All issues
Volume 14 (1995)
- Issue 2 Pages 109-
- Issue 1 Pages 1-
Volume 14, Issue 1
Displaying 1-10 of 10 articles from this issue
- |<
- <
- 1
- >
- >|
-
Yuh-Shiou LU, Huey-Wen YANG1995 Volume 14 Issue 1 Pages 1-13,101
Published: June 25, 1995
Released on J-STAGE: February 12, 2009
JOURNAL FREE ACCESSApplication of a light-cured porcelain margin is a technique which has been developed recently. In this study, we compared the porcelain margin properties of the porcelain-light-cured resin matrix system and the traditional porcelain-water system, in terms of volumetric shrinkage, density, compressive strength, surface characteristics, internal porosity, separability of the condensed porcelain from the stone die, and the marginal integrity. The experimental resin matrix was composed of BDMA or EGDMA as a base monomer, CQ as a photoinitiator, DEAEMA as a polymerization accelerator, and TEGDMA as a diluent. Compared with the conventional system, the porcelain of the resin matrix system tended to show a larger volumetric shrinkage, a smaller density and a lower compressive strength. The experimental groups containing the diluent and the traditional control group demonstrated smoother surfaces and less internal porosity than those without the diluent. The photoinitiator was thought to play an important role on the separability from the stone die and the marginal integrity; the higher the ratio of the photoinitiator (1.0wt%), the better the separability and the fit.View full abstractDownload PDF (4873K) -
Jin-Noon PARK, Yohji IMAI1995 Volume 14 Issue 1 Pages 14-22,101
Published: June 25, 1995
Released on J-STAGE: February 12, 2009
JOURNAL FREE ACCESSThe purpose of this study was to examine the feasiblity of a conditioner for treating enamel and dentin simultaneously for MMA-TBB resin bonding. Various phosphoric acid solutions containing copper salts were prepared and used as conditioners before bonding MMA-TBB resin to bovine teeth. Their effects on the surface morphology and bonding were studied by scanning electron microscopy and tensile bond strength testing. The concentrations of phosphoric acid as well as copper salts therein affected the bond strength to dentin. Ten percent phosphoric acid containing 3% copper (II) chloride appeared optimal for treating dentin and was significantly effective in improving the bond strength compared with phosphoric acid alone. This conditioner was applicable also to enamel without any adverse effect on the bond strength. Therefore, enamel and dentin may effectively be treated simultaneously with this conditioner before bonding of MMA/TBB-based resin.View full abstractDownload PDF (2828K) -
Satoshi IMAZATO, Hisashi TARUMI, Kyoko KOBAYASHI, Hideki HIRAGURI, Koz ...1995 Volume 14 Issue 1 Pages 23-30,101
Published: June 25, 1995
Released on J-STAGE: February 12, 2009
JOURNAL FREE ACCESSIn order to elucidate the relationship between the degree of conversion and internal discoloration of light-activated composite, four experimental composites which contained different amounts of Bis-GMA and TEGDMA were prepared, and the degree of conversion and discoloration of each composite, with or without annealing, were determined. The degree of conversion was measured by Fourier transformation infrared spectroscopy and the color change was determined after 1, 2, 3 and 4 weeks of immersion in water at 60°C. The non-annealed composites demonstrated a greater degree of conversion and less discoloration as the amount of TEGDMA was increased. Annealed composites showed a significantly greater degree of conversion and less discoloration compared with the non-annealed composites. The results indicate that the greater the degree of conversion, the less the discoloration of composite, and the correlation between the two factors was significant for light-activated composite.View full abstractDownload PDF (2417K) -
Laurence C. CHOW, Shozo TAKAGI1995 Volume 14 Issue 1 Pages 31-36,102
Published: June 25, 1995
Released on J-STAGE: February 12, 2009
JOURNAL FREE ACCESSRemineralization of enamel lesions in vitro by use of sequential treatments with an alkaline (pH 9) phosphate (1mol/L) solution and slightly acidic (pH 6) calcium (1mol/L) solution was reported to be relatively ineffective. An analysis of the diffusion processes that may occur during the remineralization treatments suggested that the driving force for diffusion of Ca into the lesion can be increased by making the calcium solution more alkaline than the phosphate solution. In the present study this modified treatment procedure was evaluated for remineralizing root lesions in vitro. Results show that (1) in the control group there was a slight increase in mineral density in the surface region of the lesion, (2) in the experimental group there were significant (p<0.05) increase in mineral content in the outer 40μm of the lesion, and (3) in contrast to the finding reported previously, thick mineral deposits on the surface of the root were not observed.View full abstractDownload PDF (1869K) -
Hisashi TARUMI, Mitsuo TORII, Yasuhiko TSUCHITANI1995 Volume 14 Issue 1 Pages 37-44,102
Published: June 25, 1995
Released on J-STAGE: February 12, 2009
