K) -
Shigeru HIRABAYASHI, Tadashi HIRASAWA1990 Volume 9 Issue 2 Pages 203-214,230
Published: December 25, 1990
Released on J-STAGE: February 12, 2009
JOURNAL FREE ACCESSIn an effort to improve the light transmittance of light-cured composite resins while avoiding degradation of their physical properties, 4 dimethacrylates having low refractive indices and a bulky backbones such as alicyclic or fluorine-substituted bisphenol groups were synthesized. The depths of cure and physical properties of 6 experimental composite resins containing these new monomers were, then, examined and compared to those of 3 control composite resins containing UDMA, BisMEPP, or BisGMA.
The depths of cure of the experimental group containing the synthesized monomers were greater than those of the control group with the exception of the composite containing UDMA. The depth of cure increased as the difference between the refractive indices of the matrix monomer and silica filler decreased.
The physical properties of 2 composites in the experimental group were comparable to those of the control group. The matrix monomers of these 2 composites were a mixture of 4, 8-dimethacryloxymethylene tricyclo [5.2.1.02, 6] decane or 2, 2-bis (4-methacryloxyethoxy phenyl) hexafluoropropane and TEGDMA in a molar ratio of 1/1.View full abstractDownload PDF (2838K)
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