JOURNAL FREE ACCESSThe reaction of barium glass filler with water was determined by investigation of the effects of the particle size of barium glass filler on the water sorption rate and the mechanical properties of composite resin. Barium glass and quartz were milled to obtain powders with different average particle sizes. These powders were silanized and used as inorganic filler in composite resin. Photoactivated base monomer was loaded at 65% (w/w) with these fillers to prepare the composite resin paste. The water sorption of barium glass filled resin was always more than that of quartz filled resin. The amount of sorbed water obtained by barium glass filled resin increased as the particle size decreased. The particle size of the quartz filler did not affect the water sorption. The flexural strength of barium filled resin decreased after water immersion more than that of the quartz filled resin as the particle size decreased. These results suggest that the water durability of barium glass is low and the surface of barium glass filler is damaged by water. Water would be retained in the interface between the barium glass filler and the matrix resin.View full abstractDownload PDF (1971K) -
Kenji FUJIKAWA, Akiyoshi SUGAWARA, Seidai MURAI, Minoru NISHIYAMA, Sho ...1995 Volume 14 Issue 1 Pages 45-57,103
Published: June 25, 1995
Released on J-STAGE: February 12, 2009
JOURNAL FREE ACCESSIn this study, we evaluated the osteoconductivity of calcium phosphate cement (CPC) as compared to that of a current hydroxyapatite-based material (AP) by implanting the materials in surgically formed defects in the jaws of dogs. One month post-operation, slight inflammatory reactions were observed in tissue areas adjacent to either CPC mass or AP. Three months after operation, the CPC mass-filled defects were covered with periosteum and bone tissues. The CPC mass in the defects was partially replaced by newly formed bone. In bone defects filled with AP, most of the interparticle space was filled with connective tissues including bone tissues. Six months post-operation, the CPC mass-filled defects were covered with periosteum and new bone, and most of the CPC mass was replaced by bone. Interparticle spaces of AP were filled with connective tissues and bone tissues.View full abstractDownload PDF (5185K) -
Yoshiaki TANI, Toshihiro TOGAYA1995 Volume 14 Issue 1 Pages 58-69,103
Published: June 25, 1995
Released on J-STAGE: February 12, 2009
JOURNAL FREE ACCESSEnhancement of the adhesiveness of dental restoratives, such as composite resins, has been clinically essential. A key point in enhancing adhesion is how to treat the dentin surface before bonding. We recently attempted to use an inorganic and non-acidic salt solution for pretreatment to dentin. We paid attention to the salting-in effect of rhodanides which promotes swelling of collagen and gelatin. For pretreatment, we used potassium thiocyanate (KSCN) solution. This study morphologically evaluated the effect of treatment of dentinal smear layer with rhodanides in combination with cross-linking agents such as ferric chloride. Scanning electron microscopy revealed effective removal of the smear layer on the treated dentin surface and obturation of dentinal plugs. Addition of the cross-linking agents to KSCN solution was more effective for pretreatment.View full abstractDownload PDF (12867K) -
Masao IRIE, Hiroyuki NAKAI1995 Volume 14 Issue 1 Pages 70-77,103
Published: June 25, 1995
Released on J-STAGE: February 12, 2009
JOURNAL FREE ACCESSThe purpose of this study was to characterize three base/liner materials in the initial stage of setting, i.e., dual-cured (light-activated glass ionomer), light-cured (light-activated glass ionomer analogue), and chemically-cured (conventional glass ionomer) materials. Changes in dimension, weight and flexural strength were examined from immediately after setting to the end of one week following immersion in water. The results obtained from these three types of material differed from each other, and showed a statistically significant correlation between changes in dimension and weight. This may be attributed to hygroscopic expansion. They also showed different flexural strength, indicating differences in the polymerization system. From these results, it appeared that marginal gaps following setting would be compensated for by hygroscopic expansion during immersion in water for one day or more. Physical properties would be favourably improved following the setting process which continues to advance during immersion in water.View full abstractDownload PDF (2368K) -
Hiroyuki ARIKAWA, Hiroyuki KUWAHATA, Hideo SEKI, Takahito KANIE, Koich ...1995 Volume 14 Issue 1 Pages 78-83,104
Published: June 25, 1995
Released on J-STAGE: February 12, 2009
JOURNAL FREE ACCESSThe deterioration of the mechanical properties of composite resins was examined. The bending strength and the stress relaxation rate for sixteen experimental composite resins with different filler shapes, particle sizes and filler contents immersed in distilled water for 0-60 days were measured.
The bending strength of all of the composites decreased with the increase of the immersion time in water. The composites with a high filler content (65vol%) showed a greater decreasing ratio of bending strength than those with low filler content (40vol%). The stress relaxation rate also increased with an increase of immersion time. These phenomena may be caused by the hydrolytic degradation of the silane coupling agent (γ-MPTMS).View full abstractDownload PDF (2467K) -
Kunihiro HISATSUNE, Alaa M. EL ARABY, Kenji IWANUMA, Yasuhiro TANAKA, ...1995 Volume 14 Issue 1 Pages 84-87,104
Published: June 25, 1995
Released on J-STAGE: February 12, 2009
JOURNAL FREE ACCESSDehydration in set dental stone was studied by employing specific heat measurements. Dehydration proceeds in two steps in air. In the case of bulk samples, especially those made with a lower water-powder ratio, three endothermic reaction stages are observed; a reaction of the dihydrate to the hemihydrate is apparently separated in two, one of which is not inherent. It is thought that the occurrence of a new peak is due to the difficulty for the dehydrated water to escape, depending on the porosity of the set stone.View full abstractDownload PDF (1420K)
- |<
- <
- 1
- >
- >|